Facility for Rare Isotope Beams

The aim of this talk is to shed light on our understanding of many-body correlations in nuclei. Since all theoretical calculations involve effective Hamiltonians and effective Hilbert spaces, it is crucial to have a handle on the role many-body correlations play in a many-body system. This means that a sound theory should provide error estimates on the importance of neglected many-body effects. To understand these and develop mathematically rigorous error estimates is mandatory if one wants to have a predictive theory. In order to achieve the above, I present several challenges to nuclear many-body theory and our understanding of the stability of nuclear matter. In particular, I will focus on our current understanding, or lack thereof, of many-body forces, and how they evolve as function of the number of particles. This is of fundamental importance if we wish to use theoretical results in analyzing properties like single-particle energies close to the dripline or the A-dependence of missing many-body correlations. We feel that the enormous progress which has taken place in the last years in nuclear theory, can really lead to a predictive and reliable approach to nuclear many-body systems. In this endavour, the close synthesis theory and experiments crucial in order to understand properly the limits of stability of matter.

Beta decay, the emission of a beta particle and neutrino, creates a low energy recoiling nucleus of order 100 eV. The process of beta decay is governed by the weak interaction, which can be described in the standard model by both vector and axial vector current interactions (V-A). Couplings outside of the V-A interaction may lead to physics beyond the standard model, and can be identified via angular correlations of the momenta of the emitted beta particle and neutrino. It is difficult to detect neutrinos, but by measuring the energy and position of the recoiling daughter nucleus the reaction kinematics and angular correlations can be reconstructed. However, precise measurement of the angle and energy of the low energy recoiling daughter nucleus is not a trivial task. Trapping ions or atoms at rest in a vacuum provides an advantageous environment to study such low energy processes. Magneto-optical traps (MOTs) use varying magnetic fields and lasers to confine atoms. Radioactive nuclides trapped in a MOT decay at rest and recoiling nuclei emerge unperturbed which allow MOTs to be used to study fundamental aspects of beta decay including beta-neutrino angular correlations. Sodium, an alkali, has a simple atomic structure which is advantageous for trapping. The group at University of California at Berkeley trapped and measured the beta-neutrino correlation coefficient (aβν) of ²¹Na [1]. The result was in disagreement with the standard model by over 3σ. Investigating sources of discrepancy, it was found that photo-assisted production of molecular sodium (Na₂), which impacts the measurement, was dependent on the number of trapped atoms in the MOT [2]. After a re-measurement, their result agrees with the standard model prediction. The precision of the measurement helped to constrain contributions to the weak interaction that may lie outside the standard model. References: 1. N.D. Scielzo, S.J. Freedman, B.K. Fujikawa, and P.A. Vetter, PRL 93, 102501 (2004). 2. P.A. Vetter, J.R. Abo-Shaeer, S.J. Freedman, and R. Maruyama, PRC 77, 035502 (2008).

Past colliding beam facilities have relied on operators and machine physicists to “tune up” their performance. During the last decade light sources have developed a “hands off automated” system to improve performance and stabilize their operation. It is based on online or machine models that use measurements to represent the linear properties of the real accelerator. These systems have been very successful and allow design and operation of facilities with far more challenging parameters. The constant appetite for more luminosity by BABAR users at PEP II forced the accelerator group to look at alternative approaches one being to establish an online model. I will review this effort with examples on successes and failures and discuss a possible evolution of online modeling for future accelerators as the Super-B project.

The combination of inclusive and exclusive electron scattering data from JLab in kinematic regimes that were not reachable before, together with the analysis and interpretation of older data from hadronic reactions at BNL is revealing the details of short-range nucleon-nucleon correlations in nuclei. The most significant result is the demonstration of the dominance of correlated np pairs over pp and nn pairs. I’ll review these results and discuss them in terms of short-range tensor - force dominance. I’ll also dicsuss the conection to the EMC effect.

Accurate electronic wavefunction calculations as well as precise spectroscopy data are necessary for extracting physics from parity nonconservation (PNC) measurements. PNC effect in atoms scales as Z³ [1] where Z is the atomic number. Francium (Z = 87) is an ideal candidate for PNC measurements due to its large nuclear charge and (relatively) simple atomic structure. However, there are no stable isotopes of francium, meaning that atomic spectroscopy data are sparse due to the challenges of producing sufficient quantities of the radioactive francium isotopes. This problem can be solved with the use of laser cooling and trapping of francium in a Magneto-Optical Trap (MOT), which collects enough atoms (~ 10³) to perform spectroscopy. Lifetime measurements of the 8s excited states in ²¹⁰Fr were performed at Stony Brook using a MOT and two photon excitations [2]. The 8s electronic level lifetime is important because the normally forbidden transition between the 7s ground state and the 8s excited state becomes allowed under the weak interaction. By measuring the characteristics of the 7s to 8s electronic transition, the parity mixing amplitudes can be deduced, along with the magnitude of the neutral weak interactions between atomic electrons and the nucleus. The 9s and 8p excited state lifetimes have also been measured [3]. Knowing these lifetimes to such good precision will allow interpretation of PNC observables in francium, which depend on theory. Preparations for an atomic PNC measurement in francium are currently underway at TRIUMF [4].

References:
1. M.A. Bouchiat and C. Bouchiat, J. Phys. 35, 899 (1974)
2. E. Gomez, L.A. Orozco, A. Perez Galvan, and G.D. Sprouse, PRA 71, 062504 (2005)
3. S. Aubin, E. Gomez, L.A. Orozco, and G.D. Sprouse, PRA 70, 042504 (2004)
4. E. Gomez, S. Aubin, G.D. Sprouse, L.A. Orozco, and D.P. DeMille, PRA 75, 033418 (2007)

This presentation will cover recent efforts in our group to understand the solid-state chemistry of actinide borates. This talk will detail the structures and properties of thorium, uranium, neptunium, and plutonium borates that display a wide array of atypical behavior including nonlinear optical properties, selective anion exchange, mixed-valency, and unusual bonding and coordination chemistry.

Evolving from detection methods and techniques developed in nuclear physics, Accelerator Mass Spectrometry (AMS) makes it possible to unambiguously identify the A and Z of a specific ion. This identification enables the separation of rare ions of interest from an isobaric background many orders of magnitude higher. The AMS technique has lead to many applications ranging from environmental science (detection of 14C and 39Ar at and below their natural level for applications such as archeology and oceanography) to nuclear astrophysics (measurement of the 40Ca()44Ti production cross section, the half-life of 60Fe or the production of 36Cl in the early solar system). The talk will concentrate on a number of ongoing experiments at the Nuclear Science Laboratory relying on the high isotopic and isobaric separation sensitivity of AMS.

Superfluid helium (He II) first discovered in the 1930s continues to provide scientists with a fascinating physical system rich with phenomena that challenge experimental and theoretical investigators. Moreover, much of the recent interest in He II has emanated from the wide range of technical applications for the fluid. The combination of anomalous heat transport, low viscosity and low temperature make He II an ideal medium for cooling superconducting magnets and particle accelerators. In turn, these applications have inspired new basic investigations of the fluid dynamic behavior of He II. The presentation will begin with an overview of some of the applications using He II cooling at the National High Magnetic Field Laboratory. With the audience sufficiently motivated, we will then turn to recent research on the transport properties of He II culminating in microscale investigations that may provide new insight into the basic physics of this unique fluid.

A few years ago, Tan and others derived a set of exact relations valid for strongly interacting non-relativistic Fermi gases in the regime of short interaction range and large scattering length. Recent developments have shown that a central quantity in these identities, the so-called "contact" C, actually plays a crucial role in the characterization of these systems, as it determines multiple thermodynamic properties as well as linear-response sum rules. However, computing the "contact" presents a challenge as it requires non-perturbative methods such as Quantum Monte Carlo. After a brief review on the general properties of these systems, I will present our first results for C as a function of temperature in the limit of infinite scattering length. If time permits, I will comment on our investigations on adapting Lattice QCD algorithms for these calculations.

Precise measurements of electromagnetic transitions in light nuclei: What we can learn, why it matters A new generation of calculations for light nuclei based on realistic two and three-nucleon interactions is being developed. The project is very much a “work in progress” and experimental tests of the predicted wave functions help refine the computational methods and better constrain modeling of important three-body interactions. However, to be useful, the data need to be both accurate and precise. I will concentrate on new measurements of electromagnetic matrix elements of the A=10 nuclei 10C, 10B and 10Be as an example of the interplay between measurement and calculation, and discuss some successes and still open challenges.

Like the quark gluon plasma created in ultra-relativistic heavy ion collisions, a dilute ultracold Fermi gas near a Feshbach resonance is a strongly correlated quantum fluid that exhibits nearly perfect fluidity. This means the ratio of shear viscosity to entropy density approaches a lower bound that is believed to follow from the uncertainty relation, and that has been made more precise using calculations based on string theory. We will review these arguments and summarize recent efforts to extract transport properties of ultra-cold Fermi gases from experiments involving elliptic flow and the damping of collective modes.

A variety of passive cooling technologies are finding increased application in superconducting magnets and space systems in recent years. Examples include thermosiphons, capillary pumped loops, and pulsating heat pipes. Paralleling their development at room temperature primarily for cooling electronics, the cryogenic versions of these passive cooling devices are being used to evenly distribute the cooling provided by cryocoolers to superconducting MRI and accelerator magnets and for dispersed heat loads on satellites and space-craft. This talk will describe efforts recently initiated at UW-Madison to characterize the behavior of pulsating heat pipes for use in satellite cooling and superconducting MRI magnets, and the design of thermosiphons to cool the superconducting undulator magnets being developed for insertion into the Advanced Photon Source ring at Argonne National Laboratory. Both the thermosiphon and the pulsating heat pipe transfer heat via two-phase flow mechanisms. Theoretical considerations of these mechanisms will be explored and the associated experimental activities will be described. Audience participation will be incorporated at various points during the presentation.

The advent of Penning traps and their subsequent application to nuclear physics have brought unprecedented precision to nuclear mass measurements. LEBIT, the only Penning trap system installed at a projectile-fragmentation facility, has played a unique role in the mass measurement field offering access to key elements that are difficult to produce at other types of rare isotope beam facilities. After summarizing the previous measurements done by the LEBIT group, we will concentrate on the current changes and upgrades taking place at the LEBIT facility including early work on a laser ablation ion source and project Minitrap, which utilizes a novel method for measuring and monitoring the magnetic field of the Penning trap system. We will discuss exciting new opportunities of the upgraded facility.

TIGRESS is an array of up to sixteen Compton suppressed High Purity Germanium detectors situated at TRIUMF National Laboratory in Vancouver, Canada. The array is designed to perform experiments at the ISAC-II radioactive beam facility which can provide ISOL beams up to the Coulomb barrier energy regime. Each detector is of the clover configuration, with four crystals in a single cryostat, each eight-fold segmented for sub-segment position resolution. SHARC is an array of highly segmented Double Sided Silicon Strip Detectors, covering almost four pi of solid angle with E-delta E telescope capabilities. The TIGRESS array provides up to one thousand signals and SHARC a further thousand, each of which is read out by a purpose-built digital data acquisition system based on FPGA technology and 100 MHz and 50 MHz digitizers. Details of the acceptance testing of the TIGRESS detectors and the construction of the array will be presented. In addition, some discussion will be given to the evolution of the FPGA firmware leading to analogue-equivalent energy and time resolution for the germanium and energy resolution for the silicon detectors. This project has culminated in a series of very recent experiments, one of which was performed to access medium-to-high spin states in nuclei approaching the Island of Inversion via deep inelastic collisions. Preliminary results from this experiment will also be presented.

Neutron stars with their high densities and extreme N/Z ratio present a unique environment for nuclear reactions. Accreting neutron stars in which a neutron star accretes material onto its surface from a conventional star are particularly interesting. The accreted material on the surface of the neutron star undergoes fusion with the resulting X-ray burst observed. Over the past decade a subset of X-ray bursters have been observed that is considerably more energetic than the conventional X-ray burster. For these super-bursters the energy release in a burst is 1000-fold larger than a conventional burster. While the energy source underlying the X-ray superburster is presently unknown, it has been hypothesized that fusion of 12C in the crust is the underlying energy source. However, the low crust temperature relative to the Coulomb barrier for 12C+12C fusion requires an additional energy source. It has been hypothesized that fusion of neutron-rich nuclei in the crust, namely oxygen and neon, provides the energy source for the superburster. To test this hypothesis we have initiated a research program to measure the fusion excitation function for neutron-rich light nuclei. Such measurements will also aid our understanding of the dynamics of nuclear fusion. I will detail the experimental approach chosen and some challenges to measuring such reactions. To execute this experimental approach we developed a sub-nanosecond fast timing system for segmented silicon detectors. A recent first attempt to measure the fusion excitation function for 12C + 20O at the GANIL SPIRAL facility will be described together with plans for intended experiments at MSU’s ReA3 accelerator.

Projectile fragmentation forms the basis for beam production at radioactive beam facilities such as the National Superconducting Cyclotron Laboratory (NSCL), yet un- certainties remain about the specifics of the production mechanism. The present experi- ment was designed to detect evaporated neutrons in coincidence with the fragmentation residues to provide new information on the excitation energy of the intermediate prefrag- ments. The experiment was conducted last year at NSCL at Michigan State University, with a secondary beam of ³²Mg ions at 86 MeV/nucleon. The beam was reacted with a beryllium target, and the fragmentation products were identified at the focal plane of the Sweeper magnet, while the coincident neutrons were detected in the Modular Neutron Array (MoNA). The MoNA system was split into two sections to increase the solid angle coverage. A series of neon isotopes, ranging in mass loss from
A = 3 - 10, were observed in this experiment by using three magnetic rigidity settings in the Sweeper magnet. Pre- liminary information on the neutrons detected in coincidence with these fragments will be presented.

This talk will discuss two experiments which seek to investigate the evolution of nuclear correlations with n/p asymmetry. First, the difference in total neutron cross section between symmetric Ca-40 and neutron-rich Ca-48 is sensitive to the asymmetry dependence of the surface imaginary potential for neutrons in a dispersive optical model (DOM) analysis. The measured cross sections imply very little dependence of this potential on asymmetry, for neutrons in these N≥Z isotopes, meaning that the strength of neutron correlations changes little as neutron number increases. The asymmetry dependence of this potential for protons leads to a modest dependence of the proton correlations (and thus spectroscopic factors) on asymmetry. This is consistent with results for neutron spectroscopic factors deduced from transfer reactions, but studies of hadron-induced knockout reactions indicate a much stronger trend – very strong correlations must be felt by the more deeply bound particles to explain the very small knockout cross sections. An attempt to address this discrepancy was made by studying single-nucleon knockout from the proton-rich nucleus Ca-36. The small cross section measured for knockout of the deeply bound neutron as compared to cross sections calculated using an eikonal reaction theory does imply a very small spectroscopic factor. However if one tries to locate the remaining spectroscopic strength in the excited states of the residue, very little can be accounted for, implying that the deduced spectroscopic factor may be too low (i.e. the calculated cross sections are too high). Recent intranuclear cascade calculations for knockout of deeply bound nucleons give much smaller cross sections than the eikonal model without requiring very strong correlations for these nucleons, highlighting the need for a better understanding of the reaction theory.

The study of the evolution of the shells far from stability provides useful information which can be linked to the shape and symmetry of the nuclear mean field. Nuclei with large neutron/proton ratio allow to probe the density dependence of the effective interaction. Changes of the nuclear density and size in nuclei with increasing N/Z ratios are expected to lead to different nuclear symmetries and excitations. Recently it has also been shown that tensor and three-body forces play an important role in breaking and creating magic numbers being a key element of the shell evolution along the nuclear chart. Nuclear structure studies far from stability, which mainly rely on the availability of radioactive nuclear beams, can complementary be addressed by means of high intensity beams of stable ions. In such contest, deep-inelastic and multi-nucleon transfer reactions are a powerful tool to populate yrast and non yrast states in neutron-rich nuclei. Particularly successful is here the combination of large acceptance spectrometers with highly segmented gamma-detector arrays. Such devices can provide the necessary channel selectivity to identify very rare signals. Examples are the CLARA and AGATA gamma-ray detector arrays coupled with the PRISMA spectrometer at the Legnaro National Laboratories (LNL) in Italy. Large data sets have been collected at LNL for nuclei close to the N= 20, 28, 40, 50 and 82 shell closures as well as in new regions of deformation as for example at A=60. An overview of the results will be presented together with the status of the AGATA-Demonstrator experimental campaign.

Over the past year, research at the Naval Postgraduate School has investigated the technical aspects of putting superconducting accelerators and the necessary associated helium cryogenic systems aboard Navy warships as part of a CRADA agreement with Raytheon. The overall objective of the work was to coalesce knowledge and develop tools to allow high fidelity trade and parameterization studies to be done in a straightforward and consistent way. This was accomplished by researching superconducting RF (SRF) cavity and cryomodule design and characterization techniques, select material properties at cryogenic temperatures, cryogenic engineering, and heat transfer in generic cryomodules. The results of the work have enabled performing preliminary evaluations of optimum operating temperatures and frequencies for shipboard accelerator systems that could be used for a Navy FEL and other missions.

The measurement of particle trajectories is of growing importance for many modern day experiments in nuclear physics. Presently growing demand for detectors that would provide information on the interaction point, the decay of unstable particles, angular distributions and momenta of the fragments, is the motivation behind the ongoing research and development effort on the Active Target Time Projection Chamber (AT-TPC) project at the NSCL. The ultimate goal of the AT-TPC project is to provide a high-resolution, high-granularity, versatile and cost-efficient tracking detector device that could measure rare processes requiring high detection efficiency and large acceptance, as well reconstruct low energy processes that are traditionally difficult to measure due to short ranges of reaction products. The AT-TPC uses counting gas as target and detector, or a solid target positioned inside the chamber. The Prototype Active Target Time Projection Chamber is a half-scale version of the AT-TPC, and is being constructed to test critical design aspects envisioned for the full-scale AT-TPC. The status of the prototype AT-TPC will be discussed, along with the most recent experimental results and experimental plans for the near future.

The talk will cover: Large-scale DFT mass table calculations, Optimization of Skyrme-like functionals, Correlation and sensitivity analysis, Natural units, Neutron droplets, DME functional with a new microscopically motivated density dependence, Symmetry unrestricted HFB within the MADNESS framework Future plans

A classical nova is a thermonuclear explosion occurring on the surface of a white-dwarf star that is accreting hydrogen-rich material from a companion star in a binary system. Our understanding of novae is based on astronomical observations and astrophysical models that incorporate the rates of certain nuclear reactions and decays. The temperature range for nova nucleosynthesis allows the relevant nuclear reactions to be measured in the laboratory at the energies of interest. Such measurements comprise an active area of experimental nuclear-astrophysics research. I will discuss general methods for determining reaction rates in novae and illustrate these methods with specific examples. The future holds the exciting prospect of comparing robust isotopic observations of nova ejecta with models of nova nucleosynthesis based on a complete set of experimentally determined thermonuclear reaction rates.

Abstract: Chaos reigns when the spectral fluctuation properties of a quantum system agree with predictions of random-matrix theory. The evidence for such agreement in nuclei is reviewed. Once established, quantum chaos is useful for the analysis of data (examples: isospin and parity violation). Chaos is a generic feature of nuclear dynamics and not in disagreement with known regular features such as the shell model or the collective models.

The determination of the electric quadrupole transition strength between the ground state and first excited state with spin-party of J=2+ (the B(E2; 0+2+) value) in an even-even nucleus provides a measurement of the low-lying quadrupole collectivity. The B(E2) values for 34,36,38,40,42Si were measured via intermediate-energy Coulomb excitation at NSCL. The secondary beams were produced by fragmentation of 48Ca primary beam and guided onto a high-Z target. De-excitation gamma rays indicating the inelastic process were detected around the target position with the high efficiency scintillator array CAESAR in coincidence with scattered projectiles tracked on an event-by-event basis in the S800 spectrograph. The results comprise the first measurements of the quadrupole collectivity of 40Si and 42Si. The measured B(E2) values are compared to large-scale shell model calculations and provide insight into the evolution of shell structure and deformation in this region. This work was supported by the National Science Foundation under grants PHY-0606007, PHY-0722822 and PHY-0758099

The interplay between the single-nucleon and the cluster degrees of freedom is a subject of modern theoretical interest. Detailed study of18O spectrum using α+14C elastic scattering revealed several highly clustered states in the continuum. Two of these states (0+ at 10 MeV [1] and 2+ at 12 MeV) appear to exceed single-particle limit. We interpret these states as “α-halo” structures. Presence of these states in 18O and indications that similar structures exist in 16O and 20Ne [2] suggest that this interesting feature is a general property of α+core interaction in this mass region. Potential model based on folding potential provides good description of the observed phenomenon. [1] E.D. Johnson, et al., Euro. Phys. J. A 42, 135 (2009). [2] D. R. Tilley, et al., Nucl. Phys. A 636, 249 (1998).

Universal predictions for few-body quantum bound states emerge in the limit that the two-body scattering length, a, is much larger than the range of the interaction, R: many different few-body observables are correlated with the value of a. For few-nucleon systems the effective field theory that implements the hierarchy of scales R |a|, and hence encodes these universal results in a systematic way, is the pionless effective field theory. In this talk I will first present a brief review of results obtained in the pionless EFT for systems up to A=4, and then apply its principles to two different problems in nuclear-structure physics. The first of these is the binding energy difference between Helium-3 and tritium. This is a fundamental nuclear-physics observable that constrains the extent of charge-symmetry breaking in the NN force. I will present a pionless EFT calculation of the model-independent correlation between this binding-energy difference and the neutron-neutron scattering length, and discuss the consequences of this result for a_{nn}. I will then turn to the one-neutron halo nucleus 11Be. This system can be examined within an EFT in which the degrees of freedom are the 10Be core and a neutron. The 11Be nucleus has a shallow 1/2+ and a shallow 1/2- state, and so an EFT involving both resonant s-wave and resonant p-wave interactions is needed to describe it. At leading order this EFT contains three parameters in the two-body sector, all of which can be fixed using 11Be structure data. I will show the resultant EFT prediction for the dissociation spectrum obtained from Coulomb excitation of the 11Be nucleus into 10Be plus a neutron, and compare to recent experiments. This facilitates an extraction of the s-wave scattering length and effective range and the p-wave scattering volume that parametrize the scattering of a neutron from a 10Be nucleus.

Over the last two decades, there have been many publications reporting experimental observations of excess heat generation and anomalous nuclear reactions occurring in metals at ultra-low energies, now known as ‘low-energy nuclear reactions’ (LENR). After a review of the key experimental observations, theoretical explanations of the LENR phenomena will be described based on the theory of Bose-Einstein condensation nuclear fusion (BECNF) in micro/nano-scale metal particles [1-3]. The BECNF theory is based on a single basic assumption capable of explaining the observed LENR phenomena; deuterons in metals undergo Bose-Einstein condensation. While the BECNF theory is able to make general qualitative predictions concerning LENR phenomena it is also a quantitative predictive physical theory. Proposed experimental tests of the basic assumption and theoretical predictions will be described. Some of the theoretical predictions have been confirmed by experiments reported recently. Although the BECNF theory indicates possibilities of scaling up heat generation under optimal conditions, experimental tests of theoretical predictions are needed for confirmation, improvement of the BECNF theory and to clarify potential practical applications. In view of the impending world energy crisis, the proposed experimental tests of the BECNF processes are urgently needed as LENR phenomena may well represent a viable long-term alternative form of clean energy. 1. Y. E. Kim, “Theory of Bose-Einstein Condensation Mechanism for Deuteron-Induced Nuclear Reactions in Micro/Nano-Scale Metal Grains and Particles”, Naturwissenschaften 96, 803 (2009) and references therein. 2. Y. E. Kim, “Bose-Einstein Condensate Theory of Deuteron Fusion in Metal”, J. Condensed Matter Nucl. Sci. 5, 14 (2010), Proceedings of Symposium on New Energy Technologies, the 239th National Meeting of American Chemical Society, San Francisco, March 21-26, 2010. 3. Y. E. Kim, “Theoretical interpretation of anomalous tritium and neutron productions during Pd/D co-deposition experiments”, Eur. Phys. J. Appl. Phys. 52, 31101 (2010).

The dependence of the characteristic X-ray radiation yield from solid target positioned in air (CaF2 crystal) on the produced microchannel depth under highly intensive (I~3•1015 W/cm2) laser pulses with different contrast was studied. The maximum of the characteristic and integral X-ray radiation yield at these experimental conditions corresponded to the microchannel depth of 30–50 μm. The efficiency of the laser radiation conversion to the characteristic X-ray radiation increased from 6•10–8 for the surface up to 10–7 in the microchannel. The angular dependence of K X-ray radiation yield from microchannel produced in CaF2 crystal positioned in the air by the sequence of laser pulses (up to 50 pulses in sequence) was firstly obtained. From this dependence one can make a conclusion that the plasma formation near the target surface inside the produced microchannel is formed and acts as the distributed source of K X-ray radiation.

For both scientific and security applications, the extraordinary sensitivity of cryogenic sensors enables high-confidence detection and high-precision measurement even of the faintest signals. Science applications are more mature, but several international security applications have been identified where cryogenic detectors have high potential payoff. International safeguards and nuclear forensics are areas needing new technology and methods to boost speed, sensitivity, precision and accuracy. Successfully applied, improved nuclear materials analysis will help constrain nuclear materials diversion pathways and contribute to treaty verification. Operating principles and applications of the major cryogenic sensor types will be reviewed with emphasis on microcalorimeters for nuclear spectroscopy. Cryogenic microcalorimeter detectors for X-ray, gamma-ray, neutron, and alpha-particle spectrometry are under development with these aims in mind. In each case the unsurpassed energy resolution of microcalorimeters reveals previously invisible spectral features of nuclear materials. For X- and gamma-rays in the 100 keV region energy resolution can be ten times better than planar high-purity germanium detectors. The technology is well-suited to analysis of materials with complex spectra presenting closely-spaced photopeaks, e.g. the nondestructive assay of nuclear materials for safeguards and fuel cycle applications. The high energy resolution is derived from operation at temperatures below 100 mK, a temperature range now accessible without liquid helium or liquid nitrogen. To increase detection efficiency we are pursuing the fabrication of large arrays of sensors. Beginning with a single pixel prototype device in 2005, we have rapidly advanced to the present operation of a 256-pixel array. This is the largest array of this type ever produced, and presents challenges in fabrication, operation, and calibration. We will discuss the operation and performance of the 256-pixel array, focusing on head-to-head comparison of isotopic determination measurements with HPGe. Similarly, the ultra-high resolution obtained from microcalorimeter detectors benefits a number of charged-particle detection applications related to nuclear forensics, nuclear safeguards, environmental monitoring of actinides, and nuclear data measurements. Our best achieved resolution for alpha-particle detection is approximately 1.1 keV FWHM at 5.3 MeV (Po-210), eight times better than a silicon surface-barrier detector. We will present measurements and detailed isotopic analysis of complex alpha spectra from mixed-actinide sources, such as spent nuclear fuel. We will also present preliminary results on electron spectrometry for beta-decay and conversion-electron measurements. Preliminary results of quantitative analysis indicate substantial improvements are still possible, but significant work will be required to fully understand the ultimate performance limits.

Gamow-Teller (GT) transitions are caused by the most common weak interaction of spin-isospin (στ) type. GT transitions are studied by the β decay and charge-exchange (CE) reactions. The β decay has a direct access to the absolute GT transition strengths B(GT), but it can only access states lower than the decay Q-value. In contrast, the CE reactions, e.g. (3He,t) or (t ,3He) reaction, at intermediate beam energies and 0o, can selectively excite GT states up to high excitation energies. In particular, in recent (3He,t) reactions, in comparison with the pioneering (p,n) reaction, one order-of-magnitude improvement in the energy resolution has been achieved. This has made it possible to make one-to-one comparisons of analogous GT transitions studied in (3He,t) reactions and β decays. Although the study of GT strength in the β decay is restricted by the decay Q-value, unstable nuclei can have the Q-value of 12 MeV or larger. This, in principle, allows the study of the central part of the GT resonance (GTR) where the GT strength is concentrated. Possibility of observing GTR structures in β-decay studies, e.g. at FRIB, will be discussed on the basis of the GTR studies by (3He,t) reactions assuming a good isospin symmetry of nuclear structure and transitions.

Reaction physics involving composite objects is an important subject since it is encountered in the context of nuclear processes like fusion, fission, particle decay, as well as many other branches of science. Quantum tunneling and scattering of a composite object are explored in our study. A few model Hamiltonians are chosen as examples where a two-particle system interacts, in one dimension, with an external potential. The study includes intrinsic Hamiltonians that do not allow the projectile to break up, and those that do. Different methods are applied with the aim of an exact solution to the relevant scattering problems. These methods are discussed in the context of the pertinent convergence issues related thereto, and of their applicability. Virtual excitations of the projectile into the classically forbidden energy-domain are found to play a dominant and non-perturbative role in shaping reaction observables, giving rise to enhanced or reduced tunneling in various situations. Cusps, resonances, and charge asymmetry are among other consequences of the intrinsic structure

Parallel momentum distributions of residues have long been used to study the mechanisms behind projectile fragmentation [1,2]. However, relatively few measurements have been made of the perpendicular component of the momentum distribution and only a basic picture is available. The widths of the perpendicular momentum distributions are predicted to be equal to the widths of the parallel distribution plus a similarly sized contribution from Coulomb deflection [3]. In order to test this prediction, both momentum distributions have been measured for nuclei produced by reactions of a 130 MeV/u ⁷⁶Ge primary beam on beryllium and gold targets at the National Superconducting Cyclotron Laboratory at Michigan State University. The results for the parallel and perpendicular momentum distribution widths as a function of fragment mass will be presented and compared to existing models of fragmentation reactions. This work was carried out with a new CsI(Na) hodoscope detector in the focal plane of the S800 spectrograph needed to completely identify heavy fragments by measuring the total kinetic energy of incoming fragments to the spectrograph [4]. This measurement is necessary to provide independent charge-state and mass number identification of heavy ions at the focal plane. The properties of the array were characterized with the above mentioned primary beam and projectile fragments. Results of these tests will also be presented.

References:
1. A. S. Goldhaber, Physics Letters 53B 4 (1974)
2. D. J. Morrissey, Phys. Rev. C 39 2 (1989)
3. K. Van Bibber, et. al. Phys. Rev. Lett. 43 840 (1979)
4. Meierbachtol, et. al. Nucl. Instrum. Meth. A, (2011) [in press]

The nuclear mean-field potentials obtained in the Hartree-Fock method with different choices of the in-medium nucleon-nucleon (NN) interaction have been used to study the equation of state (EOS) of the neutron star (NS) matter. The EOS of the uniform NS core has been calculated for the npe composition in the -equilibrium at zero temperature, using version Sly4 of the Skyrme interaction as well as two density-dependent versions of the finite-range M3Y interaction (CDM3Yn and M3Y-Pn), and versions D1S and D1N of the Gogny interaction. Although the considered effective NN interactions were proven to be quite realistic in numerous nuclear structure and/or reaction studies, they give quite different behaviors of the symmetry energy of nuclear matter at supranuclear densities that lead to the soft and stiff scenarios discussed recently in the literature. Different EOS’s of the NS core and the EOS of the NS crust given by the compressible liquid drop model have been used as input of the Tolman-Oppenheimer-Volkov equations for a gravitationally bound compact star to study how the nuclear symmetry energy affects the model prediction of different NS properties, like the cooling mechanism as well as the maximum gravitational mass, radius, and moment of inertia. As a direct test of the nuclear symmetry energy, the density dependent CDM3Yn and M3Y-Pn interactions have been used in a consistent folding model analysis of the (ΔS = 0;ΔT = 1) charge exchange (p; n) and (3He,t) reactions exciting the isobar analog states of the 48Ca, 90Zr, 120Sn and 208Pb targets in a two-channel coupling formalism. The results of this coupled-channel analysis were found to be quite sensitive to the density dependence of the nuclear symmetry energy, with a preference for the stiff scenario.

In this talk I wish to discuss how one can extract information about many-body correlations in nuclei. In order to achieve this I will present examples from several recent theoretical calculations, with an eye on their strengths and limitations. In particular I will try to focus and outline how one can extract information about nuclear correlations when one moves towards more neutron rich nuclei.

A new generation of calculations for light nuclei based on realistic two and three-nucleon interactions is being developed. The project is very much a “work in progress” and experimental tests of the predicted wave functions help refine the computational methods and better constrain modeling of important three-body interactions. However, to be useful, the data need to be both accurate and precise. I will concentrate on new measurements of electromagnetic matrix elements of the A=10 nuclei 10C, 10B and 10Be as an example of the interplay between measurement and calculation, and discuss some successes and still open challenges.

Abstract: For more than ten years, ion-beam cancer therapy has been successfully used clinically in Germany and Japan. Proton-beam therapy is performed in many more centers around the globe. Thousands of patients per year are being treated. These therapies appear to be a more favorable alternative to the conventional photon therapy. However, despite apparent experimental and clinical successes, a comprehensive theoretical description of a physical scenario is missing. One reason is that the phenomena initiated by an energetic ion incident on tissue happen on a variety scales in time, distance, and energy. I will present a multiscale approach to the radiation damage by ions aimed at studying different physical, chemical, and biological phenomena, leading to the cell death after irradiation with ion beams. I will discuss energy loss by projectiles, production and role of secondary electrons, mechanisms of DNA damage, and approaches to radiation damage assessment.

For both scientific and security applications, the extraordinary sensitivity of cryogenic sensors enables high-confidence detection and high-precision measurement even of the faintest signals. Science applications are more mature, but several international security applications have been identified where cryogenic detectors have high potential payoff. International safeguards and nuclear forensics are areas needing new technology and methods to boost speed, sensitivity, precision and accuracy. Successfully applied, improved nuclear materials analysis will help constrain nuclear materials diversion pathways and contribute to treaty verification. Operating principles and applications of the major cryogenic sensor types will be reviewed with emphasis on microcalorimeters for nuclear spectroscopy. Cryogenic microcalorimeter detectors for X-ray, gamma-ray, neutron, and alpha-particle spectrometry are under development with these aims in mind. In each case the unsurpassed energy resolution of microcalorimeters reveals previously invisible spectral features of nuclear materials. For X- and gamma-rays in the 100 keV region energy resolution can be ten times better than planar high-purity germanium detectors. The technology is well-suited to analysis of materials with complex spectra presenting closely-spaced photopeaks, e.g. the nondestructive assay of nuclear materials for safeguards and fuel cycle applications. The high energy resolution is derived from operation at temperatures below 100 mK, a temperature range now accessible without liquid helium or liquid nitrogen. To increase detection efficiency we are pursuing the fabrication of large arrays of sensors. Beginning with a single pixel prototype device in 2005, we have rapidly advanced to the present operation of a 256-pixel array. This is the largest array of this type ever produced, and presents challenges in fabrication, operation, and calibration. We will discuss the operation and performance of the 256-pixel array, focusing on head-to-head comparison of isotopic determination measurements with HPGe. Similarly, the ultra-high resolution obtained from microcalorimeter detectors benefits a number of charged-particle detection applications related to nuclear forensics, nuclear safeguards, environmental monitoring of actinides, and nuclear data measurements. Our best achieved resolution for alpha-particle detection is approximately 1.1 keV FWHM at 5.3 MeV (Po-210), eight times better than a silicon surface-barrier detector. We will present measurements and detailed isotopic analysis of complex alpha spectra from mixed-actinide sources, such as spent nuclear fuel. We will also present preliminary results on electron spectrometry for beta-decay and conversion-electron measurements. Preliminary results of quantitative analysis indicate substantial improvements are still possible, but significant work will be required to fully understand the ultimate performance limits.

The Large Hadron Collider at CERN in Geneva, Switzerland is arguably the world's most famous particle accelerator. How did it get that way? And how did efforts by CERN and other universities and laboratories to communicate the project help or hinder the LHC's rise in the public consciousness? In this seminar I'll discuss communication at the LHC from the last years of construction through the first high-energy collisions, in the process touching on lawsuits, live broadcasts, major breakdowns, long shutdowns, Hollywood blockbusters, God Particles and black holes.

An overview of the accelerator design for the Facility for Rare Isotope Beams (FRIB) at MSU will be presented. Relevant accelerator physics and technology developments for this important state-of-the-art facility will be explored.

The r-process is responsible for the formation of roughly half of the heavy chemical elements. It occurs in explosive astrophysical scenarios and proceeds via neutron capture on short-lived neutron-rich radioactive isotopes. The properties of these isotopes are critical to understanding this process but they have been essentially non-amenable to study up until now. The just completed CAlifornium Rare Ion Breeder (CARIBU) upgrade to the ATLAS superconducting linac facility is providing improved access to these isotopes. It utilizes newly developed technology to provide low-energy and re-accelerated beams of neutron-rich isotopes obtained from 252Cf fission. The fission products from a 252Cf source are stopped in a large gas catcher, thermalized and extracted through a radiofrequency quadrupole cooler, accelerated to 50 kV and mass separated in a high-resolution separator before being sent to either an ECR charge breeder for post-acceleration through the ATLAS linac or to a low-energy experimental area. This approach gives access to beams of very neutron-rich isotopes, many of which have not been available at low-energy previously, and provides unique opportunities for key studies along the r-process path. The various components of CARIBU were initially tested using a weak Cf source and the final commissioning of the whole facility with a 100 mCi source was recently completed. A brief description of the facility, insisting on the new technical developments that have made possible the rapid and efficient species-independent extraction and preparation, will be presented together with commissioning and first physics results. An overview of the planned nuclear structure and astrophysics physics programs will also be given.

Nguyen - Abstract: The triple-α reaction is studied by using hyperspherical harmonic (HH) method [1]. Starting from a three body model, we determine the 2+ state and the 0+ non-resonant continuum states for 12C. The triple-α reaction rate is calculated at low temperature (T ≤ 0.1 GK). The results are compared with [2], [3]. [1] I. Thompson and F. Nunes, Nuclear Reactions for Astrophysics (Cambridge University Press, Cambridge, UK, 2009). 2] K. Ogata et al., Prog.Theor.Phys., 122(2009)1055. 3] E. Garrido et al., EPL 90 (2010)52001. ************** Travis Baugher - Abstract: Intermediate-energy Coulomb excitation was performed on the neutron-rich isotopes 58,60,62Cr. Reduced transition probabilities to the first excited 2+ states in 60,62Cr were extracted for the first time. Preliminary results indicate increasing collectivity in the Cr isotopic chain approaching N=40. Results will be compared to large scale shell-model calculations using a recent interaction developed for this region.

The cores of massive stars collapse to protoneutron stars, forming, at core bounce, a hydrodynamic shock that initially travels outward in mass and radius, but soon stalls, needing revival by the supernova mechanism. If the latter lacks efficacy, the protoneutron star may reach its maximum mass before an explosion is launched, leading to a second stage of gravitational collapse resulting in the formation of a black hole. Under special, yet to be determined conditions, a black hole -- accretion torus system may form in such failing supernovae and act as the engine of a long gamma-ray burst. I present results from new 1.5D (spherical symmetry plus rotation) simulations that show the systematics of black hole formation with progenitor mass, metallicity, rotation, and nuclear EOS, and lead to new theoretical constraints on the birth spin of black holes. I go on to present the first 3D simulations of black hole forming core collapse events that track the evolution from the onset of collapse, through the protoneutron star phase and protoneutron star collapse to multiple tens of milliseconds after the appearance of the black hole horizon.

In order to interpret quantitatively X-ray burst observations it is essential to determine the effective life time of the long lived waiting points in the rp-process. Is this work we address the nuclear physics uncertainty in the lifetime of the 68Se rp-process waiting point that depends sensitively on the 68Se proton capture Q-value. The experiment was performed at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU) and the main goal is to identify branches of beta-delayed proton emission of 69Kr, particularly from lower energy states in 69Br that are of astrophysical interest, and to use these results to constrain the proton separation energy of 69Br.

The transverse flow of light charged particles (LCPs) and intermediate mass fragments (IMFs) has been investigated. The experimental data was collected using the NIMROD-ISiS array at the Texas A&M Cyclotron Institute. The transverse flow of protons, deuterons, tritons, He(3), alphas, and He(6) particles presented new isotopic and isobaric trends demonstrating a decreasing flow with increasing neutron richness of the LCPs, which is shown to be inversely proportional to their relative mid-rapidity yield. Current theoretical models were compared with the experimental results to investigate the sensitivity of the LCP and IMF transverse flows to the nuclear equation of state, specifically the density dependence of the symmetry energy. Additionally, recent experimental results from the fusion of radioactive Sn(132) and Te(134), produced at the Holifield Radioactive Ion Beam Facility, with Ni(58) and Ca(40), respectively, will be presented. These results will be discussed in relation to the sub-barrier fusion enhancement observed due to the coupling with neutron transfer channels.

The MiniBooNE experiment at Fermilab was constructed to look for (anti) electron neutrinos appearing in a (anti) muon neutrino beam over a short ~1km baseline. The experiment is motivated by the LSND experiment which observed a 3.8 sigma excess of events consistent with neutrino oscillations in the dm^2 = 1 eV^2 region. With a neutrino beam in MiniBooNE, an unexpected 3.0 sigma excess of signal candidates was observed at lower energies (200-475 MeV) than what would have been expected from a sterile neutrino interpretation of LSND. More recently, MiniBooNE has been running with an anti-neutrino beam for a more direct check of LSND. The statistics of the sample are somewhat limited but the results have been intriguing. An overview of the experiment with a summary of the most recent results will be given.

Knockout reactions from a beam of Ne-29 at 62 MeV/u were used to populate the neutron-unbound ground state of F-28, as well as unbound excited states in F-27. These unbound excited states decay through the emission of one or more neutrons, which were detected near zero degrees in the MoNA plastic scintillator array. The remaining charged fragments were deflected by the Sweeper dipole magnet, and their kinematic properties were measured in detectors behind the magnet. The decay energy was then calculated from the measured energies and angles of the neutrons and the fragments. In addition, coincident gamma-rays were measured at the target location using the recently commissioned CAESAR CsI(Na) array. The gamma-ray tagging was used to determine whether the neutron decayed to the ground state or an excited state of the daughter nucleus. In this talk, an overview of the experimental technique and results of the analysis will be presented.

**Joint Faculty Candidate**

The description of the quantum dynamics of many interacting particles is a great challenge in many fields of physics. Even simple observables such as the number of particles might be difficult to determine when the system encounters a violent perturbation. This is the case, for instance in collisions of molecules, atomic clusters, or nuclei. Our goal is rather simple: counting the number of transferred particles in such a collision. To keep the amount of work for the physicist and his computer to a reasonable level, mean-field approaches are considered rather than solving the full Schrödinger equation. The Balian-Veneroni variational principle provides a useful theoretical framework to build dynamical microscopic models, in particular at the mean-field level. The variational principle is solved for one particular type of observable of interest. For expectation values of one-body operators, like the average number of transfered particles, this leads to the time-dependent Hartree-Fock (TDHF) theory. For their fluctuations, however, we need to solve an equation equivalent to the time-dependent RPA. These formalisms are applied to heavy-ion collisions.

1:30-2:00 TORUS Overview (Ian Thompson, LLNL) 2:00-2:25 CDCC effects in Transfers (Filomena Nunes, NSCL) 2:25-2:40 Contributions to Capture (Goran Arbanas, ORNL) 2:40-3:00 New Reaction Theory (Akram Mukhamedzhanov, TAMU)

Spectral Distribution theory is a statistical theory and it is based on the operation of two-body random matrix ensembles and many-body quantum chaos in shell model spectroscopic spaces. Here distributions for spectroscopic observables are derived/constructed and they involve quantities that can be written in terms of traces of certain operators. The theory works as traces propagate from the defining spaces to m-particle spaces. In this talk we will discuss: (i) briefly the theory developed during 1966 to 1994; (ii) operation of two-body ensembles in shell model spaces as the basis for spectral distributions; (iii) the theory for transition strengths using the new example of neutrinoless double beta decay; and (iv) a number of open problems in the subject.

The experimental studies presented at this talk are directed to determining nuclear mass limit. This problem, as known, is related to the synthesis of heaviest nuclei with limiting charge and mass and to their probability against different modes of decay. The work carried out in Dubna was based on the synthesis of superheavy elements in fusion reactions between target nuclei of actinides with 48Са projectiles. The motivation for the given method of the synthesis and its advantage as compared to the previously used cold fusion reaction is demonstrated by measured production cross-sections of SHE. During the last 10 years, the superheavy elements with Z=112-118, N=170-177 have been synthesized. The characteristics of the set up and the modes of operation in a prolonged experiment are shown in the example of the synthesis of element 117, conducted in 2010. The decay properties of superheavy nuclei and their daughter products (a total of 48 nuclei) are compared with the prediction of macro-microscopic model. It follows that the fundamentals of modern theory concerning the existence of the island of stability of superheavy nuclei obtained experimental verification. The experiments were conducted in Dubna, with a heavy ion accelerator U-400 in collaboration with LLNL (Livermore), ORNL (Oak-Ridge), PSI (Villigen), Vanderbilt University (Nashville) and RIAR (Dimitrovgrad).

We have performed a series of experiments at Fermilab to explore the electron cloud phenomenon. The Main Injector will have its beam intensity increased four-fold in the Project X upgrade, and would be subject to instabilities from the electron cloud. We present measurements of the cloud formation in the Main Injector and experiments with materials for the mitigation of the Cloud. An experimental installation of Titanium-Nitride (TiN) coated beam pipes has been under study in the Main Injector since 2009; this material was directly compared to an adjacent stainless chamber through electron cloud measurement with Retarding Field Analyzers (RFAs). Over the long period of running we were able to observe the secondary electron yield (SEY) change and correlate it with electron fluence, establishing a conditioning history. Additionally, the installation has allowed measurement of the electron energy spectrum, comparison of instrumentation techniques, and energy-dependent behavior of the electron cloud. Finally, a new installation, developed in conjunction with Cornell and SLAC, will allow direct SEY measurement of material samples irradiated in the accelerator.

For the past 60 years electron and ion RF linacs have made major contributions to physics research and have enabled many important applications. During this time RF linacs have undergone remarkable development resulting in greater efficiency, brighter beams, and higher intensity. In this talk I will present an overview that illustrates the principles, history, and applications of RF linacs.

Abstract: We discuss a microscopic approach for studying nuclear matter and finite nuclei through the use of realistic nuclear forces derived within the framework of chiral effective field theory. Emphasis will be given to the importance of the leading-order chiral three-nucleon interactions and how their implementation in nuclear many-body calculations may be facilitated by employing alternatively density-dependent two-nucleon forces. Applications to finite nuclei include the description of the anomalously-long beta-decay lifetime of carbon-14 and the construction of microscopic nuclear energy density functionals. We then turn to a description of infinite nuclear matter which we study within the framework of Landau's theory of normal Fermi liquids.

During my talk, I will discuss the description of the low-lying spectroscopy with positive parity of a few even-even Si isotopes using a multiconfiguration method coupled to the D1S Gogny interaction. The possibility of reaching a high-accuracy N-body method is suggested provided that the nucleon-nucleon interaction in use has good properties in all residual ST channels. Moreover, statistical properties of highly excited configurations are revealed (exponential convergence), in agreement with the previous work by V.G. Zelevinsky et al. [Phys. Rep. 276, 85-176, (1996)] in the context of shell model approach. This result provides strong arguments towards an implicit treatment of highly excited configurations.

Pairing is an essential effect that has successfully lead to the interpretation of supraconductivity. The effect of pairing correlation is also required to correctly account for nuclear properties. The combination of functional theory where the energy is written as a functional of the density and the configuration mixing, provides an efficient method to describe nuclear ground and excited state properties. Recently, several studies have shown the lack of a clear underlying justification associated to the breaking and the restoration of symmetries within density functional theory. The aim of this work is to focus on alternative treatments of pairing correlations in finite many body systems that consider the breaking and the restoration of the particle number conservation. The ultimate goal being to provide a functional framework able to describe static, dynamic and thermodynamic properties. First, the energy is written as a functional of a projected quasi-particle vacuum and can be linked to the one obtained within the configuration mixing framework[1]. This approach has been applied to make the projection either before or after the application of the variational principle. It is more flexible than the usual configuration mixing method since it can handle more general effective interactions than the latter. Second, following a parallel path, a theory where the energy is written as a functional of the occupation number and natural orbitals is proposed. The new functional is benchmarked in an exactly solvable model, the pairing Hamiltonian. The efficiency and the applicability of the new theory have been tested for the various parameters of the test model[2, 3]. Références [1] G. Hupin, D. Lacroix, and M. Bender, Phys. Rev. C 84, 014309 (2011). [2] D. Lacroix and G. Hupin, Phys. Rev. B 82, 144509 (2010). [3] G. Hupin and D. Lacroix, Phys. Rev. C 83, 024317 (2011).

Nuclei in the neutron-rich A≈100 mass region are well suited for the understanding of evolution of nuclear deformation from spherical to strongly deformed ground-state shapes. By adding only a few neutrons to the N=50 shell closure, deformation and, thus, collective effects occur quickly. For the Z=40 (Zr) isotopes, the neutron number N=56 becomes an effective shell closure, so that 96Zr has characteristics of a doubly-magic nucleus. Adding only a few neutrons more, the Zr-isotopes get strongly deformed. This behaviour indicates a shape phase transition around N=60. For the Z=38 (Sr) isotopes the systematics show a similar behaviour, whereas for the Z=42 (Mo) and Z=44 (Ru) isotopes, this rapid change of the shape seems to be attenuated. The aim of this work was to investigate the behaviour of the even-even Z=36 (Kr) isotopes in this phase transition region by determining the energies of the 2+1 states and their E2 decay transition strengths to the ground state in 92Kr (N=56), 94Kr (N=58) and 96Kr (N=60). Information on the energies of the first excited 2+ states exist only for the Kr isotopes up to N=58. For N=60, contradictory results on this observable were published recently. To clarify this contradiction two experimental runs were performed at REX-ISOLDE at CERN in 2009 and 2010, utilizing the high-efficiency MINIBALL gamma-ray spectrometer and analyzing the emitted gamma-rays and scattered particles after the Coulomb-excitation reactions. The results of these experiments will be presented and discussed.

"The tensor interaction is a prominent ingredient of the nucleon-nucleon interaction and has an impact on the shell structure of both stable and unstable nuclei. However, until recent studies, it was mostly absent in self-consistent mean-field approaches. Within the context of the Skyrme energy density functional (EDF), the inclusion of the zero-range tensor force proposed by Skyrme gives rise to additional terms in the EDF, some of which only contribute when time-reversal invariance is broken (the so-called time-odd terms). In the specific case of spherical mean-field states, this brings no qualitatively new terms but merely modifies the coupling constants of terms that were already present for the central force. The latter, however, is no longer true for the study of superdeformed rotational bands. Moreover, the time-odd terms become active and strongly evolve with the rotational frequency. In a general introduction, I will discuss the tensor interaction within the context of Skyrme EDFs and give a brief review of its effect in spherical and deformed nuclei. Consequently, I will present a detailed analysis of the influence of the tensor terms in superdeformed bands, focussing in particular on the effect of time-odd terms. "

In 1956, Porter and Thomas1 proposed a theory to explain the surprising discoveries that resonance reduced neutron widths (n 0) spanned a very wide range while radiation widths () for the same resonances were nearly constant. Starting from three seemingly sound and fundamental assumptions, their theory predicted that n 0 values are distributed according to a 2 distribution with one degree of freedom ( = 1), which subsequently became known as the Porter-Thomas distribution (PTD). The theory predicted that  values also follow a 2 distribution, albeit a much narrower one with a much larger number of degrees of freedom ( ~ 100). Almost since that time, the overwhelming consensus has been that data and theory agree very well. In fact, faith in this theory is so strong that in the past ~30 years it has been extremely rare to find a paper in the literature in which new data have been used to test the theory. Instead, standard procedure has been to use the theory to correct new n 0 data for experimental deficiencies. In the intervening years, random matrix theory2 (RMT) was developed and has placed the theory on more formal footing, broadened its predictions, and provided a link to quantum chaos. As a consequence, n 0 data routinely are cited as some of the best proof of the veracity of RMT. Over the past few years, we have obtained new data at Oak Ridge and Los Alamos National Laboratories that are in stark disagreement with the PTD. I also have reanalyzed the most famous data set3,4 and found that it is seriously flawed, and does not constitute a striking confirmation of RMT as is routinely claimed. Although the reasons for these disagreements presently are not understood, the most likely explanation appears to be that the highly-excited nuclear states involved are not as statistical as assumed. Further evidence for nonstatistical effects appears in  and  data from ORELA. These results could have broad impact on basic and applied nuclear physics, from nuclear astrophysics to nuclear criticality safety. 1 C. E. Porter and R. G. Thomas, Phys. Rev. 104, 483 (1956). 2 H. A. Weidenmüller and G. E. Mitchell, Rev. Modern Phys. 81, 539 (2009). 3 R. U. Haq, A. Pandey, and O. Bohigas, Phys. Rev. Lett. 48, 1086 (1982). 4 O. Bohigas, R. U. Haq, and A. Pandey, in Nuclear Data for Science and Technology, edited by K. H. Bockhoff (D. Reidel, Dordrecht, 1983), p. 809.

Advanced heavy ion/rare isotope accelerators present very different challenges compared to traditional electron and proton machines. The Facility for Rare Isotope Beams (FRIB) project has therefore required research and development of new technologies and techniques to solve these problems in a timely and practical manner. While the low-energy section of this linear accelerator will use more traditional superconducting Quarter-Wave Resonators (QWRs), it was decided to use two different types of superconducting Half-Wave Resonators (HWRs) for the high-energy accelerating section. The HWRs have been the focus of an intensive design and optimization effort, with five of the higher beta HWRs having been recently prototyped and tested with promising results. A brief overview of the FRIB project and its use of HWRs will be presented. Additionally, the design progress, testing results, and challenges encountered will be discussed, including future prototyping and testing plans.

A large number of elements above Iron are synthesized in the s-process in which the neutron capture rate is slow compared to the beta-decay rate. In my talk I will present several astrophysical scenarios in which the the s-process takes place and discuss the role of (α,n) reactions as neutron sources for the s-process. I will highlight recent experimental results for several important reactions and introduce new experimental facilities which will be available at Notre Dame in the upcoming year.

The shape of the atomic nucleus is determined by the interplay of macroscopic and microscopic effects within this quantum mechanical many-body system. Self-conjugate nuclei give an opportunity to study the role of np correlations in deformation and have attracted a great interest due to drastic shape evolution along the N=Z line. Strong ground-state deformation is expected to occur for N=Z nuclei above Z=36 from the 2+ energy systematic as well as from theoretical predictions. Reduced transition strengths B(E2) can guide our understanding of the onset of collectivity along N=Z line. Here, we report on the first determination of B(E2; 2+ -> 0+) for the N=Z=38 nucleus 76Sr obtained from the measurement of the 2+ state lifetime using gamma rays line shape technique. 76Sr nuclei were produced at the NSCL in charge exchange reaction from fast secondary 76Rb beam. gamma-rays emitted at the reaction target position were measured with the SeGA HPGe array in coincidence with reaction residues detected in the S800 spectrometer. Results will be discussed in the light of available data and theoretical predictions to provide insight into the evolution of shell structure and collectivity in this region.

The single-particle structure of exotic nuclei evolves with the isospin. The well-stablished sequence of magic numbers appears to be modified as we move away from the line of stability. As drip-lines are approached most of the levels of interest are unbound which poses a great experimental challenge. One-nucleon transfer reactions selectively and directly probe the single-particle nature of nuclear levels. A campaign of experiments performed in GANIL with the TIARA+MUST2+VAMOS+EXOGAM set-up aimed to study the structure of light neutron-rich nuclei in the sd-fp region. The complete set-up allowed the study of transfer to bound and unbound states with full channel identification. Recent results of neutron transfer reactions induced by radioactive beams will be presented. Special emphasis will be given to the technical and theoretical challenges associated with the characterisation of unbound states, highlighting the interplay between structure and reaction mechanism in the transfer to states in the continuum. In addition, the present results pose a challenge to the interactions used to describe the evolution of nuclear structure in this region.

Gamow-Teller (GT) transition is a basic mode in nuclei, and also important for understanding roles of electron-capture (EC) and beta-decay in type-II and type-Ia supernovae. The charge exchange (p,n) reaction at intermediate energies is one of the most powerful tools to probe GT transitions, because it can selectively excite GT states in a wide excitation energy region to which beta-decay cannot access. Until recently, however, studies of the (p,n) reaction have been restricted to stable nuclei, or only to a few low-lying states in a few rare isotopes, because of difficulties in inverse-kinematics measurements with rare isotope beams. In this talk, we present a new experimental technique to measure the (p,n) reaction in inverse kinematics with a rare isotope in any mass region over a wide excitation energy region, and its first application to the 56Ni(p,n)56Cu reaction at 110 MeV/u. 56Ni is produced in large abundances during the pre-explosion phase of core-collapse supernovae and considered to be as one of the most important contributors to the change in the electron-to-baryon ratio in core-collapse supernovae. In addition, to study the GT transition in 56Ni serves as a stringent test of the effects of the N=Z=28 core not being inert on GT transitions for a large number of nearby nuclei in the Fe region. The obtained GT transition strengths are compared with shell-model calculations with KB3G and GXPF1A interactions.

Eighty years ago the neutrino was postulated by Pauli to explain the puzzling observations of nuclear beta decay. At the time many thought neutrinos would never be observed, but a quarter century later Reines and Cowan successfully detected their elusive signal. Following their discovery, a broad set of experiments were undertaken that culminated in the past decade with a remarkable transformation of our understanding of neutrino properties and the revelation that the standard model of particle interactions is incomplete. We have found that neutrinos morph from one species to another as they journey through matter and space. And based on these observations we know that neutrinos are not massless particles, but have tiny masses, being at least 250,000 times lighter than electrons. Even with such diminutive masses, neutrinos influence the largest scales of the cosmos. Today much remains unknown about neutrino properties. What do neutrinos “weigh?” — Why are their masses so light compared to other particles? Are neutrinos and anti-neutrinos indistinguishable from one another (Majorana particles), indicating lepton number violation? A number of next-generation experiments aim to address these questions, but the reticent nature of neutrinos presents daunting challenges for experimentalists. The talk will focus on how nuclear beta decay and double beta decay serve as sensitive probes of neutrino properties.

P-process refers to photodisintegration reactions producing nuclei on the neutron-deficient side of the valley of stability that cannot be reached by s- and r-processes. This process can be investigated via inversed reactions, i.e. proton or alpha capture with gamma emission. Gamma spectra resulting from capture reactions, may be complicated in structure and as such difficult to analyze. However, this difficulty may be omitted by implementing a summing technique, for which all gamma rays emitted during the decay cascade are summed into one peak, so called ”sum peak”. Thus, in ideal case, the resulting spectrum will comprise of one peak of the energy E=Ecm+Q. In order to apply this technique to radioactive beam experiments at ReA3 facility a new Summing NaI(Tl) (SuN) detector was designed at NSCL. The talk will cover details of the summing technique principle, the design and tests of the SuN detector as well as its future applications.

The effective bosonic Hamiltonian has long been used to describe the collective excitations in nuclear physics, first of all the geometric Bohr Hamiltonian and the interacting boson model. It describes lots of nuclear data with a few fitting parameters that change smoothly across the nuclear chart. On the other hand, the full microscopic theory of calculating these parameters from the shell-model Hamiltonian still does not exist, after decades of efforts. In this talk we give the microscopic theory based on the generalized density matrix. The exact equation of motion for the density matrix operators is projected onto the collective/boson/phonon subspace. By comparing coefficients of the same phonon structure, we get a set of equations, from which the generalized density matrices are solved in terms of the parameters of the collective Hamiltonian. Meanwhile, these parameters are fixed, together with the microscopic structure of the phonon/boson operator. As a first check, the above formalism is applied to the Lipkin model and the results are perfect. Then we give results for the quadrupole-plus-pairing Hamiltonian near the critical point, where the harmonic frequency by the random phase approximation vanishes and higher order anharmonicities are absolutely necessary.

Half a decade ago, RHIC experiments announced the discovery that a strongly interacting liquid is produced in high energy Au + Au collisions . Just a few years later, these same experiments advertised that this liquid behaves as a nearly perfect fluid, i.e. a fluid with null viscosity. Keyword "nearly". This begs the question. How perfect is the fluid? Can this be measured? I will present a summary of ongoing studies aimed at the determination of the viscosity of the quark gluon plasma. I will focus in particular on our recent measurement based on a novel technique involving two particle transverse momentum correlation functions. In this context, I will also discuss recent advances in the measurement and interpretation of two-particle correlation functions.

A blue photon detection system has been designed and fabricated for the BEam COoler and LAser spectroscopy (BECOLA) facility at NSCL to work over the wavelength range of 350-500 nm. The detection system is based on a design from the University of Mainz and relies on an ellipsoidal reflector to focus fluorescence from the atom/ion beam passing through the first focal point to a photomultiplier tube located at the second focal point. An aperture system will be used to reduce background caused by stray laser light. Commissioning was done with stable calcium ion beam and the signal to noise ratio for a variety of configurations was deduced. Ray trace simulations and measurement of signal and stray light characteristics will be discussed.

The astrophysical 26Si(p,)27P reaction is studied using the Coulomb dissociation technique. We performed a 27P Coulomb Dissociation experiment at GSI, Darmstadt (28 May-5 June 2007) using the ALADIN-LAND setup which allows completekinematic studies. A secondary 27P beam at 498 AMeV impinging a 515mg/cm2 Pb target. The relative energy of the outgoing system 26Si+p) is measured obtaining the resonant states of the 27P. The total cross section obtained for relative energies between 0 a 3 MeV has been measured and yields 557 mb. The resonance strength and radiative widths for the different resonant states are calculated and compare to previous measurements and theoretical predictions. Astrophysical implications about the competition of our reaction and the decay of the are also explained concluding that in stellar conditions the capture reaction dominates.

Effective field theory provides a systematic approach to interacting quantum systems at low energies and densities. Lattice effective field theory extends this approach to few- and many-body systems using non-perturbative lattice methods. I discuss recent applications of lattice effective field theory to the physics of cold atoms, neutron matter, and nuclei.

In the last two decades it has been demonstrated that light nuclei are described accurately as collections of particles interacting through the bare nucleon-nucleon potential and a weaker three-body interaction. This description produces good quantitative agreement between calculations and experiment for properties of nuclei up to mass-12 and beyond, and it offers the prospect of a predictive ab initio theory of nuclei that can be applied to new problems without additional tuning or extrapolation difficulties. Widths of nuclear levels and the "virtual widths" or asymptotic normalization constants (ANCs) of bound states have been mostly neglected in ab initio studies. These quantities can provide additional tests of the models, in many cases not yet probed by experiment, and they can provide estimates of astrophysical cross sections. I will describe recent ab initio calculations of ANCs and widths using quantum Monte Carlo methods, present the results, and discuss the applicability of related techniques to future calculations of reaction and scattering cross sections.

The Facility for Rare Isotope Beams (FRIB) is currently in the preliminary design phase at Michigan State University (MSU). FRIB consists of a driver linac for the acceleration of heavy ion beams, followed by a fragmentation target station and a ReAccelerating facility (RεA). While FRIB is expected to start commissioning in 2018, the first stage of RεA called ReA3 is already under commissioning and will be coupled to the Coupled Cyclotron Facility at the end of 2012. Once FRIB is completed RεA will continue operation as post-accelerator facility for FRIB. RεA consists of a gas stopper, an Electron Beam Ion Trap (EBIT) charge state booster, a room temperature radio frequency quadrupole (RFQ), a LINAC using superconducting quarter wave resonators, and an achromatic beam transport and distribution line to a new experimental area. An overview of the facility will be discussed. In particular, this talk will focus on the technical progress and R&D for the superconducting LINAC as well as its commissioning effort.

Abstract: I will discuss the rather frustrating effort to identify the site or sites of the r-process, that is, the astrophysical location in which many of the elements heavier than iron were synthesized. In particular, observations from old, metal poor stars indicate that an r-process operated in the early galaxy, at a frequency similar to that of core-collapse supernovae, producing yields that are highly variable when normalized to Fe. Efforts to explain such data lead one to unconventional mechanisms, one of which will be described.

In recent years it has become very clear that the neutron-proton interaction can have profound effects on nuclear structure. For neutron-rich nuclei this interaction leads to changes in the nuclear single-particle states resulting in changes in the shell closures. In recent years, the UNIRIB Consortium has put forth a concerted effort to study the evolution of nuclear structure near 78Ni in order to observe and understand these effects through the use of -decay spectroscopy. In this talk, I will begin by discussing the techniques we have developed to obtain purified beams for decay studies and present a survey of the nuclides from which the consortium has obtained data. I will then focus on the decays of copper and gallium isotopes for which the Mississippi State group took the lead role. Our results confirm the expected changes in the single-particle energies, indicate some significant and unexpected changes in nuclear structure in this region, and suggest an eventual weakening of the shell closures at 78Ni.

There have been many studies on the triple- reaction, one of the most important reaction in astrophysics. A drastic enhancement of the reaction rate compared with NACRE (>20 orders of magnitude) at low temperature was found in [1] and led to a conict with the observation of the red giant phase in the late stage of stellar evolution. Meanwhile, another work in [2] agreed well with NACRE at high temperature but found an increase of 7 orders of magnitude for the reaction rate at T = 0:01GK. Therefore, a more general method to resolve this problem is essential. In this work,the triple- reaction is studied by using the Faddeev hyper-spherical harmonic (HH) method [3]. Starting from a three body model, we derive the analytical formulas for the quadrupole strength function B(E2) as well as the reaction rate which is well known for the two particles but not for three particle system. The 2+ state and the 0+ resonance are well reproduced but we consider the contributions of the nonresonant continuum states to the reaction rate in a consistent manner. Considering only Coulomb interaction for the three  scattering problem we can obtain analytical continuum wave functions for the 0+ states. At low temperature our calculations agree very well with NACRE and there is an expected increase in the reaction rate at high temperature due to the nuclear contribution (resonant process). A full calculation with the R-matrix method in hyper-spherical coordinate space is being done to include nuclear and coulomb in equal footing. Final results and a detail physical analysis of the reaction mechanism will be presented.

Astrophysics measurements with gas targets and radioactive beams at HRIB The rapid consumption of hydrogen and helium fuel in explosive environments generates a nucleosynthesis and luminosity output very different from that occurring in solar burning. This explosive nature results in the generation of radioactive nuclei, which can be further processed by subsequent reactions. Many of these reactions and the radioactive nuclei involved have not been adequately calibrated or even studied in the laboratory. Such studies are crucial to our understanding of these explosive events. Exotic beam facilities are required to perform these critical calibrations. Radioactive beams are used to bombard hydrogen- and helium-gas targets in inverse kinematics. My talk will focus on the use of these gas targets with radioactive beams at the Holifield Radioactive Ion Beam Facility (HRIBF). I will further describe the evolution of the HRIBF gas target into the new JENSA supersonic gas-jet target for studies at HRIBF and at the ReA3 facility. The gas target, associated detectors, and first measurements will be described. This work is supported by the Office of Nuclear Physics, Department of Energy and the National Science Foundation.

The direct two-proton knockout reaction from 28Mg projectiles has been studied at 93 MeV/u. First coincidence measurements of the heavy 26Ne projectile residues and the removed protons enabled the relative cross sections from each elastic and inelastic nucleon removal mechanism to be determined, key for further validation of this direct reaction and its use for quantitative spectroscopy of some of the most neutron-rich nuclei. The measurements are compared to recent theoretical predictions that combine full sd-shell-model structure amplitudes and eikonal reaction dynamics. The kinematic correlations of the detected removed protons are clarified through the analysis of Dalitz plots.

Resonance properties of the neutron-deficient nuclides are crucial for the understanding of novae and X-ray burst explosions. Direct studies of the important (p,g) and (a,p) are difficult, but much information can be obtained from indirect approaches using both stable and radioactive ion beams. We have probed the proton-unbound states in 32Cl, important for the 31S(p,g)32Cl reaction rate in novae, using the 32S(3He,t)32Cl reaction at the Yale WNSL facility. New level energies and proton-branching ratios were determined and used for the 31S(p,g)32Cl reaction rate calculation. More reaction studies are planned by our new detector array targeting experiments with radioactive ion beams at FSU and MSU. The Array for Nuclear Astrophysics Studies with Exotic Nuclei (ANASEN) is a charged-particle detector array designed primarily for studies of reactions important in the ap- and rp- processes. It consists of 40 silicon-strip detectors backed with CsI scintillators and a position-sensitive annular gas proportional counter. In the presentation, the 32Cl experiment will be described and a very short ANASEN overview will be given.

The universe is full of symmetry and can be observed in the radial symmetry of a spiral galaxy or the bilateral symmetry of the human form. Examples of asymmetry are less common and are often investigated in order to understand the root cause of such deviations. In nuclei, many shapes have been exhibited, but nearly all have at least one axis of symmetry. Asymmetric nuclear shapes (or triaxial deformation) were predicted four decades ago, but conclusive evidence was only observed in the last 10 years. Indeed, by rotating triaxial nuclei a collective wobbling mode could be identified in the high-spin decay scheme of certain lutetium and tantalum nuclei. This wobbling is akin to the classical wobbling motion of an asymmetric top. A discussion of the physics associated with rapidly rotating nuclei will be presented in order to understand how the exotic wobbling mode was recently characterized in ¹⁶⁷Ta. Although several theories are able to accurately describe the characteristics of wobbling sequences, there is a significant disagreement between theory and the observed energy of the wobbling mode, which will also be addressed.

An Electron Beam Ion Trap (EBIT) charge breeder is being commissioned at the National Superconducting Cyclotron Laboratory (NSCL), Michigan State University (MSU). The EBIT is part of the ReA reaccelerator, which includes a room temperature radio-frequency quadrupole (RFQ) and superconducting radio-frequency linear accelerator modules to accelerate rare isotope beams up to ~3 MeV/n. The EBIT features a high-current electron gun and a hybrid superconducting 6-T magnet to obtain both high acceptance of the injected isotope beam and fast charge breeding. Ion injection calculations have been performed to optimize the injection and ion capture process. The results of these simulations will be presented along with the initial commissioning results.

While we know the heaviest nuclei in the galaxy are made via rapid neutron capture, or r-process, nucleosynthesis, exactly where (and how) the r-process occurs is still not understood. Progress toward answering these questions involves nuclear network simulations of the r-process, which require nuclear physics information for thousands of neutron-rich nuclei from the line of stability to the neutron drip line. Only very few of these pieces of nuclear data have been measured experimentally, and, even with the development of the next generation of radioactive beam facilities, we will never be able to measure all of the data we need. It is therefore imperative to determine which nuclear properties are most crucial for r-process simulations. Here we report on recent r-process sensitivity studies that examine the roles of individual pieces of nuclear data---neutron separation energies, beta decay rates, and neutron capture rates---in shaping the final r-process abundance distribution.

The Standard Model of particle physics describes interactions between fundamental particles. The model lays a framework but depends on numerous experimentally determined parameters. Combined with other measurements, the angular correlation between an electron and an anti-neutrino in neutron beta decay establishes a relationship between two such parameters, the coupling constants in the weak nuclear force. The aCORN experiment is designed to be the most precise measurement of this correlation ever attempted. It relies on a novel splitting of the decay phase in contrast to previous experiments which attempt precision recoil proton spectroscopy. The design, construction, commissioning and initial run of the aCORN instrument are described.

Contrary to popular mythology, most of what we experience in the everyday world cannot be explained without quantum mechanics. The weirdest aspects of quantum mechanics are quantum entanglement and wave-function collapse, which challenge our most basic assumptions about the nature of reality itself. Thanks to technology such as lasers, high-Q cavities, single-photon detectors, etc... we can study and harness quantum entanglement in systems both small and large. I will discuss three research areas in which collapse and/or entanglement play a crucial role: (1) quantum logic-gates based on the quantum Zeno effect, (2) bi-photon emission from an atomic vapor, and (3) optical potentials for electrons in semi-conductors based on the Pauli principle.

Stories from 45 years of covering physics breakthroughs and the scientists who made them.

Projectile fragmentation forms the basis for beam production at radioactive beam facilities such as NSCL, yet uncertainties reamin about the specifics of the production mechanism. For example, very little is known about the excitatio nenergy of the precursors of the observed final fragments. In the present work, isotopes of sodium, neon, and fluorine produced in the fragmentation of a ³²Mg beam at 86 MeV/nucleon in a beryllium target, ranging in mass loss from 3-12, were observed and the coincident neutrons were detected using MoNA. Neutron hit multiplicity in MoNA was compared to output from statistical evaporation model PACE, which was passed through a GEANT-4 simulation to account for detectors response. The neutron hit multiplicity distributions were used to determine the mass loss and excitation energy of the precursor fragments created in the fast step of the reaction. The mass loss and excitation energy were compared to abrasion/ablation models and an internuclear cascasde model, ISABEL. For sodium and neon observed fragments, a single precursor mass was found, with a wide range of high excitation energies, up to 60 MeV. Observed fluorine isotopes were also found to have high excitation energies, ranging from 40 - 80 MeV, but with some variation in precursor mass.

The Higgs boson could be the final piece of the puzzle in the Standard Model of particle physics and its discovery may be the key to understanding the origin of mass. Experiments at the Tevatron and LHC colliders are actively looking for signs of this elusive particle and their searches are rapidly evolving. This presentation will cover the newest results from Higgs searches at both the Tevatron and the LHC. I will also discuss the prospects for these searches as well as the interplay of the expanding LHC and Tevatron searches with a broad range of precision electroweak measurements.

A diagnostics system for low intensity stable and radioactive beams at low energies is under development at NSCL. It is largely based on detection techniques and instrumentation typically developed for nuclear physics. A description of the devices and the current status of the diagnostics system will be presented along with examples of the experience so far with the diagnostics’ operation at ReA3.

Semiconductor quantum dots are artificial nano-structures with electronic and optical properties very similar to those of atoms. Quantum dots can be charged with one excess electron or can be excited by a photon to add an electron-hole pair, or exciton. Optical techniques can then be used to control the quantum state of electrons and excitons in the dots. A new exciting idea consists in making “light-induced” quantum dots, which use intense lasers to trap carriers without recurring to nano-fabrication. These quantum dots can trap, guide, and manipulate individual electrons and excitons, and are reconfigurable in real-time. In this colloquium, I will discuss theoretical schemes and experimental realizations of optical control in nano-fabricated and “light-induced” quantum dots.

Superburst are day-long X-ray flares observed from neutron stars, and are produced by runaway thermonuclear burning of carbon. They are rare, but they probe the star's interior, providing information about the neutron star crust. We discuss recent multi-zone numerical models, that simulate superbursts in detail on time scales from microseconds to years, and we compare these models to the scarce observations (http://iopscience.iop.org/0004-637X/743/2/189). A superburst heats the atmosphere such that all hydrogen and helium burning becomes stable for a day to weeks. Only when the envelope cools down, does burning become unstable, and do short X-ray bursts return. We present detailed simulations of this transition of stable to unstable burning of hydrogen and helium after a superburst, and discuss the nuclear processes responsible for the different observable phenomena.

M.S. Oral Exam