Instruments in operation

Below are the technical specifications and capabilities of the instrumentation used to conduct experiments on the rare isotope beams created at FRIB. Also included (when applicable) are links to the dedicated groups for device and service-level descriptions.

The following images show the layouts of two areas inside of the laboratory:

The data acquisition system is documented here. This site includes tutorial and reference documentation.

 

Array for Nuclear Astrophysics Studies with Exotic Nuclei (ANASEN)

ANASEN is an extended active gas target and detector used to study transfer reactions in inverse kinematics with rare isotope beams.

Technical detail

ANASEN uses a 43-cm long position-sensitive proportional counter surrounding the beam axis to enable an active-target mode. Silicon-strip detectors surround the proportional counter in a barrel configuration with 3 rings of 12 rectangular Super X3 and annular QQQ3 detectors at forward angles form the cap of the barrel. All detectors in the array are backed by trapezoidal-shaped 2-cm thick CsI(TI) crystals.

Status: Operational

Location: Can be placed at various locations

Contact person: Jeff Blackmon

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Active Target Time Projection Chamber (AT-TPC)

Because rare isotopes can only be produced as beams, many reactions used to study these nuclei are performed in inverse kinematics, where the target nucleus is much lighter than the beam nucleus. Detecting and measuring the characteristics of the recoiling target residue can then become very challenging experimentally because of its kinematical properties. The AT-TPC addresses this challenge by using the concept of an active target in which a gas volume is used simultaneously as a target and detector medium. As the tracks left by the charged particles can be detected all the way to the location (or vertex) where the reaction took place, recoils with very small energies (down to a few 100 keV) can be efficiently detected. In addition, the energy of the beam gradually decreases as it traverses the gas volume, therefore the location of the reaction vertex is a direct measure of the energy at which the reaction took place, measured for each event. Finally, the luminosity of this detector is very large because its angular coverage is close to 4π solid angle, and the target thickness can be increased (from the gas pressure) without any loss of resolution. The AT-TPC is one the operating modes of SOLARIS.

Technical detail

The AT-TPC consists of a 250-liter cylindrical volume filled with a target gas (depending on the goals of the experiment) in which the charged particles emitted when a nuclear reaction takes place are traced in three dimensions. For experiments conducted with low energy beams from the ReAccelerator (ReA) 6 linac, the detector is placed inside the SOLARIS large bore solenoid that can apply a magnetic field up to 4 Tesla parallel to the beam direction. The resulting curved tracks can be analyzed to extract the energy, range, magnetic rigidity and emission angles of the recoils, from which the kinematical properties of the particles can be deduced.

The AT-TPC can also be placed elsewhere in the laboratory, such as in front of the S800 spectrograph, to conduct experiments at higher energies. In this configuration the sensor plane of the detector has a 4-cm hole in its center so that the high energy beam recoils can escape the gas volume and be collected and analyzed by the S800. As the solenoid cannot be placed in front of other devices, the detector records straight trajectories from the target recoils.

Status: Operational

Location: ReA6 vault

Contact person: Daniel Bazin

Funding acknowledgement: The AT-TPC was funded by the National Science Foundation (NSF)

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BEam COoler and LAser spectroscopy (BECOLA) endstation

The BECOLA endstation is a facility for collinear laser spectroscopy and beta-NMR experiments with low energy radioactive ion beams at FRIB.

Expanded description

The BECOLA endstation includes an offline ion source, a cooler/buncher, a collinear laser spectroscopy (CLS) system and a laser system. A surface ion source for production of alkali and alkali-earth elements, and Penning ionization gauge ion source for production of metallic and gaseous elements are available. The offline beam may also be used during online experiment for reference measurements. A typical time width (FWHM) of the beam bunch from the cooler/buncher is 1 to 3 micro-second with longitudinal energy spread of a few eV. The transverse emittance is about 2-pi mm mrad. The CLS system contains a charge exchange cell (CEC) and a photon detection system (PDS). The CEC and PDS are isolated from the ground potential and scanning voltage may be applied for Doppler tuning. The laser system consists of single-mode Ti:S and dye lasers. Light from either of lasers may be introduced into frequency doubler to generate second harmonic light. The overall wavelength tuning range is 275 to 1000 nanometer (nm).  

The BECOLA endstation accepts beams from the gas stopper through the D line. Maximum beam energy is 60 keV, and a typical beam energy is 30 keV. A bunched beam or DC beam may be transported to the CLS system through the cooler/buncher. Laser spectroscopy can be applied to ion or atom beams. The atomic beam requires the CEC and currently sodium vapor is used for charge exchange. A dedicated data-acquisition (DAQ) system is available, which is a field-programmable-gate-array-based time-resolved scaler with a 15-channel pulse pattern generator to control external devices (for example cooler/buncher).

Polarized beams are available for selected element, which is produced using optical pumping technique. A beta-NMR setup may be placed downstream of the BECOLA endstation to accept the polarized beam. The beta-NMR setup consists of a dipole magnet (Hmax = 0.5 T), sample holder and a radio-frequency (RF) coil, and an RF system with a resonant system and a 300 W amplifier. A multi-RF application is also available. A user provided experimental device may be used as well to accept polarized beams.

The BECOLA project is funded by NSF. More details of the project are posted at the BECOLA webpage.

Status: Operational

Location: Room 1361

Contact person: Kei Minamisono

Reference:

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The Beta-Nuclear Magnetic Resonance (NMR) Apparatus

The Beta-NMR station is used to measure ground-state moments of nuclei where the spin polarization is produced in fast fragmentation reactions or via laser optical pumping.

Technical detail

The NMR Apparatus consists of a small electromagnet with a 4-inch gap between pole faces. A foil is place at the center of the pole gap to catch the fast-moving radioactive beam. Surrounding the foil is a pair of plastic scintillator telescopes used to detect beta particles emitted from the captured radioactive beam. The telescopes are placed on the north- and south-pole faces of the electromagnet. Small, multi-turn copper coils placed around the implantation foil are used to introduce radio-frequency waves into the sample.

A beta-NMR spectrum is obtained by determining the ratio of the counting rates in the north and south beta detectors as a function of the incoming frequency of the radio waves. At resonance, a deviation of this north/south counting ratio is observed. The frequency of the radio waves required to reach resonance is directly related to the magnetic strength of the radioactive nucleus.

Typically, large samples are required for conventional NMR and magnetic resonance imaging experiments. However, by detecting the emitted beta particles from the radioactive sample, a sensitivity gain of over 14 orders of magnitude is realized by beta-NMR measurements over conventional NMR. Successful beta-NMR measurements have been completed with sample sizes as small as a few hundred radioactive nuclei implanted per second.

Status: Operational

Location: S2 vault, Stopped beam area

Contact person: Kei Minamisono

Funding acknowledgement: The beta-NMR station was constructed with support from NSF

Reference:

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Beta Counting System (BCS)

The central silicon implantation detector in the beta counting system is divided into 40 horizontal and 40 vertical strips, effectively providing 1,600 independent silicon pixels. Each pixel is used to detect the incoming radioactive beam, and the location and time of the event is recorded. Subsequent beta radiations that occur when the nuclear isotopes undergo decay are correlated in software with previous implantations using the stored position and time information. Beta decay properties that can be deduced using this device include half-lives, branching ratios, and decay energies.

Traditional beta-decay studies involved the collection of a bulk sample, whose overall decay was monitored as a function of time. By using a highly segmented silicon implantation detector, direct correlations can be made between individual radioactive isotopes and their emitted beta particles. When a beam particle implants into a pixel of the segmented silicon detector, information is recorded on a computer that helps identify the particle by mass and nuclear charge. In addition, the absolute time of the event is recorded. After some delay, a second event, corresponding to the beta decay of this particle, is detected in the same pixel. The energy of the beta particle and the absolute time of the event are recorded. The time difference between implant can be used to extract the beta decay half-life of the nuclear species.

BCS is optimized to measure the short half-lives expected with nuclei with extreme numbers of protons or neutrons, where the shortest half-lives encountered are a few milliseconds. The high segmentation of the implant silicon detector reduces the probability for improper software correlations, which in turn greatly reduces background. Such background reduction permits the application of the system to the measurement of half-lives for nuclei that are produced at rates of only a few per day.

BCS is typically supplemented with other detectors, for example, the MSU Segmented Germanium Array or the Neutron Emission Ratio Observer (NERO) to obtain additional information on the photons and neutrons, respectively, that may also be emitted by beta decay occurs.

Technical detail

BCS is built around a double-sided silicon strip detector with 1,600 pixels (40 strips in each of the horizontal and vertical directions). The detector has a thickness of 1 millimeter (mm), which is sufficient to induce a detector response as the emitted beta particle traverses the detector. Radioactive species produced by fast fragmentation are implanted in this detector. Implantation events are correlated with subsequent beta decays on a pixel-by-pixel basis, allowing the identification of the species observed to decay and a direct measurement of the decay time. A stack of silicon (Si) detectors and a germanium planar detector can be placed downstream of the BCS implantation detector to measure the total energy of emitted beta particles. The BCS can be used with other detector systems, such as the segmented germanium array (SeGA) or the neutron ratio emission observer (NERO), to study beta-delayed radiations. Readout of the detector signals from the BCS has recently been upgraded from more traditional analog electronics to an advanced digital signal processing system. Here a “snapshot” of each detector waveform is taken and translated by software into a usable data structure for subsequent analysis. The digital system offers a higher sensitivity for discriminating beta particles from background and does not introduce unwanted data loses encountered with analog electronics because of the latent data translation times.

Status: Operational

Location: Can be put at various locations

Contact person: Sean Liddick

Funding acknowledgement: Supported in part by NSF

Reference:

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Coincidence Fission Fragment Detector (CFFD)

The CFFD is used to measure binary decay products from the quasifission reaction and fusion-fission reactions as a means to understand the dynamics of heavy-ion fusion reactions important to the production of superheavy elements.

Technical detail

The CFFD consists of four large area (30 cm x 40 cm) position sensitive parallel plate avalanche counters (PPACs) surrounding a target.  Each PPAC consists of two 0.6 um foils with 1 mm spaced gold strips evaporated and a center foil. The PPAC provides position and time information for fragments emitted from the target.  A microchannel plate detector, mounted upstream of the target, provides a measure of the beam profile and a "time zero" signal. Two silicon detectors placed close to the target measure Rutherford scattering for beam monitoring purposes.

Status: Operational 

Location: ReA3 Hall

Contact person: Dave Morrissey

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Digital Data Acquisition System (DDAS)

DDAS is used to digitize the signals from radiation detectors. The pulsed-shape analysis permits tracking of gamma-ray interactions points, improving position resolution of segmented photon counters. The digitization of waveforms also allows for the identification of unique decay modes in charged-particle detectors.

Technical detail

DDAS was developed in collaboration with XIA, LLC. The system includes 39 Digital Gamma Finder Pixie-16 modules, 3 trigger modules, and 18 manager and worker modules. A total of 664 channels is available. Signal digitization is managed by 12-bit, 100 MHz analog-to-digital converters. Host communication is by 32-bit, 33 MHz PCI interface with 109 Mbyte/s data transfer rates.

Status: Operational

Location: Can be used in various locations

Contact personSean Liddick

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Gamma-ray energy tracking array (GRETINA)

Atomic nuclei can emit light called gamma rays when they are excited. Gamma rays have a much higher energy than can be seen with our eyes. Special equipment called a gamma-ray spectrometer allows study of these rays and peering into the internal structure of the nucleus.

FRIB has several detectors designed to "see" gamma rays. These include the sodium-iodide detector that uses sodium iodide to convert gamma rays into visible signals of light but has poor resolution, the Segmented Germanium Array (SeGA) that uses germanium to create a much clearer "picture" of where the gamma rays are traveling, and the scintillator array CAESAR (CAESium iodide ARray) that is optimized for high gamma-ray detection efficiency. The newest of these detectors is GRETINA, which will be available for FRIB first-user experiments.

Expanded description

A collaboration of scientists from Lawrence Berkeley National Laboratory, Argonne National Laboratory, MSU, Oak Ridge National Laboratory, and Washington University has designed and constructed a new type of gamma-ray detector to study the structure and properties of atomic nuclei. Construction started in June 2005 and was completed in March 2011. The detector is built from large crystals of hyper-pure germanium and will be the first detector to use the recently developed concept of gamma-ray energy tracking. GRETINA consists of 28 highly segmented coaxial germanium crystals. Each crystal is segmented into 36 electrically isolated elements and four crystals are combined in a single cryostat to form a quad-crystal module. Currently GRETINA consists of eleven detector modules with the twelfth underway. The modules are designed to fit a close-packed spherical geometry that will cover one quarter of a sphere. GRETINA is the first stage of the full Gamma-Ray Energy Tracking Array (GRETA).

GRETINA is a national resource that will move from laboratory to laboratory. GRETINA will be available for the first FRIB user experiments.

GRETINA website
GRETINA at NSCL Nuclear Instruments and Methods paper
Service-level description

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High Resolution Array Detector (HiRA)

HiRA consists of 20 telescopes. Each telescope consists of a stack of two silicon strip detectors, followed by a Cesium Iodide (CsI) detector. These detectors will each produce an electronic signal when a fragment enters the detector. By examining the electronic signals produced by a fragment that goes through the two silicon strip detectors and is stopped in the CsI-crystal, its mass, electrical charge and velocity can be determined. The silicon detectors have small strips, 0.079 inches in width, running vertically on one side of a detector and horizontally on another. This divides the area of each telescope into 1,024 square 0.079-inch by 0.079-inch pixels, allowing us to determine where the fragment hits the detector and therefore its direction of motion with high resolution.

Technical detail

The high resolution array (HiRA) is an array of 20 telescopes each of which contain a 65 micrometer (µm) thick Si-strip detector, a 1.5 mm thick silicon-strip detector and four 4 cm thick CsI(Tl) crystals. The silicon-strip detectors have an active area of 6.2 by 6.2 cm² which is divided into vertical 32 strips on the front. The 1.5 mm thick silicon-strip detector is double sided and has 32 vertical strips on the front side and 32 horizontal strips on the back, providing an angular resolution of 0.15 degrees at the nominal distance of 35 cm from the target. At this distance the 20 telescopes cover 70 percent of the solid angle between scattering angles of 5 degrees and 30 degrees. The telescopes are designed such that they can be independently placed, which allows optimizing the geometry for a specific experiment. The high resolution (about 30 keV) of the silicon-detectors will allow excellent isotopic resolution up to Z=16.

Status: Operational

Location: S3 vault

Contact person: Bill Lynch

Device webpage

Funding acknowledgement: The high resolution array (HiRA) was funded by NSF under Major Research Instrumentation grant PHY-9977707, NSCL at Michigan State University, the Indiana University Cyclotron Facility, Washington University in St. Louis, and the INFN Milano.

Reference:

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Joint Array for Nuclear Structure (JANUS)

JANUS enables a low-energy Coulomb excitation program using low-energy (~ 5 MeV/nucleon) beams of rare isotopes. Cross sections provide information on quadrupole excitation strength, and excitation of collective states beyond the first excited 2+ state in even-even nuclei broadens opportunities to study the evolution of collectivity as a function of excitation energy in exotic nuclei.

Technical detail

JANUS consists of two annular double-sided silicon strip detectors, with the front segmented in 32 sector strips, and the back in 24 annual strips. The detectors are mounted 3 cm upstream and downstream of the target, giving an angular range of 20-50-deg in both forward and backward directions.

Status: Operational

Location: ReA3 Hall

Contact person: Alexandra Gade

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Jet Experiments in Nuclear Structure and Astrophysics (JENSA)

Astrophysics. JENSA is a supersonic gas jet target capable of providing gas areal densities on par with commonly used solid targets for scattering, transfer, and capture reaction measurement of rare isotopes on light targets.

Technical detail

JENSA has attained areal densities of greater than 10^18 atoms/cm2 with helium. The continuously variable pressure allows users to set the desired  areal density.  The pumping system includes a custom-designed industrial diaphragm compressor with control panel, 13 dry pumps with a custom-built motor starter panel, and nine turbomolecular pumps.

Status: Operational

Location: ReA3 Hall, SECAR beamline

Contact personHendrik Schatz

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Liquid Hydrogen Target

The Liquid Hydrogen Target has a target cell that maintains liquid hydrogen at about 18 kelvin (K). The target cell can be operated in three standard configurations:

  1. Cell thickness of ~30 mm (~200 mg/cm2) and a diameter of 38 mm
  2. Cell thickness of ~8.5 mm (~60 mg/cm2) and a diameter of 30 mm
  3. Cell thickness of ~19.3 mm (~130 mg/cm2) and a diameter of 30 mm

Cell windows are currently made of Kapton foil of ~125 micrometer thick. Use of thinner foils or other materials will require further development. Instead of liquid hydrogen, the target system can also be used for liquid deuterium.

The available liquid hydrogen target infrastructure includes a dedicated gas handling system, cryo-cooler, and beam line interconnections. At present, the liquid hydrogen target is only available for use in experiments at the target position in front of the S800 spectrograph (in the S3 vault). Usage of the target in other vaults would require implementation of safety features and procedures.

Status: Operational

Service-level description

Location: Can be used in various locations

Contact Person: Jorge Pereira

Funding acknowledgement: The construction of the Liquid Hydrogen Target was funded by NSF through MRI grant PHY-0922615.

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Low-Energy Neutron Detector Array (LENDA)

LENDA is a low-energy neutron (0.15-10 MeV) detector array that consists of 24 scintillator bars, each with dimensions of 300 mm (height) by 45 mm (width) by 25 mm (depth). High-gain Hamamatsu-phototubes assemblies (H6410) are attached at the both ends of each bar. The scintillators are wrapped in nitrocellulose membrane filter paper, surrounded by aluminum foil and a layer of insulating tape to ensure efficient light collection. Two frames that each can hold up to 12 bars (vertically mounted) are available. The frames are designed to place the center of the bars at a distance of 1 m from the target location and the total solid angle coverage is 0.16 steradian (sr). Neutron energies can be determined via a time-of-flight measurement (an external time reference must be provided). The resolution that can be achieved is approximately 420 picosecond (ps) (corresponding to about 5 percent in neutron energy, almost independent of the energy, if the bars are placed 1 m from the target). The position along the bar can be determined through a measurement of the time difference between signals arriving at each end of the bar, with a resolution of about 6 cm. The data-acquisition system of LENDA is based on the Pixie-16 Digital Data Acquisition System, as supported by the FRIB Scientific Software Team.

People interested in using LENDA for experiments at FRIB should collaborate with the charge-exchange group led by Remco Zegers.

Status: Operational

Location: Can be placed at various locations

Contact Person: Remco Zegers

Reference: 

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Low Energy Beam and Ion Trap (LEBIT)

The LEBIT facility was the first to demonstrate that rare-isotope beams produced via projectile fragmentation could be stopped and used for high-precision mass measurements.  

High-energy, rare-isotope beams are produced by FRIB. These beams are purified using the FRIB fragment separator prior to being sent to the Gas Stopping Facility where the fast, relativistic beams are thermalized and extracted as low-energy beams, which is a necessary step for high-precision mass measurements.  

Next the rare-isotope beams are delivered to LEBIT where the beam is first cooled and bunched in a three-stage radiofrequency ion trap filled with a helium buffer gas. The rare isotopes are delivered in bunches to one of two Penning trap mass spectrometers where the mass measurements are performed. The original Penning trap mass spectrometer is housed within a 9.4T superconducting solenoid and is extremely versatile. A new Single-Ion Penning Trap (SIPT), in a separate 7T superconducting solenoid, has recently been developed to enable high-precision mass measurements using a single detected rare isotope.

Status: Operational

Location: Room 1361A

Contact PersonRyan Ringle

Device webpagegroups.nscl.msu.edu/lebit/

Funding acknowledgement: The construction of LEBIT was funded by Michigan State University.  The construction of SIPT was funded by an NSF Major Research Instrumentation (MRI) grant (PHY-1126282)

References:

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Modular Neutron Array and Large Multi-Institutional Scintillator Array (MoNA-LISA)

This pair of detector arrays consists of a total of 288 bars of plastic scintillator. Each of these bars measures 10 cm by 10 cm and 2 m wide. The bars are typically stacked to form two walls that are each 2 m wide and 1.6 m high, but due to its modularity, the array can be configured in other ways as well. The ends of each detector bar are equipped with photo-multipliers that are able to detect the faint scintillation light and amplify it with a gain of one to three million. The detection efficiency for neutrons with energies up to 100 MeV is about 70 percent. These photo-multipliers also measure when the light arrives very precisely, so the position of the light emission along the bar can be determined within a few centimeters by measuring the time difference of the signals at the left and the right end. This time difference has to be known to within 250 picoseconds.

With the precise timing information, we also can calculate the velocity of the neutrons. We place a start detector before the reaction target—where the neutron is still part of the rare isotope—and use MoNA-LISA as a time-of-flight detector. The neutrons travel a distance of about 10 m in less than 100 nanoseconds. The sweeper magnet that is placed between the target and MoNA-LISA deflects all charged particles; otherwise they would interfere with the measurement of the neutrons.

The Modular Neutron Array and Large Multi-Institutional Scintillator Array (MoNA-LISA) is an efficient detector for high-energy neutrons. It is operated by a collaboration between Augustana College, Central Michigan University, Davidson College, Gettysburg College, Hampton University, Hope College, Indiana University at South Bend, Indiana Wesleyan University, Michigan State University, Ohio Wesleyan University, St. John’s College, and Wabash College.

Technical detail

Status: Operational

Location: S2 vault

Contact person: Thomas Baumann

Device webpage

Funding acknowledgement: The Modular Neutron Array and the Large Multi-Institutional Scintillator Array were each funded by NSF through separate MRI grants to the participating institutions.

Reference:

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Modular Total Absorption Spectrometer (MTAS)

MTAS is used to determine the summed photon energies following radioactive decay and is needed to detect weak, high energy gamma rays that impact the beta decay strength and total decay heat.

Technical detail

MTAS consists of 19 NaI(Tl) hexagonal shaped detectors. Each crystal is 21 in long and about 8 in maximum diameter. The annular central module has a 2.5-in diameter through-hole and a total of twelve 1-in diameter photo-multiplier tubes collecting light from both sides. The eighteen detectors surrounding the central module have a 5-inch photo-multiplier at each end. The energy resolution of individual MTAS modules is better than 6% at 1.33 MeV. The efficiency for full-energy deposition of a single γ ray is about 71% at 4 MeV and the total efficiency is 96% at that energy.

Status: Operational 

Location: Can be used in various locations

Contact personKrzysztof Rykaczewski (ORNL)

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Neutron Emission Ratio Observer (NERO)

Because neutrons are electrically neutral, it is very difficult to detect them. NERO uses about 400 pounds of plastic to slow the neutrons down. Once they have low velocities they enter tubes filled with gas that contains helium or boron. When a neutron strikes one of these gas nuclei, a charged particle is created—either a proton or an alpha particle. The charged particles knock electrons off the gas atoms, and these electrons are collected by high voltage electrodes that generate an electrical signal. This electrical signal is processed by a computer and tells us that there was a neutron around.

Technical detail

The neutron emission ratio observer (NERO) is a low-energy neutron detector consisting of three concentric rings of helium-3 and boron trifluoride proportional counters embedded in a 60 by 60 by 80 cm³ polyethylene matrix and centered around a 22.4 cm diameter beam line opening. NERO detects neutrons ranging in energy from 1 keV to 5 MeV with an efficiency of approximately 30 to 40 percent. A rough estimate of the neutron energy distribution can be obtained from ratios of counts within the three rings. Layers of boron carbide and water can be placed around the detector to minimize neutron background.

Status: Operational

Website

Location: Can be put at various locations

Contact person: Fernando Montes

Funding acknowledgement: The neutron emission ratio observer (NERO) is funded by NSF and the Alfred P. Sloan Foundation.

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Positron Polarimeter

The Positron Polarimeter will be used to measure the longitudinal polarization of beta particles emitted by highly-polarized Na-21 and Mg-23 nuclei to search for deviations from maximal parity violation. The system will also serve to perform relative asymmetry measurements from mirror-transitions to determine the Gamow-Teller-to-Fermi mixing ratio, which is a crucial property for the extraction of the semi-leptonic weak strength.

Technical detail

The Positron Polarimeter consists of a pair of identical superconducting solenoids, with each solenoid capable of producing a maximum field of 2 T. The solenoid will have a warm bore, with an inner diameter of 22 cm to accommodate detector arrays. The polarimeter will be installed downstream of the BECOLA facility.

Status: Operational

Location: ReA3 Hall

Contact person: Oscar Naviliat-Cuncic

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The Proton Detector and Gaseous Detector with Germanium Tagging (GADGET) system

The Proton Detector is a cylindrical gas volume designed to detect weak, low-energy, beta-delayed protons and alpha particles. The gas phase reduces the energy deposition of beta particles in the active volume, which suppresses background at low energies in comparison to solid-state silicon. A rotatable beam-energy degrader is used to slow down a fast rare-isotope beam such that it enters through a window in the upstream end cap and stops in the middle of the gas volume where it decays. A uniform electric field in the gas drifts ionization electrons from particle emission toward the downstream end, where the end cap is a micro-pattern gaseous detector that amplifies the signal. In its current Phase I iteration, the Proton Detector operates in a calorimetric mode with 13 pick-up pads. Phase II will be completed in 2020 with 1,024 pads enabling it to operate as a time-projection chamber that can distinguish multi-particle emission events. The Proton Detector is typically surrounded by the Segmented Germanium Array (SeGA) in its barrel configuration for simultaneous detection of gamma rays. In Phase I, signals from both detectors are processed using XIA digital electronics. Phase II will employ high-density GET electronics. The complete assembly is GADGET.

Technical detail

Status: Phase I operational; Phase II under development

Location: S2 vault

Contact person: Chris Wrede

Funding acknowledgement: The Proton Detector and GADGET system were constructed with support from NSF and the U.S. Department of Energy.

Reference:

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ReAccelerator Facility

ReA is a worldwide unique, state-of-the-art accelerator for rare isotope beams. Beams of rare isotopes are produced and separated in-flight at FRIB and subsequently stopped in one of the linear gas stoppers in the N4 vault. The rare isotopes are then continuously extracted as 1+ (or in a few cases as 2+) ions or molecular ions and transported through the cooler/buncher to the ReA charge breeder. In the Electron Beam Ion Trap (EBIT) charge breeder, the 1+ beam is captured in the ion trap, ionized to a charge consistent with the operation range of the superconducting radio-frequency (SRF) linear accelerator (linac), extracted in a pulsed mode, mass analyzed and injected into the linear accelerator for to energies ranging from 300 keV/u to 6 MeV/u (ReA3) and up to 12 MeV/u (ReA6) for mass-to-charge ratios A/Q=2.

Alternatively, stable ions can be injected into the linac from the EBIT in off-line mode (by ionization of residual gas without injection from N4) or by the off-line injector source (Colutron source).

For stand-alone operation of ReA a batch-mode ion source located in N4 will provide stable and long-lived isotopes for reacceleration. .

Status: Operational

Location: ReA3 Highbay

Contact Person: Antonio Villari

Service-level description

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S800 Spectrograph

The S800 Spectrograph is equipped with sensitive detectors that measure the positions and angles of particles deflected by the magnetic fields. Sophisticated software is then used to deduce the characteristics of the particles before and after the reaction. Various types of experiments are performed using this technique, sometimes in combination with other types of detectors located around the target to get a more complete picture of each reaction. For example, strange modes of vibration of nuclei can be studied, as well as exchange of nucleons (protons or neutrons) during the split moment of a nuclear reaction between an accelerated nucleus and a target nucleus.

Technical detail

The S800 Spectrograph combines both high resolution and high acceptance in a single device and is specially designed for reaction studies with radioactive beams. Its large acceptances both in solid angle (20 millisteradians) and momentum (5 percent) are well adapted to the large emittances of secondary beams produced by projectile fragmentation. The high resolution is achieved via an analytical reconstruction method in which aberrations are calculated a priori from the magnetic field maps and used directly to correct the raw data. The spectrograph is installed vertically on a carriage that can rotate from 0 to 60 degrees. Its maximum rigidity is limited to 4 Teslameter (Tm). The S800 is preceded by an analysis line that allows for different optical modes of operations, either focusing or dispersion matched. The maximum rigidity of the analysis line is limited to 4.9 Tm.

Status: Operational

Location: S3 vault

Contact person: Jorge Pereira

Device webpage

Service-level description

S800 map server

Funding acknowledgement: The S800 construction was initiated under the NSCL Phase II construction project (NSF PHY-8215585) and completed under the NSCL Cooperative Operative Agreement (NSF PHY-9214992).

References:

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Separator for Capture Reactions (SECAR)

SECAR will separate the small flux of reaction products from the intense flux of unreacted beam particles to permit the measurement of reaction rates on proton-rich unstable nuclei in the astrophysical rapid proton capture process.

SECAR is a separator system composed of a charge state selector, velocity filter, and bending section. Slits are placed at critical points along the beam line to physically reject beam. Detector systems will be placed both at the target position (for gamma rays) and focal plane (for recoils). The device will have an angular acceptance of +/- 25 mrad, an energy acceptance of +/1 3.1%, and a maximum rigidity of 0.8 Tm.

Status: Commissioning in progress

Location: ReA3 Hall

Contact personHendrik Schatz

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Segmented germanium array (SeGA) and CAESium iodide ARray (CAESAR)

Technical detail on SeGA

SeGA allows high-resolution in-beam gamma-ray (γ-ray) spectroscopy of intermediate-energy beams from FRIB. Each of the eighteen detectors in the array is a single-crystal 75-percent relative-efficiency germanium counter with the outer surface electronically divided into 32 segments. By using the segment information, the interaction of the γ-ray can be localized within the detector, therefore reducing the uncertainty in the Doppler correction due to the finite opening angle of the detector. A detector frame is available and allows the detectors to be placed at several distances, so the experimentalist can decide on the compromise between efficiency and resolution for their particular needs. The standard configuration is 18 detectors at 20 cm, which gives an approximate 3-percent photo peak efficiency at 1.3 MeV with about 2-percent in-beam energy resolution. The detectors are also available for stopped beam experiments such as β-delayed γ-ray decay studies.

Status: Operational

Location: Can be used in various locations

Contact person: Dirk Weisshaar

Service-level description

Funding acknowledgement: NSF through MRI grant PHY-9724299 supported the acquisition of the SeGA array.

Reference:


Technical detail on CAESAR

The scintillator array CAESAR (CAESium iodide ARray) is optimized for high gamma-ray detection efficiency. It consists of 192 CsI(Na) scintillation crystals of two geometries: 2 inches x 2 inches x 4 inches (144 pieces) and 3 inches by 3 inches by 3 inches (48 pcs). The intrinsic energy resolution of the detectors is better than 8-percent full-width-at-half-max (FWHM) at 662 keV. The rectangular crystal shapes allow for a close-packed geometry around the target, yielding high solid angle coverage. A frame is currently being constructed for in-beam spectroscopy experiments in conjunction with the S800 spectrograph. The array will provide a full energy peak efficiency of 40 percent at 1 MeV. The intrinsic energy resolution of the detector units and the geometry of the array will result in an in-beam energy resolution of 10 percent (FWHM) at 1 MeV. The array was commissioned in May 2009.

Status: Operational

Location: S3 vault

Contact persons: Alexandra Gade and Dirk Weisshaar

Funding acknowledgement: NSF through MRI grant PHY-0722822.

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Silicon Array + SOLARIS

The Silicon Array would be placed inside a Solenoid Spectrometer and used to detect the time of flight, position, and energy of light particle emitted from charged-particle transfer reactions in inverse kinematics.

Technical detail

The Si Array will be similar to that used for the HELIOS spectrometer. An upstream array of rectangular silicon wafers would be arranged in a hexagonal geometry around the beam axis, with 12 modules covering ~60 cm in length. A downstream array of would be composed of rectangular silicon wafers in two sections. The most downstream section would be 30 cm long and have a decagonal arrangement around the beam axis. The other downstream section would also be 30 cm long, with a hexagonal arrangement of silicon. ANL has procured a magnet that can be used for this purpose.

Status: Under development

Location: ReA6 Hall

Contact person: Ben Kay (ANL)

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Single-Ion Penning Trap (SIPT)

SIPT is a Penning trap that will use image charge detection for ultra-high sensitivity mass measurements of short-lived rare isotopes with very low production rates.

Technical detail

SIPT is based on a 7 T superconducting magnet that will use  Fourier Transform Ion Cyclotron Resonance detection to enable mass measurements on a single ion.

Status: Under development

Location: Low Energy Area

Contact person: Ryan Ringle

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Single Event Effects (SEE) Test Facility 

The SEE Test Facility is a portable in-air irradiation station with complete diagnostic equipment and controls. While it has been tailored to measure the response of electronic components to energetic heavy ions available at FRIB (to simulate the environment in space), it can be adapted for doing other in-air irradiation measurements. At the conclusion of an experiment, the experimenters will have all the information they need on operation conditions (beam energy, current, spot size, etc.) in an easily interpreted form.

The maximum beam energies achievable with SEE are set by the requirement that beams must be degraded by approximately 15 percent in energy to get adequate spatial uniformity. A limit on the minimum beam energies is the requirement that beam from the A1900 fragment separator (located upstream of SEE) must have a rigidity of at least 1.5 Tm; beams at the SEE target position with energies lower than this limit are possible by using degraders in the SEE setup, but come at the expense of a lower beam purity and a wider energy distribution.

Status: Operational

Location: Can be installed at different beam lines

Contact Person: Thomas Baumann

Reference: 

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SOLARIS

SOLARIS is a dual-mode charged-particle solenoidal spectrometer. The design is optimized for the study of a broad range of direct reactions, such a nucleon transfer and inelastic scattering, at incident beam energies around the Coulomb barrier. It builds on two technologies developed in anticipation of FRIB, with a focus on achieving good Q-value resolution and efficiency. In one mode of operation, SOLARIS will support an on-axis Si array, like the HELIOS spectrometer at Argonne National Laboratory, primarily for reaction measurements with beam intensities greater than 104 particles per second. In the other mode, the  Active Target Time Projection Chamber (AT-TPC) will occupy the bore of the solenoid.

Technical detail

SOLARIS uses a large-bore, 92-cm diameter, superconducting solenoid that can apply a magnetic field up to 4 T parallel to the beam direction. The field strength and geometry of the spectrometer make it a highly versatile device, able to exploit the full dynamic range of ReA in terms of beam intensities, from hundreds of particles per second to stable beam intensities, beam species from hydrogen to uranium, and all beam energies available from ReA.

Status: The AT-TPC mode of SOLARIS will be operational upon completion of ReA6 and the Si-array mode is under development. A whitepaper on SOLARIS can be found here.

Location: ReA6 vault

Contact person: Ben Kay and Daniel Bazin (local contact)

Funding acknowledgement: SOLARIS is a dual-mode spectrometer. The AT-TPC component was funded by NSF. The solenoid and Si-array mode of operation was funded by the U.S. Department of Energy.

Sweeper magnet

The sweeper magnet separates the neutrons and the charged remnants of a reaction so that they can be detected in the charged particle detectors and neutron detector array. The magnet generates a strong magnetic field using superconducting coils. As neutral particles, the neutrons are not affected by the magnetic field and fly straight through the magnetic field. However, the charged remnants are “swept” away in a different direction towards the charged particle detection system. The sweeper thus acts as an auxiliary device that serves the actual detectors.

The sweeper magnet weighs about 35,000 pounds and generates a magnetic field of up to 40,000 Gauss which is about 400 times stronger than a typical refrigerator magnet. The superconducting wire is held at a temperature of –452 °F and carries a current of up to 375 Amperes.

The magnet is placed immediately behind a target where the exotic neutron-rich nuclei react and break up into a charged nuclear fragment and one, two or more neutrons. The charged fragments typically have velocities of about 40 percent of the speed of light, or 55 million miles per hour. The magnetic field is strong enough to bend these particles by 40 degrees over a distance of only 1 m.

The sweeper-charged particle-detection system can determine all the detailed properties of the fragments following the breakup—the charge, mass, angle, velocity, momentum, and energy. By combining this information with the corresponding information about the neutrons, it is possible to reconstruct the properties of the original neutron-rich exotic nucleus.

Technical detail

The sweeper magnet was built at the National High Magnetic Field Laboratory (NHMFL) at Florida State University. It is a superconducting dipole magnet with a maximum field of 4 T. The bend radius is 1 m with a bend angle of 400. It has a vertical gap of 14 cm which allows for neutron coincidence experiments (with the neutron walls or MoNA) covering about 7 degrees. The total weight of the magnet is approximately 35,000 pounds.

Status: Currently not operational; the sweeper magnet will be set up in the S2 vault with the reconfiguration for FRIB.

Location: S2 vault

Contact person: Thomas Baumann

Service-level description

Funding acknowledgement: The construction of the sweeper magnet was funded by NSF through MRI grant PHY-9871462.

References:

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Summing NaI detector (SuN)

SuN is a γ-Total Absorption Spectrometer. It is a cylindrical shape NaI(Tl) detector, 16-inch in diameter and 16-inch in height. It is segmented in eight optically separated segments, which are positioned above and below the beam axis as shown in the figures. Each segment is being read by three photomultiplier tubes (PMT) resulting in a total of 24 signals coming out of the detector. The signals from the PMTs are gain-matched using potentiometers located on the PMTs themselves as well as by appropriate high-voltage adjustment. The signals are then fed into the Digital Data Acquisition System (DDAS).

Technical details

The efficiency of SuN for a cesium-137 source (Eγ = 661 keV) is 85 percent. For the summing of the two sequential γ-rays from the decay of Co-60 the sum-peak efficiency is 65 percent. The summing efficiency of SuN highly depends on the multiplicity of the γ-cascade being detected; the higher the multiplicity the lower the efficiency. The hit-pattern from the eight segments of SuN can be used to estimate the average multiplicity of a given sum peak. SuN has been simulated in Geometry And Tracking (GEANT4) and for a given γ-decay scheme the detection efficiency can be estimated using this simulation tool.

Status: Operational

Location: ReA3 experimental hall

Contact Person: Artemis Spyrou

Website

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superORRUBA

SuperORRUBA is used to study single-nucleon transfer reactions in inverse kinematics at exotic beam facilities. The detector has good intrinsic energy resolution and large solid-angle coverage that are appropriate for detecting the light ejectiles from extremely inverse reactions at ~5 MeV/nucleon.

Technical detail

SuperORRUBA consists of two rings of silicon detectors designed to operate with one ring forward of 90° in the laboratory and the second backward of 90°. The silicon detectors are based on double-sided non-resistive silicon strip technology. The detectors cover an area, 7.5 cm by 4 cm, with the front sides divided into 64 1.2 mm by 4 cm strips, and the back sides segmented into 4 7.5 cm by 1 cm strips. The 1.2-mm strips are oriented perpendicular to the beam direction, while the 1-cm strips were parallel. The angular resolution in polar angle is less than 1-deg. The azimuthal angular resolution is less important, and thus larger strip pitches are used on the backside.

Status: Operational

Location: Can be used in various locations

Contact personSteven Pain (ORNL)

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superCHICO

SuperCHICO is a four-pi heavy-ion detector designed to exploit gamma-ray tracking arrays to study quasi-binary reactions, such as Coulomb excitation, single and multi-nucleon transfer reactions, deep inelastic reactions, and fission, at both stable and exotic beam facilities.

Technical detail

SuperCHICO is mostly used in conjunction with large gamma-ray arrays. It covers scattering angle ranges of 12° to 85° (front part) and 95° to 168° (back part). The detector has an azimuthal angle total of 280° of 360°, with position resolution of ~ 1-deg in theta and 9.3-deg in phi. It covers a solid angle of 69% of four-pi. The time resolution of the detectors is ~500 ps, with a mass resolution ~ 5%, and Q-value resolution of less than 20 MeV.

Status: Operational

Location: Can be used in various locations

Contact person: Ching-Yen Wu (LLNL)

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TRIple PLunger for EXotic beams (TRIPLEX)

The TRIPLEX plunger device allows precision level lifetime measurements of exotic nuclei. A new feature of the TRIPLEX is that it has two degraders at different distances to the target, which enables advanced techniques, such as the measurements of two different lifetimes in a single setup. The device holds three thin foils and is able to separate the foils by very precise distances. A nuclear excited state is produced in the first foil (the target) and decays in flight while traveling a distance that is related to its lifetime. If the decay occurs after the nucleus passes through the second or third foil (the degrader), the nucleus will be traveling significantly slower. The gamma rays emitted during the decay are detected by the segmented germanium array. The energies of the gamma rays are Doppler-shifted according to the velocity of the nuclei and the lifetime can be obtained from measurements with different target-degrader distances.

A target (or degrader) of dimension 50 mm by 50 mm can be mounted in the plunger, and the foil separation is controllable between 0 to 30 mm with a precision of 1 micrometer. The standard application allows lifetime measurements in the range from 1 ps to several hundred ps.

Status: Operational

Location: S3 vault

Contact Person: Hiro Iwasaki

Funding acknowledgement: The TRIPLEX plunger was constructed with support from NSF.

Reference:

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Versatile Array of Neutron Detectors at Low Energy (VANDLE)

VANDLE is used to measure delayed neutrons following beta decay, and has also been coupled with MoNA and LISA to detect neutrons following breakup, and with LENDA to detect neutrons emitted in certain charge exchange reactions.

Technical detail

VANDLE consists of 48 plastic scintillators with energy resolution of 120 keV for 1-MeV neutrons and an energy threshold of 100 keV. The plastic scintillators can be arranged in different geometries, based on experimental need.

Status: Operational

Location: Can be used in various locations

Contact person: Robert Grzywacz (UTK)

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53-inch reaction chamber

The 53-inch chamber has been used in conjunction with neutron detectors to study proton/neutron emission ratios from intermediate-energy reactions.

Technical detail

The 53-inch chamber is a vacuum vessel in the shape of a vertical cylinder with an inner diameter of 135.9 cm. The detector mounting platform is approx. 53 cm below the beam axis. The target mechanism incorporates an airlock for using chemically reactive targets, such as metallic calcium. The positioning of the targets is manual with a range of three 1.90 cm. high frames.

Status: In storage

Location: S3 Vault

Contact person: Dave Sanderson

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3HeN

3HeN is used to measure delayed neutron following radioactive decay that are important for nuclear structure, the rapid neutron capture process, and decay heat calculations for reactor design and fuel safety.

Technical detail

The 3HeN neutron consists of 16 1-in and 58 2-in diameter tubes filled with He-3 at 10 atm pressure. The tubes are arranged in four rings inside an axially symmetric 2-foot long cylinder, made out of a High Density Polyethylene (HDPE) moderator. The neutron detection efficiency is ~80% between 0.01 and 2.0 MeV.

Status: Operational

Location: Can be used in various locations

Contact person: Krzysztof Rykaczewski (ORNL)

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