Facility for Rare Isotope Beams

Understanding how the properties of matter emerge from the constituents of quantum chromodynamics (QCD) is a central goal of nuclear physics and the primary motivation behind the Electron-Ion Collider (EIC). The EIC will enable groundbreaking investigations into how quarks, anti-quarks, and gluons contribute to the nucleon's spin—an enduring question that remains unresolved despite extensive global research. With its cutting-edge capabilities, the EIC is poised to unlock critical insights into the structure and origins of matter.

The EIC builds upon the existing Relativistic Heavy Ion Collider (RHIC) facility at Brookhaven National Laboratory, leveraging its infrastructure while incorporating innovative advancements in accelerator science and technology. Key upgrades include increasing the hadron beam current threefold, integrating a state-of-the-art electron storage ring (ESR) within the RHIC tunnel, and generating and maintaining highly polarized electron bunches from the source to the storage ring. These upgrades will enable the delivery of polarized electron beams of up to 18 GeV for collisions with polarized protons and heavy ions.

To push technical boundaries and prepare for the production stage, over 10 critical R&D initiatives have been undertaken across the EIC complex. These efforts not only form the foundation for the collider’s development but also serve as training platforms, advancing expertise in accelerator science and project management while fostering innovation.

The vector – axial vector form of the electroweak interaction was established through pioneering beta-decay experiments in the 1960s and incorporated into the standard model of particle physics. However, there is no a priori reason that the other currents, scalar and tensor, could not be present. The Gamow-Teller beta decays of ⁸Li and ⁸B have extremely large Q values and the daughter nucleus in both cases, ⁸Be, is alpha unbound making these systems exemplary probes of the presence of any tensor contribution affecting the beta-neutrino angular correlation. The improvements from over a decade of high-statistics experiments on ⁸Li and ⁸B performed at Argonne National Laboratory using the Beta-decay Paul Trap (BPT) will be presented. In these measurements, the energies of the alpha and beta particles were determined using four 32x32 double-sided silicon strip detectors surrounding the BPT to precisely reconstruct the decay kinematics. The latest iteration of experiments has set the two world-leading limits on tensor currents from single beta-decay measurements. The combined BPT limits from ⁸Li and ⁸B for tensor coupling to right-handed neutrinos are comparable to a recent global evaluation of all other precision beta decay studies and are consistent with the standard model, relieving some existing tension. In addition, the high-energy neutrinos observed in solar neutrino astrophysics experiments on Earth predominately originate from ⁸B beta decay in the Sun. Results on determining the ⁸B neutrino energy spectrum, an important input for the astrophysics community, from the same data set will be discussed.

Of all the fundamental fermion masses, those of the neutrinos alone remain unmeasured. From their unknown origin to their effects on the evolution of the universe, neutrino masses are of interest across cosmology, nuclear physics, and particle physics. Neutrino oscillation experiments have set a non-zero lower limit on the mass scale, in contradiction to the original Standard Model prediction. To measure neutrino mass precisely and directly one must turn to beta decay and search for a telltale distortion in the spectrum. I will describe a new technique called Cyclotron Radiation Emission Spectroscopy (CRES), in which beta decay of tritium occurs in a magnetic field and each electron's ~1 fW of cyclotron radiation is directly detected. Electron energies are then determined via a relativistic relationship between energy and frequency. I will present the first CRES-based mass limits from the Project 8 experiment, which demonstrate the promise of this technique for surmounting the systematic and statistical barriers that currently limit the precision of direct neutrino mass measurements. I will also describe the next steps on the path to sensitivity to a mass of 40 meV/c^2, covering the entire inverted ordering of neutrino masses.

The Electron Ion Collider Project will upgrade the Brookhaven National Laboratory Relativistic Heavy Ion Collider complex to collide highly polarized (>70%) electrons and ions, from deuterons to the heaviest stable nuclei, with center-of-mass energies spanning 20 to 100 GeV at luminosities of 10³³-10³⁴ cm^-2 s^-1.  To achieve these goals a set of 4 unique superconducting radio frequency systems are required for beam acceleration, storage, and crabbing.  This seminar will briefly review the EIC as it relates to the radio-frequency systems, and then focus on the high-intensity beam interactions with the superconducting radio-frequency (SRF) systems.  Examples will include the 800 kW 2.0 K SRF cryomodules necessary for storing up to 2.5 A electron beams with ~ 10 MW of continuous power loss, 25 mrad crossing angle crab cavities, and the state-of-the-art damping required for all of the superconducting cavities.

The low energy fission in the actinide region is known to be mainly asymmetric, driven by structure effects of the nascent fragments [1]. Moreover, we know that there is a transition from asymmetric to symmetric splitting for Thorium isotopes. It was assumed that this latter split would be the main fission mode for lighter nuclei. However, unexpected asymmetric splits have been observed again in neutron- deficient exotic nuclei [2]. This observation triggered a lot of theoretical and experimental work, and further studies in this region confirmed the unexpected asymmetric fission mode [3, 4], which seems to characterize the fission of neutron-deficient nuclei in the sub-lead region.

To explore this newly identified island of asymmetric fission, a dedicated experiment was conducted at GSI, Darmstadt, Germany, using inverse kinematics at relativistic energies with the state-of-the-art R³B/SOFIA setup [5]. We present measurements of fission fragment charge distribution from 100 exotic fissioning systems, establishing a connection between the neutron-deficient sub-lead region and the well- known actinide region. These new data provide a comprehensive mapping of the asymmetric fission island, offering clear experimental evidence of the important role played by the deformed Z = 36 proton shell in the fission of sub-lead nuclei [6].

Following a detailed description of the experimental apparatus, we will discuss the fission-fragment charge yields, highlighting the significant role of Z = 36 in the light fragment in the splitting process within this region. Additionally, we will compare our findings with both microscopic and phenomenolog- ical models.

References

[1] G. Scamps and C. Simenel, Nature 564, 382-385 (2018).

[2] A. N. Andreyev et al., Phys. Rev. Lett. 105, 252502 (2010).

[3] M. Warda et al., Phys. Rev. C 86, 024601 (2012).

[4] K. Nishio et al., Phys. Lett. B 748, 89-94 (2015).

[5] A. Chatillon et al., Phys. Rev. Lett. 124, 202502 (2020).
 
[6] P. Morfouace et al., Accepted in Nature (2025).

PAN introduces participants to the fundamentals of the extremely small domain of atomic nuclei and its connection to the extremely large domain of astrophysics and cosmology.

The PAN @ Michigan State Experience

• Learn about research in one of the top rare-isotope laboratories in the world.
• Get introduced to the fascinating fields of astrophysics, precision measurement, and nuclear science.
• Perform your own nuclear physics experiments.
• Meet researchers who are exploring a wide array of questions.
• Discover the surprising array of career opportunities in science.
• Experience the atmosphere of college life.
• Participants in the 2024 program get free room and board on campus (if required).