Bulletin of the American Physical Society
APS April Meeting 2018
Volume 63, Number 4
Saturday–Tuesday, April 14–17, 2018; Columbus, Ohio
Session H11: Mini-Symposium on FRIB and ReA Instrumentation IIMini-Symposium
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Sponsoring Units: DNP Chair: Steven Pain, Oak Ridge National Lab Room: A220-221 |
Sunday, April 15, 2018 10:45AM - 10:57AM |
H11.00001: The Active Target Time Projection Chamber (AT-TPC) Daniel Bazin, Tan Ahn, Yassid Ayyad, Saul Beceiro-Novo, Lisa Carpenter, Marco Cortesi, Michelle Kuchera, William Lynch, Wolfgang Mittig, Jaspreet Randhawa, Clémentine Santamaria, Nathan Watwood, John Yurkon The AT-TPC was recently built and commissioned at the National Superconducting Cyclotron Laboratory at Michigan State University. This gas-filled detector uses an active-target design where the gas acts as both the tracking medium and the reaction target. This new type of instrument can be used with low-intensity radioactive beams in various energy regimes, from around the Coulomb barrier to a few hundreds of MeV/u. In contrast with the traditional passive target approach, the main asset of the active-target methodology is its enhanced luminosity and full kinematic acceptance combined with very good energy and angular resolutions. An overview of its present implementation and use with ReA3 re-accelerated radioactive beams will be presented, as well as the particular methods and tools used to analyze its data. A simulation of the detector's performance and results from its commissioning with a radioactive 46Ar beam will also be presented. This work is supported by the National Science Foundation under grants MRI-0923087 and PHY-1404442. [Preview Abstract] |
Sunday, April 15, 2018 10:57AM - 11:09AM |
H11.00002: SECAR: The Separator for Capture Reactions in Astrophysics Sara Ayoub, Aalayah Spencer, Fernando Montes Proton- and alpha-capture reactions on unstable proton-rich nuclei power astrophysical explosions like novae and X-ray bursts. Studying these processes is crucial to understanding the mechanisms behind those explosions and the nucleosynthesis at those sites. The Separator for Capture Reactions (SECAR) is a new recoil separator currently under construction at the National Superconducting Cyclotron Laboratory (NSCL) and the Facility for Rare Isotope Beams (FRIB) that will allow us to directly measure the astrophysical reaction rates of interest. It is designed to enable measurements with reaccelerated beams in the A$=$15-65 mass range over a broad range of astrophysical energies. Several of the magnets and other components are now installed at Michigan State University. The presentation will introduce the SECAR concept, its scientific goals, and provide an update of the current status of the project. SECAR is supported by the Department of Energy Office of Science Office of Nuclear Physics and the National Science Foundation. [Preview Abstract] |
Sunday, April 15, 2018 11:09AM - 11:21AM |
H11.00003: SOLARIS -- A Dual-Mode Spectrometer for Charged-Particle Spectroscopy at ReA Benjamin Kay The reaccelerated (ReA) beam capabilities at the National Superconducting Cyclotron Laboratory (NSCL), and in due course the Facility for Rare Isotope Beams, allow for the study of a wide range of transfer and inelastic-scattering reactions at ideal incident beam energies of a few MeV per nucleon above the Coulomb barrier. To take advantage of this capability, a dual-mode solenoidal spectrometer has been designed. In one mode, the spectrometer will operate in a manner similar to the HELIOS spectrometer at Argonne National Laboratory, with an on-axis Si array, primarily for studies with beam intensities greater than 10,000 particles per second. In the other mode, it will operate with the NSCL Active Target Time Projection Chamber inside the bore of the solenoid, taking advantage of the up to 4-T field. In this mode, reactions with beams as weak as a few hundred particles per second are possible. An overview of the instrument, planned implementation on the ReA6 beamline, and physics opportunities will be presented, with particular focus on the design of the Si-array mode of operation. [Preview Abstract] |
Sunday, April 15, 2018 11:21AM - 11:33AM |
H11.00004: A Radio-Frequency Kicker for the study of exotic nuclei Andrew Rogers, D. Bazin, P.N. Ostroumov, A. Plastun, L.G. Sobotka Exploring nuclei at the limits of stability and beyond strongly impacts our understanding of nuclear astrophysics, weak-interaction physics, and nuclear structure. Facilities based on projectile fragmentation rely on multiple stages of filtering in order to transport and selectively deliver these rare isotopes with the required purity to the experiment for study. However, for beams of neutron-deficient nuclei, it is often not possible to sufficiently filter certain fragmentation products using only magnetic and energy-loss techniques. Measurements using an existing Radio Frequency Fragment Separator (RFFS) at NSCL highlight the necessity of such a device to successfully pursue science at the proton drip line. In particular, a recent RFFS experiment was performed to investigate the 72Kr rp-process waiting point by measuring beta-delayed protons from the 73Rb nuclear sandbar. Without the additional purification factor of ~4500 due to the RFFS, the experiment would not have been feasible. Similarly, to fully realize the scientific program at FRIB a new RFFS will be required. In this talk a potential proposal for such a device will be discussed. [Preview Abstract] |
Sunday, April 15, 2018 11:33AM - 11:45AM |
H11.00005: ISLA, an Isochronous Separator with Large Acceptance for Experiments with Reaccelerated Beams at FRIB A M Amthor, D Bazin, W Mittig, A Ringhausen The Isochronous Separator with Large Acceptance (ISLA) has been identified by the ReA12 Recoil Separator working group of the FRIB Users Organization as the single device that meets the needs of all the physics cases proposed by the community for studies with reaccelerated rare isotope beams from ReA at FRIB. ReA will reaccelerate stopped FRIB beams to energies ideal for transfer reactions, multiple Coulomb excitation, fusion, and deep inelastic scattering. ISLA will provide efficient rejection of unreacted beam; large acceptances of momentum ($\pm$ 10\%), angle (64 msr), and charge state ($\pm$ 10\%) distributions; and high M/Q resolving power ($>$400) for reaction products. The purely magnetic system will accept magnetic rigidities up to 2.6 Tm, to match the fully upgraded ReA12 incoming beam rigidities, and will not be limited by electric rigidity. M/Q separation in time-of-flight and a long preceding drift will allow efficient detection at the compact focal plane, facilitating multi-physics measurements (e.g. implantation with beta-delayed gamma spectroscopy). Space at the target is sufficient for coupled operation with GRETA, and a beam swinger will allow incoming beam angles up to 50 degrees. Recent work has focused on the magnetostatic design of ISLA's four large dipoles. [Preview Abstract] |
Sunday, April 15, 2018 11:45AM - 11:57AM |
H11.00006: FRIB Decay Station -- opportunities and challenges Robert Grzywacz, Sean Liddick, Darek Seweryniak, Nicholas Scielzo A scientific program with a wide range of studies in nuclear structure, nuclear astrophysics, fundamental symmetries, and isotopes of importance to applications can be accomplished at FRIB with decay spectroscopy due to its sensitivity and selectivity. The FRIB Decay Station aims to perform experiments on the most exotic nuclei to probe the unknown parts of the chart of nuclei. A versatile multidetector array comprised of efficient, integrated detector subsystems for charged particles, gamma rays, and neutrons will comprehensively address the challenges and opportunities associated with the decays of very exotic nuclei, such as complex decay modes, large decay energies, short lifetimes and long decay chains. [Preview Abstract] |
Sunday, April 15, 2018 11:57AM - 12:09PM |
H11.00007: Penning trap mass spectrometry Q-value determinations for highly-forbidden $\beta $-decay Rachel Sandler, Matt Redshaw, Kerim Gulyuz, Nadeesha Gamage, Georg Bollen, Ryan Ringle, Martin Eibach, Alec Hamaker, Chris Izzo, Daniel Puentes, Isaac Yandow Over the last several decades, extremely sensitive, ultra-low background beta-particle and gamma-ray detection techniques have been developed. These techniques have enabled the observation of very rare processes, such as highly forbidden beta decays e.g. of $^{\mathrm{113}}$Cd , $^{\mathrm{50}}$V, and $^{\mathrm{138}}$La. Half-life measurements of highly forbidden beta decays provide a testing ground for theoretical nuclear models, and the comparison of calculated and measured energy spectra could enable a determination of the values of the weak coupling constants. Precision Q-value measurements also allow for systematic testing of the beta-particle detection techniques. We will present the results and current status of Q value determinations for highly forbidden beta decays of $^{\mathrm{113}}$Cd, $^{\mathrm{50}}$V, and $^{\mathrm{138}}$La. The Q values, corresponding to the mass difference between parent and daughter nuclides, are measured using the high precision Penning trap mass spectrometer LEBIT at the NSCL. [Preview Abstract] |
Sunday, April 15, 2018 12:09PM - 12:21PM |
H11.00008: Probing the fusion of neutron-rich nuclei with reaccelerated radioactive beams Justin Vadas, Varinderjit Singh, Blake Wiggins, Jacob Huston, Sylvie Hudan, Romualdo deSouza, Zidu Lin, Charles Horowitz, Abdou Chbihi, Dieter Ackermann, Michael Famiano, Kyle Brown Fusion in neutron-rich environments is presently a topic of considerable interest. For example, the optical emission spectrum from the neutron star merger GRB170817A clearly establishes this neutron-rich environment as an important nucleosynthetic site. A good approach to understand how fusion proceeds in neutron-rich nuclei is to measure the fusion excitation function for an isotopic chain of nuclei. Reaccelerated radioactive beam facilities provide the opportunity to systematically address this question. Using the ReA3 facility at NSCL, a $^{28}$Si target was bombarded with beams of $^{39,47}$K at near-barrier energies, 36 $<$ E$_{c.m.}$ $<$ 43 MeV. The low intensity of the radioactive $^{47}$K beam (2-4 $\times$ 10$^{4}$ ions/s) necessitated the development of an efficient experimental technique. Incident ions were identified on a particle-by-particle basis by $\Delta$E-TOF just upstream of the target. Fusion products were directly measured and identified by the E-TOF technique with an efficiency of $\sim$70\%. The measured fusion excitation functions will be presented, and compared with coupled channels calculations. [Preview Abstract] |
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