Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session R13: Mini-Symposium: FRIB and ReA instrumentation II |
Hide Abstracts |
Sponsoring Units: DNP Chair: Matt Amthor, Bucknell University Room: Sheraton Plaza Court 2 |
Monday, April 15, 2019 1:30PM - 1:42PM |
R13.00001: The Development of a Tritium Target TPC for FRIB Yassid Ayyad, Augusto O Macchiavelli The evolution of pairing correlations in exotic nuclei is a subject which has received much attention in recent years. Of specific interest is the role of pairing in neutron-rich isotopes, where the effects of weak binding and continuum coupling are important (See for example [1]). The best tool to study these correlations is the (t,p) transfer reaction, particularly suited to probe the 2n pair density. Due to the compelling capabilities offered by Active Targets TPC detectors [2], it is natural to explore the use of a tritium gas target TPC, with an equivalent thickness 100 times larger than typical solid targets, enabling experiments with exotic beams in reverse kinematics with a very low intensity. We will discuss the conceptual design of a dedicated tritium TPC (AT3PC) for FRIB, based on an inner cell containing the gas [3] to minimize safety issues associated with large quantities of tritium. 1) H. Shimoyama and M. Matsuo, Phys. Rev. C 84, 0044317 (2011) 2) S. Beceiro-Novo, et al. Prog. in Particle and Nuclear Physics 84 (2015) 1241 3) Y. Ayyad et al. NIM A https://doi.org/10.1016/j.nima.2018.10.019
|
Monday, April 15, 2019 1:42PM - 1:54PM |
R13.00002: A Radio-Frequency Fragment Separator for FRIB Daniel E Hoff, Andrew M Rogers, Daniel Bazin, Alexander Plastun Understanding nuclei at the limits of stability has been, and continues to be, one of the main focuses of nuclear physics. For studies on nuclei in the regions far from stability, clean beams of radioactive isotopes are often required. For studies at the NSCL that require purification beyond magnetic-bending and energy-loss techniques, a Radio-Frequency Fragment Separator (RFFS) is available. Several experiments at the NSCL have already been made possible with the use of the current RFFS. Results from one such experiment measuring beta-delayed protons from 73Rb, to study the 72Kr rp-process waiting point, will be presented. With the advent of FRIB, a new RFFS needs to be developed so that users can be provided high-purity radioactive beams. A proposal for such a device has already been submitted, and some LISE++ simulations of experiments requiring an RFFS at FRIB will be discussed. |
(Author Not Attending)
|
R13.00003: Using GODDESS to Constrain r-Process Neutron Capture Rates with (d,pγ) Reactions Chad C. Ummel, Jolie A. Cizewski, Steven D. Pain, Andrew Ratkiewicz, Harrison E. Sims, GODDESS Collaboration, ORRUBA Collaboration, GRETINA Collaboration Measurements of neutron-capture reactions on exotic nuclei are a sensitive input needed to understand r-process abundance patterns. Due to the short half-lives of many of the isotopes involved, direct measurements of these cross sections are often not possible. FRIB will make possible the study of many nuclei near the r-process path via indirect methods. Measurements of (d,p) reactions with the Oak Ridge-Rutgers University Barrel Array (ORRUBA) silicon detector have successfully constrained spectroscopic factors necessary for inferring direct neutron capture cross sections. Additionally, a "surrogate reaction method" has been validated to extract compound (n,γ) reaction cross sections from (d,pγ) reaction measurements. The coupled GODDESS (Gammasphere-ORRUBA: Dual Detectors for Experimental Structure Studies) detectors enable such studies. In early 2019, ORRUBA was coupled to GRETINA. The outcome of this campaign, as well as plans for G(RETINA)ODDESS campaigns at NSCL and FRIB will be discussed. |
Monday, April 15, 2019 2:06PM - 2:18PM |
R13.00004: A Hybrid Technique for Neutron Spectroscopy Using Deuterated Scintillators and Spectrum Unfolding for FRIB. Rebecca Toomey, Michael T Febbraro, Steven D. Pain, Kelly A. Chipps, Richard J DeBoer, Thomas N Massey, Zachary P Meisel, Kevin Macon, Axel Boeltzig, Carl Richard Brune, Qian Liu As the field of nuclear physics looks towards the next-generation of radioactive beam facilities, such as FRIB, it is vital that the appropriate infrastructure is in place so the full capabilities of these facilities can be exploited. Neutron spectroscopy is an example of an important area where efforts should be focused to be fully prepared for first beam at FRIB. Traditionally, neutron spectroscopy measurements are performed using the time-of-flight (ToF) method. However, to achieve reasonable energy resolution the detector must be placed a significant distance from the target, which reduces solid angle efficiency. An alternative to this is a hybrid method developed at ORNL which combines the neutron spectroscopy method of spectrum unfolding with the traditional ToF method to maximize the solid angle efficiency without sacrificing the energy resolution. An array of deuterated organic liquid scintillators has been designed and built at ORNL and characterized using the ToF tunnel at Ohio University. The light response and pulse shape discrimination capabilities of this array will be presented, and the spectrum unfolding method will be discussed. |
Monday, April 15, 2019 2:18PM - 2:30PM |
R13.00005: The next generation neutron detector for the studies of exotic nuclei Joseph Heideman, David Perez-Loureiro, Robert K. Grzywacz, Cory R Thornsberry, Shree K Neupane, Mustafa M Rajabali, Lawrence Harvey Heilbronn, Kyle Schmitt, Jason Chan, Leonard D Mostella III, Cole Howell, Joseph Owens The development of radioactive ion beam facilities which can create very neutron rich nuclei necessitates detectors with improved neutron energy resolution and neutron selection. Exotic nuclei near the neutron drip line are far from beta decay stability and become more likely to undergo beta delayed neutron emission processes. The Neutron dEtector with Tracking (NEXT) will be a high resolution neutron detector designed as neutron-gamma discriminating-plastic scintillator coupled to a segmented position readout. The NEXT configuration will be based on ToF measurements with improved time resolution and interaction localization. Recent advancements in PSD plastic scintillators as well as position sensitive detectors are the foundation of the compact design of the NEXT detector. A segmented detector prototype has been made from optically separated bars of EJ-276 (Eljen Technology) coupled to a position sensitive PMT. Results from preliminary time of flight measurements and ongoing simulations of the position dependent detector response will be presented. |
Monday, April 15, 2019 2:30PM - 2:42PM |
R13.00006: Measuring the fusion excitation functions for $^{41,45}K + $^{28}Si and $^{36,44}Ar + $^{28}Si James E Johnstone, Carley N Folluo, Sylvie Hudan, Romualdo T Desouza, D Ackermann, A Chbihi, Q Hourdille, G Verde, Alan B McIntosh, Sherry J Yennello, Kyle W Brown Fusion in neutron-rich environments is presently the topic of considerable interest. Recently, the viability of investigating near-barrier fusion with low-intensity ($\approx$10$^{4}$ ions/s), reaccelerated, radioactive beams was demonstrated by the measurement of the fusion excitation function for $^{39,47}$K + $^{28}$Si. Experiments for an isotopic chain allow systematic exploration of the dependence of fusion on neutron number. To expand the study of this system away from the closed N=20 and N=28 shells and to explore the role of the unpaired proton, Experiment 17002 was conducted at NSCL’s ReA3 facility. The experiment measured the fusion cross-section in $^{41,45}K + $^{28}Si and $^{36,44}Ar + $^{28}Si for E/A = 2-3 MeV/A, by directly measuring and identifying fusion products using E-TOF. Details of the experimental setup including improvements to the geometric efficiency will be shown. Implementation of a fast veto of elastically-scattered beam particles (yielding $\approx$3-fold increase in the data collected) will be discussed. Preliminary analysis yielding the experimental fusion excitation functions will be presented. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700