Bulletin of the American Physical Society
APS April Meeting 2021
Volume 66, Number 5
Saturday–Tuesday, April 17–20, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session Z11: Nuclear Reactions: Heavy-Ions/Rare Isotope Beams IILive
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Sponsoring Units: DNP Chair: Romualdo Desouza, Indiana University |
Tuesday, April 20, 2021 3:45PM - 3:57PM Live |
Z11.00001: Symmetry Energy Investigation With Pion Production From Sn+Sn Systems Justin Estee, William Lynch Understanding the Equation of State (EoS) of nuclear matter that supports dense objects like neutron stars (NS) against their gravitational collapse is a key scientific objective that motivates observations of neutron stars and their mergers using an array of astronomical observatories. The existence of positive charged protons in NS requires understanding of the symmetry energy, which is the penalty energy arise from imbalance of neutron and proton density in the nuclear matter. Only laboratory measurements can provide a microscopic understanding of how the nuclear EoS depends on the composition of the stellar matter. Here we focus on constraining the symmetry energy contribution to the EoS at supra-saturation densities by measuring pion production in heavy ion collisions and by varying the numbers of neutrons and protons in the region where the pions are produced. [Preview Abstract] |
Tuesday, April 20, 2021 3:57PM - 4:09PM Live |
Z11.00002: The Isoscaling Results From Ca$+$Ni and Ca$+$Sn Systems at E/A$=$56, 140MeV Rensheng Wang, Betty Tsang, Zbigniew Chajecki, Kyle Brown, Chi-En Teh When comparing 2 Heavy-Ion-Collision(HIC) systems with same temperature but different neutron and proton (isospin) content, the isotope yield ratio with neutron number and proton number (N,Z) be expressed by an exponential function R21$=$ Y\textunderscore 2(N,Z)/Y\textunderscore 1(N,Z) $=$CExp($\alpha $N$+\beta $Z). This phenomenon is called isoscaling in HIC suggesting that the nuclear system reaches chemical equilibrium in most heavy ion collisions. In this talk, a systematic isoscaling results from 40,48Ca$+$58,64Ni and 40,48Ca$+$112,124Sn systems at E/A$=$56, 140MeV and “neutron” spectra constructed from isoscaling will be presented. [Preview Abstract] |
Tuesday, April 20, 2021 4:09PM - 4:21PM Live |
Z11.00003: Abstract Withdrawn
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Tuesday, April 20, 2021 4:21PM - 4:33PM Live |
Z11.00004: Probing the asymmetry dependence of the nuclear caloric curve in fusion-evaporation reactions Alan McIntosh, Lauren McIntosh, Kris Hagel, Sherry Yennello The nuclear caloric curve is an emergent property of the nuclear equation of state. Some models predict the caloric curve depends on the neutron excess, but the magnitude and even sign of this dependence varies between models. We aim to characterize the asymmetry dependence of the nuclear caloric curve experimentally. Since the caloric curve emerges from the microscopic interaction, knowledge of the asymmetry dependence of the caloric curve may constrain the asymmetry energy in the nuclear equation of state. We have conducted an experiment to study this effect in an independent way, using fusion-evaporation reactions of 78,86Kr $+$ 12C @ 15, 25, 35 MeV/u. Light charged particles were measured to extract the temperature and heavy residues were measured to select fusion reactions. The experimental setup, calibration, and analysis of nuclear temperatures in the fusion reactions will be discussed. [Preview Abstract] |
Tuesday, April 20, 2021 4:33PM - 4:45PM Live |
Z11.00005: PID Determination and Charge State Contamination Joseph Wieske, William Lynch, Kyle Brown, Zbigniew Chajecki, Tom Ginter, Adam Anthony, Chenyang Niu, Wolfgang Mittig Studying properties and decays of heavy isotopes is a goal of rare isotope beam physics that comes with challenges. Even if separation of isotopes is achieved using particle identification (PID) systems, the isotopic species remain to be determined, and charge state contamination must be quantified. The National Superconducting Cyclotron Laboratory (NSCL) recently conducted an experiment to measure the fission properties of nuclei in the neutron deficient Pb region. A radioactive cocktail beam was tuned in the A1900 fragment separator to allow for separation of isotopes. The beam was identified using the $\Delta $E-ToF method. In order to quantify charge state contamination, a total kinetic energy measurement of the beam was made using Si PIN detectors. In addition, a high purity Germanium crystal (HPGe) measured the decay of long lived isomers for beam tagging to provide another measure of charge state contamination. This talk will discuss the methods of isomer-tagging and measurement of charge state contamination. [Preview Abstract] |
Tuesday, April 20, 2021 4:45PM - 4:57PM Live |
Z11.00006: A new $\Delta E$-ToF particle identification device Chenyang Niu, Adam Anthony, Daniel Bazin, Kyle Brown, Zbigniew Chajecki, Jie Chen, Thomas Ginter, William Lynch, Wolfgang Mittig, Chi-En Teh, Betty Tsang, Rensheng Wang, Joseph Wieske The particle identification (PID) technique plays a key role in radioactive isotope beams experiments. To support a fission experiment recently finished in the n-deficient lead region, a new PID device was developed using the time-of-flight (ToF) and energy loss ($\Delta E$) method. Two microchannel plate (MCP) detectors were installed to measure the ToF. A new gridded ion chamber with 13 segmented pads was designed and built to provided both $\Delta E$ measurement and beam tracking. The performance of the $\Delta E$-ToF device was tested with both stable and radioactive beams. The secondary beam was well separated by this device in the experiment. In this talk, the construction and experimental performance of the $\Delta E$-ToF device will be described. [Preview Abstract] |
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