Bulletin of the American Physical Society
2009 APS April Meeting
Volume 54, Number 4
Saturday–Tuesday, May 2–5, 2009; Denver, Colorado
Session X10: Nuclear Reactions: Heavy Ions/Rare Isotope Beams II |
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Sponsoring Units: DNP Chair: Jorge Piekarewicz, Florida State University Room: Governor's Square 10 |
Tuesday, May 5, 2009 1:30PM - 1:42PM |
X10.00001: Measurement of (d,p) reactions on neutron-rich nuclei around the N=82 shell closure Steven Pain The energies, spins and spectroscopic information of single-particle states around shell closures near to suggested r-process paths are of significant astrophysical interest, providing constraint on nuclear structure models and direct neutron-capture cross sections. Measurements of (d,p) reactions on n-rich nuclei yield can yield such important information. The $^{134}$Te(d,p)$^{135}$Te reaction, along with $^ {130}$Sn(d,p)$^{131}$Sn, has been measured in inverse kinematics at the Holifield Radioactive Ion Beam Facility at around 4.5 MeV/A utilizing deuterated plastic targets. Proton ejectiles were detected using an early implementation of the Oak Ridge Rutgers University Barrel Array (ORRUBA) in conjunction with the Silicon Detector Array (SIDAR). Experimental details and the data analysis, including excitation energies and angular distributions, will be presented. *This work is supported in part by the U.S. Department of Energy under contract numbers DE-FG52-03NA00143 (Rutgers), DE-AC05-00OR22725 (ORNL), DE-FG02-96-ER40955 and DE- FG02-96ER40990(TTU), and the National Science Foundation. [Preview Abstract] |
Tuesday, May 5, 2009 1:42PM - 1:54PM |
X10.00002: The Effect of N/Z on Caloric Curves S. Wuenschel, S.J. Yennello, Z.W. Kohley, L.W. May, G. Souliotis, D.V. Shetty, K. Hagel, B.C. Stein, S.N. Soisson, S. Galanpoulos For many years, the onset of multi-fragmentation in excited nuclei has been associated with a liquid-to-gas type phase transition. Phase transition studies have been conducted using yields from discrete telescopes and quasi-complete event detectors. These efforts have yielded information about nuclear phase transitions in general. However, the effect of the two-component nature of the nucleus is still unclear. The reactions of $^{86,78}$Kr projectiles on $^{64,58}$Ni targets at 35MeV/u were studied with the NIMROD-ISiS array. The 4pi coverage and excellent isotopic resolution of NIMROD-ISiS allow quasi-projectiles to be reconstructed in both Z and A. Caloric curves will be presented as a function of N/Z of this well-defined quasi-projectile source. [Preview Abstract] |
Tuesday, May 5, 2009 1:54PM - 2:06PM |
X10.00003: Studying dynamical polarization in the breakup of $^{17}$F J.F. Liang, J.R. Beene, A. Galindo-Uribarri, C.J. Gross, P.E. Mueller, D. Shapira, D.W. Stracener, R.L. Varner, H. Esbensen, A.L. Caraley, K.T. Schmitt Fluorine-17 is a drip-line nucleus where the proton is bound by 0.6 MeV. It is predicted that the valence proton would be pushed away from the target nucleus and shielded by the $^{16}$O core when $^{17}$F is incident on a high Z target. This resembles the tail of a comet pointing away from the sun when it flies close to the sun. The phenomenon is caused by a dynamic polarization effect which is of order Z$^{3}$. The relative importance of the effect is therefore expected to be smaller on a target of lower Z. We have measured inclusive and exclusive breakup of $^{17}$F bombarding $^{58}$Ni and $^{208}$Pb targets at an energy of 10 MeV per nucleon. The breakup yield of $^{17}$F will be compared between the two targets and compared to model calculations to study this dynamic polarization effect. [Preview Abstract] |
Tuesday, May 5, 2009 2:06PM - 2:18PM |
X10.00004: Isoscaling of Z=1 to 17 fragments from the reaction of $^{86,78}$Kr with $^{64,58}$Ni targets at 35MeV/nucleon R.Q. Dienhoffer, S. Wuenschel, S.J. Yennello, G. Souliotis, Z.W. Kohley, A.L. Caraley, S. Galanopoulos, K. Hagel, L.W. May, D.V. Shetty, S.N. Soisson, B.C. Stein Isoscaling is the exponential relationship found when comparing the ratio of the yields between neutron-rich and neutron-poor systems produced in nuclear reactions. The reactions of $^{86,78}$Kr projectiles on $^{64,58}$Ni targets at 35MeV/nucleon were studied with the NIMROD-ISiS array. The 4$\pi $ coverage and isotopic resolution (through Z = 17) of the NIMROD-ISiS array allows reconstruction of the quasi-projectile in both Z and A. Well-defined quasi-projectile sources were extracted from the data. Isoscaling was first attempted by comparing the yields between different systems with little success. The yields from three bins in the N/Z of the quasi-projectile (less than 1, between 1 and 1.2, and greater than 1.2) were then compared between systems with similar results. Finally, the yields from the neutron-rich and neutron-poor quasi-projectiles within each system were isoscaled successfully. The isoscaling of Z = 1-17 will be presented. [Preview Abstract] |
Tuesday, May 5, 2009 2:18PM - 2:30PM |
X10.00005: Measurement of the $^{238}$U neutron-capture cross section from 30 eV to 100 keV using the DANCE detector at LANSCE John Ullmann, Todd Bredeweg, Aaron Couture, Robert Haight, Marian Jandel, August Keksis, John O'Donnell, Robert Rundberg, David Vieira, Jan Wouters, Ching-Yen Wu, John Becker, Bayarbadrakh Baramsai, Andrii Chyzh The $^{238}$U neutron-capture cross section was measured using the DANCE detector at LANSCE. DANCE is a 4$\pi $ array consisting of 160 BaF$_{2}$ crystals, designed for studying neutron capture on small samples of rare or radioactive nuclides. These measurements were made with a 48 mg/cm$^{2}$ $^{238}$U target. The measured cross sections are in substantial agreement with previous work. This measurement made use of a water-moderated neutron beam at the Manuel J. Lujan, Jr. Neutron Scattering Center at the Los Alamos National Laboratory, which is supported by the U.S. D.O.E. under contract DE-AC52-06NA25396. [Preview Abstract] |
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