Bulletin of the American Physical Society
2005 2nd Joint Meeting of the Nuclear Physics Divisions of the APS and The Physical Society of Japan
Sunday–Thursday, September 18–22, 2005; Maui, Hawaii
Session DH: Nuclear Reactions: Rare Ion Beams |
Hide Abstracts |
Sponsoring Units: DNP JPS Chair: M. Thoennessen Room: Ritz-Carlton Hotel Plantation 1 |
Tuesday, September 20, 2005 7:00PM - 7:15PM |
DH.00001: Structure of exotic isotope $^{9}$C via resonance elastic scattering. Grigory Rogachev, James Kolata, Larry Lamm, Frederick Becchetti, You Chen, Donald Roberts, Paul DeYoung, Jerry Hinnefeld Light exotic nuclei provide important insights into the understanding of nuclear forces at large neutron to proton ratios. The progress in development of modern theoretical approaches such as quantum Monte-Carlo calculations (QMC) and no-core shell model (NCSM) allows for predictions of properties of light nuclei (A$\le$12) from the basic principles. Unfortunately, experimental information on the structure of many light exotic isotopes is very incomplete making it difficult to judge the accuracy of the \textit{ab initio} models in case of large excess of neutrons or protons. The focus of this experimental study is the structure of neutron-deficient carbon isotope $^{9}$C. Only one excited state was known in this nucleus. Excited states in $^9$C were populated in resonance elastic scattering of protons on $^{8}$B using method of inverse kinematics and very thick target. The analysis was made using combined R-matrix - Continuum Shell Model approach. The structure of $^{9}$C will be discussed and comparison with the predictions of modern theoretical models will be made. [Preview Abstract] |
Tuesday, September 20, 2005 7:15PM - 7:30PM |
DH.00002: CDCC analysis of breakup reactions of $^{11}$Be on $^{208}$Pb Takuma Matsumoto, Kazuyuki Ogata, Masanobu Yahiro, Yasunori Iseri, Tomoaki Egami $^{11}$Be is a typical example of one-neutron halo nuclei, where the valence neutron has a large spatial extension with respect to the core nucleus. In the present work, we analyze breakup reactions of $^{11}$Be on $^{208}$Pb at energies around 70 MeV/nucleon with the method of continuum-discretized coupled-channels (CDCC). As the internal state of $^{11}$Be, we take s-, p-wave states including the ground $1/2^+$ state and the first excited $1/2^-$ state and breakup continuum states. In the CDCC calculation, effects of the Coulomb excitation to the first excited $1/2^-$ state on the breakup cross section is investigated. The effects are expected to be significant in Coulomb breakup processes. Also, we discuss effects of the nuclear interaction on the breakup processes. [Preview Abstract] |
Tuesday, September 20, 2005 7:30PM - 7:45PM |
DH.00003: $^{16}$C inelastic scattering studied with microscopic coupled-channels method Masaaki Takashina, Yoshiko Kanada-En'yo, Yukinori Sakuragi In order to test the $^{16}$C internal wave function, we perform microscopic coupled-channels (MCC) calculations of the $^{16}$C($0_1^+ \to 2_1^+$) inelastic scattering by $^{208}$Pb target at $E/A$=52.7 MeV using the antisymmetrized molecular dynamics (AMD) wave functions of $^{16}$C, and compare the calculated differential cross sections with the measured ones. The MCC calculations with AMD wave functions reproduce the experimental data fairly well, although they slightly underestimate the magnitude of the cross sections. The absolute magnitude of calculated differential cross sections is found to be sensitive to the neutron excitation strength. We prove that the MCC method is a useful tool to connect the inelastic scattering data with the internal wave functions. [Preview Abstract] |
Tuesday, September 20, 2005 7:45PM - 8:00PM |
DH.00004: Isoscalar monopole and dipole responces in 14O Hidetada Baba Isoscalar monopole and dipole responses in unstable nucleus $^ {14}$O with broad excitation energy range have been studied by inelastic $\alpha$ scattering at 60 $A$ MeV in inverse kinematics. The experiment was performed at the RIKEN Accelerator Research Facility. The $^{14}$O beam was produced by using the projectile fragmentation reaction and selected by the RIKEN Projectile Fragment Separator (RIPS). A radioactive $^ {14}$O beam was incident on a liquid-helium target. The excitation energy spectra were obtained from invariant-mass of each decay channel of $^{14}$O$^*$ $\rightarrow$ $^{13}$N + p, $^{12}$C + p + p, $^{12}$C$^*$ + p + p, $^{10}$C + $\alpha$, and $^{10} $C$^*$ + $\alpha$. The isoscalar monopole and dipole strength distributions were deduced by the multipole decomposition analysis with the DWBA calculations. For measured decay channels, the integrated isoscalar monopole and dipole strengths up to $Ex$ = 25 MeV were identified corresponding to about half of the full energy-weighted sum rule. In addition to the fragmented strength distributions as seen in light stable nuclei, substantial continuum strength below 10 MeV for the isoscalar monopole and dipole responses were newly observed. [Preview Abstract] |
Tuesday, September 20, 2005 8:00PM - 8:15PM |
DH.00005: Single Particle Strengths from the (d,p) Reaction on $^{18}$F R.L. Kozub, D.W. Bardayan, J.C. Blackmon, C.J. Gross, C.D. Nesaraja, J.P. Scott, D. Shapira, M.S. Smith, J.C. Batchelder, C.R. Brune, A.E. Champagne, L. Sahin, J.A. Cizewski, J.S. Thomas, U. Greife, C.C. Jewett, R.J. Livesay, Z. Ma, B.H. Moazen The $^{19}$F nucleus has been studied extensively. However, there have previously been no direct measurements of $^{18}$F+n single-particle components in $^{19}$F, and no measure of neutron vacancies in the $^{18}$F ground state, as such experiments require a (radioactive) $^{18}$F target or beam. We have used the $^2$H($^{18}$F,p)$^{19}$F reaction to selectively populate such states in $^{19}$F. The 108.5-MeV radioactive $^{18}$F$^{+9}$ beam was provided by the HRIBF at ORNL. Proton-recoil coincidence data were taken for both $\alpha$-decaying and particle-stable final states. Angular distributions and spectroscopic factors were measured for eight proton groups, corresponding to 12 states in $^{19}$F. The results will be compared to model calculations. Results for states of astrophysical significance were reported earlier.$^1$ \\ \\ $^1$R. L. Kozub {\em et al.}, Phys. Rev. C \underline{71}, 032801 (R) (2005). \\ \\ Research supported by U. S. DOE and NSF. [Preview Abstract] |
Tuesday, September 20, 2005 8:15PM - 8:30PM |
DH.00006: $\alpha$-Cluster States in $^{18}$O Simon Brown, Grigory Rogachev, Bert Green, Kirby Kemper, Alexander Momotyuk, Brian Roeder, Vladilen Goldberg, Changbo Fu $\alpha$ clustering is a remarkable phenomenon, which plays a very important role in our understanding of nuclear forces. The $\alpha$-cluster structures of N=Z nuclei $^{12}$C, $^{16}$O and $^{20}$Ne has been extensively studied. It was the observation of $\alpha$-cluster rotational bands in these nuclei that inspired the development of theoretical models capable of treating clustering phenomena in nuclei. Much less is known, however, about the alpha cluster structure in N$\ne$Z nuclei. It was recently shown in studies [1,2] that $\alpha$-cluster states can be observed in $^{22}$Ne, with unusual findings such as the doubling of $\alpha$-cluster rotational bands. The focus of this discussion will be the alpha cluster structure of the $^{18}$O nucleus. The $\alpha$ cluster states in $^{18}$O were populated via elastic scattering of radioactive beam $^{14}$C (from the Florida State Tandem-LINAC facility) on $\alpha$-particles using the Thick Target Inverse Kinematics technique [3]. Features of $^{14}$C+$\alpha$ molecular rotational bands will be considered. \newline [1] G.V. Rogachev et al., Phys. Rev. C64, 051302R (2001).\newline [2] V.Z. Goldberg et al., Phys. Rev. C69, 024602 (2004).\newline [3] K.P. Atremov et al., Sov. J. Nucl. Phys. 52, 408 (1990). [Preview Abstract] |
Tuesday, September 20, 2005 8:30PM - 8:45PM |
DH.00007: Search for high-spin isomsers using radioactive-isotope $^{17}$N beam Y. Wakabayashi, T. Teranishi, A. Odahara, T. Fukuchi, S. Kubono, H. Yamaguchi, A. Saitoh, H. Fujikawa, G. Amadio, J.J. He, E. Ideguchi, S. Shimoura, H. Baba, Y. Gono, S. Nishimura, M. Nishimura, S. Michimasa, T. Kishida, S. Ota, J.Y. Moon, T. Ishii High spin isomers are known in $\it{N}$=83 isotones systematically. These isomers are considered to be shape isomers caused by sudden shape changes from near spherical to oblate shapes. In order to search for high-spin isomers in other mass regions, we selected $\it{N}$=51 isotones which have one neutron outside a magic 50 core and proton numbers close to semi-magic 40 core. High spin isomers of $\it{N}$=51 isotones can be expected, which have similar mechanism to those of N=83 isotones. An experiment for isomer search in $\it{N}$=51 isotones was performed using a $^{17}$N secondary beam produced by the low-energy radioisotope beam separator(CRIB) of the Center for Nuclear Study(CNS),University of Tokyo. A $^{9}$Be primary target of 2.3 mg/cm$^{2}$ was bombarded by an $^{18}$O$^{8+}$ primary beam of 126 MeV to obtain a $^{17}$N beam of 104 MeV. A $^{82}$Se secondary target of 4.9 mg/cm$^{2}$ was placed at a final focal plane. Two clover Ge detectors were set to measure $\gamma$ rays emitted from nuclei produced by the secondary fusion reaction. In this experimnet, some $\gamma$-rays from nuclei, such as $^{92}$Nb, produced by the $^{82}$Se+$^{17}$N reaction were observed. In this talk, I will report the result. [Preview Abstract] |
Tuesday, September 20, 2005 8:45PM - 9:00PM |
DH.00008: Search for particle-bound $^{26}$O and $^{28}$F in $p$-stripping Andreas Schiller, Thomas Baumann, Janet Dietrich, Steffen Kaiser, William Peters, Michael Thoennessen We have searched for particle-bound $^{26}$O and $^{28}$F isotopes in the reaction products of secondary $^{27}$F and $^{29}$Ne beams, respectively. No events have been observed. Upper limits for the respective production cross sections by one-$p$-stripping reactions are established under the assumption that $^{26}$O and $^{28}$F are particle bound. Since the experimental upper limits are much lower than common estimates we conclude that neither $^{26}$O nor $^{28}$F are likely particle bound. [Preview Abstract] |
Tuesday, September 20, 2005 9:00PM - 9:15PM |
DH.00009: Measurement of Transfer Reactions on Z=50 Fission Fragments in Inverse Kinematics S.D. Pain, D.W. Bardayan, J.C. Blackmon, J.A. Cizewski, M.S. Johnson, K.L. Jones, R.L. Kozub, R.J. Livesay, B.H. Moazen, C.D. Nesaraja, M.S. Smith, J.S. Thomas The development of high quality radioactive beams, such as those at the HRIBF at Oak Ridge National Laboratory, has made possible the performance of transfer reactions in inverse kinematics on unstable nuclei. Measurement of (d,p) reactions on neutron-rich nuclei yield data on the development of nuclear structure away from stability, and are of astrophysical interest due to the proximity to suggested r-process paths. Experimentally, (d,p) reactions on heavy (Z=50) fission fragments are complicated by the strongly inverse kinematics, and the relatively low beam intensities. Consequently, ejectile detection with high resolution in position and energy, a high dynamic range and a high solid angular coverage is required. A proof of principle experiment has been performed on $^{124}$Sn (d,p) in inverse kinematics [1] demonstrating successfully the technique, and the first experiments using radioactive beams ($^ {130,132}$Sn(d,p)) are due to be performed in 2005. The Oak Ridge Rutgers University Barrel Array (ORRUBA), a Si detector array with a high solid angular coverage around $90^{\circ}$, is currently under development to facilitate future measurements. \noindent 1. K.L. Jones \emph{et al}., Phys. Rev. C 70 067602 (2004) [Preview Abstract] |
Tuesday, September 20, 2005 9:15PM - 9:30PM |
DH.00010: Recent Results from Target Development for RIB -- Refractory Elements H.K. Carter, A. Kronenberg, E.H. Spejewski, D.W. Stracener Development of ion beams of short-lived isotopes is crucial for modern nuclear structure and nuclear astrophysics. The Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory uses the ISOL (Isotope Separator Online) technique to provide radioactive ion beams. So far, refractory elements are not accessible with this technique. The code HSC-5 [1], with an extensive thermochemical database predicts possible chemical sidebands which may be transported within the target-ion source. We are working on the release of Vanadium, Zirconium, and Molybdenum isotopes in molecular form for example as oxides, fluorides, chlorides, sulfides. A number of new targets have been fabricated and tested for use and recent results from off-line and on-line tests will be presented. This research was sponsored by the NNSA under Stewardship Science Academic Alliance program through DOE Cooperative Agreement {\#} DE-FC03-3NA00143.\newline \newline [1] HSC Chemistry for Windows -- Chemical Reaction and Equilibrium Software with extensive Thermochemical Database, Outokumpu Research Oy, Pori, Finland [Preview Abstract] |
Tuesday, September 20, 2005 9:30PM - 9:45PM |
DH.00011: LISE++ development: Abrasion -- Fission Oleg Tarasov The fission of $^{238}$U is induced by both electro-magnetic and nuclear processes. At large impact parameters and for high-Z targets, the long-range Coulomb force prevails (Coulomb fission). For smaller impact parameters, peripheral nuclear collisions take place and the fissile projectile is left abraded and excited (Abrasion-Fission). After de-excitation by nucleon emission, it can undergo fission with a finite probability. Coulomb Fission and Abrasion-Fission are both included in the production cross section calculations in the latest version of the LISE++ code (www.nscl.msu.edu/lise). Abrasion-Fission is significantly more difficult to model since there are more than 100 fissile nuclei produced after the initial abrasion stage of the fast heavy projectile (there is only one fissile nucleus in the case of Coulomb fission). To overcome this problem, the LISE code models the Abrasion-Fission fragment production with three excitation energy regions. Post-scission nucleon emission is the final stage. Use of the LisFus method to define the number of post-scission nucleons is a big advantage of the LISE++ code that allows one to observe shell effects in the TKE distribution, and enables the user to make a rapid qualitative estimate of the final fission fragment yield. Another advantage of the code is the speed of its calculations. Kinematic models of the fission process are used to perform the fragment transmission calculations and estimate the fragment rates at the end of spectrometer. [Preview Abstract] |
Tuesday, September 20, 2005 9:45PM - 10:00PM |
DH.00012: Production of Neutron-Rich Isotopes from UC Targets for RIB Development E.H. Spejewski, H.K. Carter, A. Kronenberg, D.W. Stracener, J.-C. Bilheux, A.L. Gaddis, W.H. Brantley, J.A. Nolen, Jr., A.C.C. Villari, J.P. Greene, T.A. Burtseva, W.L. Talbert The Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory (ORNL) provides radioactive beams for research in nuclear physics. An essential function is to produce a variety of radioactive species to meet the intensity, energy, and purity requirements of specific experiments. A primary production method has been proton-induced fission of uranium. The principal targets employed have been constructed at ORNL in the form of uranium carbide (UC) bound within a matrix of carbon fibers ($\sim $0.8-1.3 g/cm$^{3})$. Recently, pressed-powder targets of uranium carbide, fabricated at ANL from uranium oxide (2.61 g/cm$^{3})$ or uranium carbide (6.03 g/cm$^{3})$, have been used. These pellets (2.61 and 6.03 g/cm$^{3}$, respectively) produced yields in ratios of approximately 1 to 10 compared to the fiber materials, with the amount of increase differing by chemical element. Deuteron-induced fission on an ANL pellet has also been investigated with, however, no significant improvement in yields observed. Possible causes for the differing results will be discussed. \textit{Supported in part by the U. S. Department of Energy} [Preview Abstract] |
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