Bulletin of the American Physical Society
4th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 59, Number 10
Tuesday–Saturday, October 7–11, 2014; Waikoloa, Hawaii
Session EC: Mini-Symposium on Transfer and Charge Exchange Reaction Studies with Stable and Radioactive Ion Beams I |
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Chair: Hiroyasu Ejiri, Research Center for Nuclear Physics, Osaka University Room: Kohala 3 |
Thursday, October 9, 2014 7:00PM - 7:45PM |
EC.00001: Transfer Reactions: From Nuclear Structure to Astrophysics Invited Speaker: Catherine Deibel Transfer reactions are powerful tools for studying the single-particle structure of nuclei and improving our understanding of astrophysical reaction rates. While historically much of the progress of the past has focused on the study of nuclei close to stability using stable beams, recent developments of radioactive ion beams have extended transfer reaction studies farther from stability, opening up hitherto unexplored areas of the nuclear chart. New experimental techniques to take full advantage of these beams have been developed to study transfer reactions in inverse kinematics with high efficiency and resolution. For example, the new HELIcal Orbit Spectrometer (HELIOS) at ATLAS and the Oak Ridge Rutgers University Barrel Array (ORRUBA) at HRIBF have allowed the study of multiple neutron-rich isotopes through ($d,p$) reactions on unstable beams ranging from $^{15}$C [1] to $^{132}$Sn [2]. In addition, stable beam transfer reactions still play a crucial role, both through providing stringent tests of theoretical models and via new experimental approaches using coincidence techniques. Reaction rates involving proton-rich nuclei have been studied indirectly with light, stable beams using, for example, high-resolution charged-particle spectroscopy of neutron pick-up reactions such as ($d,t$) [3] and ($^3$He,$\alpha$) [4] enabling measurements of excitation energies, spins and particle partial widths of resonances important in explosive nucleosynthesis. The general mechanism of transfer reactions will be discussed and several recent examples of transfer reaction studies, using both stable and radioactive ion beams, relevant for nuclear structure and nuclear astrophysics will be presented.\\[4pt] [1] A. H. Wuosmaa {\it et al.}, Phys. Rev. Lett. {\bf 105}, 132501 (2010).\\[0pt] [2] K. L. Jones {\it et al.}, Nature {\bf 465}, 454 (2010).\\[0pt] [3] D. Irvine {\it et al.}, Phys. Rev. C {\bf 88}, 055803 (2013).\\[0pt] [4] C. M. Deibel {\it et al.}, Phys. Rev. C {\bf 80}, 035806 (2009). [Preview Abstract] |
Thursday, October 9, 2014 7:45PM - 8:00PM |
EC.00002: Using R-matrix ideas to describe one-nucleon transfers to resonance states J.E. Escher, I.J. Thompson, G. Arbanas, Ch. Elster, V. Eremenko, L. Hlophe, F. Nunes (d,p) transfer reactions have long been used to investigate nuclear structure. Carried out in inverse kinematics, they are expected to play a central role in the study of weakly-bound systems at modern RIB facilities. While the theoretical framework and its computational implementation for describing (d,p) reactions have seen much progress, open questions remain. Resonances in the low-energy spectra of weakly-bound nuclei, e.g., are of interest for astrophysical applications and can in principle be studied with transfer reactions. Applying standard transfer reaction theories is problematic, both practically in terms of achieving converged solutions and conceptually in terms of interpreting the results. Recently, a new formalism that utilizes concepts known from the successful and popular R-matrix theory was proposed for the description of (d,p) reactions [Mukhamedzhanov, PRC 2011]. The formalism covers transfers to bound and resonance states and is general enough to include deuteron breakup. We present tests of the proposed formalism, compare calculations to measured cross sections, and discuss implications [Escher et al, PRC 2014]. [Preview Abstract] |
Thursday, October 9, 2014 8:00PM - 8:15PM |
EC.00003: Neutron spectroscopy measurements of the d($^{7}$Be,n)$^{8}$B reaction with a deuterated scintillator array (UM-DSA) Michael Febbraro, Cory Thornsberry, Kate Jones, Karl Smith, Giordano Cerizza, Patrick O'Malley, Dan Bardayan, Steve Pain, Fred Becchetti, James Kolata, Sabrina Strauss, Matt Hall We present the first results of neutron spectroscopy studies for the d($^{7}$Be,n)$^{8}$B reaction at E($^{7}$Be) $=$ 31 MeV with the University of Michigan deuterated scintillator array (UM-DSA). The experiment was performed at the \textit{TwinSol }radioactive ion beam (RIB) facility at the University of Notre Dame. The UM-DSA was developed for neutron spectroscopy studies with radioactive ion beams. It has demonstrated the capability to extract neutron spectra without the use of neutron time-of-flight (n-ToF) [1-2] by utilizing spectrum unfolding techniques. This permits the measurement of cross sections of bound and unbound states with high efficiency and angular coverage. In the case of RIB measurements where low beam intensities limit long path n-ToF, short path n-ToF can be used to discriminate neutrons of interest from room return and background neutrons. High resolution n-ToF is not required since neutron spectra can be extracted using spectrum unfolding. This hybrid method appears to be a useful spectroscopic technique to study neutron reactions with RIBs. [1] M. Febbraro, et al., IEEE TNS (2013) [2] M. Febbraro, et al., EJP (2014) [Preview Abstract] |
Thursday, October 9, 2014 8:15PM - 8:30PM |
EC.00004: Hole-states of 55Ni from (p,d) transfer reactions Betty Tsang, Alisher Sanetullaev, William Lynch, Jenny Lee, Daniel Bazin, K.P. Chan, Daniel Coupland, Vlad Henzl, Daniela Henzlova, Micha Kilburn, Andrew Rogers, Z.Y. Sun, Michael Youngs, Robert Charity, Lee Sobotka, Michael Famiano, Sylvie Hudan, Daniel Shapira, W.A. Peters, C Barbieri, M. Hjorth-Jensen, M. Horoi, T. Otsuka, T. Suzuki, Y. Utsuno Spectroscopic information has been extracted on the hole-states of $^{55}$Ni. Using the $^1$H($^{56}$Ni,d)$^{55}$Ni transfer reaction in inverse kinematics, neutron spectroscopic factors, spins and parities have been extracted for the f$_{7/2}$, p$_{3/2}$ and the s$_{1/2}$ hole-states of $^{55}$Ni. These new data provide a benchmark for large basis calculations that include nucleonic orbits in both the sd and pf shells. Most shell models describe the ground state and the first p$_{3/2}$ excited state very well. However, most models have difficulties describing the deep hole state in the sd orbits. In this talk, we will compare the experimental energy levels and spectroscopic factors to state of the art shell model calculations. [Preview Abstract] |
Thursday, October 9, 2014 8:30PM - 8:45PM |
EC.00005: Reducing Ambiguities in Spectroscopic Factors and the 86Kr(d,p) Reaction at 35 MeV/u D. Walter, J.A. Cizewski, T. Baugher, A. Ratkiewicz, B. Manning, S.J. Lonsdale, S. Burcher, S.D. Pain, K.A. Chipps, F.M. Nunes, S. Ahn, P. Thompson, G. Cerizza, C. Thornsberry, K.L. Jones, D.W. Bardayan, P.D. O'Malley, R.L. Kozub, S. Ota Spectroscopic information for neutron-rich nuclei near the N$=$50 shell closure is important for understanding nuclear structure far from stability. The standard method of extracting spectroscopic factors suffers from serious ambiguities. Mukhamedzhanov and Nunes [1] have proposed that measuring a transfer reaction at both low (peripheral reaction) and higher (less-peripheral) energies should enable spectroscopic factors to be more reliably deduced, with uncertainties dominated by the experimental cross-sections rather than uncertainties in the bound-state potential. We have measured 86Kr(d,p) at 35MeV/u in inverse kinematics at the NSCL using the ORRUBA and SIDAR arrays of position-sensitive silicon strip detectors. The differential cross-section measurements will be combined with the published measurements at 5.5MeV/u [2] to extract spectroscopic factors for low-lying states in 87Kr, and to test the efficacy of this method. Preliminary results will be presented as well as plans to extend this approach to studies with radioactive ion beams. This work is supported in part by the NSF and the U.S. DOE. \\[4pt] [1] A.M. Mukhamedzhanov and F.M. Nunes, Phys. Rev. C 72, 017602 (2005).\\[0pt] [2] K. Haravu et al., Phys. Rev C 1,938 (1970). [Preview Abstract] |
Thursday, October 9, 2014 8:45PM - 9:00PM |
EC.00006: $^{89}$Zr(n,$\gamma$) from a surrogate reaction approach Shuya Ota, J.T. Burke, R.J. Casperson, J.E. Escher, R.O. Hughes, J.J. Ressler, N.D. Scielzo, I. Thompson, R.A.E. Austin, E. McCleskey, M. McCleskey, A. Saastamoinen, J. Benstead, T. Ross While recent studies have demonstrated the validity of the surrogate reaction approach for studying fission cross sections of short-lived actinides, its applicability for (n,$\gamma$) is still under investigation. We studied the $\gamma$-decay of $^{90}$Zr produced by $^{91}$Zr(p,d) in order to infer the $^{89}$Zr(n,$\gamma$) cross sections. The experiments were carried out at the K150 Cyclotron facility at Texas A\&M University with a 28.5-MeV proton beam. The reaction deuterons were measured at forward angles of 30-60$^{\circ}$ with the STARS (Silicon Telescope Array for Reaction Studies) array of three segmented Micron S2 silicon detectors. Compound nuclei with energies up to a few MeV above the neutron separation thresholds were populated. The coincident $\gamma$-rays were measured with the LiTeR (Livermore Texas Richmond) array of five Compton-suppressed HPGe clovers. We will present results of $\gamma$-emission probabilities of $^{89}$Zr(n,$\gamma$) and some theoretical discussions. [Preview Abstract] |
Thursday, October 9, 2014 9:00PM - 9:15PM |
EC.00007: Neutron hole states in $^{131}$Sn studied via the $^{132}$Sn(d,t)$^{131}$Sn reaction Riccardo Orlandi, S.D. Pain, D.W. Bardayan, C.J. Gross, M.S. Smith, A. Jungclaus, S. Ahn, K.L. Jones, S.T. Pittman, K.T. Schmitt, K.A. Chipps, J.A. Cizewski, M. Howard, B. Manning, P.D. O'Malley, A. Ratkiewicz, W.A. Peters, M. Matos, R. Chapman, J.F. Smith, W. Catford, C. Shand Knowledge of single-particle energies in the vicinity of exotic doubly-magic nuclei is of critical importance to understand evolution of nuclear structure. In the present work, the $^{132}$Sn(d,t)$^{131}$Sn reaction (Q=-1.055 MeV) was studied in inverse kinematics at HRIBF of Oak Ridge National Laboratory. The $^{132}$Sn ISOL beam was post-accelerated to an energy of 4.39~MeV/u using the ORNL HRIBF accelerator. The beam (average intensity of $\sim$1.2e4 pps) impinged on a $\sim$250-$\mu$g/cm$^2$ deuterated polyethylene target, for approximately 4 days. Ejected tritons were detected using the Super ORRUBA array of segmented Si telescopes. Low-lying states in $^{131}$Sn were populated in the experiment. Preliminary results will be shown. [Preview Abstract] |
Thursday, October 9, 2014 9:15PM - 9:30PM |
EC.00008: Study of the levels in $^{12}$N using the $^{14}$N(p,t) reaction with JENSA K.A. Chipps, U. Greife, D.W. Bardayan, J.C. Blackmon, L.E. Linhardt, A. Kontos, H. Schatz, R.L. Kozub, M. Matos, S.D. Pain, M.S. Smith, S.T. Pittman, A. Sachs, K.T. Schmitt, P. Thompson Based on consideration of the isobaric analogues $^{12}$B and $^{12}$C, the experimental information on $^{12}$N is incomplete, with a number of inconsistencies between the compilations and the results of individual studies. As one of a series of commissioning physics measurements to demonstrate the benefit of the new Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas jet target for enabling next-generation transfer reaction studies, the $^{14}$N(p,t)$^{12}$N reaction was studied using a pure 300 psig jet of nitrogen, in order to help elucidate the structure of $^{12}$N. The experiment and results will be discussed. [Preview Abstract] |
Thursday, October 9, 2014 9:30PM - 9:45PM |
EC.00009: Systematic study of excited $0^+$ states in the Er isotopes populated in the $(p,t)$ reaction P.E. Garrett, A. Finlay, D. Kisliuk, S. Chagnon-Lessard, A. Diaz Varela, R. Dunlop, D.S. Jamieson, K.G. Leach, C.E. Svensson, G.C. Ball, S. Triambak, T. Faestermann, R. Hertenberger, H.-F. Wirth The nature of excited $0^+$ states in well-deformed nuclei continue to pose a challenge in nuclear structure. Often, even the nature of the first excited $0^+$ state, $0^+_2$, is unclear and interpretations involving $\beta$ vibrations, pairing excitations, two-phonon $\gamma$ vibrations, etc., have been advanced with different degrees of success. A major issue historically has been lack of data on excited $0^+$ states. In light of this, the study of the Er isotopes has been extended via the $^{162}$Er and $^{164}$Er $(p,t)$ reactions. The experiments were performed at the Maier-Leibnitz Laboratory using 22 MeV proton beams on highly-enriched targets of $^{162,164}$Er, and the reaction products were analyzed with the Q3D spectrograph. Strong populations of the $0^+_2$ states have been observed. The systematics of the strong population of the $0^+$ states in the Er$(p,t)$ reactions sheds light on the underlying nature of these levels. [Preview Abstract] |
Thursday, October 9, 2014 9:45PM - 10:00PM |
EC.00010: Thermonuclear Reaction Rate of T(t,2n)$\alpha$ Measured in ICF Plasmas C.R. Brune, D.T. Casey, J.A. Caggiano, R. Hatarik, D.P. McNabb, D.B. Sayre, V.A. Smalyuk, A.D. Bacher, J.A. Frenje, M. Gatu-Johnson, A.B. Zylstra, M. Couder Measurements of charged-particle reactivity have been performed in inertial confinement fusion experiments at the National Ignition Facility. Time-of-flight detectors were used to measure neutrons from the T(t,2n) and T(d,n) reactions produced by implosions with tritium-filled targets (0.1\% deuterium). Along with the measured target fuel composition and reactant ion temperature, the well-known T(d,n) reactivity was used to convert the measured neutron yields into a T(t,2n) reactivity. The ion temperature was determined to be 3.3(3)~keV, corresponding to an effective energy of 16~keV. In comparison to accelerator measurements of the low-energy T(t,2n) cross section, the source of all previous data, our experiment has resulted in T(t,2n) data with better statistics and lower backgrounds. [Preview Abstract] |
Thursday, October 9, 2014 10:00PM - 10:15PM |
EC.00011: Screening potential of the d(d,p)t reaction in liquid In and Sn measured for 10 $\leq$ $E_{D_3^+}$ $\leq$ 60 keV Yuki Honda Although large values of the screening potential of the d+d reaction in metals were reported, the experiments so far performed are not faultless but possibly bring large errors due to uncertainties of target deuteron density. We have found a new reaction process which ensures to determine the screening potential more accurately. The process is unique to the molecular beam: we call it ``cooperative colliding mechanism''(CCM). Liquid In and Sn were bombarded by $D_3^+$ beams from 10 to 60 keV. Protons from the d(d,p)t reaction were measured by a Si detector. Characteristics of the results are: 1. For the proton peak, the shape is very broad and is largely skewed. 2. An excitation function of the yield is different from the thick target yield of the d(d,p)t reaction. 3. No yields of the d+d reaction for the bombardment with an atomic $D^+$ beam. These features are well explained by introducing the CCM in which two deuterons in a molecule collide after one deuteron in the molecule is elastically scattered by a host metal. Thus the target deuteron density can be determined very accurately. Detailed analyses give reliable information on the screening potential of the d+d reaction surrounded by conduction electrons; they are Ue=100$\pm$50 and 350$\pm$50eV for In and Sn, respectively. [Preview Abstract] |
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