Bulletin of the American Physical Society
2011 Fall Meeting of the APS Division of Nuclear Physics
Volume 56, Number 12
Wednesday–Saturday, October 26–29, 2011; East Lansing, Michigan
Session CB: Mini-Symposium on Experimental Advances in Transfer Reactions I |
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Chair: Ernst Rehm, Argonne National Laboratory Room: Auditorium |
Thursday, October 27, 2011 8:30AM - 9:06AM |
CB.00001: Perspectives in the Study of Transfer Reactions Invited Speaker: Sean Freeman The push to study the properties of nuclei far from stability has led to a renewed interest in the use of direct transfer reactions. For example, establishing the single-particle excitations in nuclei is essential to determining a framework within which to properly understand nuclear structure; single-nucleon transfer reactions provide an important experimental probe to accomplish this. In addition, reactions involving the exchange of several nucleons can provide probes of the evolution of pairing and clustering in exotic systems. Recent glimpses into the structure of exotic nuclei have indicated considerable changes in shell structure away from stability and these findings have acted as a spur for both radioactive beam measurements, as well as detailed investigations using stable projectiles. This talk will discuss the experimental requirements for performing transfer-reaction studies. Results from recent experiments will be used to highlight the different experimental techniques that can be adopted to take advantage of the opportunities that will be made available by the new facilities that are currently being designed and constructed. [Preview Abstract] |
Thursday, October 27, 2011 9:06AM - 9:18AM |
CB.00002: Knockout, Transfer and Spectroscopic Factors Kirby Kemper, Nicholas Keeley, Krzysztof Rusek As derived quantities rather than observables, spectroscopic factors extracted from fits to data are model dependent. The main source of uncertainty is the choice of binding potential, but other factors such as adequate modeling of the reaction mechanism, the Perey effect, choice of distorting nuclear potentials etc.\ can also play a significant role. Recently, there has been some discussion of apparent discrepancies in spectroscopic factors derived from knockout reactions compared to those obtained from low-energy direct reactions. It should be possible to reconcile these discrepancies and we explore this prospect by attempting to describe the $^{10}$Be(d,t)$^9$Be data of Nucl. Phys. {\bf A157}, 305 (1970) using the $^{10}$Be/$^9$Be form factors from a recent knockout study, Phys. Rev. Lett. {\bf 106}, 162502 (2011). The influence of such factors as choice of distorting potentials and multi-step reactions paths will be explored. [Preview Abstract] |
Thursday, October 27, 2011 9:18AM - 9:30AM |
CB.00003: Study of the $^{19}$O$(d,p)$ reaction in inverse kinematics with HELIOS C.R. Hoffman, M. Alcorta, B.B. Back, S.I. Baker, P.F. Bertone, J.A. Clark, B. DiGiovine, B.P. Kay, R.C. Pardo, K.E. Rehm, J.P. Schiffer, C.M. Deibel, S.T. Marley, J.C. Lighthall, S. Bedoor, D.V. Shetty, A.H. Wuosmaa, S.J. Freeman, D.K. Sharp, J.S. Thomas, A. Rojas, D. Santiago-Gonzalez, I. Wiedenh\"{o}ver The neutron single-particle components of states in $^{20}$O have been probed through the $(d,p)$ reaction in inverse kinematics. The experiment consisted of a 125 MeV radioactive $^{19}$O beam, produced by the ATLAS In-Flight facility at Argonne National Laboratory, impinging on a [(C$_{2}$D$_{4}$)$_{\rm n}$] target located inside the HELIcal Orbit Spectrometer (HELIOS). A Q-value resolution of $\sim150$~KeV was achieved for states in $^{20}$O. Absolute cross sections and angular distributions have been determined for a number of levels in $^{20}$O up to 7~MeV in excitation energy. A strong candidate for the previously unobserved $\ell=0$ $3^{+}$ level at 5.2~MeV has been identified. The extracted spectroscopic factors for $\ell=2$ (presumably $\nu0d_{5/2}$) and $\ell=0$ ($\nu1s_{1/2}$) transitions will be compared to those along the $Z=8$ isotopic chain and to microscopic calculations. [Preview Abstract] |
Thursday, October 27, 2011 9:30AM - 9:42AM |
CB.00004: The evaluation of a new method to extract spectroscopic factors using asymptotic normalization coefficients and the astrophysical $^{14}$C(n,$\gamma$)$^{15}$C reaction rate M. McCleskey, A.M. Mukhamedzhanov, L. Trache, A. Banu, V. Goldberg, B.T. Roeder, E.N. Simmons, A. Spiridon, R.E. Tribble A new method to determine spectroscopic factors (SFs) that utilizes asymptotic normalization coefficients (ANCs) has been tested at Texas A$\&$M, using $^{15}$C as a test case. The method would use the ANC to fix the external contribution to a non-peripheral reaction which would otherwise be free to vary to unphysical values in a traditional approach. The investigation consisted of two parts. First, the ANC for the $^{14}$C+n configuration in $^{15}$C was determined from the heavy ion neutron transfer reaction $^{13}$C($^{14}$C,$^{15}$C)$^{12}$C and the inverse kinematics reaction d($^{14}$C,p)$^{15}$C. Both of these reactions were measured at sufficiently low energy to be peripheral. Next, a non-peripheral reaction $^{14}$C(d,p)$^{15}$C was measured with an incident deuteron energy of 60 MeV, and this reaction was used along with the previously determined ANC to attempt to find the SF. The ANC was also used to calculate the astrophysical neutron direct capture rate for $^{14}$C(n,$\gamma$)$^{15}$C, which was compared with recent direct experimental results. [Preview Abstract] |
Thursday, October 27, 2011 9:42AM - 9:54AM |
CB.00005: One and two-neutron transfer reactions at REX-ISOLDE Kathrin Wimmer In this contribution we will report on one and two neutron transfer reaction experiments in inverse kinematics at the REX-ISOLDE facility (CERN). Light charged target-like reaction products were detected and identified by the T-REX particle detector [1] while coincident $\gamma$-rays were detected by the MINIBALL Germanium detector array. Recent results on (d,p) as well as (t,p) reactions with radioactive beams ranging from 11Be to 78Zn isotopes will be presented. The two-neutron transfer reactions involved for the first time the use of a radioactive tritium target in combination with a radioactive heavy ion beam [2]. \\[4pt] [1] V. Bildstein et al., Prog. Part. Nucl. Phys. 59 (2007) 386. \\[0pt] [2] K. Wimmer et al., Phys. Rev. Lett. 105 (2010) 252501. [Preview Abstract] |
Thursday, October 27, 2011 9:54AM - 10:06AM |
CB.00006: Measurement of the 26Al(d,p)27Al Reaction to Constrain the 26Al(p,gamma) Reaction Rate Steven Pain Detailed observations of the 1809-keV $\gamma$ ray from the beta decay of $^{26}$Al within the galaxy has provided an insight into ongoing nucleosynthesis. Understanding the abundance of $^{26}$Al requires knowledge of the production and destruction rates for $^{26}$Al. For temperatures where the ground-state and metastable state of $^{26}$Al are decoupled, the $^{26}$Al(p,$\gamma$)$^{27}$Si reaction, which is determined by states near the proton threshold in $^{27}$Si, contributes to the destruction rate. Though the strength of many of these resonances have been measured directly, the information there remain uncertainties for the lowest resonances, which are relevant for giant star temperatures. We have measured mirror states in $^{27}$Al to inform the $^{27}$Si structure, via the $^{26}$Al(d,p)$^{27}$Al reaction in inverse kinematics at the HRIBF. A beam of $\sim$5 million $^{26}$Al per second impinged on a $\sim$150 $\mu$g/cm$^2$ CD$_2$ target. Proton ejectiles were detected in the SIDAR and ORRUBA silicon detector arrays. Details of the experimental setup and results will be presented. Work supported in part by U.S. Department of Energy and National Science Foundation. [Preview Abstract] |
Thursday, October 27, 2011 10:06AM - 10:18AM |
CB.00007: Exploring the single-particle structure of $^{11}$Be with the one-neutron transfer reaction $^2$H$(^{10}$Be$,p)^{11}$Be Kyle Schmitt The one-neutron transfer reaction $^2$H$(^{10}$Be$,p)^{11}$Be was studied at equivalent deuteron energies of 12.0, 15.0, 18.0, and 21.4 MeV using batch mode beams at the HRIBF at ORNL. Elastic (d,d) and inelastic (d,d') scattering were observed simultaneously with transfer to the bound states and low-lying resonances in inverse kinematics. The energies and angles of light ions emitted from the reactions were measured in the SIDAR and ORRUBA silicon detector arrays. These data are compared with reaction calculations to extract spectroscopic factors. Comparison of analyses using DWBA and more sophisticated reaction theories will be presented as well as several new experimental tools useful for transfer reaction experiments. [Preview Abstract] |
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