Bulletin of the American Physical Society
2007 APS April Meeting
Volume 52, Number 3
Saturday–Tuesday, April 14–17, 2007; Jacksonville, Florida
Session Y15: Minisymposium on Nuclear Astrophysics with Transfer Reactions II |
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Sponsoring Units: DNP Chair: Michael Wiescher, University of Notre Dame Room: Hyatt Regency Jacksonville Riverfront City Terrace 11 |
Tuesday, April 17, 2007 1:30PM - 1:42PM |
Y15.00001: $^{26}$Si and $^{30}$S studied via $(p,t)$ reactions using the Silicon Detector Array (SIDAR) D.W. Bardayan, J.C. Blackmon, J.F. Liang, M.S. Smith, C.R. Brune, K.Y. Chae, Z. Ma, J.A. Howard, R.L. Kozub, M.S. Johnson, K.L. Jones, S.D. Pain, J.S. Thomas, R.J. Livesay, D.W. Visser Spectroscopic studies of proton-rich nuclei are critical to evaluating thermonuclear reaction rates of importance to Hot- CNO and $rp$-process nucleosynthesis. One powerful method is to measure the energy and angular distributions of tritons produced in the $(p,t)$ reaction on stable targets. We have recently implemented such studies at ORNL using $\sim$40 MeV proton beams. Tritons were identified and detected in the SIDAR array, which allows data to be acquired over a large solid angle and at 16 angles simultaneously. Our first studies are of the $^ {26}$Si and $^{30}$S nuclei, which are produced by the $^{25}$Al ($p,\gamma$)$^{26}$Si and $^{29}$P($p,\gamma$)$^{30}$S reactions in novae, respectively. Details of the method and results will be presented. [Preview Abstract] |
Tuesday, April 17, 2007 1:42PM - 1:54PM |
Y15.00002: Studying the $^{25}$Al(p,gamma)$^{26}$Si reaction using the analogous single proton transfer reaction d($^{25}$Al,$^{26}$Si)n. Patrick Peplowski, Ingo Wiedenhoever, Lagy T. Baby, Alexander Rojas, Eric Diffenderfer A radioactive beam of $^{25}$Al has successfully been created via the d($^{24}$Mg,$^{25}$Al)n reaction using the RESOLUT radioactive beam facility located at Florida State University. This beam has been used in an experiment with the d($^{25}$Al,$^{26}$Si)n single proton transfer reaction, which is analogous to the astrophysically interesting $^{25}$Al(p,gamma)$^{26}$Si proton capture. The experiment aims to identify the astrophysically significant lowest 3$^{+}$ state above the proton threshold, which is expected to be the dominant contributor to $^{25}$Al(p,gamma)$^{26}$Si. The proton-transfer reaction allows to identify the l=0 proton transfer to the resonances in question. Results from this experiment, will be presented. Details of $^{25}$Al beam production and conditioning using the new RESOLUT facility will also be discussed. \newline [Preview Abstract] |
Tuesday, April 17, 2007 1:54PM - 2:06PM |
Y15.00003: Alpha-cluster resonances in $^{23}$Na near $^{19}$F+$\alpha$ threshold. B.W. Green, G.V. Rogachev, E. Johnson, A.M. Crisp, K.W. Kemper, V.Z. Goldberg, A. Mukhamedzhanov, M. La Cognita, R.G. Pizzone, S. Romano, C. Spitaleri, A. Tumino Abundance of $^{19}$F in AGB stars is enhanced by a factor of 2-30 with respect to the solar abundance [1]. This observation provides strong evidence that $^{19}$F is produced in the interior of AGB stars. It was shown in [2] that the final abundance of $^{19}$F depends strongly on the $^{19}$F($\alpha$,p) reaction rate. No experimental data is available for the $^{19}$F($\alpha$,p) reaction cross section below $E_{\alpha}$ = 1.3 MeV. Extrapolation of the $^{19}$F($\alpha$,p) cross section down to the relevant energy range is uncertain due to the unknown properties of relevant resonances in $^{23}$Na. It is the main goal of this work to identify resonances in $^{23}$Na, which may be important for the $^{19}$F($\alpha$,p) reaction. Resonances in $^{23}$Na were populated with a $^{19}$F($^6$Li,d)$^{23}$Na reaction, using a 23 MeV $^6$Li beam. Deuterons were detected at forward angles in coincidence with protons from the proton decay of $^{23}$Na resonances. Angular correlation between deuterons and protons allows for spin-parity assignments for the populated resonances while the magnitude of the $^{19}$F($^6$Li,d) cross section gives information regarding the $\alpha$ spectroscopic factor of the $^{23}$Na. [1] A. Jorissen, et al., A\&A, 261 (1992) 164. [2] M. Lugaro, et al., ApJ, 615 (2004) 934. [Preview Abstract] |
Tuesday, April 17, 2007 2:06PM - 2:18PM |
Y15.00004: The level structure of $^{19}$Ne via measurement of the $^{2}$H($^{18}$F,$\alpha +^{15}$O)n reaction. A.S. Adekola, C.R. Brune, Z. Heinen, M.J. Hornish, T.N. Massey, A.V. Voinov, D.W. Bardayan, J.C. Blackmon, C.D. Nesaraja, M.S. Smith, A. Chae, C. Domizioli, Z. Ma, B. Moazen, A.E. Champagne, D.W. Visser, U. Greife, R. Livesay, M. Porter - Peden, M. Johnson, K.L. Jones, S.D. Pain, J.S. Thomas, R.L. Kozub, J.F. Shriner, N.D. Smith The $^{18}$F(d,n)$^{19}$Ne and $^{18}$F(d,p)$^{19}$F reactions have been measured simultaneously at E$_{c.m. }$= 14.9 MeV at ORNL's HRIBF with a radioactive $^{18}$F beam. The $^{19}$Ne excited states near the proton threshold are potentially important for the $^{18}$F(p,$\alpha )$ reaction rate in novae. These states decay by breakup into $\alpha +^{15}$O which were detected in coincidence with position-sensitive E--$\Delta $E telescopes. The neutron (proton) angular distributions for states in $^{19}$Ne ($^{19}$F) were extracted using momentum conservation. Information on the spins and spectroscopic strengths of these states will be presented and $^{19}$Ne -- $^{19}$F mirror symmetry will be discussed. [Preview Abstract] |
Tuesday, April 17, 2007 2:18PM - 2:30PM |
Y15.00005: The $^{130}$Sn(d,p)$^{131}$Sn Reaction in Inverse Kinematics R.L. Kozub, J.F. Shriner, Jr., A. Adekola, D.W. Bardayan, J.C. Blackmon, F. Liang, C.D. Nesaraja, D. Shapira, M.S. Smith, K.Y. Chae, K.L. Jones, Z. Ma, B.H. Moazen, K. Chipps, U. Greife, L. Erikson, J.A. Cizewski, R. Hatarik, S.D. Pain, C. Matei, W. Krolas, T.P. Swan The r-process is thought to be responsible for the synthesis of about half of the nuclear species heavier than Fe, but little experimental information is available for nuclear structure and the r-process near the N=82 closed neutron shell and the A$\sim$130 abundance peak. We have acquired (d,p) reaction data on $^{130}$Sn and $^{132}$Sn$^1$ in inverse kinematics using 630 MeV beams (4.85 MeV/u for $^{130}$Sn) and a CD$_2$ target of effective thickness $\simeq$160 $\mu$g/cm$^2$. An array of 20 Si strip detectors was used to detect reaction products in the range $\theta_{lab}\simeq$67$^{\circ}$-167$^{\circ}$. The $^2$H($^{130}$Te,p)$^{131}$Te reaction was used for calibration purposes. More experimental details and a status report on the analysis will be presented. \\ \\ $^1$K. L. Jones, invited talk at this meeting. \\ \\ Research supported by the U. S. Dept. of Energy, the National Science Foundation, and the LDRD program at ORNL. [Preview Abstract] |
Tuesday, April 17, 2007 2:30PM - 2:42PM |
Y15.00006: Measurement of the $^{134}$Te(d,p)$^{135}$Te reaction in inverse kinematics S.D. Pain, J.A. Cizewski, R. Hatarik, P.D. O'Malley, T.P. Swan, D.W. Bardayan, J.C. Blackmon, F. Liang, C.D. Nesaraja, D. Shapira, M.S. Smith, K.Y. Chae, K.L. Jones, B.H. Moazen, R.L. Kozub, J.F. Shriner, Jr., C. Matei, K. Chipps, R.J. Livesay \noindent The development of high quality radioactive beams, such as those at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory, along with new large solid-angle detector arrays such as ORRUBA, have made possible the performance of transfer reactions in inverse kinematics on unstable nuclei. The measurement of (d,p) reactions on neutron- rich fission fragments yield data on the development of nuclear structure away from stability, which is of astrophysical interest due to the proximity to suggested r-process paths. A campaign of (d,p) measurements on neutron-rich N$\sim$82 nuclei is underway at the HRIBF. The $^{134}$Te(d,p)$^{135}$Te reaction has been measured in inverse kinematics at the HRIBF utilizing a beam of $^{134}$Te at 643 MeV and a deuterated plastic target. Proton ejectiles were detected forward and backwards of $\theta_{lab}$ = $90^{\circ}$ using an early implementation of the ORRUBA silicon detector array. Details of the experiment, and a report of the current stage of the analysis will be presented. [Preview Abstract] |
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