Bulletin of the American Physical Society
2007 Annual Meeting of the Division of Nuclear Physics
Volume 52, Number 10
Wednesday–Saturday, October 10–13, 2007; Newport News, Virginia
Session JD: Mini-Symposium on Radioactive Beams and Observations in Nuclear Astrophysics II |
Hide Abstracts |
Chair: Ani Aprahamian, University of Notre Dame Room: Newport News Marriott at City Center Grand Salon IV |
Saturday, October 13, 2007 2:00PM - 2:12PM |
JD.00001: New Insights and Opportunities from Thermonuclear X-ray Bursts Tod Strohmayer, Sudip Bhattacharyya The last decade has seen great strides in our observational understanding of thermonuclear X-ray bursts from accreting neutron stars. This observational renaissance has largely been enabled by sensitive, high time resolution observations with NASA's Rossi X-ray Timing Explorer (RXTE). These new observations provide an opportunity to probe neutron stars, and their complex physics, with unprecedented detail. I will discuss recent work on observations and modeling of double-peaked bursts and burst oscillations. This will include a description of what these phenomena can tell us about neutron stars, as well as highlighting the important connections to the nuclear physics which ultimately drives the bursts. [Preview Abstract] |
Saturday, October 13, 2007 2:12PM - 2:24PM |
JD.00002: Measurements of Lifetimes of States in $^{19}$Ne and the $^{15}$O($\alpha,\gamma)^{19}$Ne Reaction Rate Barry Davids, Mythili Subramanian We have measured the lifetimes of several states in $^{19}$Ne above the $\alpha$ emission threshold important in the $^{15}$O($\alpha,\gamma)^{19}$Ne reaction. Combining these and other lifetime measurements with measurements of the $\alpha$ decay branching ratios of these states, we evaluate the rate of the $^{15}$O($\alpha,\gamma)^{19}$Ne reaction and discuss its role in Type-I X-ray bursts. [Preview Abstract] |
Saturday, October 13, 2007 2:24PM - 2:36PM |
JD.00003: High precision $^{24}$Mg(p,t)$^{ 22}$Mg reaction to determine the $^{18}$Ne($\alpha $,p)$^{21}$Na reaction rates A. Matic, A.M. van den Berg, H.J. W\"ortche, M.N. Harakeh, T. Adachi, Y. Fujita, Y. Shimbara, H. Fujita, K. Fujita, K. Hatanaka, Y. Sakemi, Y. Shimizu, Y. Tameshige, A. Tamii, M. Yosoi, J. G\"orres, P. Leblanc, M. Wiescher, G.P.A. Berg, S. O'Brien, H. Schatz, T. Wakasa The direct measurements of astrophysically interesting reactions are best possible tools in order to investigate stellar reaction rates. Often indirect techniques can be used to obtain nuclear physics information needed by astrophysical models. We performed $^{24}$Mg(p,t)$^{ 22}$Mg experiment at RCNP by use the Grand Raiden spectrometer and the WS beam line. In this experiment we achieved an unprecedented resolution of 13 keV for (p,t) experiment and we were able to resolve 12 new levels in $^{22}$Mg. We shoved that for $^{18}$Ne($\alpha $,p)$^{21}$Na reaction the most dominant resonances at low stellar temperatures are 5 very closely spaced resonances between 8.2-8.6 MeV. Present experiment gave a valuable data necessary for the calibration and guidance for the future direct experiments. We showed that resolution necessary for the direct $^{18}$Ne($\alpha $,p)$^{21}$Na reaction measurements need to be about 30 keV. The experimental technique will be discussed, experimental results and reaction rates will be presented. [Preview Abstract] |
Saturday, October 13, 2007 2:36PM - 2:48PM |
JD.00004: Indirect rp-process Rate Measurements from Single Neutron Removal A.M. Amthor, D. Bazin, A. Becerril, A. Cole, J. Cook, A. Estrade, A. Gade, M. Howard, G. Lorusso, M. Matos, J. Pereira, M. Portillo, H. Schatz, B. Sherrill, K. Smith, A. Stolz, D. Weisshaar, R.G.T. Zegers, D. Galaviz, A. Chen, Zs. Fulop, E. Smith, M. Wiescher The structure of nuclei along the rp-process path in Type I X-ray bursts has been studied using neutron removal from radioactive beams produced at the National Superconducting Cyclotron Laboratory. Recently, $^{37}$Ca and $^{36}$K have been studied in this way to reduce the uncertainty in $^{35}$Ar(p,$\gamma$)$^{36}$K and $^{36}$K(p,$\gamma$)$^{37}$Ca reaction rates, which are important during burst rise. Under burst conditions these rates are dominated by resonant capture contributions from individual resonances because of the low level density just above the proton threshold, precluding the use of statistical methods based on level density to determine the reaction rates. Therefore, precise structure measurements are required to reduce the orders of magnitude rate uncertainty in these key reactions and thereby constrain X-ray burst models. Preliminary results will be presented along with the implications for X-ray burst models. [Preview Abstract] |
Saturday, October 13, 2007 2:48PM - 3:00PM |
JD.00005: Nuclear energy levels of $^{31}$S and astrophysical implications C. Wrede, J.A. Caggiano, J.A. Clark, C. Deibel, D.A. Hutcheon, R. Lewis, A. Parikh, P.D. Parker, C. Westerfeldt Nucleosynthesis in the mass range from silicon to calcium in oxygen-neon novae is heavily influenced by the unmeasured strength of the $^{30}$P$(p,\gamma)^{31}$S reaction. We have studied the $^{31}$P$(^{3}$He$,t)^{31}$S and $^{31}$P$(^{3}$He$,t)^{31}$S$^{*}(p)^{30}$P reactions to measure resonance energies and proton branching ratios in the $^{30} $P$~+~p$ system. Our results will be presented in the contexts of novae, x-ray bursts and oxygen burning in massive stars. A direct measurement of resonance strengths in the $^{30}$P$(p,\gamma)^ {31}$S reaction is planned for the future. [Preview Abstract] |
Saturday, October 13, 2007 3:00PM - 3:12PM |
JD.00006: First experimental evidence of the rp-process nucleus $^{96}$Cd A. Becerril Reyes, V. Andreev, B. Arend, D. Bazin, M. Doleans, R. Fontus, P. Glennon, P. Mantica, J. Ottarson, D. Sanderson, H. Schatz, J. Stoker, O. Tarasov, J. Vincent, J. Wagner, X. Wu, A. Zeller The rapid proton capture process has been proposed as the mechanism that powers the observed type I X-ray bursts in the universe. The time scale for the rp-process is governed by the beta-decay half-lives of several even-even N = Z waiting point nuclei, in particular, $^{96}$Cd is the only one with an unknown beta decay half-life between $^{56}$Ni and $^{100}$Sn. The recently built Radio Frequency Fragment Separator (RFFS) at the NSCL filters out unwanted particles in rare proton rich beams according to their velocities, thus improving the beam purity by several orders of magnitude. The RFFS was successfully commissioned in May 2007 and used to identify $^{96}$Cd nuclei for the first time. Preliminary results on the production rate of $^{96}$Cd will be presented. [Preview Abstract] |
Saturday, October 13, 2007 3:12PM - 3:24PM |
JD.00007: St. George a first step toward a recoil separator for FRIB Manoel Couder, Georg P. Berg, Joachim Goerres, Larry O. Lamm, P.J. Leblanc, Edward Stech, Michael Wiescher In explosive environments, nuclear reactions involving radioactive ions play a crucial role. The advent of high intensity radioactive beams triggered the development of recoil separators to study proton and $\alpha$ radiative capture. However, existing devices have typically been designed based on a single reaction which limits, de facto, their specifications. At the University of Notre Dame, a large acceptance recoil separator to study radiative capture induced by stable beams (A$<$40) has been developed. Based on our experience we will expose the possible directions of a separator for FRIB (Facility for Rare-isotope Beams) dedicated to the study of reaction of astrophysical interest. [Preview Abstract] |
Saturday, October 13, 2007 3:24PM - 3:36PM |
JD.00008: The JINA Reaclib Database and Nuclear Astrophysics Applications. Richard Cyburt, Hendrik Schatz, Karl Smith, Scott Warren Nuclear astrophysics is a rich and vital field of study, using experimental/theoretical input for calculations of processes that create the elements we are made from. In order to facilitate this research further, the Joint Institute for Nuclear Astrophysics (JINA) has created a public, web-based database for nuclear reaction rates. Data are stored in the standard Reaclib format and are continually updated as new data or new compilations become available. A versioning system has been adopted to keep track of new rates. Recommended rate libraries representing ``snap shots'' of the live database are stored for users wanting a fixed/unchanging set of rates. The database and its use will be presented with emphasis on its role in nuclear astrophysics calculations. For more information, see the JINA Reaclib website: http://www.nscl.msu.edu/$\sim$nero/db. [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