Bulletin of the American Physical Society
2016 Fall Meeting of the APS Division of Nuclear Physics
Volume 61, Number 13
Thursday–Sunday, October 13–16, 2016; Vancouver, BC, Canada
Session HJ: Mini-symposium on Nuclear AstrophysicsMini-Symposium
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Chair: Iris Dillmann, TRIUMF Room: Junior Ballroom A |
Saturday, October 15, 2016 8:30AM - 9:06AM |
HJ.00001: Thermonuclear runaways investigated using drip line beta decays Invited Speaker: Christopher Wrede In close binary star systems, mass transfer onto the surface of a white dwarf or neutron star can lead to spectacular periodic emissions including classical novae and x-ray bursts. Accurate nuclear reaction rates are needed to model energy generation and nucleosynthesis in these thermonuclear runaways enabling meaningful comparisons to observations. An experimental program has been established at the National Superconducting Cyclotron Laboratory to constrain the most influential nuclear physics uncertainties using the beta decays of nuclides adjacent to the proton drip line. In particular, the beta decays of $^{\mathrm{20}}$Mg, $^{\mathrm{26}}$P, and $^{\mathrm{31}}$Cl have been used to investigate the $^{\mathrm{15}}$O($\alpha $,$\gamma )^{\mathrm{19}}$Ne, $^{\mathrm{25}}$Al(p,$\gamma )^{\mathrm{26}}$Si, and $^{\mathrm{30}}$P(p,$\gamma )^{\mathrm{31}}$S reaction rates, respectively. These studies relate to the shapes of x-ray burst light curves, the production of the radionuclide $^{\mathrm{26}}$Al in the Milky Way, and the identification of presolar nova grains in meteoritic material. [Preview Abstract] |
Saturday, October 15, 2016 9:06AM - 9:18AM |
HJ.00002: Measurement of ${}^{34}$Ar(α,p)${}^{37}$K using the JENSA Gas Jet Target Justin Browne, Kelly Chipps, Hendrik Schatz, Konrad Schmidt X-ray bursts are very luminous thermonuclear explosions that occur in binary star systems. In these systems, a neutron star accreting matter from a companion star undergoes increased thermonuclear burning, which causes a breakout from the hot CNO cycle into the αp-process. The rates of (α,p) reactions can significantly impact the lightcurve and elemental abundances resulting from the X-ray burst. Using a radioactive ion beam at the National Superconducting Cyclotron Laboratory (NSCL), the Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas jet target is used to directly measure (α,p) reactions. The ${}^{34}$Ar(α,p)${}^{37}$K reaction rate was measured by detecting reaction products in the SuperORRUBA silicon detector array and a position-sensitive ionization chamber, while γ-rays were detected in the HAGRiD LaBr${}_{3}$ detector array. Preliminary results from this experiment will be presented. [Preview Abstract] |
Saturday, October 15, 2016 9:18AM - 9:30AM |
HJ.00003: Reduced Uncertainties in the Supernova Production of the Gamma Emitting Nuclei $^{26}$Al, $^{44}$Ti, and $^{60}$Fe Using Effective Helium Burning Rates Sam M Austin, Christopher West, Alexander Heger Uncertainties in the helium burning reaction rates caused large uncertainties in previous predictions of the production of the gamma emitting nuclei $^{26}$Al and (especially) $^{60}$Fe in core collapse supernovae. This precluded a meaningful comparison of the predictions with observed gamma ray intensities. We present results using a newly developed effective reaction rate (ERR) for the helium burning reactions to predict the yields of $^{26}$Al, $^{44}$Ti, and $^{60}$Fe. The resulting yield uncertainties using the ERR are much smaller than obtained previously, and smaller than other uncertainties. The yield ratio, $^{60}$Fe/$^{26}$Al, had variations of less than 20 percent and appears to be the most robust observable related to the production of these nuclei. We also estimated the effects of failed supernovae on the yields by using a compactness filter. This substantially reduced the three yields but the ratio, $^{60}$Fe/$^{26}$Al, was little affected. [Preview Abstract] |
Saturday, October 15, 2016 9:30AM - 9:42AM |
HJ.00004: Evaluation of resonances above the proton threshold in $^{26}$Si K.A. Chipps $^{26}$Al remains an intriguing target for observational gamma-ray astronomy, thanks to its characteristic decay. The $^{25}$Al(p,$\gamma$)$^{26}$Si reaction is the crucial link in a sequence that bypasses the production of the observable $^{26}$Al$^{g.s.}$ in favor of the isomeric state, and as such has been the focus of many studies. Considerable confusion in this regard has arisen from the use of outdated excitation energies and masses in reaction studies and rate evaluations. Recalibration of existing data from the literature has resulted in updated excitation and resonance energies, but open questions remain, particularly with regard to spin assignments and partial widths/resonance strengths. A discussion of the levels just above the proton threshold in $^{26}$Si relevant to the astrophysical $^{25}$Al(p,$\gamma$)$^{26}$Si reaction rate will be presented. [Preview Abstract] |
Saturday, October 15, 2016 9:42AM - 9:54AM |
HJ.00005: Study of the $^{17}$F($p,\alpha$)$^{14}$O reaction at $TwinSol$ D.W. Bardayan, T. Ahn, J.M. Allen, M. Brodeur, B. Frentz, Y.K. Gupta, M.R. Hall, O. Hall, S. Henderson, J. Hu, J.M. Kelly, J.J. Kolata, A. Long, C. Nicoloff, P.D. O'Malley, K. Ostdiek, M.K. Smith, S. Strauss, F.D. Becchetti, J. Riggins, R.O. Torres-Isea, J.C. Blackmon, K. Macon, S.D. Pain The $^{14}$O($\alpha,p$)$^{17}$F reaction is an important trigger reaction to the $\alpha p$ process in X-ray bursts. The best experimental constraints on its astrophysical rate come from measurements of the time-inverse reaction, $^{17}$F($p,\alpha$)$^{14}$O. Previous studies of this inverse reaction have nicely characterized the high-energy dependence of the cross section but there are still significant uncertainties at lower energies. A new measurement of the $^{17}$F($p,\alpha$)$^{14}$O cross section is underway at the University of Notre Dame $TwinSol$ facility using an in-flight secondary $^{17}$F beam. Initial tests will be presented along with plans for the completion of the measurement. [Preview Abstract] |
Saturday, October 15, 2016 9:54AM - 10:06AM |
HJ.00006: Ab initio calculations of nuclear reactions important for astrophysics Petr Navratil, Jeremy Dohet-Eraly, Angelo Calci, Wataru Horiuchi, Guillaume Hupin, Sofia Quaglioni In recent years, significant progress has been made in \textit{ab initio} nuclear structure and reaction calculations based on input from QCD employing Hamiltonians constructed within chiral effective field theory. One of the newly developed approaches is the No-Core Shell Model with Continuum (NCSMC) [1-4], capable of describing both bound and scattering states in light nuclei simultaneously. We will present NCSMC results for reactions important for astrophysics that are difficult to measure at relevant low energies, such as $^{\mathrm{3}}$He($\alpha $,$\gamma )^{\mathrm{7}}$Be and $^{\mathrm{3}}$H($\alpha $,$\gamma )^{\mathrm{7}}$Li [5] and $^{\mathrm{11}}$C(p,$\gamma )^{\mathrm{12}}$N radiative capture, as well as the $^{\mathrm{3}}$H(d,n)$^{\mathrm{4}}$He fusion. We will also address prospects of calculating the $^{\mathrm{2}}$H($\alpha $,$\gamma )^{\mathrm{6}}$Li capture reaction within the NCSMC formalism. [1] S. Baroni, P. Navratil, and S. Quaglioni, Phys. Rev. Lett. \textbf{110}, 022505 (2013). [2] G. Hupin, S. Quaglioni, P. Navratil, Phys. Rev. Lett. \textbf{114}, 212502 (2015). [3] J. Langhammer, P. Navratil, S. Quaglioni, G. Hupin, A. Calci, R. Roth, Phys. Rev. C \textbf{91}, 021301(R) (2015). [4] P. Navratil, S. Quaglioni, G. Hupin, C. Romero-Redondo, A. Calci, Physica Scripta \textbf{91}, 053002 (2016). [5] J. Dohet-Eraly, P. Navratil, S. Quaglioni, W. Horiuchi, G. Hupin, F. Raimondi, Phys. Lett. B \textbf{757}, 430 (2016). [Preview Abstract] |
Saturday, October 15, 2016 10:06AM - 10:18AM |
HJ.00007: Basic Equations Interrelate Atomic and Nuclear Properties to Patterns at the Size Scales of the Cosmos, Extended Clusters of Galaxies, Galaxies, and Nebulae. Rob Allen Structures within molecules and nuclei have relationships to astronomical patterns. The COBE cosmic scale plots, and large scale surveys of galaxy clusters have patterns also repeating and well known at atomic scales. The Induction, Strong Force, and Nuclear Binding Energy Periods within the Big Bang are revealed to have played roles in the formation of these large scale distributions. Equations related to the enormous patterns also model chemical bonds and likely nucleus and nucleon substructures. ratios of the forces that include gravity are accurately calculated from the distributions and shapes. In addition, particle masses and a great many physical constants can be derived with precision and accuracy from astrophysical shapes. A few very basic numbers can do modelling from nucleon internals to molecules to super novae, and up to the Visible Universe. Equations are also provided along with possible structural configurations for some Cold Dark Matter and Dark Energy. [Preview Abstract] |
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