Thu·Apr 27, 2017Thursday·April 27, 2017

1. 01*

   Low-lying level structure of ${}^{56}$Cu and its implications on the rp process

   W-J. Ong · C. Langer🇩🇪 · F. Montes🇺🇸 · A. Aprahamian🇺🇸 · D. W. Bardayan🇺🇸 · D. Bazin🇺🇸 · B. A. Brown🇺🇸 · J. Browne🇺🇸 · H. Crawford🇺🇸 · R. Cyburt🇺🇸 · E. B. Deleeuw · C. Domingo-Pardo🇪🇸 and 30 other authors

   The low-lying energy levels of proton-rich ${}^{56}$Cu have been extracted using in-beam $\gamma$-ray spectroscopy with the state-of-the-art $\gamma$-ray tracking array GRETINA in conjunction with the S800 spectrograph at the National Superconducting Cyclotron Laboratory at Michigan State University. Excited states in ${}^{56}$Cu serve as resonances in the ${}^{55}$Ni(p,$\gamma$)${}^{56}$Cu reaction, which is a part of the rp-process in type I x-ray bursts. To resolve existing ambiguities in the reaction Q-value, a more localized IMME mass fit is used resulting in $Q=639\pm 82$~keV. We derive the first experimentally-constrained thermonuclear reaction rate for ${}^{55}$Ni(p,$\gamma$)${}^{56}$Cu. We find that, with this new rate, the rp-process may bypass the ${}^{56}$Ni waiting point via the ${}^{55}$Ni(p,$\gamma$) reaction for typical x-ray burst conditions with a branching of up to $\sim$40$\%$. We also identify additional nuclear physics uncertainties that need to be addressed before drawing final conclusions about the rp-process reaction flow in the ${}^{56}$Ni region.

   nucl-exastro-ph.HEPRC(2017)·22 citations
2. 02*

   Structure of ${}^{20}$Ne states in the resonance ${}^{16}$O+$\alpha$ elastic scattering

   D. K. Nauruzbayev · V. Z. Goldberg🇺🇸 · A. K. Nurmukhanbetova · M. S. Golovkov · A. Volya🇺🇸 · G. V. Rogachev🇺🇸 · R. E. Tribble🇺🇸

   Background The nuclear structure of the cluster bands in ${}^{20}$Ne presents a challenge for different theoretical approaches. It is especially difficult to explain the broad 0${}^{+}$, 2${}^{+}$ states at 9 MeV excitation energy. Simultaneously, it is important to obtain more reliable experimental data for these levels in order to quantitatively assess the theoretical framework. Purpose To obtain new data on ${}^{20}$Ne $\alpha$ cluster structure. Method Thick target inverse kinematics technique was used to study the ${}^{16}$O+$\alpha$ resonance elastic scattering and the data were analyzed using an \textit{R} matrix approach. The ${}^{20}$Ne spectrum, the cluster and nucleon spectroscopic factors were calculated using cluster-nucleon configuration interaction model (CNCIM). Results We determined the parameters of the broad resonances in \textsuperscript{20}Ne: 0${}^{+}$ level at 8.77 $\pm$ 0.150 MeV with a width of 750 (+500/-220) keV; 2${}^{+}$ level at 8.75 $\pm$ 0.100 MeV with the width of 695 $\pm$ 120 keV; the width of 9.48 MeV level of 65 $\pm$ 20 keV and showed that 9.19 MeV, 2${}^{+}$ level (if exists) should have width $\le$ 10 keV. The detailed comparison of the theoretical CNCIM predictions with the experimental data on cluster states was made. Conclusions Our experimental results by the TTIK method generally confirm the adopted data on $\alpha$ cluster levels in ${}^{20}$Ne. The CNCIM gives a good description of the ${}^{20}$Ne positive parity states up to an excitation energy of $\sim$ 7 MeV, predicting reasonably well the excitation energy of the states and their cluster and single particle properties. At higher excitations, the qualitative disagreement with the experimentally observed structure is evident, especially for broad resonances.

   nucl-exnucl-thphysics.acc-phPRC(2017)·26 citations
3. 03*

   Reduced transition probabilities for the gamma decay of the 7.8 eV isomer in ${}^{229}$Th

   Nikolay Minkov🇧🇬 · Adriana Pálffy🇩🇪

   The reduced magnetic dipole and electric quadrupole transition probabilities for the radiative decay of the ${}^{229}$Th 7.8 eV isomer to the ground state are predicted within a detailed nuclear-structure model approach. We show that the presence and decay of this isomer can only be accounted for by the Coriolis mixing emerging from a remarkably fine interplay between the coherent quadrupole-octupole motion of the nuclear core and the single-nucleon motion within a reflection-asymmetric deformed potential. We find that the magnetic dipole transition probability which determines the radiative lifetime of the isomer is considerably smaller than presently estimated. The so-far disregarded electric quadrupole component may have non-negligible contributions to the internal conversion channel. These findings support new directions in the experimental search of the ${}^{229}$Th transition frequency for the development of a future nuclear frequency standard.

   ↳ nucl-thnucl-exPRL(2017)·78 citations
4. 04*

   Theoretical Perspective on Quarkonia from SPS via RHIC to LHC

   Ralf Rapp🇺🇸 · Xiaojian Du🇺🇸

   The objective of this paper is to assess the current theoretical understanding of the extensive set of quarkonium observables (for both charmonia and bottomonia) that have been attained in ultrarelativistic heavy-ion collisions over two orders of magnitude in center-of-mass energy. We briefly lay out and compare the currently employed theoretical frameworks and their underlying transport coefficients, and then analyze excitation functions of quarkonium yields to characterize the nature of the varying production mechanisms. We argue that an overall coherent picture of suppression and regeneration mechanisms emerges which enables to deduce insights on the properties of the in-medium QCD force from SPS via RHIC to LHC, and forms a basis for future quantitative studies.

   ↳ hep-phnucl-exnucl-thNPA(2017)·36 citations
5. 05*

   Recent results from NA61/SHINE

   Antoni Aduszkiewicz (for the NA61/SHINE Collaboration)🇵🇱

   The NA61/SHINE fixed-target experiment at the CERN SPS studies the onset of deconfinement and searches for the critical point of strongly interacting matter by measuring hadron production as a function of the collision energy and the colliding system size. This contribution summarises recent results on hadron spectra and fluctuations, in particular new results on charged kaon production in ${}^7$Be+${}^9$Be collisions. Also an overview of the proposed future program of NA61/SHINE is presented.

   ↳ hep-exnucl-exNPA(2017)·18 citations
6. 06*

   Clear indication of a strong I=0 Kbar-N attraction in the Lambda (1405) region from the CLAS photo-production data

   M. Hassanvand🇮🇷 · Y. Akaishi🇯🇵 · T. Yamazaki🇯🇵

   Possible existence of deeply bound kaonic nuclear systems was proposed Akaishi and Yamazaki (2002} more than a decade ago, based on an ansatz that the Lambda* = Lambda(1405) mass is 1405 MeV/c2, where the Lambda* is a Kbar-N quasi-bound state decaying to Sigma-pi. Recently, a large number of data on photo-production of Lambda(1405) in the gamma p to K+ pi{0+-} Sigma{0-+} reaction were provided by the CLAS collaboration Moriya et al.(2013}, and double-pole structure of the Lambda* has been intensively discussed by chiral dynamics analyses {Roca (2013),Mai 2015}, whereas we show that a Lambda* mass of 1405 MeV/c2 is deduced from the same CLAS data.

   ↳ nucl-thnucl-ex11 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.