Wed·Nov 18, 2015Wednesday·November 18, 2015

1. 01*

   Three new low-energy resonances in the ${}^{22}$Ne(p,$\gamma$)${}^{23}$Na reaction

   F. Cavanna🇮🇹 · R. Depalo🇮🇹 · M. Aliotta🇬🇧 · M. Anders🇩🇪 · D. Bemmerer🇩🇪 · A. Best🇮🇹 · A. Böltzig🇮🇹 · C. Broggini🇮🇹 · C.G. Bruno🇬🇧 · A. Caciolli🇮🇹 · P. Corvisiero🇮🇹 · T. Davinson🇬🇧 and 22 other authors

   The ${}^{22}$Ne(p,$\gamma$)${}^{23}$Na reaction takes part in the neon-sodium cycle of hydrogen burning. This cycle affects the synthesis of the elements between ${}^{20}$Ne and ${}^{27}$Al in asymptotic giant branch stars and novae. The ${}^{22}$Ne(p,$\gamma$)${}^{23}$Na reaction rate is very uncertain because of a large number of unobserved resonances lying in the Gamow window. At proton energies below 400\,keV, only upper limits exist in the literature for the resonance strengths. Previous reaction rate evaluations differ by large factors. In the present work, the first direct observations of the ${}^{22}$Ne(p,$\gamma$)${}^{23}$Na resonances at 156.2, 189.5, and 259.7\,keV are reported. Their resonance strengths have been derived with 2-7\% uncertainty. In addition, upper limits for three other resonances have been greatly reduced. Data were taken using a windowless ${}^{22}$Ne gas target and high-purity germanium detectors at the Laboratory for Underground Nuclear Astrophysics in the Gran Sasso laboratory of the National Institute for Nuclear Physics, Italy, taking advantage of the ultra-low background observed deep underground. The new reaction rate is a factor of 5 higher than the recent evaluation at temperatures relevant to novae and asymptotic giant branch stars nucleosynthesis.

   nucl-exastro-ph.SRPRL(2015)·78 citations
2. 02*

   Azimuthal anisotropy of charged jet production in $\sqrt{{\text{s}}_{\mathrm{NN}}}$ = 2.76 TeV Pb--Pb collisions

   Redmer Alexander Bertens (for the ALICE collaboration)🇳🇱

   Measurements of charged jet production with respect to the second-order harmonic event plane, quantified as $v_2^{\mathrm{ch}\mathrm{jet}}$, in $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV Pb--Pb collisions are presented. The contribution of hydrodynamic flow to the underlying event energy is corrected for on a jet-by-jet basis. Remaining effects from instrumental resolution and regional fluctuations in the energy density of the underlying event are corrected for by unfolding. Significant $v_2^{\mathrm{ch}\mathrm{jet}}$ is observed in semi-central collisions. Qualitative agreement is found with $v_2^{\mathrm{ch}+\mathrm{emjet}}$ of jets reconstructed from charged and neutral fragments and $v_2$ of single charged particles, as well as with predictions from the JEWEL Monte Carlo model.

   nucl-exNPA(2016)·4 citations
3. 03*

   Event-Shape Engineering and Muon-Hadron Correlations with ALICE

   Jan Fiete Grosse-Oetringhaus (for the ALICE collaboration)🇨🇭

   Angular correlations of two and more particles are a sensitive probe of the initial state and the transport properties of the system produced in heavy-ion collisions. Two recent results of the ALICE collaboration are presented. Event-shape engineering, a novel method, is applied to Pb-Pb collisions which splits events within the same centrality interval into classes with different average flow. The results indicate an interplay between radial and elliptic flow likely related to the initial-state eccentricity. In pp and p-Pb collisions, recent results revealed intriguing long-range correlation structures reminiscent of features observed in heavy-ion collisions. The use of forward detectors allowed to show that long-range correlation structures persist also at large rapidities in p-Pb collisions.

   nucl-exhep-exPoS(2015)·1 citation
4. 04*

   Concurrent tests of Lorentz invariance in $\beta$-decay experiments

   K.K. Vos🇳🇱 · H.W. Wilschut🇳🇱 · R.G.E. Timmermans🇳🇱

   Modern experiments on neutron and allowed nuclear $\beta$ decay search for new semileptonic interactions, beyond the ``left-handed'' electroweak force. We show that ongoing and planned $\beta$-decay experiments, with isotopes at rest and in flight, can be exploited as sensitive tests of Lorentz invariance. The variety of correlations that involve the nuclear spin, the direction of the emitted $\beta$ particle, and the recoil direction of the daughter nucleus allow for relatively simple experiments that give direct bounds on Lorentz violation. The pertinent observables are decay-rate asymmetries and their dependence on sidereal time. We discuss the potential of several asymmetries that together cover a large part of the parameter space for Lorentz violation in the gauge sector. High counting statistics is required.

   ↳ hep-phhep-exnucl-exnucl-thPRC(2015)·15 citations
5. 05*

   Consistent analysis of one-nucleon spectroscopic factors involving weakly- and strongly-bound nucleons

   J. Okołowicz🇵🇱 · Y.H. Lam🇨🇳 · M. Płoszajczak🇫🇷 · A.O. Macchiavelli🇺🇸 · N.A. Smirnova🇫🇷

   There is a considerable interest in understanding the dependence of one-nucleon removal cross sections on the asymmetry of the neutron $S_n$ and proton $S_p$ separation energies, following a large amount of experimental data and theoretical analyses in a framework of sudden and eikonal approximations of the reaction dynamics. These theoretical calculations involve both the single-particle cross section and the shell-model description of the projectile initial state and final states of the reaction residues. The configuration mixing in shell-model description of nuclear states depends on the proximity of one-nucleon decay threshold but does it depend sensitively on $S_n-S_p$? To answer this question, we use the shell model embedded in the continuum to investigate the dependence of one-nucleon spectroscopic factors on the asymmetry of $S_n$ and $S_p$ for mirror nuclei ${}^{24}$Si, ${}^{24}$Ne and ${}^{28}$S, ${}^{28}$Mg and for a series of neon isotopes ($20\le A\le 28$).

   ↳ nucl-thnucl-exPLB(2016)·6 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.