Mon·Feb 5, 2018Monday·February 5, 2018

1. 01*

   Shape and angular distribution of the 4.438-MeV line from proton inelastic scattering off 12C

   J. Kiener🇫🇷

   The emission of the 4.438-MeV gamma-ray line in proton inelastic scattering off 12C has been investigated in detail. For this, two independent descriptions of the correlated scattering and emission process have been developed, one for the direct reaction mechanism and the other for the compound-nucleus (CN) component. Direct reactions were calculated in the framework of the coupled-channels formalism, while the CN component was described as a superposition of separate resonances with definite spin and parity, treated with the angular momentum coupling theory. Both components were incoherently added and compared to a comprehensive data set on measured line shapes and gamma-ray angular distributions in the proton energy range Ep = 5.44 - 25.0 MeV. In the range Ep ~ 14 - 25 MeV, good agreement with data was obtained with a dominating direct reaction component. At lower energy, an important CN component was required to describe line shape and angular distribution data. In general, a good decription of the data could be found for a CN component with spin and parity corresponding to a known nearby resonance. The new calculation improves significantly the agreement with line shape data compared to previous ones. Based on these results, predictions for line shapes and gamma-ray angular distributions up to Ep = 100 MeV were made and applied to gamma-ray emissions in solar flares and proton radiotherapy.

   nucl-exastro-ph.HEPRC(2019)·10 citations
2. 02*

   A high-resolution study of levels in the astrophysically important nucleus ${}^{26}$Mg and resulting updated level assignments

   P. Adsley🇫🇷 · J.W. Brümmer🇿🇦 · T Faestermann🇩🇪 · S. P. Fox🇬🇧 · F. Hammache🇫🇷 · R. Hertenberger🇩🇪 · A. Meyer🇫🇷 · R. Neveling🇿🇦 · D. Seiler🇩🇪 · N. de Séréville🇫🇷 · H.-F. Wirth🇩🇪

   The ${}^{22}$Ne($\alpha ,n$)${}^{25}$Mg reaction is an important source of neutrons for the s-process. Due to the difficulty in directly measuring the cross section of this reaction and the competing ${}^{22}$Ne($\alpha ,\gamma$)${}^{26}$Mg reaction, indirect methods are frequently used to try to instead calculate the relevant reaction rates. Uncertainty, however, persists in the number and properties of the pertinent excited states of ${}^{26}$Mg. In this paper, the results of proton and deuteron scattering from ${}^{26}$Mg are presented, giving a list of levels in ${}^{26}$Mg. In addition, level assignments in ${}^{26}$Mg are discussed, including some possible changes to the previously accepted assignments in ${}^{26}$Mg.

   nucl-exastro-ph.SRPRC(2018)·20 citations
3. 03*

   Prompt and non-prompt J/$\psi$ production and nuclear modification at mid-rapidity in p-Pb collisions at $\sqrt{s_{\text{NN}}}=5.02$ TeV

   ALICE Collaboration

   A measurement of beauty hadron production at mid-rapidity in proton-lead collisions at a nucleon-nucleon centre-of-mass energy $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV is presented. The semi-inclusive decay channel of beauty hadrons into J/$\psi$ is considered, where the J/$\psi$ mesons are reconstructed in the dielectron decay channel at mid-rapidity down to transverse momenta of 1.3 GeV/$c$. The $\mathrm{b}\overline{\mathrm{b}}$ production cross section at mid-rapidity, $\mathrm{d}{\sigma }_{\mathrm{b}\overline{\mathrm{b}}}/\mathrm{d}y$, and the total cross section extrapolated over full phase space, ${\sigma }_{\mathrm{b}\overline{\mathrm{b}}}$, are obtained. This measurement is combined with results on inclusive J/$\psi$ production to determine the prompt J/$\psi$ cross sections. The results in p-Pb collisions are then scaled to expectations from pp collisions at the same centre-of-mass energy to derive the nuclear modification factor $R_{\mathrm{pPb}}$, and compared to models to study possible nuclear modifications of the production induced by cold nuclear matter effects. $R_{\mathrm{pPb}}$ is found to be smaller than unity at low $p_{\mathrm{T}}$ for both J/$\psi$ coming from beauty hadron decays and prompt J/$\psi$.

   nucl-exhep-exEPJC(2018)·44 citations
4. 04*

   Comparing transverse momentum balance of b jet pairs in pp and PbPb collisions at $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV

   CMS Collaboration

   The transverse momentum balance of pairs of back-to-back b quark jets in PbPb and pp collisions recorded with the CMS detector at the LHC is reported. The center-of-mass energy in both collision systems is 5.02 TeV per nucleon pair. Compared to the pp collision baseline, b quark jets have a larger imbalance in the most central PbPb collisions, as expected from the jet quenching effect. The data are also compared to the corresponding measurement with inclusive dijets. In the most central collisions, the imbalance of b quark dijets is comparable to that of inclusive dijets.

   ↳ hep-exnucl-exJHEP(2018)·52 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.