Fri·Dec 7, 2018Friday·December 7, 2018

1. 01*

   The Future of High-Energy Heavy-Ion Facilities

   Jan Fiete Grosse-Oetringhaus🇨🇭

   The plans within the next decade of the high-energy heavy-ion facilities RHIC at BNL and LHC at CERN are reviewed in detail, focusing on the physics programme for $\sqrt{s_{NN}}\ge$ 200 GeV. The expected data samples are presented, together with a discussion of the physics programme and reach. Selected performance studies are presented. An outlook is given on the plans with these and new facilities beyond 2030.

   nucl-exhep-exNPA(2019)·3 citations
2. 02*

   First experimental constraint on the ${}^{191}$Os$(n,\gamma )$ reaction rate relevant to $s$-process nucleosynthesis

   I. K. B. Kullmann · A. C. Larsen🇳🇴 · T. Renstrø m · K. S. Beckmann🇳🇴 · F. L. Bello Garrote🇳🇴 · L. Crespo Campo🇳🇴 · A. Görgen🇳🇴 · M. Guttormsen🇳🇴 · J. E. Midtbø🇳🇴 · E. Sahin🇳🇴 · S. Siem🇳🇴 · G. M. Tveten🇳🇴 · F. Zeiser🇳🇴

   The nuclear level density and $\gamma$-decay strength of ${}^{192}$Os have been extracted using particle-$\gamma$ coincidence data from the ${}^{192}$Os($\alpha ,{\alpha }^{\prime }\gamma$)${}^{192}$Os reaction by means of the Oslo method. The level density is found to be a rather smooth function of excitation energy, approximately following the constant temperature model. The $\gamma$-decay strength is compared to photoneutron cross-section data above the neutron separation energy, and to $E1$ and $M1$ strengths for nuclei in this mass region derived from primary transitions following neutron capture. Our results are in good agreement with these previous data and draw a consistent picture of the $\gamma$-strength function in the range $E_{\gamma }\approx 1.5-6$ MeV. Using the measured nuclear level density and $\gamma$-decay strength as input to the nuclear-reaction code TALYS, we provide the first experimentally constrained Maxwellian-averaged cross section (MACS) for the ${}^{191}$Os($n,\gamma$)${}^{192}$Os reaction relevant to $s$-process nucleosynthesis. The systematic uncertainties introduced by the normalization procedure of the level density and $\gamma$-strength function were investigated and propagated to the calculated Maxwellian-averaged cross section. The obtained result of the Maxwellian-averaged cross section at $k_{B}T=30$ keV, $⟨\sigma {⟩}_{n,\gamma }=1134\pm 375$ mb, is in very good agreement with the theoretical estimate provided by the KADoNiS project, giving experimental support to the adopted KADoNiS value. Good agreement is also found with MACS values obtained from other libraries, such as TENDL-2017, ENDF/B-VII.0, and JEFF.

   nucl-exPRC(2019)·13 citations
3. 03*

   Do deviations of neutron scattering widths distribution from the Porter-Thomas law indicate on failure of the Random Matrix theory?

   Oleg V. Zhirov🇷🇺

   Deviations of neutron scattering width distributions from the Porter-Thomas law due to resonances overlapping are calculated in the extended framework of the random matrix approach.

   ↳ nucl-thnucl-ex0 citations
4. 04*

   Defining the Proton Radius: a Unified Treatment

   Gerald A. Miller🇺🇸

   Background: There is significant current interest in knowing the value of the proton radius and also its proper definition. Purpose: Combine the disparate literatures of hydrogen spectroscopy and diverse modern parton distributions to show that the quantity $r_p^2\equiv -6G_E^{\prime }(0)$ is the relativistically proper definition that originates from the separate bodies of work. Methods: Use perturbation theory, light-front dynamics and elementary techniques to find relativistically correct definitions of the proton radius and charge density. Results: It is found that the very same proton radius is accessed by measurements of hydrogen spectroscopy and elastic lepton scattering. The derivation of the mean-square radius as a moment of a spherically symmetric three-dimensional density is shown to be incorrect. A relativistically-correct, two-dimensional charge density is related to the diverse modern literature of various parton distributions. Relativistically invariant moments thereof are derived in a new moment expansion, the RME.

   ↳ nucl-thhep-phnucl-exphysics.atom-phPRC(2019)·138 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.