Tue·Oct 30, 2018Tuesday·October 30, 2018

1. 01*

   Mass Measurements of Neutron-Rich Gallium Isotopes Refine Production of Nuclei of the First r-Process Abundance Peak in Neutron Star Merger Calculations

   M.P. Reiter🇨🇦 · S. Ayet San Andrés🇩🇪 · S. Nikas · J. Lippuner🇺🇸 · C. Andreoiu🇨🇦 · C. Babcock🇨🇦 · B.R. Barquest🇨🇦 · J. Bollig🇨🇦 · T. Brunner🇨🇦 · T. Dickel🇩🇪 · J. Dilling🇨🇦 · I. Dillmann🇨🇦 and 24 other authors

   We report mass measurements of neutron-rich Ga isotopes ${}^{80-85}$Ga with TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN). The measurements determine the masses of ${}^{80-83}$Ga in good agreement with previous measurements. The masses of ${}^{84}$Ga and ${}^{85}$Ga were measured for the first time. Uncertainties between $25-48$ keV were reached. The new mass values reduce the nuclear uncertainties associated with the production of A $\approx$ 84 isotopes by the \emph{r}-process for astrophysical conditions that might be consistent with a binary neutron star (BNS) merger producing a blue kilonova. Our nucleosynthesis simulations confirm that BNS merger may contribute to the first abundance peak under moderate neutron-rich conditions with electron fractions $Y_e=0.35-0.38$.

   nucl-exastro-ph.HEnucl-thPRC(2020)·27 citations
2. 02*

   Radiative-capture cross sections for the ${}^{139}$La($n,\gamma$) reactionusing thermal neutrons and structural properties of ${}^{140}$La

   A.M. Hurst · A. Sweet · B.L. Goldblum🇺🇸 · R.B. Firestone🇺🇸 · M.S. Basunia · L.A. Bernstein🇺🇸 · Zs. Revay · L. Szentmiklosi🇭🇺 · T. Belgya🇭🇺 · J.E. Escher🇺🇸 · I. Harsanyi · M. Krticka🇨🇿 · B.W. Sleaford · J. Vujic

   A set of prompt partial $\gamma$-ray production cross sections from thermal neutron-capture were measured for the ${}^{139}$La($n,\gamma$) reaction using a guided beam of subthermal (thermal and cold) neutrons incident upon a ${}^{\mathrm{nat}}$La${}_2$O${}_3$ target at the Prompt Gamma Activation Analysis facility of the Budapest Research Reactor. Absolute ${}^{140}$La cross sections were determined relative to the well-known comparator ${}^{35}$Cl($n,\gamma$) cross sections from the irradiation of a stoichiometric ${}^{\mathrm{nat}}$LaCl${}_3$ sample. The total cross section for radiative thermal neutron-capture on ${}^{139}$La from the sum of experimentally measured cross sections observed to directly feed the ${}^{140}$La ground state was determined to be ${\sigma }_0^{\mathrm{expt}}=8.58(50)$ b. To assess completeness of the decay scheme and as a consistency check, the measured cross sections for transitions feeding the ground state from levels below a critical energy of $E_c=285$ keV were combined with a modeled contribution accounting for ground-state feeding from the quasicontinuum to arrive at a total cross section of ${\sigma }_0=9.36(74)$ b. In addition, a neutron-separation energy of $S_n=5161.005(21)$ keV was determined from a least-squares fit of the measured primary $\gamma$-ray energies to the low-lying levels of the ${}^{140}$La decay scheme. Furthermore, several nuclear structure improvements are proposed for the decay scheme. The measured cross-section and separation-energy results are comparable to earlier measurements of these quantities.

   nucl-exPRC(2019)·2 citations
3. 03*

   An event mixing method with invariant-mass/energy hierarchy correspondence cut for Bose-Einstein correlations in $\pi \pi X$ system

   Q. He🇯🇵

   A new event mixing constraint, namely invariant-mass/energy hierarchy correspondence (IMEHC) cut, is introduced for the low-multiplicity event mixing technique for the purpose of measuring Bose-Einstein correlations (BEC) in exclusive reactions with $\pi \pi X$ final state particles.The mixing cut is relevant to the hierarchy of the invariant mass of $\pi X$ system and two bosons energy hierarchy. Numerical tests are performed to check the validity of the new mixing method. As long as the measurements of BEC parameters $r_0$ and ${\lambda }_2$ are considered, this new mixing method is effective to observe BEC effects and the systematic bias of $r_0$ and ${\lambda }_2$ are smaller than the previously proposed mixing cut.

   nucl-exnucl-thActa Phys.Polon.B(2018)·0 citations
4. 04*

   Direct determination of the neutron skin thicknesses in ${}^{40,48}$Ca from proton elastic scattering at $E_p=295$ MeV

   J. Zenihiro🇯🇵 · H. Sakaguchi · S. Terashima🇨🇳 · T. Uesaka🇯🇵 · G. Hagen🇺🇸 · M. Itoh🇯🇵 · T. Murakami🇯🇵 · Y. Nakatsugawa🇯🇵 · T. Ohnishi · H. Sagawa🇯🇵 · H. Takeda🇯🇵 · M. Uchida🇯🇵 and 3 other authors

   The neutron density distributions and neutron skin thicknesses in ${}^{40,48}$Ca are determined from the angular distributions of the cross sections and analyzing powers of polarized proton elastic scattering at $E_p=295$ MeV. Based on the framework of the relativistic impulse approximation with the density-dependent effective $NN$ interaction, the experimental data is successfully analyzed, providing precise information of neutron and proton density profiles of ${}^{40,48}$Ca with small uncertainties. The extracted neutron and proton density distributions give neutron skin thicknesses in ${}^{40,48}$Ca for $-0.010_{-0.024}^{+0.022}$ fm and $0.168_{-0.028}^{+0.025}$ fm, respectively. The results of the density profiles and the neutron skin thickness in ${}^{48}$Ca are directly compared with the {\it ab initio} coupled-cluster calculations with interactions derived from chiral effective field theory, as well as relativistic and non-relativistic energy density functional theories.

   nucl-exnucl-th54 citations
5. 05*

   Calculations of Neutron Reflectivity in the eV Energy Range from Mirrors made of Heavy Nuclei with Neutron-Nucleus Resonances

   W. M. Snow🇺🇸 · K. A. Dickerson🇺🇸 · J. S. Devaney🇺🇸 · C. Haddock🇺🇸

   We evaluate the reflectivity of neutron mirrors composed of certain heavy nuclei which possess strong neutron-nucleus resonances in the eV energy range. We show that the reflectivity of such a mirror for some nuclei can in principle be high enough near energies corresponding to compound neutron-nucleus resonances to be of interest for certain scientific applications in non-destructive evaluation of subsurface material composition and in the theory of neutron optics beyond the kinematic limit.

   ↳ physics.ins-detnucl-exPRA(2019)·1 citation
6. 06*

   What can we know about hypernuclei via analysis of bremsstrahlung photons?

   Xin Liu (1 and 2)🇨🇳 · Sergei P. Maydanyuk (2 and 3)🇨🇳 · Peng-Ming Zhang (2)🇨🇳 · Ling Liu (1) ((1) College of Physical Science and Technology, Shenyang Normal University, Shenyang, 110034, China, (2) Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000, China, (3) Institute for Nuclear Research, National Academy of Sciences of Ukraine, Kiev, 03680, Ukraine)🇨🇳

   We investigate possibility of emission of the bremsstrahlung photons in nuclear reactions with hypernuclei for the first time. A new model of the bremsstrahlung emission which accompanies interactions between $\alpha$ particles and hypernuclei is constructed, where a new formalism for the magnetic momenta of nucleons and hyperon inside hypernucleus is added. For first calculations, we choose $\alpha$ decay of the normal nucleus ${}^{210}\mathrm{Po}$ and the hypernucleus ${}_{\Lambda }^{211}\mathrm{Po}$. We find that (1) emission for the hypernucleus ${}_{\Lambda }^{211}\mathrm{Po}$ is larger than for normal nucleus ${}^{210}\mathrm{Po}$, (2) difference between these spectra is small. We propose a way how to find hypernuclei, where role of hyperon is the most essential in emission of bremsstrahlung photons during $\alpha$ decay. As demonstration of such a property, we show that the spectra for the hypernuclei ${}_{\Lambda }^{107}\mathrm{Te}$ and ${}_{\Lambda }^{109}\mathrm{Te}$ are essentially larger than the spectra for the normal nuclei ${}^{106}\mathrm{Te}$ and ${}^{108}\mathrm{Te}$. Such a difference is explained by additional contribution of emission to the full bremsstrahlung, which is formed by magnetic moment of hyperon inside hypernucleus. The bremsstrahlung emission formed by such a mechanism, is of the magnetic type. A new formula for fast estimations of bremsstrahlung spectra for even-even hypernuclei is proposed, where role of magnetic moment of hyperon of hypernucleus in formation of the bremsstrahlung emission is shown explicitly. Such an analysis opens possibility of new experimental study of properties of hypernuclei via bremsstrahlung study.

   ↳ nucl-thhep-phnucl-ex5 citations
7. 07*

   Etaprime and Eta Mesons with Connection to Anomalous Glue

   Steven D. Bass🇵🇱 · Pawel Moskal🇵🇱

   We review the present understanding of etaprime and eta meson physics and these mesons as a probe of gluon dynamics in low-energy QCD. Recent highlights include the production mechanism of eta and etaprime mesons in proton-nucleon collisions from threshold to high-energy, the etaprime effective mass shift in the nuclear medium, searches for possible eta and etaprime bound states in nuclei as well as precision measurements of eta decays as a probe of light-quark masses. We discuss recent experimental data, theoretical interpretation of the different measurements and the open questions and challenges for future investigation.

   ↳ hep-phhep-exnucl-exnucl-thRMP(2019)·100 citations
8. 08*

   ${\gamma }^{\ast }\gamma \to \eta ,{\eta }^{\prime }$ transition form factors

   Minghui Ding🇮🇹 · Khepani Raya🇨🇳 · Adnan Bashir🇲🇽 · Daniele Binosi🇮🇹 · Lei Chang🇨🇳 · Muyang Chen🇨🇳 · Craig D. Roberts🇺🇸

   Using a continuum approach to the hadron bound-state problem, we calculate ${\gamma }^{\ast }\gamma \to \eta ,{\eta }^{\prime }$ transition form factors on the entire domain of spacelike momenta, for comparison with existing experiments and in anticipation of new precision data from next-generation $e^{+}{e}^{-}$ colliders. One novel feature is a model for the contribution to the Bethe-Salpeter kernel deriving from the non-Abelian anomaly, an element which is crucial for any computation of $\eta ,{\eta }^{\prime }$ properties. The study also delivers predictions for the amplitudes that describe the light- and strange-quark distributions within the $\eta ,{\eta }^{\prime }$. Our results compare favourably with available data. Important to this at large-$Q^2$ is a sound understanding of QCD evolution, which has a visible impact on the ${\eta }^{\prime }$ in particular. Our analysis also provides some insights into the properties of $\eta ,{\eta }^{\prime }$ mesons and associated observable manifestations of the non-Abelian anomaly.

   ↳ nucl-thhep-exhep-lathep-ph+1PRD(2019)·83 citations
9. 09*

   Experimental investigation of the low molecular weight fluoropolymer for the ultracold neutrons storage

   C. Düsing🇩🇪 · P. Geltenbort🇫🇷 · C. Plonka🇩🇪 · Yu.N. Pokotilovski🇷🇺

   The experimental setup for examining the low-molecular-weight fluoropolymer CF${}_3$(CF${}_2{)}_3$-O-CF${}_2$-O-(CF${}_2{)}_3$CF${}_3$, which is a promising coating material for the walls of storage chambers for ultracold neutrons, is described. The results are detailed. The measurement data are interpreted in the model of a multilayer complex quantum-mechanical potential of the chamber walls.

   ↳ physics.ins-detnucl-exPhys.Part.Nucl.Lett.(2018)·0 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.