Thu·Aug 8, 2019Thursday·August 8, 2019

1. 01*

   Spectroscopy and excited-state $g$~factors in weakly collective ${}^{111}$Cd: confronting collective and microscopic models

   B. J. Coombes🇦🇺 · A. E. Stuchbery🇦🇺 · A. Blazhev🇩🇪 · H. Grawe🇩🇪 · M. W. Reed🇦🇺 · A. Akber🇦🇺 · J. T. H. Dowie🇦🇺 · M. S. M. Gerathy🇦🇺 · T. J. Gray🇦🇺 · T. Kibédi🇦🇺 · A. J. Mitchell🇦🇺 · T. Palazzo

   The even cadmium isotopes near the neutron midshell have long been considered good examples of vibrational nuclei. However, the vibrational nature of these nuclei has been questioned based on E2 transition rates that are not consistent with vibrational excitations. In the neighbouring odd-mass nuclei, the g factors of the low-excitation collective states have been shown to be more consistent with a deformed rotational core than a vibrational core. Beyond the comparison of vibrational versus rotational models, recent advances in computational power have made shell-model calculations feasible for Cd isotopes, which may give insights into the emergence and nature of collectivity in the Cd isotopes. Collective excitations in the A ~ 100 region were studied through magnetic moments and electromagnetic transitions in 111Cd. The spectroscopy of 111Cd has been studied following Coulomb excitation. Angular correlation measurements, transient-field g-factor measurements and lifetime measurements by the Doppler-broadened line shape method were performed. The structure of the nucleus was explored in relation to particle-vibration versus particle-rotor interpretations. Large-scale shell-model calculations were performed with the SR88MHJM Hamiltonian. Excited-state g factors have been measured, spin assignments examined and lifetimes determined. Attention was given to the reported $5/2^{+}$ 753-keV and $3/2^{+}$ 755-keV states. The $3/2^{+}$ 755-keV level was not observed; evidence is presented that the reported $3/2^{+}$ state was a misidentification of the $5/2^{+}$ 753-keV state. It is shown that the g factors and level structure of 111Cd are not readily explained by the particle-vibration model. A particle-rotor approach has both successes and limitations. The shell-model approach successfully reproduces much of the known low-excitation structure in 111Cd.

   nucl-exnucl-thPRC(2019)·14 citations
2. 02*

   Cross Section for $\gamma n\to {\pi }^{0}n$ measured at Mainz/A2

   W. J. Briscoe · M. Hadzimehmedovi · A. E. Kudryavtsev · V. V. Kulikov · M. A. Martemianov · I. I. Strakovsky · A. Svarc · V. E. Tarasov · R. L. Workman · S. Abt · P. Achenbach · C. S. Akondi and 80 other authors

   The $\gamma n\to {\pi }^{0}n$ differential cross section evaluated for 27 energy bins span the photon-energy range 290-813 MeV (W = 1.195-1.553 GeV) and the pion c.m. polar production angles, ranging from 18 deg to 162 deg, making use of model-dependent nuclear corrections to extract pi0 production data on the neutron from measurements on the deuteron target. Additionally, the total photoabsorption cross section was measured. The tagged photon beam produced by the 883-MeV electron beam of the Mainz Microtron MAMI was used for the 0-meson production. Our accumulation of 3.6 x 10^6 $\gamma n\to {\pi }^{0}n$ events allowed a detailed study of the reaction dynamics. Our data are in reasonable agreement with previous A2 measurements and extend them to lower energies. The data are compared to predictions of previous SAID, MAID, and BnGa partial-wave analyses and to the latest SAID fit MA19 that included our data. Selected photon decay amplitudes $N^{\ast }\to \gamma n$ at the resonance poles are determined for the first time.

   nucl-exhep-exhep-phnucl-thPRC(2019)·39 citations
3. 03*

   Review of opportunities at the HESR-Collider with PANDA at FAIR

   Leonid Frankfurt🇮🇱 · Mark Strikman🇺🇸 · Alexei Larionov🇩🇪 · Andreas Lehrach🇩🇪 · Rudolf Maier🇩🇪 · Hendrik van Hees🇩🇪 · Christian Spieles🇩🇪 · Volodymyr Vovchenko🇩🇪 · Horst Stoecker🇩🇪

   Exciting new scientific opportunities are presented for the PANDA detector at the High Energy Storage Ring in the redefined $\overline{\text{p}}\text{p}(A)$ collider mode, HESR-C, at the Facility for Antiproton and Ion Research (FAIR) in Europe. The high luminosity, $L\sim 10^{31}$ cm${}^{-2}$ s${}^{-1}$, and a wide range of intermediate and high energies, $\sqrt{s_{\text{NN}}}$ up to 30 GeV for $\overline{\text{p}}\text{p}(A)$ collisions will allow to explore a wide range of exciting topics in QCD, including the study of the production of excited open charm and bottom states, nuclear bound states containing heavy (anti)quarks, the interplay of hard and soft physics in the dilepton production, probing short-range correlations in nuclei, and the exploration of the early, complete $\overline{\text{p}}$-p-annihilation phase, where an intially pure Yang-Mills gluon plasma is formed.

   ↳ nucl-thhep-phnucl-exEPJA(2020)·9 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.