Thu·Feb 13, 2020Thursday·February 13, 2020

1. 01*

   Emerging nuclear collectivity in ${}^{124-130}$Te

   B. J. Coombes🇦🇺 · A. E. Stuchbery🇦🇺 · J. M. Allmond🇺🇸 · A. Gargano🇮🇹 · J. T. H. Dowie🇦🇺 · G. Georgiev🇫🇷 · M. S. M. Gerathy🇦🇺 · T. J. Gray🇦🇺 · T. Kibédi🇦🇺 · G. J. Lane🇦🇺 · B. P. McCormick🇦🇺 · A. J. Mitchell🇦🇺 · N. J. Spinks🇦🇺 · B. P. E. Tee🇦🇺

   The emergence of nuclear collectivity near doubly-magic ${}^{132}$Sn was explored along the stable, even-even ${}^{124-130}$Te isotopes. Preliminary measurements of the $B(E2;4_1^{+}\to 2_1^{+})$ transition strengths are reported from Coulomb excitation experiments primarily aimed at measuring the $g$ factors of the $4_1^{+}$ states. Isotopically enriched Te targets were excited by 198-205 MeV ${}^{58}$Ni beams. A comparison of transition strengths obtained is made to large-scale shell-model calculations with successes and limitations discussed.

   nucl-exEPJ Web Conf.(2020)·5 citations
2. 02*

   Testing ab initio nuclear structure in neutron-rich nuclei: lifetime measurements of second 2+ states in 16C and 20O

   M. Ciemala🇵🇱 · S. Ziliani🇮🇹 · F.C.L. Crespi🇮🇹 · S. Leoni🇮🇹 · B. Fornal🇵🇱 · A. Maj🇵🇱 · P. Bednarczyk🇵🇱 · G. Benzoni🇮🇹 · A. Bracco🇮🇹 · C. Boiano🇮🇹 · S. Bottoni🇮🇹 · S. Brambilla🇮🇹 and 82 other authors

   To test the predictive power of ab initio nuclear structure theory, the lifetime of the second 2+ state in neutron-rich 20O, tau(2+_2 ) = 150(+80-30) fs, and an estimate for the lifetime of the second 2+ state in 16C have been obtained, for the first time. The results were achieved via a novel Monte Carlo technique that allowed us to measure nuclear state lifetimes in the tens-to-hundreds femtoseconds range, by analyzing the Doppler-shifted gamma-transition line shapes of products of low-energy transfer and deep-inelastic processes in the reaction 18O (7.0 MeV/u) + 181Ta. The requested sensitivity could only be reached owing to the excellent performances of the AGATA gamma-tracking array, coupled to the PARIS scintillator array and to the VAMOS++ magnetic spectrometer. The experimental lifetimes agree with predictions of ab initio calculations using two- and three-nucleon interactions, obtained with the valence-space in-medium similarity renormalization group for 20O, and with the no-core shell model for 16C. The present measurement shows the power of electromagnetic observables, determined with high-precision gamma spectroscopy, to assess the quality of first-principles nuclear structure calculations, complementing common benchmarks based on nuclear energies. The proposed experimental approach will be essential for short lifetimes measurements in unexplored regions of the nuclear chart, including r-process nuclei, when intense ISOL-type beams become available.

   nucl-exnucl-thPRC(2020)·30 citations
3. 03*

   NA61/SHINE results on fluctuations and correlations at CERN SPS energies

   Maja Mackowiak-Pawlowska (for the NA61/SHINE Collaboration)🇵🇱

   The aim of the NA61/SHINE strong interaction programme is to explore the phase diagram of strongly interacting matter. The main physics goals are the study of the onset of deconfinement and the search for the critical point of strongly interacting matter. These goals are pursued by performing a beam momentum (13A -- 150/158A GeV/c) and system size (p+p, p+Pb, Be+Be, Ar+Sc, Xe+La, Pb+Pb) scan. This contribution presents new results from NA61/SHINE on fluctuations and correlations which include in particular quantum correlations, as well as multiplicity and net-charge fluctuations, proton density fluctuations and anisotropic collective flow. Obtained results are compared with other experiments and with model predictions.

   nucl-exNPA(2021)·24 citations
4. 04*

   Multiplicity Dependence of Shear Viscosity, Isothermal Compressibility and Speed of Sound in $pp$ collisions at $\sqrt{s}$ = 7 TeV

   Dushmanta Sahu🇮🇳 · Sushanta Tripathy🇮🇳 · Raghunath Sahoo🇮🇳 · Archita Rani Dash🇮🇳

   In order to understand the detailed dynamics of systems produced in $pp$ collisions, it is essential to know about the Equation of State (EoS) and various thermodynamic properties. In this work, we study the shear viscosity to entropy density ratio, isothermal compressibility and speed of sound of the system by considering a differential freeze-out scenario. We have used a thermodynamically consistent Tsallis non-extensive statistics to have a better explanation for the dynamics of $pp$ collision systems. While the shear viscosity to entropy density ratio provides information about the measure of fluidity of a system formed in high energy collisions, the isothermal compressibility gives a clear idea about the deviation of the system from a perfect fluid. The speed of sound in the system as a function of $⟨d{N}_{\mathrm{ch}}/d\eta ⟩$ gives us a vivid picture of the dynamics of the system. The results show quite an intuitive perspective on high multiplicity $pp$ collisions and give us a limit of $⟨d{N}_{\mathrm{ch}}/d\eta ⟩$ $\gtrsim$ (10 - 20), after which a change in the dynamics of the system may be observed.

   ↳ hep-phhep-exnucl-exnucl-thEPJA(2020)·19 citations
5. 05*

   Precise determination of proton magnetic radius from electron scattering data

   J. M. Alarcón🇪🇸 · D. W. Higinbotham🇺🇸 · C. Weiss🇺🇸

   We extract the proton magnetic radius from the high-precision electron-proton elastic scattering cross section data. Our theoretical framework combines dispersion analysis and chiral effective field theory and implements the dynamics governing the shape of the low-$Q^2$ form factors. It allows us to use data up to $Q^2\sim$ 0.5 GeV${}^2$ for constraining the radii and overcomes the difficulties of empirical fits and $Q^2\to 0$ extrapolation. We obtain a magnetic radius $r_M^p$ = 0.850 $\pm$0.001 (fit 68%) $\pm$0.010 (theory full range) fm, significantly different from earlier results obtained from the same data, and close to the extracted electric radius $r_E^p$ = 0.842 $\pm$0.002 (fit) $\pm$0.010 (theory) fm.

   ↳ hep-phhep-latnucl-exnucl-th+1PRC(2020)·43 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.