Tue·Apr 16, 2019Tuesday·April 16, 2019

1. 01*

   Beta-delayed-neutron studies of ${}^{135,136}$Sb and ${}^{140}$I performed with trapped ions

   B. S. Alan · S. A. Caldwell · N. D. Scielzo🇺🇸 · A. Czeszumska · J. A. Clark · G. Savard🇺🇸 · A. Aprahamian🇺🇸 · M. T. Burkey · C. J. Chiara🇺🇸 · J. Harker · A. F. Levand · S. T. Marley🇺🇸 and 10 other authors

   Beta-delayed-neutron ($\beta$n) spectroscopy was performed using the Beta-decay Paul Trap and an array of radiation detectors. The $\beta$n branching ratios and energy spectra for ${}^{135,136}$Sb and ${}^{140}$I were obtained by measuring the time of flight of recoil ions emerging from the trapped ion cloud. These nuclei are located at the edge of an isotopic region identified as having $\beta$n branching ratios that impact the r-process abundance pattern around the A~130 peak. For ${}^{135,136}$Sb and ${}^{140}$I, $\beta$n branching ratios of 14.6(11)%, 17.6(28)%, and 7.6(28)% were determined, respectively. The $\beta$n energy spectra obtained for ${}^{135}$Sb and ${}^{140}$I are compared with results from direct neutron measurements, and the $\beta$n energy spectrum for ${}^{136}$Sb has been measured for the first time.

   nucl-exastro-ph.IMPRC(2020)·7 citations
2. 02*

   Diversity of shapes and rotations in the gamma-soft 130Ba nucleus: first observation of a t-band in the A=130 mass region

   C. M. Petrache🇫🇷 · P. M. Walker🇬🇧 · S. Guo🇨🇳 · Q. B. Chen🇩🇪 · S. Frauendorf🇺🇸 · Y. X. Liu🇨🇳 · R. A. Wyss🇸🇪 · D. Mengoni🇮🇹 · Y. Qiang🇨🇳 · A. Astier🇫🇷 · E. Dupont🇫🇷 · R. Li🇫🇷 and 29 other authors

   Several new bands have been identified in 130Ba, among which there is one with band-head spin 8+. Its properties are in agreement with the Fermi-aligned \nu h11/2^2 , 7/2+[523] \otimes 9/2-[514] Nilsson configuration. This is the first observation of a two-quasiparticle t-band in the A=130 mass region. The t-band is fed by a dipole band involving two additional h11/2 protons. The odd-spin partners of the proton and neutron S-bands and the ground-state band at high spins are also newly identified. The observed bands are discussed using several theoretical models, which strongly suggest the coexistence of prolate and oblate shapes polarized by rotation aligned two-proton and two-neutron configurations, as well as prolate collective rotations around axes with different orientations. With the new results, 130Ba presents one of the best and most complete sets of collective excitations that a gamma-soft nucleus can manifest at medium and high spins, revealing a diversity of shapes and rotations for the nuclei in the A = 130 mass region.

   nucl-exnucl-thPLB(2019)·39 citations
3. 03*

   Total absorption $\gamma$-ray spectroscopy of niobium isomers

   V. Guadilla🇪🇸 · A. Algora🇪🇸 · J. L. Tain🇪🇸 · J. Agramunt🇪🇸 · J. Äystö🇫🇮 · J. A. Briz🇫🇷 · A. Cucoanes🇫🇷 · T. Eronen🇫🇮 · M. Estienne🇫🇷 · M. Fallot🇫🇷 · L. M. Fraile🇪🇸 · E. Ganioğlu🇹🇷 and 33 other authors

   The $\beta$ intensity distributions of the decays of ${}^{100\text{gs},100\text{m}}$Nb and ${}^{102\text{gs},102\text{m}}$Nb have been determined using the Total Absorption $\gamma$-Ray Spectroscopy technique. The JYFLTRAP double Penning trap system was employed to disentangle the isomeric states involved, lying very close in energy, in a campaign of challenging measurements performed with the Decay Total Absorption $\gamma$-ray Spectrometer at the Ion Guide Isotope Separator On-Line facility in Jyväskylä. The low-spin isomeric state of each niobium case was populated through the decay of the zirconium parent, that was treated as a contaminant. We have applied a method to extract this contamination, and additionally we have obtained $\beta$ intensity distributions for these zirconium decays. The $\beta$-strength distributions evaluated with these results were compared with calculations in quasiparticle random-phase approximation, suggesting a prolate configuration for the ground states of ${}^{100,102}$Zr. The footprint of the Pandemonium effect was found when comparing our results for the analyses of the niobium isotopes with previous decay data. The $\beta$-intensities of the decay of ${}^{102\text{m}}$Nb were obtained for the first time. A careful evaluation of the uncertainties was carried out, and the consistency of our results was validated taking advantage of the segmentation of our spectrometer. The final results were used as input in reactor summation calculations. A large impact on antineutrino spectrum calculations was already reported and here we detail the significant impact on decay heat calculations.

   nucl-exPRC(2019)·28 citations
4. 04*

   Jet Structure Studies in Small Systems

   Z. Varga🇭🇺 · R. Vertesi🇭🇺 · G. G. Barnafoldi🇭🇺

   A study investigating a possible jet shape dependence on the charged event multiplicity was performed on collision samples generated by Monte-Carlo (MC) event generators PYTHIA and HIJING++. We calculated the integral jet shape and found a significant modification caused by multiple-parton interactions. By interchanging and enabling different model ingredients in the simulations and analyzing the results in several $p_T$ bins and event multiplicity classes, we found a characteristic jet size measure that was independent of the chosen tunes, settings, and jet reconstruction algorithms.

   ↳ hep-phnucl-exUniverse(2019)·8 citations
5. 05*

   Hydrodynamic flow in small systems, or: "How the heck is it possible that a system emitting only a dozen particles can be described by fluid dynamics?"

   Ulrich W. Heinz (Ohio State University)🇺🇸 · J. Scott Moreland (Duke University)🇺🇸

   The "unreasonable effectiveness" of relativistic fluid dynamics in describing high energy heavy-ion and even proton-proton collisions are demonstrated and discussed. Several recent ideas of optimizing relativistic fluid dynamics for the specific challenges posed by such collisions will be presented, and some thoughts will be offered why the framework works better than originally expected. I will also address the unresolved question where exactly hydrodynamics breaks down, and why.

   ↳ nucl-thhep-phnucl-exJ.Phys.Conf.Ser.(2019)·39 citations
6. 06*

   A search for solar axion induced signals with COSINE-100

   P. Adhikari · G. Adhikari · E. Barbosa de Souza🇺🇸 · N. Carlin🇧🇷 · S. Choi🇰🇷 · M. Djamal🇮🇩 · A.C. Ezeribe🇬🇧 · C. Ha🇰🇷 · I.S. Hahn🇰🇷 · E.J. Jeon🇰🇷 · J.H. Jo🇺🇸 · H.W. Joo🇰🇷 and 36 other authors

   We present results from a search for solar axions with the COSINE-100 experiment. We find no evidence of solar axion events from a data-set of 6,303.9 kg$\cdot$days exposure and set a 90\,\% confidence level upper limit on the axion-electron coupling, $g_{ae}$, at 1.70~$\times$~$10^{-11}$ for an axion mass less than 1\,keV/c${}^2$. This limit excludes QCD axions heavier than 0.59\,eV/c${}^2$ in the DFSZ model and 168.1\,eV/c${}^2$ in the KSVZ model.

   ↳ hep-exastro-ph.IMnucl-exAstropart.Phys.(2020)·10 citations
7. 07*

   Sensitivity of the evaporation residue observables to the symmetry energy

   S. Mallik🇮🇳 · G. Chaudhuri🇮🇳 · F. Gulminelli🇫🇷

   The static properties of the heaviest residue and unbound particles produced in central ${}^{64,58}Ni$ on ${}^{64,58}Ni$ collisions at 50 MeV/nucleon are predicted within the BUU transport model, in order to explore the sensitivity of those observables to the density dependence of the symmetry energy. We include fluctuations in the collision integral and use a meta-modelling for the mean-field which allows an independent variation of the different empirical parameters of the equation of state. We find that the isospin ratio of pre-equilibrium particles is a good estimator of the stiffness of the symmetry energy, in agreement with previous works. In addition to that, whatever be the functional form of the equation of state, we show that a higher symmetry energy at subsaturation densities leads to an increased size and isotopic ratio for the heaviest residue. This is understood in terms of energy sharing between the pre-equilibrium particles and the (quasi)fused system. The combination of the two observables might be an interesting tool to constrain the different density dependence below and above saturation, which is linked to the relatively poorly known parameter $K_{sym}$.

   ↳ nucl-thnucl-exPRC(2019)·13 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.