Fri·Oct 2, 2020Friday·October 2, 2020

1. 01*

   Gamma-ray and conversion-electron spectroscopy of the high-spin isomer in 145Sm

   Matthew Gerathy🇦🇺 · Gregory Lane · Andrew Stuchbery🇦🇺 · George Dracoulis · Tibor Kibedi🇦🇺 · Aqeel Akber🇦🇺 · Lindsey Bignell🇦🇺 · Ben Coombes🇦🇺 · Jackson Dowie🇦🇺 · Timothy Gray🇦🇺 · Boon Lee · Brendan McCormick🇦🇺 · Alan Mitchell🇩🇪 · Nyaladzi Palalani

   Background: High-spin isomers at {\approx}9-MeV excitation energies have been reported in several N = 83 isotones near Z = 64. Spin and parity assignments of J{^\pi} = 49/2+ remain tentative for a number of these states in the odd-A nuclei. Purpose: To study the decay of the (49/2 +) high-spin isomer in 145 Sm, make firm spin and parity assignments to the isomer and states populated in its decay, and investigate the structure of the nucleus. Methods: The 145Sm isomer was populated in the 124Sn(26Mg,5n) reaction. Gamma-ray and conversion-electron data were collected using the Solenogam array. Results: A revised lifetime of t1/2 = 3.52(16) mus was measured for the high-spin isomer. Several new states have been added to the level scheme, and a new state at 8815 keV is proposed as the isomer, based on decay-property systematics, transition strengths, and spin and parity assignments. Firm spin and parity assignments have been made to states up to and including the isomer and the new level scheme is interpreted using shell-model calculations performed with the KShell program. Conclusions: The interpretation of the 49/2+ isomer as a deformed excitation of the core neutrons remains unchanged, although there has been a significant revision of the level scheme below the isomer, and hence significant reinterpretations of the lower-lying states.

   nucl-exPRC(2020)·0 citations
2. 02*

   Dynamical fission of the quasiprojectile and isospin equilibration for the system 80Kr+ 48 Ca at 35 MeV/nucleon

   S. Piantelli🇮🇹 · G. Casini🇮🇹 · A. Ono🇯🇵 · G. Poggi🇮🇹 · G. Pastore🇮🇹 · S. Barlini🇮🇹 · A. Boiano🇮🇹 · E. Bonnet🇫🇷 · B. Borderie🇫🇷 · R. Bougault🇫🇷 · M. Bruno🇮🇹 · A. Buccola🇮🇹 and 35 other authors

   Experimental results concerning the dynamical fission of quasiprojectiles in semiperipheral collisions for the system 80 Kr+ 48 Ca at 35 MeV/nucleon are presented. Data have been collected with four blocks of the FAZIA setup in the first physics experiment of the FAZIA Collaboration. The degree of isospin equilibration between the two fission fragments and its dependence on their charge asymmetry is investigated. The data are compared with the results of the AMD model coupled to GEMINI as an afterburner, in order to get hints about the timescale of the process.

   nucl-exPRC(2020)·29 citations
3. 03*

   Review of the $\mathbf{\Lambda }$(1405): A curious case of a strange-ness resonance

   Maxim Mai🇺🇸

   During its long-lasting history, the $\Lambda (1405)$ has become a benchmark for our understanding of the $\mathrm{SU}(3)$ hadron dynamics. Starting with its theoretical prediction and later experimental verification, until the most recent debates on the existence of the second broad pole, it emerged as a fruitful research area sparking many theoretical and experimental developments. This review intends to provide the reader with the current status of research on the $\Lambda (1405)$-resonance, reflecting on historical, experimental and theoretical developments. A common database for experimental results and a comparison of most recent theoretical approaches will be provided in the last two parts of this manuscript.

   ↳ nucl-thhep-lathep-phnucl-exEur.Phys.J.ST(2021)·108 citations
4. 04*

   Influence of fast emissions and statistical de-excitation on the isospin transport ratio

   A. Camaiani🇮🇹 · S. Piantelli🇮🇹 · A. Ono🇯🇵 · G. Casini🇮🇹 · B. Borderie🇫🇷 · R. Bougault🇫🇷 · C. Ciampi🇮🇹 · J.A. Duenas🇪🇸 · C. Frosin🇮🇹 · J. D. Frankland🇫🇷 · D. Gruyer🇫🇷 · N. LeNeindre🇫🇷 and 9 other authors

   Isospin transport ratio is a powerful method to estimate the neutron-proton (n-p) equilibration in heavy-ion collisions, and extensively used to obtain information on the asy-stiffness of the nuclear Equation of State. In fact such a ratio is expected to bypass any perturbations introducing a linear transformation of the chosen observable. In particular, it is supposed to overcome contributions due to emission, either of dynamical or statistical nature, from the primary fragments formed during the collisions. In this paper we explore the validity of this assumption, looking at the quasi-projectile n-p ratio ($N/Z$) in peripheral and semi-peripheral events for Ca+Ca reactions at 35\amev{}, simulated via the Antisymmetrized Molecular Dynamics transport model, coupled to different statistical decay codes. The statistical de-excitation of the primary fragments introduces a linear transformation at relatively high excitation energies (above 2\amev{}) when the residue approaches the Evaporation Attractor Line, while some effect is produced at lower excitation energies due to the occurrence of some non-linearities. As for fast emissions after the end of the projectile-target interaction it is shown that they introduce a non-linear transformation too.

   ↳ nucl-thnucl-exPRC(2020)·22 citations
5. 05*

   Neutron Spectroscopy for Pulsed Beams with Frame Overlap using a Double Time-of-Flight Technique

   K. P. Harrig (1) · B. L. Goldblum (1)🇺🇸 · J. A. Brown (1)🇬🇧 · D. L. Bleuel (2)🇺🇸 · L. A. Bernstein (1 and 3)🇺🇸 · J. Bevins (1) · M. Harasty (1)🇺🇸 · T. A. Laplace (1)🇺🇸 · E. F. Matthews (1) ((1) Univesity of California, Berkeley, (2) Lawrence Livermore National Laboratory, (3) Lawrence Berkeley National Laboratory)

   A new double time-of-flight (dTOF) neutron spectroscopy technique has been developed for pulsed broad spectrum sources with a duty cycle that results in frame overlap, where fast neutrons from a given pulse overtake slower neutrons from previous pulses. Using a tunable beam at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory, neutrons were produced via thick-target breakup of 16 MeV deuterons on a beryllium target in the cyclotron vault. The breakup spectral shape was deduced from a dTOF measurement using an array of EJ-309 organic liquid scintillators. Simulation of the neutron detection efficiency of the scintillator array was performed using both GEANT4 and MCNP6. The efficiency-corrected spectral shape was normalized using a foil activation technique to obtain the energy-dependent flux of the neutron beam at zero degrees with respect to the incoming deuteron beam. The dTOF neutron spectrum was compared to spectra obtained using HEPROW and GRAVEL pulse height spectrum unfolding techniques. While the unfolding and dTOF results exhibit some discrepancies in shape, the integrated flux values agree within two standard deviations. This method obviates neutron time-of-flight spectroscopy challenges posed by pulsed beams with frame overlap and opens new opportunities for pulsed white neutron source facilities.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2018)·16 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.