Fri·May 22, 2020Friday·May 22, 2020

1. 01*

   Improved Plutonium and Americium Photon Branching Ratios from Microcalorimeter Gamma Spectroscopy

   Michael D. Yoho🇺🇸 · Katrina E. Koehler🇺🇸 · Daniel T. Becker🇺🇸 · Douglas A. Bennett · Matthew H. Carpenter🇺🇸 · Mark P. Croce🇺🇸 · Johnathon D. Gard🇺🇸 · J. A. Ben Mates🇺🇸 · David J. Mercer🇺🇸 · Nathan J. Ortiz · Daniel R. Schmidt🇺🇸 · Chandler M. Smith🇺🇸 and 6 other authors

   Photon branching ratios are critical input data for activities such as nuclear materials protection and accounting because they allow material compositions to be extracted from measurements of gamma-ray intensities. Uncertainties in these branching ratios are often a limiting source of uncertainty in composition determination. Here, we use high statistics, high resolution (~60-70eV full-width-at-half-maximum at 100 keV) gamma-ray spectra acquired using microcalorimeter sensors to substantially reduce the uncertainties for 11 plutonium (238Pu,239Pu,241Pu) and 241Am branching ratios important for material control and accountability and nuclear forensics in the energy range of 125 keV to 208 keV. We show a reduction in uncertainty of over a factor of three for one branching ratio and a factor of 2{3 for four branching ratios.

   nucl-exphysics.ins-detNucl.Instrum.Meth.A(2020)·7 citations
2. 02*

   Shape coexistence revealed in the $N=Z$ isotope ${}^{72}$Kr through inelastic scattering

   K. Wimmer🇯🇵 · T. Arici🇩🇪 · W. Korten🇫🇷 · P. Doornenbal🇯🇵 · J.-P. Delaroche🇫🇷 · M. Girod🇫🇷 · J. Libert🇫🇷 · T. R. Rodríguez🇪🇸 · P. Aguilera🇨🇱 · A. Algora🇭🇺 · T. Ando🇯🇵 · H. Baba🇯🇵 and 32 other authors

   The $N=Z=36$ nucleus ${}^{72}$Kr has been studied by inelastic scattering at intermediate energies. Two targets, ${}^9$Be and ${}^{197}$Au, were used to extract the nuclear deformation length, ${\delta }_{\text{N}}$, and the reduced $E2$ transition probability, $B(E2)$. The previously unknown non-yrast $2^{+}$ and $4^{+}$ states as well as a new candidate for the octupole $3^{-}$ state have been observed in the scattering on the Be target and placed in the level scheme based on $\gamma -\gamma$ coincidences. The second $2^{+}$ state was also observed in the scattering on the Au target and the $B(E2;2_2^{+}\to 0_1^{+})$ value could be determined for the first time. Analyzing the results in terms of a two-band mixing model shows clear evidence for a oblate-prolate shape coexistence and can be explained by a shape change from an oblate ground state to prolate deformed yrast band from the first $2^{+}$ state. This interpretation is corroborated by beyond mean field calculations using the Gogny D1S interaction.

   nucl-exEPJA(2020)·23 citations
3. 03*

   Recent developments in chiral and spin polarization effects in heavy-ion collisions

   Jian-Hua Gao🇨🇳 · Guo-Liang Ma🇨🇳 · Shi Pu🇨🇳 · Qun Wang🇨🇳

   We give a brief overview of recent theoretical and experimental results on the chiral magnetic effect and spin polarization effect in heavy-ion collisions. We present updated experimental results for the chiral magnetic effect and related phenomena. The time evolution of the magnetic fields in different models is discussed. The newly developed quantum kinetic theory for massive fermions is reviewed. We present theoretical and experimental results for the polarization of $\Lambda$ hyperons and the ${\rho }_{00}$ value of vector mesons.

   ↳ hep-phnucl-exnucl-thNucl.Sci.Tech.(2020)·134 citations
4. 04*

   alpha+28Si and 16O+16O molecular states, and their isoscalar monopole strengths

   M. Kimura🇯🇵 · Y. Taniguchi🇯🇵

   The properties of the alpha+28Si and 16O+16O molecular states which are embedded in the excited states of 32S and can have an impact on the stellar reactions are investigated using the antisymmetrized molecular dynamics. From the analysis of the cluster spectroscopic factors, the candidates of alpha+28Si and 16O+16O molecular states are identified close to and above the cluster threshold energies. The calculated properties of the alpha+28Si molecular states are consistent with those reported by the alpha+28Siresonant scattering experiments. On the other hand, the 16O+16O molecular state, which is predicted to be identical to the superdeformation of 32S, is inconsistent with the assignment proposed by an alpha inelastic scattering experiment. Our calculation suggests that the monopole transition from the ground state to the 16O+16O molecular state is rather weak and is not strongly excited by the alpha inelastic scattering.

   ↳ nucl-thnucl-exPRC(2020)·3 citations
5. 05*

   The S$\pi$RIT Time Projection Chamber

   J. Barney · J. Estee · W.G. Lynch · T. Isobe · G. Jhang · M. Kurata-Nishimura · A.B. McIntosh · T. Murakami · R. Shane · S. Tangwancharoen · M.B. Tsang · G. Cerizza and 28 other authors

   The SAMURAI Pion Reconstruction and Ion-Tracker Time Projection Chamber (S$\pi$RIT TPC) was designed to enable measurements of heavy ion collisions with the SAMURAI spectrometer at the RIKEN Radioactive Isotope Beam Factory and provide constraints on the Equation of State of neutron-rich nuclear matter. The S$\pi$RIT TPC has a 50.5 cm drift length and an 86.4 cm $\times$ 134.4 cm pad plane with 12,096 pads that are equipped with the Generic Electronics for TPCs readout electronics. The S$\pi$RIT TPC allows excellent reconstruction of particles and provides isotopic resolution for pions and other light charged particles across a wide range of energy losses and momenta. Details of the S$\pi$RIT TPC are presented, along with discussion of the TPC performance based on cosmic ray and experimental data.

   ↳ physics.ins-detnucl-exRev.Sci.Instrum.(2021)·16 citations
6. 06*

   Exploring $J/\psi$ production mechanism at the future Electron-Ion Collider

   Jian-Wei Qiu🇺🇸 · Xiang-Peng Wang🇺🇸 · Hongxi Xing🇨🇳

   We propose to use transverse momentum $p_T$ distribution of $J/\psi$ production at the future Electron Ion Collider (EIC) to explore the production mechanism of heavy quarkonia in high energy collisions. We apply QCD and QED collinear factorization to the production of a $c\bar{c}$ pair at high $p_T$, and non-relativistic QCD factorization to the hadronization of the pair to a $J/\psi$. We evaluate $J/\psi$ $p_T$-distribution at both leading and next-to-leading order in strong coupling, and show that production rates for various color-spin channels of a $c\bar{c}$ pair in electron-hadron collisions are very different from that in hadron-hadron collisions, which provides a strong discriminative power to determine various transition rates for the pair to become a $J/\psi$. We predict that the $J/\psi$ produced in electron-hadron collisions is likely unpolarized, and the production is an ideal probe for gluon distribution of colliding hadron (or nucleus). We find that the $J/\psi$ production is dominated by the color-octet channel, providing an excellent probe to explore the gluon medium in large nuclei at the EIC.

   ↳ hep-phhep-exnucl-exnucl-thChin.Phys.Lett.(2021)·21 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.