Wed·May 8, 2024Wednesday·May 8, 2024

1. 01*

   Letter of Intent: Open Charm at JLab with the sPHENIX MAPS tracker

   Miguel Arratia🇺🇸 · Sebouh J. Paul🇺🇸 · Yuri Gotra🇺🇸 · Hayk Hakobyan🇨🇱 · Bryan McKinnon🇬🇧

   We propose a physics program at JLab with CLAS12 focusing on open-charm measurements, aiming to complement and expand current studies of $J/\psi$ at (sub) threshold. This program will aid us in elucidating the $J/\psi$ production mechanisms, which is crucial for interpreting data in terms of gluon form factors and offer potential insights into the intrinsic charm hypothesis and cold-nuclear matter effects. We discuss the technical feasibility of integrating the sPHENIX monolithic-active-pixel sensor (MAPS) tracker, known as MVTX, with the CLAS12 detector. The sPHENIX MTVX would support an open-charm program by providing excellent secondary-vertex performance for tagging $D$ mesons. We study the kinematics of $\gamma p\to {\bar{D}}^0{\Lambda }_c$ through phase-space simulations and estimate rates for the tagged quasi-photoproduction regime available with the CLAS12 forward tagger. While open-charm cross-sections at threshold remain uncertain, various predictions suggest that these measurements could be feasible when combined with conservative estimates of detector acceptance and luminosity. These preliminary estimates motivate detailed Geant detector simulations of signals and backgrounds, along with thorough technical assessments of operating conditions, to further explore the feasibility of these measurements in future dedicated CLAS12 experiments at JLab.

   nucl-ex0 citations
2. 02*

   Comment on "Spin-trap isomers in deformed, odd-odd nuclei in the light rare-earth region near $N=98$"

   M. Stryjczyk🇫🇮 · A. Jaries🇫🇮 · A. Kankainen🇫🇮 · T. Eronen🇫🇮

   A new isomeric $(4^{-})$ state at 285.5(32) keV in ${}^{162}$Tb was reported by R. Orford et al. [Phys. Rev. C 102, 011303(R) (2020)] based on a Penning-trap mass measurement. Here we show that this result is not compatible with existing experimental data. The state identified as ${}^{162}$Tb${}^m$ with a mass-excess value of $-65593.9(25)$ keV is actually the $1^{-}$ ground state. The state identified as the ground state of ${}^{162}$Tb is most likely a molecular contaminant with the same mass-over-charge ratio.

   ↳ nucl-thnucl-exPRC(2025)·2 citations
3. 03*

   Circular polarization measurement for individual gamma rays in capture reactions with intense pulsed neutrons

   S. Endo · R. Abe · H. Fujioka · T. Ino · O. Iwamoto · N. Iwamoto · S. Kawamura · A. Kimura · M. Kitaguchi · R. Kobayashi · S. Nakamura · T. Oku T. Okudaira and 12 other authors

   Measurements of circular polarization of $\gamma$-ray emitted from neutron capture reactions provide valuable information for nuclear physics studies. The spin and parity of excited states can be determined by measuring the circular polarization from polarized neutron capture reactions. Furthermore, the $\gamma$-ray circular polarization in a neutron capture resonance is crucial for studying the enhancement effect of parity nonconservation in compound nuclei. The $\gamma$-ray circular polarization can be measured using a polarimeter based on magnetic Compton scattering. A polarimeter was constructed, and its performance indicators were evaluated using a circularly polarized $\gamma$-ray beam. Furthermore, as a demonstration, the $\gamma$-ray circular polarization was measured in ${}^{32}$S($\vec{\text{n}}$,$\gamma$)${}^{33}$S reactions with polarized neutrons.

   ↳ physics.ins-detnucl-exEPJA(2024)·4 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.