Mon·Feb 14, 2022Monday·February 14, 2022

1. 01*

   Observation of the ${\pi }^2{\sigma }^2$-bond linear-chain molecular structure in ${}^{16}$C

   J. X. Han🇨🇳 · Y. Liu🇨🇳 · Y. L. Ye🇨🇳 · J. L. Lou🇨🇳 · X. F. Yang🇨🇳 · T. Baba🇯🇵 · M. Kimura🇯🇵 · B. Yang🇨🇳 · Z. H. Li · Q. T. Li🇨🇳 · J. Y. Xu🇨🇳 · Y. C. Ge🇨🇳 and 28 other authors

   Measurements of the ${}^2$H(${}^{16}$C,${}^{16}$C${}^{\ast }$${\to }^4$He+${}^{12}$Be or ${}^6$He+${}^{10}$Be)${}^2$H inelastic excitation and cluster-decay reactions have been carried out at a beam energy of about 23.5 MeV/u. A specially designed detection system, including one multi-layer silicon-strip telescope at around zero degrees, has allowed the high-efficiency three-fold coincident detection and therefore the event-by-event determination of the energy of the unstable nucleus beam. The decay paths from the ${}^{16}$C resonances to various states of the final ${}^{10}$Be or ${}^{12}$Be nucleus are recognized thanks to the well-resolved $Q$-value spectra. The reconstructed resonances at 16.5(1), 17.3(2), 19.4(1) and 21.6(2) MeV are assigned as the $0^{+}$, $2^{+}$, $4^{+}$ and $6^{+}$ members, respectively, of the positive-parity $(3/2_{\pi }^{-}{)}^2(1/2_{\sigma }^{-}{)}^2$-bond linear-chain molecular band in ${}^{16}$C, based on the angular correlation analysis for the 16.5 MeV state and the excellent agreement of decay patterns between the measurements and theoretical predictions. Moreover, another intriguing high-lying state was observed at 27.2(1) MeV which decays almost exclusively to the $\sim$6 MeV states of ${}^{10}$Be, in line with the newly predicted pure $\sigma$-bond linear-chain configuration.

   nucl-exPRC(2022)·13 citations
2. 02*

   Border of the Island of Inversion: Unbound states in ${}^{29}$Ne

   M. Holl🇸🇪 · S. Lindberg🇸🇪 · A. Heinz🇸🇪 · Y. Kondo🇯🇵 · T. Nakamura🇯🇵 · J. A. Tostevin🇬🇧 · H. Wang🇯🇵 · T. Nilsson🇸🇪 · N. L. Achouri🇫🇷 · H. Al Falou🇱🇧 · L. Atar🇩🇪 · T. Aumann🇩🇪 and 80 other authors

   The nucleus ${}^{29}$Ne is situated at the border of the island of inversion. Despite significant efforts, no bound low-lying intruder $f_{7/2}$-state, which would place ${}^{29}$Ne firmly inside the island of inversion, has yet been observed. Here, the first investigation of unbound states of ${}^{29}$Ne is reported. The states were populated in ${}^{30}\mathrm{Ne}(p,pn)$ and ${}^{30}\mathrm{Na}(p,2p)$ reactions at a beam energy of around $230$ MeV/nucleon, and analyzed in terms of their resonance properties, partial cross sections and momentum distributions. The momentum distributions are compared to calculations using the eikonal, direct reaction model, allowing $\ell$-assignments for the observed states. The lowest-lying resonance at an excitation energy of 1.48(4) MeV shows clear signs of a significant $\ell$=3-component, giving first evidence for $f_{7/2}$ single particle strength in ${}^{29}$Ne. The excitation energies and strengths of the observed states are compared to shell-model calculations using the sdpf-u-mix interaction

   nucl-exPRC(2022)·6 citations
3. 03*

   A Novel Silicon Photomultiplier Readout Architecture for Low-light Applications

   V. Cianciolo · Yu. V. Efremenko · L. Fabris · S. K. Imam · S. I. Penttila J. C. Ramsey · R. Santos Estrada

   In this article we describe the photon detection readout electronics for the nEDM@SNS experiment. The chosen "photon counting" architecture, which utilizes high-efficiency silicon photomultipliers (SiPMs) and is appropriate for low-light applications, allows the use of a relatively high SiPM operating voltage. This maximizes photon detection efficiency and minimizes gain/efficiency voltage-dependence while eliminating optical cross-talk.

   ↳ physics.ins-detnucl-exJINST(2022)·1 citation

* 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.