Thu·Dec 5, 2024Thursday·December 5, 2024

1. 01*

   Sensitivity of Double Deeply Virtual Compton Scattering observables to GPDs

   J. S. Alvarado🇫🇷 · M. Hoballah🇫🇷 · E. Voutier🇫🇷

   Generalized Parton Distributions (GPDs) are multidimensonal structure functions that encode the information about the internal structure of hadrons. Using privileged channels such as Deeply Virtual Compton Scattering (DVCS) or Timelike Compton Scattering (TCS), it is possible to make direct measurements at points where the momentum fraction of the parton equals the respective scaling variable. Double Deeply Virtual Compton Scattering (DDVCS) is a not yet measured and promising channel for GPD studies as it allows to perform more general measurements at independent momentum fraction and scaling variable values. GPDs are extracted from Compton Form Factors which arise naturally in experimental observables from different combinations of beam and target configurations. In the context of the Continuous Electron Beam Accelerator Facility (CEBAF) and the Electron Ion Collider (EIC), we report the results of an exhaustive study of the DDVCS observables from polarized electron and positron beams directed to a polarized proton target. The study focuses on the sensitivity of the observables to the parton helicity conserving proton GPDs, particularly the consequences for GPDs measurements via DDVCS at CEBAF and EIC based on the VGG and GK19 model predictions.

   nucl-exhep-phPoS(2025)·2 citations
2. 02*

   Spectroscopy of ${}^{52}$K

   M. Enciu🇩🇪 · A. Obertelli🇩🇪 · P. Doornenbal🇯🇵 · M. Heinz🇩🇪 · T. Miyagi🇩🇪 · F. Nowacki🇫🇷 · K. Ogata🇯🇵 · A. Poves🇪🇸 · A. Schwenk🇩🇪 · K. Yoshida🇯🇵 · N.L. Achouri🇫🇷 · H. Baba🇯🇵 and 69 other authors

   The first spectroscopy of ${}^{52}$K was investigated via in-beam $\gamma$-ray spectroscopy at the RIKEN Radioactive Isotope Beam Factory after one-proton and one-neutron knockout from ${}^{53}$Ca and ${}^{53}$K beams impinging on a 15-cm liquid hydrogen target at $\approx$ 230~MeV/nucleon. The energy level scheme of ${}^{52}$K was built using single $\gamma$ and $\gamma$-$\gamma$ coincidence spectra. The spins and parities of the excited states were established based on momentum distributions of the fragment after the knockout reaction and based on exclusive cross sections. The results were compared to state-of-the-art shell model calculations with the SDPF-Umod interaction and ab initio IMSRG calculations with chiral effective field theory nucleon-nucleon and three-nucleon forces.

   nucl-exPRC(2024)·3 citations
3. 03*

   Overview of the latest ALICE UPC and photonuclear results

   Simone Ragoni (for the ALICE collaboration)🇺🇸

   Ultra-peripheral collisions (UPC) are events characterised by large impact parameters between the two projectiles, larger than the sum of their radii. In UPCs, the protons and ions accelerated by the LHC do not interact via the strong interaction and can be regarded as sources of quasireal photons. Using the Run 2 data, the ALICE Collaboration has carried out various measurements of different final-state systems, such as exclusive four pion photoproduction as well as photoproduction of $K^{+}{K}^{-}$ pairs, measured for the first time in ultra-peripheral collisions. In addition, vector meson production in Pb--Pb provides the unique opportunity to carry out an analogy of the double-slit experiment at femtometre scales, owing to the interference between the production sources of the two lead nuclei. These results and prospects for UPC measurements using Run 3 data will be presented.

   ↳ hep-exnucl-exActa Phys.Polon.Supp.(2025)·3 citations
4. 04*

   Evolution of shell structure at $\mathbf{N}=32$ and 34: Insights from realistic nuclear forces

   Subhrajit Sahoo🇮🇳 · Praveen C. Srivastava🇮🇳

   We investigated the evolution of shell structure at $N=32$ and 34 in neutron-rich nuclei beyond the stability line using realistic nuclear forces, employing the state-of-the-art valence-space in-medium similarity renormalization group method. The shell gaps are discussed from the excitation energies of the first $2^{+}$ states and the evolution of effective single-particle energies. We addressed different components of the nuclear interaction--central, spin-orbit, and tensor--and their roles in the development of shell gaps far from stability. The calculated results align well with the available experimental data and suggest a strengthening of the $N=34$ subshell gap and a weakening of the $N=32$ subshell gap below Ca. Additionally, the low-energy structures of the exotic $N=32$ isotones below Ca revealed that their ground states exhibit large deformation and coexist with a weakly deformed band at low excitation energy. The present work demonstrates essential components of the nuclear force in shaping magic numbers far from stability and provides deeper insights into the structure of exotic nuclei from the underlying nuclear forces.

   ↳ nucl-thnucl-exPRC(2025)·6 citations
5. 05*

   YSO implantation detector for beta-delayed neutron spectroscopy

   M. Singh🇺🇸 · R. Yokoyama🇯🇵 · R. Grzywacz🇺🇸 · A. Keeler · T. T. King🇺🇸 · J. Agramunt🇪🇸 · N. T. Brewer🇺🇸 · S. Go🇺🇸 · J. Liu🇨🇳 · S. Nishimura🇯🇵 · P. Parkhurst · V. H. Phong🇯🇵 and 7 other authors

   A segmented-scintillator-based implantation detector was developed to study the energy distribution of beta-delayed neutrons emitted from exotic isotopes. The detector comprises a 34 $\times$ 34 YSO scintillator coupled to an 8 $\times$ 8 Position-Sensitive Photo-Multiplier Tube (PSPMT) via a tapered light guide. The detector was used at RIBF, RIKEN, for time-of-flight-based neutron spectroscopy measurement in the ${}^{78}$Ni region. The detector provides the position and timing resolution necessary for ion-beta correlations and ToF measurements. The detector provides a high $\sim$ 80 $\%$ beta-detection efficiency and a sub-nanosecond timing resolution. This contribution discusses the details of the design, operation, implementation, and analysis developed to obtain neutron time-of-flight spectrum and the analysis methods in the context of neutron-rich nuclei in the ${}^{78}$Ni region.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2025)·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.