Mon·Jan 15, 2024Monday·January 15, 2024

1. 01*

   First Exploration of Monopole-Driven Shell Evolution above the N = 126 shell closure: new Millisecond Isomers in 213Tl and 215Tl

   T.T. Yeung · A.I. Morales · J. Wu · M. Liu · C. Yuan · S. Nishimura · V. H. Phong · N. Fukuda · J.L. Tain · T. Davinson · K.P. Rykaczewski · R. Yokoyama and 43 other authors

   Isomer spectroscopy of heavy neutron-rich nuclei beyond the N=126 closed shell has been performed for the first time at the Radioactive Isotope Beam Factory of the RIKEN Nishina Center. New millisecond isomers have been identified at low excitation energies, 985.3(19) keV in 213Tl and 874(5) keV in 215Tl. The measured half-lives of 1.34(5) ms in 213Tl and 3.0(3) ms in 215Tl suggest spins and parities 11/2- with the single proton-hole configuration h11/2 as leading component. They are populated via E1 transitions by the decay of higher-lying isomeric states with proposed spin and parity 17/2+, interpreted as arising from a single s1/2 proton hole coupled to the 8+ seniority isomer in the (A+1)Pb cores. The lowering of the 11/2- states is ascribed to an increase of the h11/2 proton effective single-particle energy as the second g9/2 orbital is filled by neutrons, owing to a significant reduction of the proton-neutron monopole interaction between the h11/2 and g9/2 orbitals. The new ms-isomers provide the first experimental observation of shell evolution in the almost unexplored N>126 nuclear region below doubly-magic 208Pb.

   nucl-exPRL(2024)·9 citations
2. 02*

   Experimental study of $\alpha$-induced reactions on ${}^{113}$In for astrophysical $p$-process

   Dipali Basak · Tanmoy Bar · Abhijit Roy · Lalit Kumar Sahoo · Sukhendu Saha · Jagannath Datta · Sandipan Dasgupta · Chinmay Basu

   Neutron deficient nuclei from ${}^{74}$Se${-}^{196}$Hg are thought to be produced by $\gamma$-induced reactions ($\gamma$,n), ($\gamma$,p) and ($\gamma ,\alpha$) processes. The relatively high abundance of ${}^{113}$In odd A $p$-nuclei has inspired to study its production processes. As reaction with $\gamma$-beam is difficult to perform in the laboratory, $\gamma$-induced reaction rate is calculated from the inverse reaction data employing reciprocity theorem. Stacked foil activation method was used to measure the ${}^{113}$In($\alpha ,\gamma$) and ${}^{113}$In($\alpha$, n) reactions cross-section near the astrophysical energies. Theoretical statistical model calculations were performed with different nuclear input parameters and compared with the experimental results. An appropriate $\alpha$-optical potential has been identified from the ($\alpha ,\gamma$) and ($\alpha$, n) fitting, which provides the major source of uncertainty in the statistical model calculations. The other nuclear input parameters like level density, and $\gamma$-ray strength function were also constrained for theoretical calculations. ${}^{113}$In($\alpha ,\gamma$)${}^{117}$Sb and ${}^{117}$Sb($\alpha ,\gamma$)${}^{113}$In reaction rates were calculated using best-fitted input parameters.

   nucl-exastro-ph.SRPRC(2024)·5 citations
3. 03*

   Imaging Shapes of Atomic Nuclei in High-Energy Nuclear Collisions

   STAR Collaboration

   Atomic nuclei are self-organized, many-body quantum systems bound by strong nuclear forces within femtometer-scale space. These complex systems manifest a variety of shapes, traditionally explored using non-invasive spectroscopic techniques at low energies. However, at these energies, their instantaneous shapes are obscured by long-timescale quantum fluctuations, making direct observation challenging. Here we introduce the ``collective flow assisted nuclear shape imaging'' method, which images the nuclear global shape by colliding them at ultrarelativistic speeds and analyzing the collective response of outgoing debris. This technique captures a collision-specific snapshot of the spatial matter distribution within the nuclei, which, through the hydrodynamic expansion, imprints patterns on the particle momentum distribution observed in detectors. We benchmark this method in collisions of ground state Uranium-238 nuclei, known for their elongated, axial-symmetric shape. Our findings show a large deformation with a slight deviation from axial symmetry in the nuclear ground state, aligning broadly with previous low-energy experiments. This approach offers a new method for imaging nuclear shapes, enhances our understanding of the initial conditions in high-energy collisions and addresses the important issue of nuclear structure evolution across energy scales.

   nucl-exhep-exhep-phnucl-thNature(2024)·148 citations
4. 04*

   High Resolution Study of ${}^{40}$Ca to Constrain Potassium Nucleosynthesis in NGC 2419

   William Fox · Richard Longland🇺🇸 · Caleb Marshall🇺🇸 · Federico Portillo Chaves

   The globular cluster NGC 2419 was the first to exhibit a Mg-K anticorrelation, linked to hydrogen burning at temperatures between 80-260 MK. However, the key K-destroying reaction, ${}^{39}\mathrm{K}(p,\gamma {)}^{40}\mathrm{Ca}$, has a large rate uncertainty in this range. We significantly constrain this rate with a high resolution ${}^{39}\mathrm{K}{(}^3\mathrm{He},d{)}^{40}\mathrm{Ca}$ study. We resolve the E${}_{\text{r}}^{\text{c.m.}}=154$ keV resonance in ${}^{39}\mathrm{K}+p$ for the first time, increasing the previous rate by up to a factor 13 and reducing its $1\sigma$ width by up to a factor of 42. Reaction network calculations for NGC 2419 suggest that this could lower temperatures needed to reproduce the Mg-K anticorrelation.

   nucl-exastro-ph.SRPRL(2024)·2 citations
5. 05*

   SIDIS at small $x$ at next-to-leading order: gluon contribution

   Filip Bergabo🇺🇸 · Jamal Jalilian-Marian🇺🇸

   We calculate the contribution of gluons to single inclusive hadron production at next-to-leading order (NLO) accuracy in Deep Inelastic Scattering (DIS) at small $x$ using the Color Glass Condensate formalism. It is shown that the only divergence present is the standard collinear divergence which is absorbed into evolution of gluon-hadron fragmentation function. Our calculations are performed at finite $N_c$ and we provide general finite $N_c$ expressions for the structure of Wilson lines appearing in inclusive dihadron and single hadron production cross sections. We also comment on how one can obtain rapidity distribution of hadron multiplicities from our results.

   ↳ hep-phnucl-exnucl-thPRD(2024)·15 citations
6. 06*

   Spin squeezed states and wobbling motion in collective Hamiltonian

   Q. B. Chen🇨🇳 · S. Frauendorf

   A semiclassical approach is proposed to calculate the collective potential and mass parameters to formulate a collective Hamiltonian capable of describing the wobbling motion in both even-even and odd-mass systems. By diagonalizing the resulting collective Hamiltonian (CH), one can obtain the energies and wave functions associated with the wobbling states. Furthermore, a novel technique called spin squeezed state (SSS) maps is introduced based on the derived wave functions. To validate the results obtained from the collective Hamiltonian, a comparative analysis is conducted against predictions from the triaxial rotor model (TRM) and particle triaxial rotor (PTR) model. Notably, the SSS plots determined using the TRM and PTR models exhibit a strong correlation with the probability density distributions of the wave functions obtained from the CH. This correlation highlights the consistency and coherence between the different theoretical approaches when describing the wobbling phenomenon and associated rotational dynamics.

   ↳ nucl-thnucl-exPRC(2024)·11 citations
7. 07*

   Understanding the Nonlinear Response of SiPMs

   Victor Moya · Jaime Rosado🇪🇸

   A systematic study of the nonlinear response of Silicon Photomultipliers (SiPMs) has been conducted through Monte Carlo simulations. SiPMs have been proven to show a universal nonlinear response when it is expressed in terms of relative parameters independent of both the gain and the photon detection efficiency (PDE). Nonlinearity has been shown to mainly depend on the balance between the photon rate and the pixel recovery time. However, exponential-like and finite light pulses have been found to lead to different nonlinear behaviors, which also depend on the correlated noise, the overvoltage dependence of the PDE, and the impedance of the readout circuit. Correlated noise has been shown to have a minor impact on nonlinearity, but it can significantly affect the shape of the SiPM output current. Considering these dependencies and previous statistical analysis of the nonlinear response of SiPMs, two simple fitting models have been proposed for exponential-like and finite light pulses, explaining the role of their various terms and parameters. Even though these models have only three fitting parameters, they provide an accurate description of the nonlinear response of SiPMs for a wide range of situations.

   ↳ physics.ins-dethep-exnucl-exphysics.med-phSensors(2024)·1 citation
8. 08*

   Neutron-rich nuclei and neutron skins from chiral low-resolution interactions

   P. Arthuis🇫🇷 · K. Hebeler🇩🇪 · A. Schwenk🇩🇪

   Neutron-rich nuclei provide important insights to nuclear forces and to the nuclear equation of state. Advances in ab initio methods combined with new opportunities with rare isotope beams enable unique explorations of their properties based on nuclear forces applicable over the entire nuclear chart. In this paper, we develop novel chiral low-resolution interactions that accurately describe bulk properties from ${}^{16}$O to ${}^{208}$Pb. With these, we investigate density distributions and neutron skins of neutron-rich nuclei. Our results show that neutron skins are narrowly predicted over all nuclei with interesting sensitivities for the most extreme, experimentally unexplored cases.

   ↳ nucl-thnucl-exEPJA(2026)·57 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.