Tue·Jul 9, 2024Tuesday·July 9, 2024

1. 01*

   Isomer production studied with simultaneous decay curve analysis for alpha-particle induced reactions on natural platinum up to 29 MeV

   Naohiko Otuka · Sandor Takacs · Masayuki Aikawa · Shuichiro Ebata🇯🇵 · Hiromitsu Haba

   The isomeric ratios of ${}^{198}$Au, ${}^{197}$Hg and ${}^{195}$Hg produced by $\alpha$-particle induced reactions on natural platinum were investigated experimentally up to 29 MeV by using the standard stacked foil activation technique and $\gamma$-ray spectrometry. The isomeric ratios of ${}^{197}$Hg and ${}^{195}$Hg determined by the conventional activation cross section formula showed strong cooling time dependence. The time dependence was resolved by adjusting the isomeric transition branching ratios for the two isotopes within a simultaneous decay curve analysis framework. Our analysis suggests 94.5$\pm$0.7% and 48.9$\pm$1.8% as the isomeric transition branching ratios of ${}^{197m}$Hg (24 h) and ${}^{195m}$Hg (42 h), respectively. The isomeric ratios and independent production cross sections of ${}^{198}$Au, ${}^{197}$Hg, ${}^{195}$Hg and some other Hg, Au and Pt isotopes were also measured down to 6 MeV with these corrected isomeric transition branching ratios, and compared with predictions of statistical and pre-equilibrium models by TALYS-2.0 to discuss spin cuto? parameter dependence. We found the measured isomeric ratios are better predicted if we reduce the spin cuto? parameter to half or less from that estimated with the rigid body moment of inertia.

   nucl-exEPJA(2024)·4 citations
2. 02*

   Search for nuclear modifications of B${}^{+}$ meson production in pPb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 8.16 TeV

   CMS Collaboration

   Nuclear medium effects on B${}^{+}$ meson production are studied using the binary-collision scaled cross section ratio between events of different charged-particle multiplicities from proton-lead collisions. Data, collected by the CMS experiment in 2016 at a nucleon-nucleon center-of-mass energy of $\sqrt{s_{\mathrm{NN}}}$ = 8.16 TeV, corresponding to an integrated luminosity of 175 nb${}^{-1}$, were used. The scaling factors in the ratio are determined using a novel approach based on the Z $\to$ ${\mu }^{+}{\mu }^{-}$ cross sections measured in the same events. The scaled ratio for B${}^{+}$ is consistent with unity for all event multiplicities, putting stringent constraints on nuclear modification for heavy flavor.

   nucl-exhep-exPRL(2025)·3 citations
3. 03*

   Improved limit on neutrinoless double beta decay of ${}^{100}$Mo from AMoRE-I

   A. Agrawal · V.V. Alenkov · P. Aryal · J. Beyer · B. Bhandari · R.S. Boiko · K. Boonin · O. Buzanov · C.R. Byeon · N. Chanthima · M.K. Cheoun · J.S. Choe and 96 other authors

   AMoRE searches for the signature of neutrinoless double beta decay of ${}^{100}$Mo with a 100 kg sample of enriched ${}^{100}$Mo. Scintillating molybdate crystals coupled with a metallic magnetic calorimeter operate at milli-Kelvin temperatures to measure the energy of electrons emitted in the decay. As a demonstration of the full-scale AMoRE, we conducted AMoRE-I, a pre-experiment with 18 molybdate crystals, at the Yangyang Underground Laboratory for over two years. The exposure was 8.02 kg$\cdot$year (or 3.89 kg${}_{{}^{100}\mathrm{Mo}}\cdot$year) and the total background rate near the Q-value was 0.025 $\pm$ 0.002 counts/keV/kg/year. We observed no indication of $0\nu \beta \beta$ decay and report a new lower limit of the half-life of ${}^{100}$Mo $0\nu \beta \beta$ decay as $T_{1/2}^{0\nu }>2.9\times 10^{24}\mathrm{yr}$ at 90\% confidence level. The effective Majorana mass limit range is $m_{\beta \beta }<$(210--610) meV using nuclear matrix elements estimated in the framework of different models, including the recent shell model calculations.

   nucl-exhep-exPRL(2025)·50 citations
4. 04*

   Isochronous mass spectrometry at the RIKEN Rare-RI Ring facility

   D. Nagae · S. Omika · Y. Abe🇯🇵 · Y. Yamaguchi🇯🇵 · F. Suzaki · K. Wakayama · N. Tadano · R. Igosawa · K. Inomata · H. Arakawa · K. Nishimuro · T. Fujii and 19 other authors

   A dedicated isochronous storage ring, named the Rare-RI Ring, was constructed at the RI Beam Factory of RIKEN, aiming at precision mass measurements of nuclei located in uncharted territories of the nuclear chart. The Rare-RI Ring employs the isochronous mass spectrometry technique with the goal to achieve a relative mass precision of $10^{-6}$ within a measurement time of less than 1 ms. The performance of the facility was demonstrated through mass measurements of neutron-rich nuclei with well-known masses. Velocity or magnetic rigidity is measured for every particle prior to its injection into the ring, wherein its revolution time is accurately determined. The latter quantity is used to determine the mass of the particle, while the former one is needed for non-isochronicity corrections. Mass precisions on the order of $10^{-5}$ were achieved in the first commissioning, which demonstrates that Rare-RI Ring is a powerful tool for mass spectrometry of short-lived nuclei.

   nucl-exPRC(2024)·3 citations
5. 05*

   Effect of ground-state deformation on the Isoscalar Giant Monopole Resonance and the first observation of overtones of the Isoscalar Giant Quadrupole Resonance in rare-earth Nd isotopes

   M. Abdullah · S. Bagchi🇩🇪 · M.N. Harakeh🇳🇱 · H. Akimune · D. Das🇮🇳 · T. Doi🇯🇵 · L. M. Donaldson🇿🇦 · Y. Fujikawa · M. Fujiwara🇯🇵 · T. Furuno🇯🇵 · U. Garg🇺🇸 · Y.K. Gupta🇮🇳 and 24 other authors

   The strength distributions of the Isoscalar Giant Monopole Resonance (ISGMR) and Isoscalar Giant Quadrupole Resonance (ISGQR) in 142,146-150Nd have been determined via inelastic alpha-particle scattering with the Grand Raiden (GR) Spectrometer at the Research Center for Nuclear Physics (RCNP), Japan. In the deformed nuclei 146-150Nd, the ISGMR strength distributions exhibit a splitting into two components, while the nearly spherical nucleus 142Nd displays a single peak in the ISGMR strength distribution. A noteworthy achievement in this study is the first-time detection of overtones in the Isoscalar Giant Quadrupole Resonance (ISGQR) strength distributions within Nd isotopes at an excitation energy around 25 MeV obtained through Multipole Decomposition Analysis (MDA).

   nucl-exnucl-thPLB(2024)·6 citations
6. 06*

   Single-Neutron Adding on ${}^{34}$S

   A. N. Kuchera🇺🇸 · C. R. Hoffman🇺🇸 · G. Ryan · I. B. D'Amato🇺🇸 · O. M. Guarinello · P. S. Kielb🇺🇸 · R. Aggarwal🇮🇳 · S. Ajayi🇺🇸 · A. L. Conley🇺🇸 · I. Conroy🇺🇸 · P. D. Cottle🇺🇸 · J. C. Esparza and 16 other authors

   Purpose: Single-neutron adding data was collected in order to determine the distribution of the single-neutron strength of the $0f_{7/2}$, $1p_{3/2}$, $1p_{1/2}$ and $0f_{5/2}$ orbitals outside of $Z=16,N=18$, ${}^{34}$S. Methods: The ${}^{34}$S($d$,$p$)${}^{35}$S reaction has been measured at 8 MeV/u to investigate cross sections to excited states in ${}^{35}$S. Outgoing proton yields and momenta were analyzed by the Super-Enge Split-Pole Spectrograph in conjunction with the CeBrA demonstrator located at the John D. Fox Laboratory at Florida State University. Angular distributions were compared with Distorted Wave Born Approximation calculations in order to extract single-neutron spectroscopic overlaps. Results: Spectroscopic overlaps and strengths were determined for states in ${}^{35}$S up through 6 MeV in excitation energy. Each orbital was observed to have fragmented strength where a single level carried the majority. The single-neutron centroids of the $0f_{7/2}$, $1p_{3/2}$, $1p_{1/2}$ and $0f_{5/2}$ orbitals were determined to be $2360_{-40}^{+90}$ keV, $3280_{-50}^{+80}$ keV, $4780_{-40}^{+60}$ keV, and $\gtrsim 7500$ keV, respectively. Conclusion: A previous discrepancy in the literature with respect to distribution of the neutron $1p_{1/2}$ strength was resolved. The integration of the normalized spectroscopic strengths, up to 5.1 MeV in excitation energy, revealed fully-vacant occupancies for the $0f_{7/2}$, $1p_{3/2}$, and $1p_{1/2}$ orbitals, as expected. The spacing in the single-neutron energies highlighted a reduction in the traditional $N=28$ shell-gap, relative to both the $1p$ spin-orbit energy difference ($N=32$) and the lower limit on the $N=34$ shell spacing.

   nucl-exEPJA(2024)·4 citations
7. 07*

   QCD Masterclass Lectures on Jet Physics and Machine Learning

   Andrew J. Larkoski🇺🇸

   These lectures were presented at the 2024 QCD Masterclass in Saint-Jacut-de-la-Mer, France. They introduce and review fundamental theorems and principles of machine learning within the context of collider particle physics, focused on application to jet identification and discrimination. Numerous examples of binary discrimination in jet physics are studied in detail, including $H\to b\bar{b}$ identification in fixed-order perturbation theory, generic one-versus two-prong discrimination with parametric power counting techniques, and up versus down quark jet classification by assuming the central limit theorem, isospin conservation, and a convergent moment expansion of the single particle energy distribution. Quark versus gluon jet discrimination is considered in multiple contexts, from using additive, infrared and collinear safe observables, to using hadronic multiplicity, and to including measurements of the jet charge. While many of the results presented here are well known, some novel results are presented, the most prominent being a parametrized expression for the likelihood ratio of quark versus gluon discrimination for jets on which hadronic multiplicity and jet charge are simultaneously measured. End-of-lecture exercises are also provided.

   ↳ hep-phhep-exhep-thnucl-ex+1EPJC(2024)·20 citations
8. 08*

   Statistical Production of $B_c$ Mesons in Heavy-Ion Collisions at the LHC Energy

   Shouxing Zhao🇨🇳 · Min He🇨🇳

   The recombination production of $B_c$ mesons in heavy-ion collisions at the LHC energy is facilitated by the abundant and highly thermalized charm ($c$) quarks transported in the deconfined medium created. We study the production of $B_c$ mesons via $c$ and bottom ($b$) quark recombination in a statistical fashion by placing $B_c$ in the position of a member of the family of open $b$ hadrons, which allows us to make quantitative predictions for the modifications of the production fraction ($f_c$) of $B_c$ mesons and its relative production to $B$ mesons in $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV Pb-Pb collisions with respect to proton-proton ($pp$) collisions at the same energy. The statistical production yield of $B_c$ mesons is converted into the transverse momentum ($p_T$) distribution with the shape computed from resonance recombination using the $c$- and $b$-quark phase space distributions that have been simulated via Langevin diffusion and constrained by open $c$- and $b$-hadron observables. Supplemented with the component fragmented from $b$-quark spectrum that dominates at high $p_T$, the total $p_T$ spectrum of $B_c$ mesons is obtained and converted into the $p_T$ dependent nuclear modification factor ($R_{\mathrm{AA}}$). Both $f_c$ and the integrated $R_{\mathrm{AA}}$ exhibit a $\sim 5$-fold enhancement in central Pb-Pb collisions relative to the $pp$ reference. Comparison with data measured by the CMS experiment shows decent agreement within theoretical and experimental uncertainties.

   ↳ nucl-thhep-phnucl-exPLB(2025)·6 citations
9. 09*

   Volume effect on the extraction of sound velocity in high-energy nucleus-nucleus collisions

   Jing-An Sun🇨🇳 · Li Yan🇨🇳

   The determination of the speed of sound in quark-gluon plasma is a crucial aspect of understanding the properties of strongly interacting matter created in relativistic heavy-ion collisions. In this study, we investigate the impact of initial-state fluctuations on the extraction of the speed of sound in a quark-gluon plasma in the ultra-central collisions. By employing the TRENTo model for simulating initial conditions, we demonstrate that these fluctuations lead to sizable volume effect, which in turn corrects the measured values of the sound velocity. With respect to realistic conditions of high-energy heavy-ion experiments, we provide quantitative estimate of these corrections.

   ↳ nucl-thhep-phnucl-exPLB(2025)·9 citations
10. 10*

    Combining Hybrid and Opaque Scintillator Techniques in the Search for Double Beta Plus Decays

    NuDoubt++ Collaboration: Manuel Böhles🇩🇪 · Sebastian Böser🇩🇪 · Magdalena Eisenhuth🇩🇪 · Cloé Girard-Carillo🇩🇪 · Kitzia M. Hernandez Curiel🇩🇪 · Bastian Keßler🇩🇪 · Kyra Mossel🇩🇪 · Veronika Palušová🇩🇪 · Stefan Schoppmann🇩🇪 · Alfons Weber🇩🇪 · Michael Wurm🇩🇪

    Double beta plus decay is a rare nuclear disintegration process. Difficulties in its measurement arise from suppressed decay probabilities, experimentally challenging decay signatures and low natural abundances of suitable candidate nuclei. In this article, we propose a new detector concept to overcome these challenges. It is based on the first-time combination of hybrid and opaque scintillation detector technology paired with novel light read-out techniques. This approach is particularly suitable detecting positron (beta plus) signatures. We expect to discover two-neutrino double beta plus decay modes within 1 tonne-week exposure and are able to probe neutrinoless double beta plus decays at several orders of magnitude improved significance compared to current experimental limits.

    ↳ physics.ins-dethep-exnucl-exEPJC(2025)·16 citations
11. 11*

    Angular anisotropy in prefission neutron spectra and PFNS of ${}^{240}$Pu$(n,F)$

    V.M. Maslov

    Angular anisotropy of secondary neutrons was evidenced in neutron emission spectra (NES) of ${}^{239}$Pu+n in 1972, and prompt fission neutron spectra (PFNS) of ${}^{239}$Pu$(n,F)$ in 2019, it might be predicted for ${}^{240}$Pu(n,F) PFNS now. In case of NES angular anisotropy is due to direct excitation of collective levels and pre-equilibrium/semi-direct (states in the continuum are excited) mechanism of neutron emission of first neutron in (n,nX) reaction, while in case of PFNS it is due to exclusive spectra of pre-fission neutrons of (n, xnf) reactions. In ${}^{239}$Pu$(n,xnf)$ and ${}^{240}$Pu(n,xnf) reactions observed PFNS envision different response to the emission of first pre-fission neutron in forward or backward semi-spheres with respect to the momentum of incident neutrons. Since energies of (n,nf) neutrons and their average values depend on angle of emission theta with respect to the incident neutron momentum, the observed PFNS, average prompt fission neutron multiplicity, fission cross section, average total kinetic energy TKE, etc. also would be quite dependent on angle theta. Exclusive spectra of (n, xnf) neutrons at theta of 90 degrees are consistent with ${}^{240}$Pu(n, F)(${}^{239}$Pu$(n,F)$, ${}^{239}$Pu$(n,2n)$) observed cross sections and neutron emission spectra of ${}^{239}$Pu+n interaction at En up to 20 MeV. The correlations of the angular anisotropy of PFNS with the relative contribution of the $(n,nf)$ fission chance to the observed fission cross section and angular anisotropy of pre-fission neutron emission are ascertained.

    ↳ nucl-thnucl-ex0 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.