Mon·Jul 7, 2025Monday·July 7, 2025

1. 01*

   Energy dependence of isomeric ratios for alpha-particle-induced reactions on natural platinum up to 50 MeV studied by simultaneous decay curve analysis

   Naohiko Otuka · Masayuki Aikawa · Sándor Takács · Damdinsuren Gantumur · Shuichiro Ebata🇯🇵 · Lkhagvasuren Bold · Akihiro Nambu · Hiromitsu Haba

   The isomeric ratios and cross sections were measured up to 50 MeV for production of ${}^{198m,g}$Au, ${}^{197m,g}$Hg, ${}^{195m,g}$Hg and other Hg, Au and Pt radionuclides in irradiation of natural platinum by alpha-particles using the stacked foil activation technique and offline gamma-ray spectrometry. The simultaneous decay curve analysis was applied to the emission rates of more than 40 gamma lines to directly derive the independent cross sections of all products without determining the cumulative cross sections. The measured cross sections and isomeric ratios were compared with those compiled in the EXFOR library and simulated by TALYS-2.0. We found that the ${}^{nat}$Pt($\alpha$,x)198g+mAu, ${}^{197g+m}$Hg and ${}^{195g+m}$Hg cross sections are fairly reproduced by the simulation, while the simulation result requires adjustment of the spin cutoff parameter for better reproduction of the isomeric ratios.

   nucl-exEPJA(2025)·1 citation
2. 02*

   News from the strong interaction program of NA61/SHINE

   Antoni Marcinek (for the NA61/SHINE Collaboration)🇵🇱

   The NA61/SHINE experiment at the CERN SPS is a multipurpose fixed-target spectrometer for charged and neutral hadron measurements. Its research program includes studies of strong interactions as well as reference measurements for neutrino and cosmic-ray physics. This contribution summarizes a selected set of new results from our strong interaction program, including system-size and energy dependence of charged kaon to pion production, $\varphi$(1020) spectra in Ar+Sc collisions and enhancement over p+p reactions, femtoscopy of like-sign pions 0 in Ar+Sc and Be+Be collisions, $D^0+{\overline{D}}^0$ (open charm) yield in Xe+La interactions, and finally an unexpected excess of charged over neutral kaon production indicating a strong violation of isospin symmetry in Ar+Sc collisions.

   nucl-exhep-ex1 citation
3. 03*

   Search for the Efimov state near the 3$\alpha$ threshold

   A. Baishya · S. Santra · T. Singh · P. C. Rout · A. Pal🇮🇳 · H. Kumawat · T. Santhosh · P. Taya · M. Meher · Jyotisankar Das

   A high-precision experiment in search of the predicted Efimov state in ${}^{12}\mathrm{C}$ at 7.458 MeV excitation energy was performed. Using a state-of-the-art detector system and novel analysis techniques, it was possible to observe the Efimov state at the predicted energy level above the 3$\alpha$ threshold with much better sensitivity in the ${}^{12}\mathrm{C}$ excitation energy spectrum compared to the existing data. The mutual ${}^8\mathrm{Be}$ resonance (91.84 keV) condition filters out a total of 21 probable Efimov state events around 7.458 MeV. With 2$\sigma$ confidence, it gives an upper limit of 0.014$\%$ for the Efimov state $\alpha$-decay width relative to that of the Hoyle state, which is about an order of magnitude smaller than the latest upper limit found in the literature. This observation was supported by a new penetrability calculation assuming a relatively extended structure of the Efimov state compared to the Hoyle state. The effect of the Efimov state was also explored in a nuclear astrophysical scenario, where the triple-$\alpha$ reaction rate, including both the Hoyle state and the Efimov state, was found to be larger than the allowed limit, while the temperature dependence of the combined rate was found to be compatible with the helium shell flash criterion of the AGB stars.

   nucl-exnucl-thPRC(2026)·1 citation
4. 04*

   Selection bias effects on high-$p_{\mathrm{T}}$ yield and correlation measurements in Oxygen+Oxygen collisions

   JaeBeom Park🇺🇸 · J.L. Nagle🇺🇸 · Dennis V. Perepelitsa🇺🇸 · Sanghoon Lim🇰🇷 · Constantin Loizides🇺🇸

   Oxygen+Oxygen (O+O) collisions at RHIC and the LHC offer a unique experimental opportunity to observe the onset of jet quenching in intermediate relativistic collision systems. As with the smaller proton-nucleus or larger nucleus-nucleus systems, measurements of centrality-selected high-$p_{\mathrm{T}}$ processes in O+O collisions are expected to be sensitive to selection bias effects, which will be necessary to quantify or mitigate before a definitive conclusion on the presence of jet quenching. Using two Monte Carlo heavy-ion event generators, we provide a survey of centrality bias effects on high-$p_{\mathrm{T}}$ yield and correlation measurements. Some highlights of our findings include that (1) bias factors for the accessible kinematic range at RHIC show a non-trivial $p_{\mathrm{T}}$ dependence, compared to a negligible one at the LHC given the smaller accessible Bjorken-$x$ range, (2) centrality definitions based on multiplicity are less sensitive to bias effects than those based on the transverse energy, (3) the Angantyr generator gives qualitatively similar but larger-magnitude bias factors than HIJING, and (4) correlation measurements have a much smaller sensitivity to bias effects than do yield measurements. The findings here are intended to guide the experimental design and interpretation of O+O jet quenching and other hard-process measurements.

   nucl-exPRC(2025)·8 citations
5. 05*

   Observation and research on cosmic ray muons and solar modulation effect based on plastic scintillator detector

   Wang Dexin · Zhang Rui🇨🇳 · Yu Dekang · Na Hui · Yao Zhangha · Wu Linghe · Zhang Suyalatu · Liang Tairan · Huang Meirong · Wang Zhilong · Bai Yu · Huang Yongshun and 8 other authors

   Cosmic rays, originating from stars, supernovae, and other astrophysical sources, are composed of high-energy particles that enter Earths atmosphere. Upon interaction with atmospheric nuclei, these primary cosmic rays generate secondary particles, including neutrons, electrons, and muons, with muons constituting a dominant component at ground level. Muons, due to their relative abundance, stability, and well-characterized energy loss mechanisms, serve as critical probes for investigating the fundamental properties of cosmic rays. Studies of muon energy distribution, diurnal anisotropy, and their modulation by solar activity provide critical insights into the mechanism of particle acceleration in cosmic ray sources and the effects of solar and atmospheric.This study aims to characterize the counting spectra and anisotropic properties of cosmic ray muons by using a plastic scintillator detector system. The experiment was conducted over a three-month period, from December 2023 to February 2024, leveraging long-bar plastic scintillator detectors equipped with dual-end photomultiplier tubes (PMTs) and a high-resolution digital data acquisition system. A dual-end coincidence measurement technique was used to enhance the signal-to-noise ratio by suppressing thermal noise and other background interferences. Diurnal variations in muon count rates exhibit a pronounced pattern, with a systematic reduction occurring between 8:00 AM and 1:00 PM. This phenomenon is attributed to the solar shielding effects, where enhanced solar activity during daytime hours modulates the flux of galactic cosmic rays reaching Earths surface. The study further corroborates these findings through cross-comparisons with data from the Yangbajing Cosmic Ray Observatory. These observations underscore the robustness of the plastic scintillator detector system for capturing detailed muon spectra and anisotropic patterns.

   ↳ astro-ph.HEastro-ph.IMnucl-exphysics.ins-detActa Phys.Sin.(2025)·0 citations
6. 06*

   Rotational susceptibility of a hot and dense hadronic matter

   Bhagyarathi Sahoo🇮🇳 · Kshitish Kumar Pradhan🇮🇳 · Dushmanta Sahu🇲🇽 · Raghunath Sahoo🇮🇳

   We study the effect of global rotation on rotational susceptibilities (${\chi }_{\omega }^{(1)}$, ${\chi }_{\omega }^2$, etc.), which quantify how much the system responds to small angular velocities, in a hadron resonance gas produced by ultra-relativistic heavy ion collisions. The higher-order rotational susceptibilities and their ratios are estimated in the presence and absence of baryon chemical potential (${\mu }_{\mathrm{B}}$) in the system. The effect of particle spin ($s$) and system size ($R$) on the first- and second-order rotational susceptibility is explored. To consider a more realistic scenario, the effect of interactions between hadrons is taken into account by considering van der Waals-like interactions, which include both attractive and repulsive interactions. To validate our results, a comparison with the ideal HRG as a baseline and a 3-flavour NJL model is shown. A nuclear liquid-gas phase transition, which is the characteristic feature of the van der Waals hadron resonance gas model, absent in an ideal hadron gas model, is probed via global rotation.

   ↳ hep-phhep-exhep-thnucl-ex+1EPJA(2026)·2 citations
7. 07*

   Online Electron Reconstruction at CLAS12

   Richard Tyson🇺🇸 · Gagik Gavalian🇺🇸

   Online reconstruction is key for monitoring purposes and real time analysis in High Energy and Nuclear Physics experiments. A necessary component of reconstruction algorithms is particle identification that combines information left by a particle passing through several detector components to identify the particle's type. Of particular interest to electroproduction Nuclear Physics experiments such as CLAS12 is electron identification which is used to trigger data recording. A machine learning approach was developed for CLAS12 to reconstruct and identify electrons by combining raw signals at the data acquisition level from several detector components. This approach achieves an electron identification purity above 75% whilst retaining an efficiency close to 100%. The machine learning tools are capable of running at high rates exceeding the data acquisition rates and will allow electron reconstruction in real time. This work enhances online analyses and monitoring and can contribute to improved triggering at CLAS12. This machine learning driven approach will also be crucial for experiments aiming to transition to streaming readout operations where online reconstruction will be a key component of the data taking paradigm.

   ↳ physics.ins-dethep-exnucl-exEPJ Web Conf.(2025)·0 citations
8. 08*

   Neutron EDM Experiment with an Advanced Ultracold Neutron Source at TRIUMF

   T. Higuchi🇯🇵 · B. Algohi🇨🇦 · D. Anthony🇨🇦 · L. Barrón-Palos🇲🇽 · M. Bradley🇨🇦 · A. Brossard🇨🇦 · T. Bui🇨🇦 · J. Chak🇨🇦 · R. Chiba🇨🇦 · C. Davis🇨🇦 · R. de Vries🇨🇦 · K. Drury🇨🇦 and 58 other authors

   The TRIUMF Ultracold Advanced Neutron (TUCAN) collaboration has been developing a high-intensity ultracold neutron (UCN) source aimed at searching for the neutron electric dipole moment (EDM) with a sensitivity goal of $10^{-27}e\mathrm{cm}$. This article reports on recent progress in commissioning of the UCN source and in the development of the neutron EDM spectrometer. In its final configuration, the accelerator-driven super-thermal UCN source will enable a neutron EDM experiment with two orders of magnitude improved statistics compared to the current best experiment. Substantial progress in 2024 allowed the collaboration to operate the complete source system, with the exception of the liquid deuterium cold moderator, resulting in the first production of UCNs. The status of the EDM spectrometer is also presented, with emphasis on UCN handling components and magnetic subsystems relevant to field control, shielding, and magnetometry.

   ↳ physics.ins-dethep-exnucl-exphysics.atom-ph4 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.