Tue·Aug 26, 2025Tuesday·August 26, 2025

1. 01*

   Exploring shell effects in fission yields of neutron-deficient Th, Ac, and Ra isotopes near N=126

   J.L. Rodríguez-Sánchez🇪🇸 · J. Taïeb🇫🇷

   Studies of nuclear fission over recent decades have led to a well-defined mapping of neutron and proton shell effects across the nuclear chart, particularly within the valley of stability. These shell effects play a crucial role in driving the asymmetric splitting of fissioning nuclei, as reflected in fission yields that are strongly influenced by spherical and deformed shell closures. In the actinide region, the existence of two primary fission modes, standard I and standard II, has been well-established. These fission modes are associated with the proton (neutron) shells at $Z=52$ ($N=82$) and $Z=56$ ($N=88$), respectively. Recently, a new proton shell around $Z=36$ has been found for the lighter fission fragments of pre-actinide nuclei. This discovery demonstrates that as we expand fission studies towards more exotic regions of the nuclear chart, new shell structures emerge. In this proposal, we aim to explore for the first time the most neutron-deficient isotopes of Th, Ac, and Ra. This region offers a unique opportunity to investigate stabilization effects around the spherical neutron shell $N=50$. To achieve this, we plan to use a primary beam of ${}^{238}$U at 1~GeV/u together with the Fragment Separator (FRS) to produce secondary beams of ${}^{213-216}$Th, ${}^{209-214}$Ac and ${}^{207-213}$Ra. For the investigation of the fission process, we will use the experimental methodology successfully applied in the S415, S438, and S455 experiments, being a continuation of those studies. Fission will be induced by electromagnetic-excitation (Coulex) reactions in inverse kinematics on an active target composed of Pb and C foils. The resulting fission fragments, together with emitted neutrons, will be measured using the R${}^3$B experimental setup, which allows for complete kinematic measurements.

   nucl-ex0 citations
2. 02*

   Polarization Observables $T$ and $F$ in the $\gamma p\to {\pi }^{0}p$ Reaction at CLAS

   H. Jiang · S. Strauch · I.I. Strakovsky · D. Rönchen · R. Workman · The CLAS Collaboration

   Pion photoproduction in the $\overrightarrow{\gamma }\overrightarrow{p}\to {\pi }^{0}p$ reaction has been measured in the FROST experiment at the Thomas Jefferson National Accelerator Facility. In this experiment, circularly polarized photons with energies up to 3.082 GeV impinged on a transversely polarized frozen-spin target. Final-state protons were detected in the CEBAF Large Acceptance Spectrometer. Results of the polarization observables $T$ and $F$ have been extracted for $W$ from 1445 MeV to 2525 MeV. The data generally agree with predictions of present partial-wave analyses, but also show marked differences for higher $W$ ranges. By incorporating the present data into the databases, the SAID fits have been improved with relatively small ${\chi }^2$ and significant changes in the parameters of the $\Delta (1910)1/2^{+}$ and $N(2190)7/2^{-}$ have been found with the JüBo model.

   nucl-exPRC(2026)·1 citation
3. 03*

   Studying the onset of deconfinement at NA61/SHINE

   Syed Uzair Ahmed Shah (for the NA61/SHINE Collaboration)🇵🇱

   The study of particle production in high-energy collisions of heavy ions offers a unique opportunity to explore the phase transition of strongly interacting matter. The NA61/SHINE experiment, a fixed-target setup located in the CERN SPS North Area, plays a crucial role in this investigation. To perform a two-dimensional scan of the phase diagram of strongly interacting matter, the experiment varies both the beam momentum (ranging from 13 to 150/158 GeV/c per nucleon) and the size of the colliding ions (p+p, p+Pb, Be+Be, Ar+Sc, Xe+La, Pb+Pb). This article presents a study of the properties of the onset of deconfinement by measuring the K+/pi+ ratio, which is proportional to the strangeness to entropy ratio of the produced system. New results from central Pb+Pb collisions at 30A GeV/c, focusing on the spectra of charged kaons and pions, confirm the presence of the horn structure in the energy dependence of the K+/pi+ ratio, consistent with earlier observations by NA49 and STAR, which could be interpreted as a hint of the onset of deconfinement at middle SPS energies.

   nucl-exhep-ex1 citation
4. 04*

   Measurement of the branching ratio of ${}^{16}\mathrm{N}$, ${}^{15}\mathrm{C}$, ${}^{12}\mathrm{B}$, and ${}^{13}\mathrm{B}$ isotopes through the nuclear muon capture reaction in the Super-Kamiokande detector

   Y. Maekawa🇯🇵 · K. Abe🇯🇵 · S. Abe🇯🇵 · Y. Asaoka🇯🇵 · M. Harada🇯🇵 · Y. Hayato🇯🇵 · K. Hiraide🇯🇵 · K. Hosokawa🇯🇵 · K. Ieki🇯🇵 · M. Ikeda🇯🇵 · J. Kameda🇯🇵 · Y. Kanemura🇯🇵 and 256 other authors

   The Super-Kamiokande detector has measured solar neutrinos for more than $25$ years. The sensitivity for solar neutrino measurement is limited by the uncertainties of energy scale and background modeling. Decays of unstable isotopes with relatively long half-lives through nuclear muon capture, such as ${}^{16}\mathrm{N}$, ${}^{15}\mathrm{C}$, ${}^{12}\mathrm{B}$ and ${}^{13}\mathrm{B}$, are detected as background events for solar neutrino observations. In this study, we developed a method to form a pair of stopping muon and decay candidate events and evaluated the production rates of such unstable isotopes. We then measured their branching ratios considering both their production rates and the estimated number of nuclear muon capture processes as $Br({}^{16}\mathrm{N})=(9.0\pm 0.1)\%$, $Br({}^{15}\mathrm{C})=(0.6\pm 0.1)\%$, $Br({}^{12}\mathrm{B})=(0.98\pm 0.18)\%$, $Br({}^{13}\mathrm{B})=(0.14\pm 0.12)\%$, respectively. The result for ${}^{16}\mathrm{N}$ has world-leading precision at present and the results for ${}^{15}\mathrm{C}$, ${}^{12}\mathrm{B}$, and ${}^{13}\mathrm{B}$ are the first branching ratio measurements for those isotopes.

   nucl-exhep-exPRC(2025)·3 citations
5. 05*

   Measurement of the isoscalar giant monopole resonance in ${}^{86}$Kr via deuteron inelastic scattering using an active target CAT-M

   Fumitaka Endo🇯🇵 · Shinsuke Ota🇯🇵 · Masanori Dozono🇯🇵 · Reiko Kojima · Jiawei Cai🇯🇵 · Stefano Fracassetti🇧🇪 · Shutaro Hanai🇯🇵 · Tomoya Harada🇯🇵 · Seiya Hayakawa🇯🇵 · Yuto Hijikata🇯🇵 · Nobuaki Imai🇯🇵 · Tadaaki Isobe🇯🇵 and 12 other authors

   Deuteron inelastic scattering on ${}^{86}$Kr was measured in inverse kinematics with the gaseous active target CAT-M, as part of a systematic investigation aimed at determining the nuclear matter incompressibility. The isoscalar monopole strength distribution was extracted via multipole decomposition analysis, and the energy of the isoscalar giant monopole resonance was determined to be 17 $\pm$ 1 MeV. The nuclear incompressibility of ${}^{86}$Kr and the isospin-dependent term of the nuclear matter incompressibility are discussed.

   nucl-exPTEP(2026)·0 citations
6. 06*

   Enhanced Tritium Production in Irradiated TiD2 from Collisional Fusion in the Solid-State

   Andrew K. Gillespie (1) · Cuikun Lin (1)🇨🇳 · Ian Jones (1) · Brad Jeffries (2) · Joseph Caleb Philipps (3) · Sandeep Puri (1) · John Gahl (4) · John Brockman (3and 5) · R. V. Duncan (1) ((1) Texas Tech University, (2) Pacific Northwest National Laboratory, (3) University of Missouri Research Reactor, (4) Department of Electrical and Computer Engineering, University of Missouri, (5) Department of Chemistry, University of Missouri)

   Ongoing research in new nuclear mechanisms hold the potential for beneficial developments in nuclear power cycle designs. Recent reports investigated the possibility of lattice dynamics to influence nuclear processes in metals. Results from Steinetz et al., at the NASA Glenn Research Center indicated that it may be feasible to initiate deuterium deuterium fusion reactions that are enhanced using electron screening to reduce the deuterium deuterium fusion barrier. This article presents tritium production results from both simulations and experiments targeting specific nuclear processes in an effort to identify the source of higher energy neutrons observed in those results. We explore two pathways of tritium generation in TiD2 through this fusion cycle. Tritium production from TiD2 in the University of Missouri Research Reactor, where the neutron spectrum was approximately 90 percent thermal, was within 25 percent of the predicted amount from simulations, and well explained by known nuclear reactions without invoking screening enhanced recoil-induced fusion. Tritium production from TiD2 in the cyclotron vault at MURR, where the neutron spectrum was completely energetic with almost no thermal neutrons, was a factor of 2.9 to 5.1 times higher than predicted from simulations using known nuclear reactions. This indicates the likelihood of an additional mechanism, such as collision-induced fusion in the solid state, increasing the credibility in the results from Steinetz et al.

   nucl-ex0 citations
7. 07*

   Laser Mössbauer spectroscopy of ^{229}Th

   Takahiro Hiraki · Takahiko Masuda🇯🇵 · Sayuri Takatori🇯🇵 · Fabian Schaden🇦🇹 · Michael Bartokos🇦🇹 · Kjeld Beeks🇦🇹 · Yuta Fukunaga · Andreas Grüneis · Ming Guan · Georgy Kazakov · Thomas LaGrange · Adrian Leitner and 14 other authors

   Mössbauer spectroscopy is widely used in biochemistry, geology, and solid-state physics to obtain structural information on materials. Here, we extend this technique into the optical range using a vacuum ultraviolet laser to probe the low-energy nuclear transitions of thorium-229, doped in calcium fluoride crystals. We discover four distinct doping sites for the thorium ions, determine the characteristic electric field gradients emerging in the interaction with the host crystal, and identify the microscopic structure of the two dominant configurations. Site-selective laser excitation allows to study the isomeric state lifetime and laser-induced quenching for all sites. This laser-based Mössbauer spectroscopy provides a powerful probe of the nuclear environment, yielding foundational data for designing future solid-state nuclear clocks.

   nucl-excond-mat.mtrl-sciphysics.atom-phquant-phScience(2026)·10 citations
8. 08*

   Baryon Electric Charge Correlation as QCD Magnetometer

   Heng-Tong Ding🇨🇳 · Jin-Biao Gu🇨🇳 · Arpith Kumar🇨🇳 · Sheng-Tai Li🇨🇳

   The detection of strong magnetic fields in peripheral heavy-ion collisions is crucial for observing effects such as the chiral magnetic effect but has proven exceptionally difficult. To address this, we propose the baryon electric charge correlation ${\chi }_{11}^{\mathrm{BQ}}$ and the chemical potential ratio ${\mu }_{\mathrm{Q}}/{\mu }_{\mathrm{B}}$ as sensitive probes of magnetic fields, based on (2+1)-flavor lattice QCD simulations at the physical pion mass. Along the transition line, ${\chi }_{11}^{\mathrm{BQ}}$ and $({\mu }_{\mathrm{Q}}/{\mu }_{\mathrm{B}}{)}_{\mathrm{LO}}$ in Pb-Pb collisions increase by factors of 2.1 and 2.4 at $eB\simeq 8M_{\pi }^2$, respectively. To bridge theoretical predictions with experimental observables, we implement systematic kinematic cuts that emulate detector acceptances of the STAR and ALICE experiments within the hadron resonance gas model. This allows us to construct experimentally relevant proxy observables. Furthermore, we demonstrate that $({\mu }_{\mathrm{Q}}/{\mu }_{\mathrm{B}}{)}_{\mathrm{LO}}$ is also sensitive to the collision system, showing a $1.5$-fold increase from Zr-Zr to Ru-Ru isobar collisions. Our findings offer new insights into thermo-magnetic effects and provide experimentally relevant guidance for the detection of magnetic fields in heavy-ion collisions.

   ↳ hep-lathep-phnucl-exnucl-thEPJ Web Conf.(2026)·2 citations
9. 09*

   Sensitivity of neutrinoless double beta decays from a combined analysis of ground and excited states

   C. R. Ding🇨🇳 · K. Han🇨🇳 · S.B. Wang🇨🇳 · J. M. Yao🇨🇳

   Next-generation neutrinoless double-beta ($0\nu \beta \beta$) decay experiments, with projected half-life sensitivities approaching $10^{28}$ years, aim to probe the entire parameter space of the inverted neutrino mass ordering in the light-neutrino-exchange scenario. However, this reach remains uncertain by the substantial model dependence of the nuclear matrix elements (NMEs). In this work, we propose a strategy based on a combined analysis of $0\nu \beta \beta$ decays to both the ground state and the first excited $0^{+}$ state of the daughter nucleus. We show that such a multi-channel approach can significantly enhance experimental sensitivity, depending on the underlying NME predictions. This method is particularly well-suited for large liquid xenon detectors, such as the proposed PandaX-xT and XLZD experiments, which can efficiently identify transitions of ${}^{136}$Xe to excited states. Our results highlight the importance of exploiting multiple decay channels in future $0\nu \beta \beta$ searches to maximize their discovery potential.

   ↳ hep-phhep-exnucl-exnucl-thPLB(2026)·0 citations
10. 10*

    Probing in-medium effect via giant dipole resonance in the extended quantum molecular dynamics model

    Chen-Zhong Shi · Xiang-Zhou Cai🇨🇳 · Yu-Gang Ma🇨🇳

    Rather than using the geometric method employed in the original Extended Quantum Molecular Dynamics (EQMD) model, this article employs a stochastic approach to analyze the collision term and examine the width of the isovector giant dipole resonance (GDR) in ${}^{208}$Pb. Based on the ``soft" EQMD model, which we recently developed, the response and strength functions are self-consistently determined for various symmetry energy coefficients and in-medium reduction factor values. The results confirm that the peak position and GDR width in ${}^{208}$Pb are highly sensitive to the symmetry energy and the in-medium nucleon-nucleon ({\it NN}) cross section. This provides an opportunity to study the nuclear equation of state (EoS) and the medium effect. A significant reduction in free {\it NN} elastic cross sections within the medium is necessary to accurately reproduce the GDR width, as demonstrated by a comparison with the evaluation data.

    ↳ nucl-thnucl-exPRC(2026)·0 citations
11. 11*

    Probing the Linewidth of the 12.4-keV Solid-State ${}^{45}$Sc Isomeric Resonance

    Peifan Liu · Miriam Gerharz · Berit Marx-Glowna🇩🇪 · Willi Hippler🇩🇪 · Jan-Etienne Pudell · Alexey Zozulya · Brandon Stone · Deming Shu · Robert Loetzsch🇩🇪 · Sakshath Sadashivaiah🇩🇪 · Lars Bocklage🇩🇪 · Christina Boemer and 28 other authors

    The ${}^{45}$Sc nuclear transition from the ground to the isomeric state at 12.389~keV, with a lifetime of 0.46~s, exhibits an extraordinarily narrow natural width of 1.4~feV and a quality factor $\simeq 10^{19}$ -- surpassing those of the most precise atomic clocks -- making ${}^{45}$Sc a compelling platform for advanced metrology and nuclear clocks. Here we investigate how closely the spectral width and quality factor of the solid-state ${}^{45}$Sc resonance can approach these natural limits. Using the European X-ray Free-Electron Laser, we confirm the isomer's lifetime via time-delayed incoherent $K_{\alpha ,\beta }$ fluorescence and observe previously unreported elastic fluorescence, yielding a partial internal conversion coefficient of 390(60). The absence of a clear nuclear forward scattering signal beyond a 2-ms delay implies environmental broadening of at least $500{\Gamma }_0$ under experimental conditions, placing bounds on solid-state decoherence mechanisms. These findings set new experimental benchmarks for solid-state nuclear clock development.

    ↳ quant-phcond-mat.othernucl-exphysics.optics3 citations
12. 12*

    Impact of a Reflecting Material on a Search for Neutron--Antineutron Oscillations using Ultracold Neutrons

    Hiroyuki Fujioka🇯🇵 · Takashi Higuchi🇯🇵

    We investigate neutron--antineutron oscillations of ultracold neutrons in a storage bottle represented by a one-dimensional potential. The experimental sensitivity is determined by the annihilation rate of antineutrons. Its dependence on the antineutron reflectivity and the relative phase shift between the neutron and the antineutron wavefunctions by a reflection from the wall is derived. Optimization of the antineutron pseudopotential was found crucial to maximize the sensitivity of the experiment. Furthermore, methods are discussed for determining the antineutron pseudopotential, which has only been studied indirectly thus far.

    ↳ hep-exnucl-exnucl-thquant-phPTEP(2026)·4 citations
13. 13*

    Two-flavored heavy mesons' nuclear bound states

    G. N. Zeminiani🇧🇷 · S. L. P. G. Beres🇧🇷 · K. Tsushima🇧🇷

    We calculate the $B_c$- and $B_s$-nucleus bound state energies and coordinate space radial wave functions by solving the Klein-Gordon equation in momentum space. The attractive strong potentials for the $B_c$ and $B_s$ mesons in nuclei are calculated from the respective mass shifts of these mesons in nuclear matter using a local density approximation. This negative mass shift may be regarded as a signature of partial restoration of chiral symmetry in medium in an empirical sense, because the origin of the negative mass shift in the present study is not directly related to the chiral symmetry mechanism.

    ↳ nucl-thhep-exhep-phnucl-exPoS(2026)·0 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.