Wed·Oct 8, 2025Wednesday·October 8, 2025

1. 01*

   Underground nuclear astrophysics: Status and recent results from Felsenkeller laboratory

   Eliana Masha🇩🇪 · Daniel Bemmerer🇩🇪 · Axel Boeltzig🇩🇪 · Konrad Schmidt🇩🇪 · Anup Yadav🇮🇳 · Steffen Turkat🇩🇪 · Kai Zuber🇩🇪

   For almost three decades it has been known that the study of astro-physically important nuclear reactions between stable nuclei requires the use of low-background, underground accelerator laboratories. The Felsenkeller shallow-underground laboratory in Dresden, shielded by a 45 m thick rock cover, hosts a 5 MV Pelletron ion accelerator with an external sputter ion source (mainly able to provide carbon and oxygen beams) and an internal radio-frequency ion source (providing proton and alpha beams). The reduced muon, neutron and gamma-ray background achieved both with natural and active shielding situate the laboratory well in line with deep underground accelerator labs worldwide and allows highly sensitive nuclear reaction experiments. Currently, measurements affecting the solar fusion and Big Bang nucleosynthesis are ongoing. In addition to in-house research by HZDR and TU Dresden, the lab is an open facility for scientific users worldwide, with beam time applications reviewed by an independent science advisory board. Furthermore, EU-supported transnational access is available via the ChETEC- INFRA network for nuclear astrophysics. A brief introduction to underground nuclear astrophysics, status of the Felsenkeller shallow-underground laboratory and some preliminary results are discussed.

   nucl-exEPJ Web Conf.(2024)·1 citation
2. 02*

   Advances in Radiative Capture Studies at LUNA with a Segmented BGO Detector

   Jakub Skowronski🇮🇹 · Riccardo Maria Gesuè · Axel Boeltzig🇩🇪 · Giovanni Francesco Ciani · Denise Piatti🇮🇹 · David Rapagnani🇮🇹 · Marialuisa Aliotta · Chemsedinne Ananna🇮🇹 · Francesco Barile · Daniel Bemmerer🇩🇪 · Andreas Best🇮🇹 · Carlo Broggini🇮🇹 and 34 other authors

   Studies of charged-particle reactions for low-energy nuclear astrophysics require high sensitivity, which can be achieved by means of detection setups with high efficiency and low backgrounds, to obtain precise measurements in the energy region of interest for stellar scenarios. High-efficiency total absorption spectroscopy is an established and powerful tool for studying radiative capture reactions, particularly if combined with the cosmic background reduction by several orders of magnitude obtained at the Laboratory for Underground Nuclear Astrophysics (LUNA). We present recent improvements in the detection setup with the Bismuth Germanium Oxide (BGO) detector at LUNA, aiming to reduce high-energy backgrounds and to increase the summing detection efficiency. The new design results in enhanced sensitivity of the BGO setup, as we demonstrate and discuss in the context of the first direct measurement of the 65 keV resonance ($E_x=5672$ keV) of the ${}^{17}$O($p,\gamma$)${}^{18}$F reaction. Moreover, we show two applications of the BGO detector, which exploit its segmentation. In case of complex $\gamma$-ray cascades, e.g. the de-excitation of $E_x=5672$ keV in ${}^{18}$F, the BGO segmentation allows to identify and suppress the beam-induced background signals that mimic the sum peak of interest. We demonstrate another new application for such a detector in form of in-situ activation measurements of a reaction with ${\beta }^{+}$ unstable product nuclei, e.g., the ${}^{14}$N($p,\gamma$)${}^{15}$O reaction.

   nucl-exphysics.ins-detJ.Phys.G(2023)·20 citations
3. 03*

   Direct measurement of photons from the electron-hadron bremsstrahlung at the EIC

   L. Adamczyk🇵🇱 · Y. Ali · J. J. Chwastowski🇵🇱 · A. B. Kowalewska · B. Pawlik🇵🇱 · K. Piotrzkowski🇵🇱 · M. Przybycien🇵🇱

   Direct detection of bremsstrahlung photons, in principle, offers the most straightforward and most robust method of luminosity determination at the EIC, but requires an extraordinary performance of the photon detector. In this paper, we first discuss the extreme working conditions for such detectors at the EIC and the resulting technology choices. Then, we report the initial results of Monte Carlo simulations, using Geant4, of the proposed sampling calorimeter, which is made of a copper absorber with embedded quartz fibres read out by silicon photomultipliers. Finally, the tentative requirements for appropriate readout electronics are formulated.

   ↳ physics.ins-dethep-exnucl-exActa Phys.Polon.B(2025)·0 citations
4. 04*

   Prediction of Spallation Induced Transmutation Rates For Long Lived Fission Products via Proton Accelerator

   Grigor Tukharyan · William Reed Kendrick · Areg Danagoulian · Benoit Forget

   Long lived fission products represent a major challenge in nuclear waste management due to persistent radiotoxicity over very long timescales. This study focuses on six of these fission products: Se-79, Zr-93, Tc-99, Sn-126, I-127, Cs-135. This study investigates the feasibility of spallation driven transmutation, in which a high energy proton beam strikes a heavy spallation target to generate neutrons that induce transmutation in the fission products surrounding the target. Lead and depleted uranium are identified as the principal spallation target candidates, reflecting contrasting trade offs in neutron yield, secondary reactions, and heat generation. Simulations assess nuclide specific behavior under reactor scale inventories and practical geometric constraints. Results demonstrate that technetium, iodine, and selenium are strong candidates for transmutation using this pathway, while tin shows partial resistance but benefits from thermal flux. By contrast, zirconium is neutron transparent and inefficient to transmute, and cesium suffers from low net reduction due to competition with lighter isotopes. Cost effectiveness is highly isotope dependent: technetium is most favorable, whereas cesium and zirconium remain expensive. These findings highlight the advantages and limitations of spallation driven systems and motivate strategies with optimized target-blanket designs.

   ↳ physics.acc-phnucl-exSci.Rep.(2026)·0 citations
5. 05*

   Beyond ${\rho }^{2/3}$ Scaling: Microscopic Origins and Multimessengers of High-Density Nuclear Symmetry Energy

   Bao-An Li🇺🇸

   Nuclear symmetry energy $E_{\mathrm{sym}}(\rho )$ encoding the cost to make nuclear matter more neutron rich has been the most uncertain component of the EOS of dense neutron-rich nucleonic matter. It affects significantly the radii, tidal deformations, cooling rates and frequencies of various oscillation modes of isolated neutron stars as well as the strain amplitude and frequencies of gravitational waves from their mergers, besides its many effects on structures of nuclei as well as the dynamics and observables of their collisions. Siemens (1970s) observed that $E_{\mathrm{sym}}(\rho )$ scales as $(\rho /{\rho }_0{)}^{2/3}$ near the saturation density ${\rho }_0$ of nuclear matter, since both the kinetic part and the potential contribution (quadratic in momentum) exhibit this dependence. The scaling holds if: (1) the nucleon isoscalar potential is quadratic in momentum, and (2) the isovector interaction is weakly density dependent. After examining many empirical evidences and understanding theoretical findings in the literature we conclude that: (1) Siemens' ${\rho }^{2/3}$ scaling is robust and serves as a valuable benchmark for both nuclear theories and experiments up to $2{\rho }_0$ but breaks down at higher densities, (2) Experimental and theoretical findings about $E_{\mathrm{sym}}(\rho )$ up to $2{\rho }_0$ are broadly consistent, but uncertainties remain large for its curvature $K_{\mathrm{sym}}$ and higher-order parameters, (3) Above $2{\rho }_0$, uncertainties grow due to poorly constrained spin-isospin dependent tensor and three-body forces as well as the resulting nucleon short-range correlations. Looking forward, combining multimessengers from both observations of neutron stars and terrestrial heavy-ion reaction experiments is the most promising path to finally constraining precisely the high-density $E_{\mathrm{sym}}(\rho )$ and the EOS of supradense neutron-rich matter.

   ↳ nucl-thastro-ph.HEhep-phhep-th+1Eur. Phys. J. Spec. Top. (2026)·10 citations
6. 06*

   Microscopic study of nuclei synthesis in pycnonuclear reaction ${}^{12}$C + ${}^{12}$C in neutron stars

   S.P. Maydanyuk (1 and 2)🇨🇳 · Ju-Jun Xie (1, 3 and 4)🇨🇳 · V.S. Vasilevsky (5)🇺🇦 · K.A. Shaulskyi (2) ((1) Southern Center for Nuclear-Science Theory (SCNT), Institute of Modern Physics, Chinese Academy of Sciences, Huizhou 516000, China, (2) Institute for Nuclear Research, National Academy of Sciences of Ukraine, Kyiv, 03680, Ukraine, (3) Heavy Ion Science and Technology Key Laboratory, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China, (4) School of Nuclear Sciences and Technology, University of Chinese Academy of Sciences, Beijing 101408, China, (5) Bogolyubov Institute for Theoretical Physics, Metrolohichna str., 14b, Kyiv, 03143, Ukraine)

   Purpose To investigate synthesis of nuclei in pycnonuclear reactions in dense medium of neutron stars on the basis of understanding, how the compound nucleus is formed during collision of two nuclei. To implement microscopic formulation of nuclear interactions and fusion in pycnonuclear reactions in dense medium. Methods (1) Nuclei synthesis in pycnonuclear reaction in dense medium of neutron star is investigated in the folding approximation of the cluster model. (2) Formation of compound nucleus in dense medium is studied with the method of Multiple Internal Reflections. Results (1) Wave functions of resonance states of ${}^{24}$Mg are determined by interaction of two ${}^{12}$C nuclei. (2) Clear maxima of probability of formation of compound nucleus in dense stellar medium are established at first time. (3) Difference between quasibound energies for potential of Woods-Saxon type and folding potentials with the shell-model approximation for wave functions is essential. (4) Formation of the compound nucleus is much more probable in the quasibound states than in states of zero-point vibrations. (5) Only the first quasibound energies for ${}^{12}$C + ${}^{12}$Care smaller than the barrier maximums. At these energies compound nuclear system has barrier which prevents its decay going through tunneling phenomenon. This is the new excited nucleus ${}^{24}$Mg synthesised in the neutron star. \item[Conclusions] Cluster approach with folding potential provides significant modification of picture of formation of compound nucleus, previously obtained concerning the potential of Woods-Saxon type. The highest precision is provided by the folding potential, created by semi-realistic nucleon-nucleon potential and shell-model description of the internal structure of interacting $p$-shell nuclei.

   ↳ nucl-thastro-ph.SRhep-thnucl-exPhysics Letters B, 140191, (2026), ISSN 0…·0 citations
7. 07*

   nCTEQ global analysis of nuclear PDFs

   M. Klasen🇩🇪

   We review the series of specific nCTEQ analyses of nuclear parton distribution functions (PDFs) published since 2020 and present preliminary results of a new global analysis. Building on a modern proton baseline without nuclear data and extending the kinematic range, it combines and updates the previous separate analyses that focused on Jefferson Lab neutral-current deep-inelastic scattering (DIS), neutrino DIS and dimuon production, and the currently available CERN LHC data, in particular on W/Z-boson, single inclusive hadron, and heavy-quark production.

   ↳ hep-phhep-exnucl-exPoS(2025)·3 citations
8. 08*

   Low-energy Cross Section Measurements of ${}^{12}\mathsf{C}(\mathsf{p},\gamma )$ Deep Underground at LUNA

   Jakub Skowronski🇮🇹 · Axel Boeltzig🇩🇪

   The ${}^{12}\mathsf{C}(\mathsf{p},\gamma )$ reaction cross section is currently under investigation in the low-background environment of the Laboratory for Underground Nuclear Astrophysics (LUNA). It is being studied using different types of solid targets, and employing two complementary detection techniques: HPGe spectroscopy and activation counting. To reduce systematic uncertainties, targets have been accurately characterized and their degradation under the intense beam of the LUNA-400 accelerator monitored. We present the experimental techniques and the corresponding analyses used to extract the reaction cross section.

   ↳ physics.ins-detastro-ph.SRnucl-exEPJ Web Conf.(2023)·1 citation
9. 09*

   Energy-Energy Flow Networks

   Arianna Garcia Caffaro🇺🇸 · Ian Moult🇺🇸 · Chase Shimmin🇺🇸

   Jet substructure provides one of the most exciting new approaches for searching for physics in and beyond the Standard Model at the Large Hadron Collider. Modern jet substructure searches are often performed with Neural Network (NN) taggers which study the jets' radiation distributions in great detail, far beyond what is theoretically described by parton shower generators. While this represents a great opportunity, as NNs look deeper into the structure of jets they become increasingly sensitive both to perturbative and non-perturbative theoretical uncertainties. It is therefore important to be able to control which aspects of both regimes the networks focus on, and to develop techniques for quantifying these uncertainties. In this paper we take two steps in this direction: First, we introduce EnFNs, a generalization of the Energy Flow Networks (EFNs) which directly probes higher point correlations in jets, as motivated by recent advances in the study of energy correlators. Second, we introduce a number of techniques to quantify and visualize their robustness to non-perturbative corrections. We highlight the importance of such considerations in a toy study incorporating systematics into a search, and maximizing for the network's discovery significance, as opposed to absolute tagging performance. We hope this study continues the interest in understanding the role QCD systematics play in Machine Learning applications and opens the door to a better interplay between theory and experiment in HEP.

   ↳ hep-phhep-exnucl-ex3 citations
10. 10*

    A Beamdump Facility at Jefferson Lab

    Patrick Achenbach🇺🇸 · Andrei Afanasev🇺🇸 · Pawel Ambrozewicz🇺🇸 · Adi Ashkenazi🇮🇱 · Dipanwita Banerjee🇨🇭 · Marco Battaglieri🇮🇹 · Jay Benesch🇺🇸 · Mariangela Bondi🇮🇹 · Paul Brindza🇺🇸 · Alexandre Camsonne🇺🇸 · Eric M. Christy🇺🇸 · Ethan W. Cline🇺🇸 and 38 other authors

    This White Paper is exploring the potential of intense secondary muon, neutrino, and (hypothetical) light dark matter beams produced in interactions of high-intensity electron beams with beam dumps. Light dark matter searches with the approved Beam Dump eXperiment (BDX) are driving the realization of a new underground vault at Jefferson Lab that could be extended to a Beamdump Facility with minimal additional installations. The paper summarizes contributions and discussions from the International Workshop on Secondary Beams at Jefferson Lab (BDX & Beyond). Several possible muon physics applications and neutrino detector technologies for Jefferson Lab are highlighted. The potential of a secondary neutron beam will be addressed in a future edition.

    ↳ physics.acc-phhep-exnucl-exEPJA(2025)·3 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.