Wed·Aug 7, 2024Wednesday·August 7, 2024

1. 01*

   First direct measurement of the 64.5 keV resonance strength in ${}^{17}$O(p,$\gamma$)${}^{18}$F reaction

   R. M. Gesuè · G. F. Ciani · D. Piatti🇮🇹 · A. Boeltzig🇩🇪 · D. Rapagnani🇮🇹 · M. Aliotta🇬🇧 · C. Ananna🇮🇹 · L. Barbieri · F. Barile · D. Bemmerer🇩🇪 · A. Best🇮🇹 · C. Broggini🇮🇹 and 41 other authors

   The CNO cycle is one of the most important nuclear energy sources in stars. At temperatures of hydrostatic H-burning (20 MK $<$ T $<$ 80 MK) the ${}^{17}$O(p,$\gamma$)${}^{18}$F reaction rate is dominated by the poorly constrained 64.5~keV resonance. Here we report on the first direct measurements of its resonance strength and of the direct capture contribution at 142 keV, performed with a new high sensitivity setup at LUNA. The present resonance strength of $\omega {\gamma }_{(p,\gamma )}$\textsuperscript{bare} = (30 $\pm$ 6\textsubscript{stat} $\pm$ 2\textsubscript{syst})~peV is about a factor of 2 higher than the values in literature, leading to a $\Gamma$\textsubscript{p}\textsuperscript{bare} = (34 $\pm$ 7\textsubscript{stat} $\pm$ 3\textsubscript{syst})~neV, in agreement with LUNA result from the (p,$\alpha$) channel. Such agreement strengthen our understanding of the oxygen isotopic ratios measured in red giant stars and in O-rich presolar grains.

   nucl-exPRL(2024)·5 citations
2. 02*

   G4CASCADE: A data-driven implementation of (n, $\gamma$) cascades in Geant4

   Leo Weimer · Emma Ellingwood🇨🇦 · Otis Fischer · Michela Lai🇺🇸 · Shawn Westerdale🇺🇸

   De-excitation $\gamma$ cascades from neutron captures form a dominant background to MeV-scale signals. The Geant4 Monte Carlo simulation toolkit is widely used to model backgrounds in nuclear and particle physics experiments. While its current modules for simulating (n, $\gamma$) signals, G4NDL and G4PhotoEvaporation, are excellent for many applications, they do not reproduce known gamma-ray lines and correlations relevant at 2-15 MeV. G4CASCADE is a new data-driven Geant4 module that simulates (n, $\gamma$) de-excitation pathways, with options for how to handle shortcomings in nuclear data. Benchmark comparisons to measured gamma-ray lines and level structures in the ENSDF database show significant improvements, with decreased residuals and full energy conservation. This manuscript describes the underlying calculations performed by G4CASCADE, its various usage options, and benchmark comparisons. G4CASCADE for Geant4-10 is available on GitHub at https://github.com/UCRDarkMatter/CASCADE

   ↳ physics.comp-phnucl-exNucl.Instrum.Meth.A(2027)·4 citations
3. 03*

   First Indication of Solar ${}^8$B Neutrinos via Coherent Elastic Neutrino-Nucleus Scattering with XENONnT

   E. Aprile🇺🇸 · J. Aalbers🇳🇱 · K. Abe🇯🇵 · S. Ahmed Maouloud🇫🇷 · L. Althueser🇩🇪 · B. Andrieu🇫🇷 · E. Angelino🇮🇹 · D. Antón Martin🇺🇸 · F. Arneodo🇦🇪 · L. Baudis🇨🇭 · M. Bazyk🇫🇷 · L. Bellagamba🇮🇹 and 155 other authors

   We present the first measurement of nuclear recoils from solar ${}^8$B neutrinos via coherent elastic neutrino-nucleus scattering with the XENONnT dark matter experiment. The central detector of XENONnT is a low-background, two-phase time projection chamber with a 5.9 t sensitive liquid xenon target. A blind analysis with an exposure of 3.51 t$\times$yr resulted in 37 observed events above 0.5 keV, with ($26.4_{-1.3}^{+1.4}$) events expected from backgrounds. The background-only hypothesis is rejected with a statistical significance of 2.73 $\sigma$. The measured ${}^8$B solar neutrino flux of $(4.7_{-2.3}^{+3.6})\times 10^6{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$ is consistent with results from the Sudbury Neutrino Observatory. The measured neutrino flux-weighted CE$\nu$NS cross section on Xe of $(1.1_{-0.5}^{+0.8})\times 10^{-39}{\mathrm{cm}}^2$ is consistent with the Standard Model prediction. This is the first direct measurement of nuclear recoils from solar neutrinos with a dark matter detector.

   ↳ hep-exastro-ph.SRnucl-exphysics.ins-detPRL(2024)·205 citations
4. 04*

   Neutrinoless $\beta \beta$ decay nuclear matrix elements complete up to N${}^2$LO in heavy nuclei

   Daniel Castillo🇪🇸 · Lotta Jokiniemi🇨🇦 · Pablo Soriano🇪🇸 · Javier Menéndez🇪🇸

   We evaluate all nuclear matrix elements (NMEs) up to next-to-next-to leading order (N${}^2$LO) in chiral effective field theory ($\chi$EFT) for the neutrinoless double-beta ($0\nu \beta \beta$) decay of the nuclei most relevant for experiments, including ${}^{76}$Ge, ${}^{100}$Mo, and ${}^{136}$Xe. We use the proton-neutron quasiparticle random-phase approximation (pnQRPA) and the nuclear shell model to calculate the N${}^2$LO NMEs from very low-momentum (ultrasoft) neutrinos and from loop diagrams usually neglected in $0\nu \beta \beta$ studies. Our results indicate that the overall N${}^2$LO contribution is centered around $-(5$-$10)\%$ for the shell model and $+(10$-$15)\%$ for the pnQRPA, with sizable uncertainties due to the scale dependence of the ultrasoft NMEs and the short-range nature of the loop NMEs. The sign discrepancy between many-body methods is common to all studied nuclei and points to the different behaviour of the intermediate states of the $0\nu \beta \beta$ decay. Within uncertainties, our results for the ultrasoft NME are of similar size as contributions usually referred to as ``beyond the closure approximation''.

   ↳ nucl-thhep-exhep-phnucl-exPLB(2025)·19 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.