Wed·Nov 6, 2024Wednesday·November 6, 2024

1. 01*

   Precise ${}^{113}$Cd $\beta$ decay spectral shape measurement and interpretation in terms of possible $g_A$ quenching

   I. Bandac🇪🇸 · L. Berge🇫🇷 · J.M. Calvo-Mozota🇪🇸 · P. Carniti🇮🇹 · M. Chapellier🇫🇷 · F. A. Danevich🇺🇦 · T. Dixon🇫🇷 · L. Dumoulin🇫🇷 · F. Ferri🇫🇷 · A. Giuliani🇫🇷 · C. Gotti🇮🇹 · Ph. Gras🇫🇷 and 20 other authors

   Highly forbidden $\beta$ decays provide a sensitive test to nuclear models in a regime in which the decay goes through high spin-multipole states, similar to the neutrinoless double-$\beta$ decay process. There are only 3 nuclei (${}^{50}$V, ${}^{113}$Cd, ${}^{115}$In) which undergo a $4^{\mathrm{th}}$ forbidden non-unique $\beta$ decay. In this work, we compare the experimental ${}^{113}$Cd spectrum to theoretical spectral shapes in the framework of the spectrum-shape method. We measured with high precision, with the lowest energy threshold and the best energy resolution ever, the $\beta$ spectrum of ${}^{113}$Cd embedded in a 0.43 kg CdWO${}_4$ crystal, operated over 26 days as a bolometer at low temperature in the Canfranc underground laboratory (Spain). We performed a Bayesian fit of the experimental data to three nuclear models (IBFM-2, MQPM and NSM) allowing the reconstruction of the spectral shape as well as the half-life. The fit has two free parameters, one of which is the effective weak axial-vector coupling constant, $g_A^{\text{eff}}$, which resulted in $g_A^{\text{eff}}$ between 1.0 and 1.2, compatible with a possible quenching. Based on the fit, we measured the half-life of the ${}^{113}$Cd $\beta$ decay including systematic uncertainties as $7.73_{-0.57}^{+0.60}\times 10^{15}$ yr, in agreement with the previous experiments. These results represent a significant step towards a better understanding of low-energy nuclear processes.

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

   Medium-induced modification of groomed and ungroomed jet mass and angularities in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

   ALICE Collaboration

   The ALICE Collaboration presents a new suite of jet substructure measurements in Pb-Pb and pp collisions at a center-of-mass energy per nucleon pair ${\sqrt{s}}_{\mathrm{NN}}=5.02$ TeV. These measurements provide access to the internal structure of jets via the momentum and angle of their constituents, probing how the quark--gluon plasma modifies jets, an effect known as jet quenching. Jet grooming additionally removes soft wide-angle radiation to enhance perturbative accuracy and reduce experimental uncertainties. We report the groomed and ungroomed jet mass $m_{\mathrm{jet}}$ and jet angularities ${\lambda }_{\alpha }^{\kappa }$ using $\kappa =1$ and $\alpha >0$. Charged-particle jets are reconstructed at midrapidity using the anti-$k_{\mathrm{T}}$ algorithm with resolution parameter $R=0.2$. A narrowing of the jet mass and angularity distributions in Pb-Pb collisions with respect to pp is observed and is enhanced for groomed results, confirming modification of the jet core. By using consistent jet definitions and kinematic cuts between the mass and angularities for the first time, previous inconsistencies in the interpretation of quenching measurements are resolved, rectifying a hurdle for understanding how jet quenching arises from first principles and highlighting the importance of a well-controlled baseline. These results are compared with a variety of theoretical models of jet quenching, providing constraints on jet energy-loss mechanisms in the quark--gluon plasma.

   nucl-exhep-exPLB(2025)·14 citations
3. 03*

   Primary activity measurement of an Am-241 solution using microgram inkjet gravimetry and decay energy spectrometry

   Ryan P. Fitzgerald · Bradley Alpert🇺🇸 · Denis E. Bergeron🇺🇸 · Max Carlson · Richard Essex · Sean Jollota · Kelsey Morgan · Shin Muramoto · Svetlana Nour🇺🇸 · Galen O`Neil · Daniel R. Schmidt🇺🇸 · Gordon Shaw · Daniel Swetz🇺🇸 · R. Michael Verkouteren

   We demonstrate a method for radionuclide assay that is spectroscopic with 100 % counting efficiency for alpha decay. Advancing both cryogenic decay energy spectrometry (DES) and drop-on-demand inkjet metrology, a solution of Am-241 was assayed for massic activity (of order 100 kBq/g) with a relative combined standard uncertainty less than 1 %. We implement live-timed counting, spectroscopic analysis, validation by liquid scintillation (LS) counting, and confirmation of quantitative solution transfer. Experimental DES spectra are well modeled with a Monte Carlo simulation. The model was further used to simulate Pu-238 and Pu-240 impurities, calculate detection limits, and demonstrate the potential for tracer-free multi-nuclide analysis, which will be valuable for new cancer therapeutics based on decay chains, Standard Reference Materials (SRMs) containing impurities, and more widely in nuclear energy, environmental monitoring, security, and forensics.

   ↳ physics.ins-detnucl-exMetrologia(2025)·1 citation

* 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.