A precision measurement of the beta + decay of 8 B was performed using the Beta -decay Paul Trap to determine the beta -nu angular correlation coefficient a beta nu . The experimental results were combined with new ab initio symmetry -adapted no -core shell -model calculations to yield the second -most precise measurement from Gamow-Teller decays, a beta nu = -0.3345 +/- 0.00 19 stat +/- 0.00 21 syst . This value agrees with the standard model value of -1 / 3 and improves uncertainties in 8 B by nearly a factor of 2. By combining results from 8 B and 8 Li, a tight limit on tensor current coupling to right-handed neutrinos was obtained. A recent global evaluation of all other precision beta decay studies suggested a nonzero value for right-handed neutrino coupling in contradiction with the standard model at just above 3 sigma. The present results are of comparable sensitivity and do not support this finding.

Studies aiming to determine the astrophysical origins of nuclei produced by the rapid neutron capture process (r process) rely on nuclear properties as inputs for simulations. The solar abundances can be used as a benchmark for such calculations, with the r-process rare-earth peak (REP) around mass number (A) 164 being of special interest due to its presently unknown origin. With the advancement of rare isotope beam production over the last decade and improvement in experimental sensitivities, many of these REP nuclides have become accessible for measurement. Masses are one of the most critical inputs as they impact multiple nuclear properties, namely the neutron-separation energies, neutron capture rates, β-decay rates, and β-delayed neutron emission probabilities. In this work, we report masses of 20 neutron-rich nuclides (along the Ba, La, Ce, Pr, Nd, Pm, Gd, Dy and Ho isotopic chains) produced at the CAlifornium Rare Isotope Breeder Upgrade (CARIBU) facility at Argonne National Laboratory. The masses were measured with the Canadian Penning trap (CPT) mass spectrometer using the Phase-Imaging Ion-Cyclotron-Resonance (PI-ICR) technique. We then use these new masses along with previously published CPT masses to inform predictions for a Markov Chain Monte Carlo (MCMC) procedure aiming to identify the astrophysical conditions consistent with both solar data and mass measurements. We show that the MCMC responds to this updated mass information, producing refined results for both mass predictions and REP abundances.

The Beta-decay Paul Trap is an open-geometry, linear trap used to measure the decays of 8Li and 8B to search for a tensor contribution to the weak interaction. In the latest 8Li measurement of Burkey et al. (2022), β scattering was the dominant experimental systematic uncertainty. The Beta-decay Paul Trap Mk IV reduces the prevalence of β scattering by a factor of 4 through a redesigned electrode geometry and the use of glassy carbon and graphite as electrode materials. The trap has been constructed and successfully commissioned with 8Li in a new data campaign that collected 2.6 million triple coincidence events, an increase in statistics by 30% with 4 times less β scattering compared to the previous 8Li data set.

For many fission products, the $\ensuremath{\gamma}$ rays emitted following $\ensuremath{\beta}$ decay provide an easily detectable signature that can be used to identify their quantities and distributions in a sample. As a result, $\ensuremath{\gamma}$-ray spectroscopy is often exploited to study fission-product yields, provided sufficiently accurate information on the $\ensuremath{\gamma}$-ray intensities is available. In many cases, the uncertainties in the existing nuclear data are large enough that they compromise the precision achievable for modern experiments and applications. In this paper, we present high-precision results for the absolute $\ensuremath{\gamma}$-ray emission intensities for the most intense transitions in the $\ensuremath{\beta}$ decays of $^{144}\mathrm{Ce}$ and $^{147}\mathrm{Nd}$. We measured these intensities to $\ensuremath{\lesssim}1%$ accuracy by producing radiopure samples with fission-product beams at CARIBU and detecting the emitted radiation with a $4\ensuremath{\pi}\ensuremath{\beta}$ counter and a meticulously efficiency-calibrated high purity germanium detector at Texas A University.

Recent discussions about the origin of the Gallium Anomaly have motivated a remeasurement of the half life of $^{71}$Ge. We have conducted three separate measurements using dedicated planar Ge detectors: one with $^{55}$Fe as a standard, one with $^{57}$Co as a standard, and one stand alone 71Ge measurement. Our results yield a half life of 11.468 +- 0.008 days, which is consistent with but significantly more precise than the currently accepted value. With this experiment, the potential explanation of the Gallium Anomaly being due to an unexpectedly long $^{71}$Ge half life has been ruled out, leaving the origin of the anomaly as an open question.

This work presents the first experimentally determined nuclear level density and gamma -ray strength function of the short-lived fission product 93Sr, accomplished using the n-Oslo method. Direct measurement of the 92Sr(n, gamma ) 93Sr cross section is not currently possible, as the half-life of 2.66 hours is too short; instead, 93Sr was formed through n decay of 93Rb to excitation energies around the neutron separation energy. The gamma -ray spectra were measured using a total absorption spectrometer at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU). The statistical properties of the 93Sr nucleus were experimentally determined, including the gamma -ray strength function and nuclear level density. At low energies, the gamma -ray strength function exhibits a constant gamma -decay strength, rather than a slightly increasing strength with decreasing gamma -ray energy as had been previously observed for several nuclei in this mid-mass region. These statistical properties were then implemented in the reaction code TALYS1.95 to calculate the 92Sr(n, gamma ) 93Sr cross section.

For many fission products, the gamma rays emitted following beta decay provide an easily detectable signature that can be used to identify their quantities and distributions in a sample. As a result, gamma-ray spectroscopy is often exploited to study fission-product yields, provided sufficiently accurate information on the gamma-ray intensities is available. In many cases, the uncertainties in the existing nuclear data are large enough that they compromise the precision achievable for modern experiments and applications. In this paper, we present high-precision results for the absolute gamma-ray emission intensities for the most intense transitions in the beta decays of Ce-144 and (147) Nd. We measured these intensities to less than or similar to 1% accuracy by producing radiopure samples with fission-product beams at CARIBU and detecting the emitted radiation with a 4 pi beta counter and a meticulously efficiency-calibrated high purity germanium detector at Texas A&M University.

We present a methodology for absolute activity counting of long-lived isotopes based on cryogenic Decay Energy Spectroscopy. A 146Sm source was produced at the TRIUMF Laboratory and then processed and purified at Lawrence Livermore National Laboratory, yielding a pure sample. The source was embedded within a 4π thermal absorber coupled to a magnetic microcalorimeter achieving nearly 100% counting efficiency. Experimental uncertainties were studied and modeled, including thermal coupling of the source to the absorber, pulse pile-up, trigger, and event selection efficiencies. The absolute activity of the pure 146Sm source was measured to better than 1% uncertainty.

Nuclear isomer effects are pivotal in understanding nuclear astrophysics, particularly in the rapid neutron-capture process where the population of metastable isomers can alter the radioactive decay paths of nuclei produced during astrophysical events. The beta-decaying isomer Sb-128m was identified as potentially impactful since the beta-decay pathway along the A = 128 isobar funnels into this state bypassing the ground state. We report the first direct mass measurements of the Sb-128 isomer and ground state using the Canadian Penning Trap mass spectrometer at Argonne National Laboratory. We find mass excesses of -84564.8(25) keV and -84608.8(21) keV, respectively, resulting in an excitation energy for the isomer of 43.9(33) keV. These results provide the first key nuclear data input for understanding the role of Sb-128m in nucleosynthesis, and we show that it will influence the flow of the rapid neutron-capture process.

The 0+ decay of 8B provides the dominant source of solar neutrinos above 2 MeV. Consequently, experiments that detect neutrinos from the sun require an accurate determination of the 8B neutrino energy spectrum. In this work, the 0-decay Paul trap surrounded by double-sided silicon strip detectors was utilized to precisely measure the decay products of trapped 8B ions. The results were used to determine the 8Be final-state distribution and to reconstruct the neutrino energy spectrum. This measurement using trapped ions is the first of its kind and puts the neutrino energy spectrum on much firmer footing by discriminating between recently reported values for the maximum of the final-state distribution.

This white paper was submitted to the 2022 Fundamental Symmetries, Neutrons, and Neutrinos (FSNN) Town Hall Meeting in preparation for the next NSAC Long Range Plan. We advocate to support current and future theoretical and experimental searches for physics beyond the Standard Model using nuclear β decay

In this contribution we present the achievements of the CUORE experiment so far. It is the first tonne-scale bolometric detector and it is in stable data taking since 2018. We reached to collect about 1800 kgxyr of exposure of which more than 1 tonxyear have been analysed. The CUORE detector is meant to search for the neutrinoless double 0 decay (0v00) of the 130Te isotope. This is a beyond Standard Model process which could establish the nature of the neutrino to be Dirac or a Majorana particle. It is an alternative mode of the two-neutrinos double 0 decay, a rare decay which have been precisely measured by CUORE in the 130Te. We found no evidence of the 0v 00 and we set a Bayesian lower limit of 2.2 x1025yr on its half-life. The expertise achieved by CUORE set a milestone for any future bolometric detector, including CUPID, which is the planned next generation experiment searching for 0v0 0 with scintillating bolometers.

This corrects the article DOI: 10.1103/PhysRevLett.126.171801.

This whitepaper presents the research priorities decided on by attendees of the 2022 Town Meeting for Fundamental Symmetries, Neutrons and Neutrinos, which took place December 13-15, 2022 in Chapel Hill, NC, as part of the Nuclear Science Advisory Committee (NSAC) 2023 Long Range Planning process. A total of 275 scientists registered for the meeting. The whitepaper makes a number of explicit recommendations and justifies them in detail.

We present the first measurement of the α-β-ν angular correlation in the Gamow-Teller β^{+} decay of ^{8}B. This was accomplished using the Beta-decay Paul Trap, expanding on our previous work on the β^{-} decay of ^{8}Li. The ^{8}B result is consistent with the V-A electroweak interaction of the standard model and, on its own, provides a limit on the exotic right-handed tensor current relative to the axial-vector current of |C_{T}/C_{A}|^{2}<0.013 at the 95.5% confidence level. This represents the first high-precision angular correlation measurements in mirror decays and was made possible through the use of an ion trap. By combining this ^{8}B result with our previous ^{8}Li results, we demonstrate a new pathway for increased precision in searches for exotic currents.

initial studies of these nuclei have been featured on the cover of the journal Nature (Gaffney et al. 2013). All the octupole deformed nuclei of interest are radioactive and therefore available only in limited quantities. The primary challenge for an EDM experiment using radon is to collect large enough samples to perform sensitive searches.