Nuclear Experiment
See recent articles
Showing new listings for Thursday, 14 November 2024
- [1] arXiv:2411.08542 [pdf, html, other]
-
Title: Neutrino mass experiments: current and futureComments: 7 pages, no figures. Conference proceeding for neutrino mass summary talk at the "22nd Conference on Flavor Physics and CP Violation" (FPCP 2024)Subjects: Nuclear Experiment (nucl-ex)
Nearly 70 years since the neutrino was discovered, and 25 years since discovery of neutrino oscillations established its non-zero mass, the absolute neutrino-mass scale remains unknown. Due to its unique characteristics, determining this neutrino property requires new measurement techniques to be developed. Currently, there are four measurement approaches: using cosmological models, inference from time-of-arrival from supernovae, through observation of neutrinoless double beta decay, and the kinematics of weak decay processes. I will review the theoretical basis underlying neutrino mass measurement and present key experiments in this field. I will highlight the current best upper limits, how neutrino mass experiments are complementary to other neutrino property searches, and summarize the challenges that lie ahead of the neutrino mass community.
- [2] arXiv:2411.08856 [pdf, other]
-
Title: High-temperature $^{205}$Tl decay clarifies $^{205}$Pb dating in early Solar SystemG. Leckenby, R. S. Sidhu, R. J. Chen, R. Mancino, B. Szányi, M. Bai, U. Battino, K. Blaum, C. Brandau, S. Cristallo, T. Dickel, I. Dillmann, D. Dmytriiev, T. Faestermann, O. Forstner, B. Franczak, H. Geissel, R. Gernhäuser, J. Glorius, C. Griffin, A. Gumberidze, E. Haettner, P.-M. Hillenbrand, A. Karakas, T. Kaur, W. Korten, C. Kozhuharov, N. Kuzminchuk, K. Langanke, S. Litvinov, Y. A. Litvinov, M. Lugaro, G. Martínez-Pinedo, E. Menz, B. Meyer, T. Morgenroth, T. Neff, C. Nociforo, N. Petridis, M. Pignatari, U. Popp, S. Purushothaman, R. Reifarth, S. Sanjari, C. Scheidenberger, U. Spillmann, M. Steck, T. Stöhlker, Y. K. Tanaka, M. Trassinelli, S. Trotsenko, L. Varga, D. Vescovi, M. Wang, H. Weick, A. Yagüe López, T. Yamaguchi, Y. Zhang, J. ZhaoComments: 21 pages and 11 figures/tables. Published in Nature (2024)Subjects: Nuclear Experiment (nucl-ex); Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Radioactive nuclei with lifetimes on the order of millions of years can reveal the formation history of the Sun and active nucleosynthesis occurring at the time and place of its birth. Among such nuclei whose decay signatures are found in the oldest meteorites, $^{205}$Pb is a powerful example, as it is produced exclusively by slow neutron captures (the s process), with most being synthesized in asymptotic giant branch (AGB) stars. However, making accurate abundance predictions for $^{205}$Pb has so far been impossible because the weak decay rates of $^{205}$Pb and $^{205}$Tl are very uncertain at stellar temperatures. To constrain these decay rates, we measured for the first time the bound-state $\beta^-$ decay of fully ionized $^{205}$Tl$^{81+}$, an exotic decay mode that only occurs in highly charged ions. The measured half-life is 4.7 times longer than the previous theoretical estimate and our 10% experimental uncertainty has eliminated the main nuclear-physics limitation. With new, experimentally backed decay rates, we used AGB stellar models to calculate $^{205}$Pb yields. Propagating those yields with basic galactic chemical evolution (GCE) and comparing with the $^{205}$Pb/$^{204}$Pb ratio from meteorites, we determined the isolation time of solar material inside its parent molecular cloud. We find positive isolation times that are consistent with the other s-process short-lived radioactive nuclei found in the early Solar System. Our results reaffirm the site of the Sun's birth as a long-lived, giant molecular cloud and support the use of the $^{205}$Pb--$^{205}$Tl decay system as a chronometer in the early Solar System.
New submissions (showing 2 of 2 entries)
- [3] arXiv:2411.08076 (cross-list from physics.ins-det) [pdf, html, other]
-
Title: High-Precision Excited-State Nuclear Recoil Spectroscopy with Superconducting SensorsC. Bray, S. Fretwell, L. A. Zepeda-Ruiz, I. Kim, A. Samanta, K. Wang, C. Stone-Whitehead, W. K. Warburton, F. Ponce, K. G. Leach, R. Abells, P. Amaro, A. Andoche, R. Cantor, D. Diercks, M. Guerra, A. Hall, C. Harris, J. Harris, L. Hayen, P. A. Hervieux, G. B. Kim, A. Lennarz, V. Lordi, J. Machado, P. Machule, A. Marino, D. McKeen, X. Mougeot, C. Ruiz, J. P. Santos J. Smolsky, B. D. Waters, S. FriedrichSubjects: Instrumentation and Detectors (physics.ins-det); Nuclear Experiment (nucl-ex)
Superconducting sensors doped with rare isotopes have recently demonstrated powerful sensing performance for sub-keV radiation from nuclear decay. Here, we report the first high-resolution recoil spectroscopy of a single, selected nuclear state using superconducting tunnel junction (STJ) sensors. The STJ sensors were used to measure the eV-scale nuclear recoils produced in $^7$Be electron capture decay in coincidence with the 478 keV $\gamma$-ray emitted in decays to the excited nuclear state in $^7$Li. Details of the Doppler broadened recoil spectrum depend on the slow-down dynamics of the recoil ion and can constrain the interaction potential between the recoiling Li and the Ta matrix of the STJ sensor. The results have implications in several areas from nuclear structure and stopping powers at eV-scale energies to direct searches for dark matter, neutrino mass measurements, and other physics beyond the standard model.
- [4] arXiv:2411.08130 (cross-list from nucl-th) [pdf, html, other]
-
Title: Triaxial nuclear shapes from simple ratios of electric-quadrupole matrix elementsComments: 9 pages, 7 figuresSubjects: Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
Theoretical models often invoke triaxial nuclear shapes to explain elusive collective phenomena, but such assumptions are usually difficult to confirm experimentally. The only direct measurements of the nuclear axial asymmetry $\gamma$ is based on rotational invariants of zero-coupled products of the electric-quadrupole (E2) operator, the Kumar-Cline sum rule analysis, which generally require knowledge of a large number of E2 matrix elements connecting the state of interest. We propose an alternative assumptions-free method to determine $\gamma$ of even-even rotating nuclei using only two E2 matrix elements, which are among the easiest to measure. This approach is based on a simple description of nuclear rotation, where the underlying assumptions of the Davydov-Filippov model are either empirically proven or unnecessary. The $\gamma$ values extracted here are found in agreement with the values deduced from Kumar-Cline sum rules measurements (where available), providing further evidence that the proposed approach represents a reliable, model-independent deduction of $\gamma$. The technique was applied to more than 60 deformed even-even rotating nuclei and the results indicate that rotating nuclei generally exhibit well-defined stable axially-asymmetric shapes.
- [5] arXiv:2411.08337 (cross-list from nucl-th) [pdf, html, other]
-
Title: Investigating the possibility of extracting neutron-skin thickness in nuclei by their collisions at intermediate energiesComments: 11 pages, 10 figuresSubjects: Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
Inspired by various studies on extracting the density distributions of nuclei from their collisions at ultrarelativistic energies, in the present work we investigate the possibility of extracting the neutron-skin thickness $\Delta r_{np}$ in nuclei by their collisions at intermediate energies. We have analyzed the free neutron-to-proton yield ratio $n/p$ as a candidate probe at both midrapidities and forward rapidities in peripheral and central $^{124}$Sn+$^{124}$Sn collisions based on an isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model, and found that the resulting $n/p$ yield ratio is more sensitive to the symmetry potential in the collision dynamics than to the initial $\Delta r_{np}$ in colliding nuclei in most cases. The largest effect on the $n/p$ yield ratio from the initial $\Delta r_{np}$ is observed for nucleons at large transverse or longitudinal momenta in central collisions at the collision energy of a few GeV/nucleon.
- [6] arXiv:2411.08682 (cross-list from nucl-th) [pdf, html, other]
-
Title: Multiple shape coexistence in the $N=Z$ $^{84}$Mo nucleusComments: submitted to the proceedings of NSD 2024Subjects: Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
The structure of the nucleus $^{84}$Mo has been studied using the projected generator coordinate method (PGCM) with the Gogny D1S interaction. The calculations incorporate a mixing of particle-number and angular-momentum projected intrinsic wave functions, defined over triaxial quadrupole degrees of freedom. This approach yields an excellent agreement with the scarce experimental data for this nucleus and several bands based on different shapes are predicted.
Cross submissions (showing 4 of 4 entries)
- [7] arXiv:2411.06310 (replaced) [pdf, html, other]
-
Title: Mass measurements of neutron-rich nuclides using the Canadian Penning Trap to inform predictions in the $r$-process rare-earth peak regionD. Ray, N. Vassh, B. Liu, A.A. Valverde, M. Brodeur, J.A. Clark, G.C. McLaughlin, M.R. Mumpower, R. Orford, W.S. Porter, G. Savard, K. S. Sharma, R. Surman, F. Buchinger, D.P. Burdette, N. Callahan, A.T. Gallant, D.E.M. Hoff, K. Kolos, F.G. Kondev, G. E. Morgan, F. Rivero, D. Santiago-Gonzalez, N.D. Scielzo, L. Varriano, C.M. Weber, G. E. Wilson, X.L. YanComments: 11 pages, 8 figuresSubjects: Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
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, $\beta$-decay rates, and $\beta$-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.
- [8] arXiv:2405.17119 (replaced) [pdf, html, other]
-
Title: Isoscalar, isovector and orbital contributions in $M1$ transitions from analogous $M1$ and Gamow-Teller transitions in $T=\frac{1}{2}$ mirror nucleiComments: 13 pages, 7 figuresJournal-ref: Physical Review C 110, 054305 (2024)Subjects: Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
The isoscalar and isovector components and their contributions to $M1$ transitions are discussed in the odd-$A$, $T=1/2$ mirror nuclei with mass number ranging from $A=23$ to 37. The orbital contributions in various $M1$ transitions and ground state magnetic moments are calculated by comparing analogous $M1$ and Gamow-Teller transitions between mirror pairs. The orbital contributions in different $M1$ transitions are explained on the basis of configurations of the initial and final states involved. In magnetic moments, the orbital contributions are found to be dependent on the deformation and single-particle nature of the states. All the $T=1/2$ mirror pairs are studied using isospin non-conserving interaction. The results are also compared with predictions from \textit{ab initio} effective interaction derived from realistic nuclear forces.