Tue·Aug 6, 2024Tuesday·August 6, 2024

1. 01*

   On the decay properties of the neutron-deficient isotope 242Es

   J. Khuyagbaatar · R.A. Cantemir · Ch.E. Duellmann · E. Jaeger · B. Kindler🇩🇪 · J. Krier · N. Kurz🇩🇪 · B. Lommel🇩🇪 · B. Schausten · A. Yakushev

   The radioactive decay properties of ${}^{242}$Es were studied with significantly improved statistics compared to available literature data. This isotope was produced in the 3n evaporation channel of the fusion reaction of ${}^{48}$Ca+${}^{197}$Au. A half-life of 16.9(8)~s was deduced from 662 $\alpha$ decays of ${}^{242}$Es, resulting in an $\alpha$-decay branching of 41(3)\%. Twenty-six fission events with a half-life of 18.2${}_{-3.0}^{+4.5}$~s were assigned to originate from the electron-capture delayed fission of ${}^{242}$Es. The probability for the electron-capture delayed fission was measured to be 0.015(4), which improves and resolves ambiguities in available experimental data. We discuss all known cases for electron-capture delayed fission in Es, Bk, and Am isotopes and compare experimental data with predictions from a recent semi-empirical model. A cross section of 27(3)~nb was measured for the production of ${}^{242}$Es.

   nucl-exPRC(2024)·6 citations
2. 02*

   Search for Pauli Exclusion Principle Violations with Gator at LNGS

   L. Baudis🇨🇭 · R. Biondi🇩🇪 · A. Bismark🇨🇭 · A. Clozza🇮🇹 · C. Curceanu🇮🇹 · M. Galloway🇨🇭 · F. Napolitano🇮🇹 · F. Piastra🇨🇭 · K. Piscicchia🇮🇹 · A. Porcelli🇮🇹 · D. Ramírez García🇨🇭

   The Pauli Exclusion Principle (PEP) appears from fundamental symmetries in quantum field theories, but its physical origin is still to be understood. High-precision experimental searches for small PEP violations permit testing key assumptions of the Standard Model with high sensitivity. We report on a dedicated measurement with Gator, a low-background, high-purity germanium detector operated at the Laboratori Nazionali del Gran Sasso, aimed at testing PEP-violating atomic transitions in lead. The experimental technique, relying on forming a new symmetry state by introducing electrons into the pre-existing electron system through a direct current, satisfies the conditions of the Messiah-Greenberg superselection rule. No PEP violation has been observed, and an upper limit on the PEP violation probability of ${\beta }^2/2<4.8\cdot 10^{-29}$ (90% CL) is set. This improves the previous constraint from a comparable measurement by more than one order of magnitude.

   nucl-exquant-phEPJC(2024)·3 citations
3. 03*

   Ternary fission with the emission of long-range $\alpha$ particles in fission of the heaviest nuclei

   J. Khuyagbaatar

   The most probable outcome of the ternary fission is the emission of two heavy fragments and one light-charged particle. In about 90\%, these are $\alpha$ particles, which often referred to as the long-range alpha (LRA). Such decay has been extensively studied over decades in various heavy fissioning systems. The probability of such a process has been found to be about (2-4)$\times 10^{-3}$ relative to binary fission. The experimental data showed an increasing trend in the probability of such a process with an increase in fissility parameter within the range of 35 - 39. In the last decades, a region of the heaviest nuclei has been substantially expanded in both proton and neutron numbers. This includes neutron-deficient heavy and superheavy nuclei with fissility parameters, which are significantly exceeding the aforementioned range. In the present work, the currently available experimental data on the probability of the LRA emission, which is a representative of ternary fission, are discussed. The probabilities of LRA emission were calculated within the various empirical approaches, including the presently suggested semi-empirical expression. The latter one was derived on the basis of the $\alpha$-decay property of the fissioning nucleus. The results of all approaches discussed show that the probabilities of LRA emission are substantial (up to a percentage) in the fission of neutron-deficient heavy and superheavy nuclei.

   ↳ nucl-thnucl-exPRC(2024)·4 citations
4. 04*

   The $p\Lambda$ and $pp\Lambda$ correlation functions

   E. Garrido🇪🇸 · A. Kievsky🇮🇹 · M. Gattobigio🇫🇷 · M. Viviani🇮🇹 · L.E. Marcucci🇮🇹 · R. Del Grande🇩🇪 · L. Fabbietti🇩🇪 · D. Melnichenko🇩🇪

   In this work we present the study of $p\Lambda$ and $pp\Lambda$ scattering processes using femtoscopic correlation functions. This observable has been recently used to access the low-energy interaction of hadrons emitted in the final state of high-energy collisions, delivering unprecedented precision information of the interaction among strange hadrons. The formalism for particle pairs is well established and it relates the measured correlation functions with the scattering wave function and the emission source. In the present work we analyze the $NN\Lambda$ scattering in free space and relate the corresponding wave function to the $pp\Lambda$ correlation measurement performed by the ALICE collaboration. The three-body problem is solved using the hyperspherical adiabatic basis. Regarding the $p\Lambda$ and $pp\Lambda$ interactions, different models are used and their impact on the correlation function is studied. The three body force considered in this work is anchored to describe the binding energy of the hypertriton and to give a good description of the two four-body hypernuclei. As a main result we have observed a huge, low-energy peak in the $pp\Lambda$ correlation function, mainly produced by the $J^{\pi }=1/2^{+}$ three-body state. The study of this peak from an experimental as well as a theoretical point of view will provide important constraints to the two- and three-body interactions.

   ↳ nucl-thhep-exhep-phnucl-exPRC(2024)·18 citations
5. 05*

   Correlation of neutrinoless double-beta decay nuclear matrix elements with nucleon-nucleon phase shifts

   A. Belley🇨🇦 · J. Pitcher🇨🇦 · T. Miyagi🇩🇪 · S. R. Stroberg🇺🇸 · J. D. Holt🇨🇦

   We present an ab initio study of the correlation between nuclear matrix elements of neutrinoless double-beta ($0\nu \beta \beta$) decay and nucleon-nucleon scattering phase shifts in the ${}^1{S}_0$ channel. Starting from thirty-four statistically weighted interactions derived from chiral effective field theory, we apply the valence-space in-medium similarity renormalization group to calculate nuclear matrix elements in four key experimental isotopes. Comparing with the ${}^1{S}_0$-channel phase shifts given from each interaction, in all cases we observe a strong correlation for scattering energies above 75 MeV. Furthermore, a global sensitivity analysis, enabled by newly developed machine-learning emulators, confirms that the nuclear matrix elements of the decay depend primarily on the $C_{1S0}$ low-energy constant, which is associated with the phase shifts in that partial wave. These results provide the first clear correlation between $0\nu \beta \beta$ decay nuclear matrix elements and a measured observable and will therefore serve as a crucial component in ongoing and future refinements of ab initio uncertainty estimates.

   ↳ nucl-thhep-exhep-phnucl-exPRC(2026)·12 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.