Tue·Mar 22, 2022Tuesday·March 22, 2022

1. 01*

   Structure of ${}^{83}$As, ${}^{85}$As and ${}^{87}$As: from semi-magicity to $\gamma$-softness

   K. Rezynkina🇫🇷 · D. D. Dao🇫🇷 · G. Duchene🇫🇷 · J. Dudouet🇫🇷 · F. Nowacki🇫🇷 · E. Clement🇫🇷 · A. Lemasson🇫🇷 · C. Andreoiu🇨🇦 · A. Astier🇫🇷 · G. de Angelis🇮🇹 · G. de France🇫🇷 · C. Delafosse🇫🇷 and 32 other authors

   The structure of ${}^{83}$As, ${}^{85}$As and ${}^{87}$As have been studied in fusion-fission reaction ${}^{238}$U+${}^9$Be. Fission fragments were identified in mass and atomic number using the VAMOS++ spectrometer and the coincident $\gamma$-rays were detected in the $\gamma$-ray tracking array AGATA. New transitions in ${}^{83}$As and ${}^{85}$As are reported and placed in the level schemes. A level scheme of the excited states in ${}^{87}$As is proposed for the first time. The data are interpreted in frame of Large-Scale Shell-Model calculations, SU3 symmetries and Beyond Mean-Field frameworks. A spherical regime at magic number $N$=50 is predicted and the location of the proton $g_{9/2}$ orbital is proposed for the first time. Development of collectivity in a prolate deformed, $\gamma$-soft regime in the open shell cases ${}^{85}$As and ${}^{87}$As, most neutron-rich isotopes beyond $N$=50, is concluded. Data and theoretical calculations give confidence to a relatively high extrapolated excitation energy about 4 MeV of the $9/2^{+}$ state in ${}^{79}$Cu, one proton above ${}^{78}$Ni.

   nucl-exPRC(2022)·11 citations
2. 02*

   Mapping the $N=40$ Island of Inversion: Precision Mass Measurements of Neutron-rich Fe Isotopes

   W. S. Porter🇨🇦 · B. Ashrafkhani🇨🇦 · J. Bergmann🇩🇪 · C. Brown🇺🇸 · T. Brunner🇨🇦 · J. D. Cardona🇨🇦 · D. Curien🇫🇷 · I. Dedes🇵🇱 · T. Dickel🇩🇪 · J. Dudek🇫🇷 · E. Dunling🇨🇦 · G. Gwinner🇨🇦 and 23 other authors

   Nuclear properties across the chart of nuclides are key to improving and validating our understanding of the strong interaction in nuclear physics. We present high-precision mass measurements of neutron-rich Fe isotopes performed at the TITAN facility. The multiple-reflection time-of-flight mass spectrometer (MR-ToF-MS), achieving a resolving power greater than $600000$ for the first time, enabled the measurement of ${}^{63-70}$Fe, including first-time high-precision direct measurements ($\delta m/m\sim 10^{-7}$) of ${}^{68-70}$Fe, as well as the discovery of a long-lived isomeric state in ${}^{69}$Fe. These measurements are accompanied by both mean-field and ab initio calculations using the most recent realizations which enable theoretical assignment of the spin-parities of the ${}^{69}$Fe ground and isomeric states. Together with mean-field calculations of quadrupole deformation parameters for the Fe isotope chain, these results benchmark a maximum of deformation in the $N=40$ island of inversion in Fe, and shed light on trends in level densities indicated in the newly-refined mass surface.

   nucl-exnucl-thPRC(2022)·23 citations
3. 03*

   First application of Markov Chain Monte Carlo-based Bayesian data analysis to the Doppler-Shift Attenuation Method

   L. J. Sun🇺🇸 · C. Fry · B. Davids🇨🇦 · N. Esker🇨🇦 · C. Wrede · M. Alcorta🇨🇦 · S. Bhattacharjee🇨🇦 · M. Bowry · B. A. Brown🇺🇸 · T. Budner🇺🇸 · R. Caballero-Folch🇨🇦 · L. Evitts and 22 other authors

   Motivated primarily by the large uncertainties in the thermonuclear rate of the ${}^{30}$P$(p,\gamma {)}^{31}$S reaction that limit our understanding of classical novae, we carried out lifetime measurements of ${}^{31}$S excited states using the Doppler Shift Lifetimes (DSL) facility at the TRIUMF Isotope Separator and Accelerator (ISAC-II) facility. The ${}^{31}$S excited states were populated by the ${}^3$He${(}^{32}$S$,\alpha {)}^{31}$S reaction. The deexcitation $\gamma$ rays were detected by a clover-type high-purity germanium detector in coincidence with the $\alpha$ particles detected by a silicon detector telescope. We have applied modern Markov chain Monte Carlo-based Bayesian methods to perform lineshape analyses of Doppler-shift attenuation method $\gamma$-ray data for the first time. We have determined the lifetimes of the two lowest-lying ${}^{31}$S excited states. First experimental upper limits on the lifetimes of four higher-lying states have been obtained. The experimental results were compared to shell-model calculations using five universal $sd$-shell Hamiltonians. Evidence for $\gamma$ rays originating from the astrophysically important $J^{\pi }=3/2^{+}$, 260-keV ${}^{30}$P$(p,\gamma {)}^{31}$S resonance has also been observed, although strong constraints on the lifetime will require better statistics.

   nucl-exPLB(2023)·2 citations
4. 04*

   Modeling Heavy-Ion Fusion Cross Section Data via a Novel Artificial Intelligence Approach

   Daniele Dell'Aquila🇮🇹 · Brunilde Gnoffo🇮🇹 · Ivano Lombardo🇮🇹 · Francesco Porto · Marco Russo

   We perform a comprehensive analysis of complete fusion cross section data with the aim to derive, in a completely data-driven way, a model suitable to predict the integrated cross section of the fusion between light to medium mass nuclei at above barrier energies. To this end, we adopted a novel artificial intelligence approach, based on a hybridization of genetic programming and artificial neural networks, capable to derive an analytical model for the description of experimental data. The approach enables, for the first time, to perform a global search for computationally simple models over several variables and a considerable body of nuclear data. The derived phenomenological formula can serve to reproduce the trend of fusion cross section for a large variety of light to intermediate mass collision systems in an energy domain ranging approximately from the Coulomb barrier to the onset of multi-fragmentation phenomena.

   nucl-exnucl-thJ.Phys.G(2023)·12 citations
5. 05*

   Explaining the hints for lepton flavour universality violation with three $S_2$ leptoquark generations

   Andreas Crivellin🇨🇭 · Benjamin Fuks🇫🇷 · Luc Schnell🇩🇪

   Leptoquarks are prime candidates for explaining the intriguing hints for lepton flavour universality violation. In particular, the $SU(2{)}_L$ doublet of scalar leptoquarks $S_2$ is capable of providing an explanation for the tensions between the measurements and the Standard Model predictions in $(g-2{)}_{\mu }$, $b\to s{\ell }^{+}{\ell }^{-}$ and $b\to c\tau \nu$ processes, as well as in non-resonant di-electron production. However, in the minimal setup with a single leptoquark generation, a common explanation for all these issues is not possible as this would lead to unacceptably large charged lepton flavour violation. We therefore propose a model with three generations of $S_2$, each coupling exclusively to a single lepton flavour, \textit{i.e.}~a model extending the Standard Model particle content by an electroquark, a muoquark and a tauquark. We show that after taking into account other constraints, such as those originating from electroweak precision observables and $\Delta F=2$ processes, it is possible to provide a combined explanation for all these hints of lepton flavour universality violation. Moreover, we find that the presence of the tauquark can generate a dimension-six ${\mathcal{O}}_9^U$ operator via off-shell photon penguin diagrams, which, together with the muoquark contribution, further improves the global fit to $b\to s{\ell }^{+}{\ell }^{-}$ data.

   ↳ hep-phhep-exnucl-exnucl-thJHEP(2022)·42 citations
6. 06*

   The Ion Fluorescence Chamber (IFC): A new concept for directional dark matter and topologically imaging neutrinoless double beta decay searches

   B. J. P. Jones🇺🇸 · F. W. Foss🇺🇸 · J. A. Asaadi🇺🇸 · E. D. Church🇺🇸 · J. deLeon🇺🇸 · E. Gramellini🇺🇸 · O. H. Seidel🇺🇸 · T. T. Vuong🇺🇸

   We introduce a novel particle detection concept for large-volume, fine granularity particle detection: The Ion Fluorescence Chamber (IFC). In electronegative gases such as SF${}_6$ and SeF${}_6$, ionizing particles create ensembles of positive and negative ions. In the IFC, positive ions are drifted to a chemically active cathode where they react with a custom organic turn-on fluorescent monolayer encoding a long-lived 2D image. The negative ions are sensed electrically with course resolution at the anode, inducing an optical microscope to travel to and scan the corresponding cathode location for the fluorescent image. This concept builds on technologies developed for barium tagging in neutrinoless double beta decay, combining the ultra-fine imaging capabilities of an emulsion detector with the monolithic sensing of a time projection chamber. The result is a high precision imaging detector over arbitrarily large volumes without the challenges of ballooning channel count or system complexity. After outlining the concept, we discuss R\&D to be undertaken to demonstrate it, and explore application to both directional dark matter searches in SF${}_6$ and searches for neutrinoless double beta decay in large ${}^{82}$SeF${}_6$ chambers.

   ↳ physics.ins-dethep-exnucl-ex6 citations
7. 07*

   Comment on "Tests and calibrations of nuclear track detectors (CR39) for operation in high neutron flux" by E.E. Kading et al., Phys. Rev. Res. 2, 023279 (2020)

   Michael Paul🇮🇱 · Ulli Köster🇫🇷

   The conditions of tests and calibrations described in the article E.E Kading et al. [Phys. Rev. Res. 2, 023279 (2020)] show striking flaws. The interpretation and extraction of quantitative results from this experiment are considered unreliable. All results of cross sections based on the results described in this article must be disregarded.

   ↳ physics.ins-detnucl-ex0 citations
8. 08*

   Status on the DESIR High Resolution Separator Commissioning

   J. Michaud (1)🇫🇷 · P. Alfaurt (1)🇫🇷 · A. Balana (1)🇫🇷 · B. Blank (1)🇫🇷 · L. Daudin (1)🇫🇷 · T. Kurtukian Nieto (1)🇫🇷 · B. Lachacinski (1)🇫🇷 · L. Serani (1)🇫🇷 · F. Varenne (2) ((1) Univ. Bordeaux, (2) Grand Accélérateur National d'Ions Lourds)🇫🇷

   Many nuclear reactions used to create radioactive isotopes for nuclear research produce, in addition to the isotope of interest, many contaminants, which are often produced in much larger amounts than the isotope of interest. Many installations using the ISOL approach are therefore equipped with high-resolution mass separators to remove at least isotopes with a different mass number. In the present paper, we present the results of the commissioning of the DESIR HRS presently under development at LP2I Bordeaux (formerly CENBG). Optical aberrations are corrected up to 3rd order and a mass resolution of M/$\Delta$M of 25000 is reached with a transmission of about 70% for a 133Cs+ beam at 25 keV.

   ↳ physics.ins-detnucl-ex3 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.