Thu·Aug 25, 2022Thursday·August 25, 2022

1. 01*

   Identification of a potential ultra-low Q value electron capture decay branch in ${}^{75}$Se via a precise Penning trap measurement of the mass of ${}^{75}$As

   M. Horana Gamage🇺🇸 · R. Bhandari🇺🇸 · G. Bollen🇺🇸 · N. D. Gamage🇺🇸 · A. Hamaker🇺🇸 · D.Puentes🇺🇸 · M. Redshaw🇺🇸 · R. Ringle🇺🇸 · S. Schwarz🇺🇸 · C. S. Sumithrarachchi🇺🇸 · I. Yandow🇺🇸

   Background: Low energy $\beta$ and electron capture (EC) decays are important systems in neutrino mass determination experiments. An isotope with an ultra-low Q value $\beta$-decay to an excited state in the daughter with Qes < 1 keV could provide a promising alternative candidate for future experiments. ${}^{75}$Se EC and ${}^{75}$Ge $\beta$-decay represent such candidates, but a more precise determination of the mass of the common daughter, ${}^{75}$As, is required to evaluate whether their potential decay branches are energetically allowed and ultra-low. Purpose: Perform a precise atomic mass measurement of ${}^{75}$As and combine the result with the precisely known atomic masses of ${}^{75}$Se and ${}^{75}$Ge, along with nuclear energy level data for ${}^{75}$As to evaluate potential ultra-low Q value decay branches in the EC decay of ${}^{75}$Se and the $\beta$-decay of ${}^{75}$Ge. Method: The LEBIT Penning trap mass spectrometer at the Facility for Rare Isotope Beams was used to perform a high-precision measurement of the atomic mass of ${}^{75}$As via cyclotron frequency ratio measurements of ${}^{75}$As${}^{+}$ to a ${}^{12}$C${}_6^{+}$ reference ion. Results: The ${}^{75}$As mass excess was determined to be ME(${}^{75}$As)= -73 035.98(43) keV, from which the ground-state to ground-state Q values for ${}^{75}$Se EC and ${}^{75}$Ge $\beta$-decay were determined to be 866.50(44) keV and 1179.01(44) keV, respectively. These results were compared to energies of excited states in ${}^{75}$As at 865.4(5) keV and 1172.0(6) keV to determine Q values of 1.1(7) keV and 7.0(7) keV for the potential ultra-low EC and $\beta$-decay branches of ${}^{75}$Se and ${}^{75}$Ge, respectively. Conclusion: The ${}^{75}$Se EC decay to the 865.4 keV excited state in ${}^{75}$As is potentially ultra-low with Qes $\approx$ 1 keV. However, a more precise determination of the 865.4(5) keV level in ${}^{75}$As is required.

   nucl-exPRC(2022)·10 citations
2. 02*

   Particle production as a function of underlying-event activity and very forward energy with ALICE

   Feng Fan (for the ALICE Collaboration)🇨🇳

   Measurements of charged-particle production in pp and p-Pb collisions at ${\sqrt{s}}_{\mathrm{NN}}=5.02$ TeV in the toward, away and transverse regions are discussed. These three regions are defined event by event relative to the track with the largest transverse momentum ($p_{\mathrm{T}}^{\mathrm{trig}}$). The transverse region is sensitive to the underlying event (UE), but it also includes contributions from initial- and final-state radiation (ISR-FSR). Therefore, it is further subdivided in two regions, defined according to their relative multiplicity: trans-max (the sub-transverse region with the largest multiplicity) and trans-min (the sub-transverse region with the smallest multiplicity) regions which are sensitive to UE and ISR-FSR, respectively. KNO-like scaling properties are explored in the three defined transverse regions. Finally, the relationship between $p_{\mathrm{T}}^{\mathrm{trig}}$ and the energy detected in a region close to beam rapidity (very forward energy) is reported.

   nucl-exhep-exEPJ Web Conf.(2023)·4 citations
3. 03*

   Scaling of the ${}^{19}$B two-neutron halo properties close to unitarity

   Emiko Hiyama🇯🇵 · Rimantas Lazauskas🇫🇷 · Jaume Carbonell🇫🇷 · Tobias Frederico🇧🇷

   We explore the description of the bound ${}^{19}$B isotope in terms of a ${}^{17}$B+n+n three-body system where the two-body subsystems ${}^{17}$B+n and neutron-neutron (nn) have virtual states close to the continuum. Dimensionless scaling functions for the root-mean-square (rms) radii are defined and studied for different parameters of the neutron-core potential and considering three different models for neutron-neutron interaction. The scaling functions for the radii are rooted on the universal behavior of three-body systems close to the Efimov limit and depend only on dimensionless quantities formed by the two-neutron separation energies and scattering lengths. Our results show in practice the model independence of these scaling functions close to unitarity. We provide an estimation of the different rms relative separation distances between the constituents, as well as of the proton and matter radii.

   ↳ nucl-thnucl-exPRC(2022)·11 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.