Wed·Oct 23, 2024Wednesday·October 23, 2024

1. 01*

   Shape evolution in even-mass ${}^{98-104}$Zr isotopes via lifetime measurements using the $\gamma \gamma$-coincidence technique

   G. Pasqualato🇫🇷 · S. Ansari🇫🇷 · J.S. Heines🇳🇴 · V. Modamio🇳🇴 · A. Görgen🇳🇴 · W. Korten🇫🇷 · J. Ljungvall🇫🇷 · E. Clément🇫🇷 · J. Dudouet🇫🇷 · A. Lemasson🇫🇷 · T.R. Rodríguez🇪🇸 · J.M. Allmond🇺🇸 and 73 other authors

   The Zirconium (Z = 40) isotopic chain has attracted interest for more than four decades. The abrupt lowering of the energy of the first $2^{+}$ state and the increase in the transition strength B(E2; $2_1^{\to }{0}_1^{+}$ going from ${}^{98}$Zr to ${}^{100}$Zr has been the first example of "quantum phase transition" in nuclear shapes, which has few equivalents in the nuclear chart. Although a multitude of experiments have been performed to measure nuclear properties related to nuclear shapes and collectivity in the region, none of the measured lifetimes were obtained using the Recoil Distance Doppler Shift method in the $\gamma \gamma$-coincidence mode where a gate on the direct feeding transition of the state of interest allows a strict control of systematical errors. This work reports the results of lifetime measurements for the first yrast excited states in ${}^{98-104}$Zr carried out to extract reduced transition probabilities. The new lifetime values in $\gamma \gamma$-coincidence and $\gamma$-single mode are compared with the results of former experiments. Recent predictions of the Interacting Boson Model with Configuration Mixing, the Symmetry Conserving Configuration Mixing model based on the Hartree-Fock-Bogoliubov approach and the Monte Carlo Shell Model are presented and compared with the experimental data.

   nucl-exEPJA(2023)·8 citations
2. 02*

   Extension of the particle x-ray coincidence technique: The lifetimes and branching ratios apparatus

   L. J. Sun · J. Dopfer🇺🇸 · A. Adams🇺🇸 · C. Wrede · A. Banerjee🇩🇪 · B. A. Brown🇺🇸 · J. Chen · E. A. M. Jensen🇩🇰 · R. Mahajan🇺🇸 · T. Rauscher🇨🇭 · C. Sumithrarachchi🇺🇸 · L. E. Weghorn🇺🇸 · D. Weisshaar🇺🇸 · T. Wheeler🇺🇸

   The particle x-ray coincidence technique (PXCT) was originally developed to measure average lifetimes in the $10^{-17}-10^{-15}$~s range for proton-unbound states populated by electron capture (EC). We have designed and built the Lifetimes and Branching Ratios Apparatus (LIBRA) to be used in the stopped-beam area at the Facility for Rare Isotope Beams that extends PXCT to measure lifetimes and decay branching ratios of resonances populated by EC/${\beta }^{+}$ decay. The first application of LIBRA aims to obtain essential nuclear data from ${}^{60}$Ga EC/${\beta }^{+}$ decay to constrain the thermonuclear rates of the ${}^{59}$Cu$(p,\gamma {)}^{60}$Zn and ${}^{59}$Cu$(p,\alpha {)}^{56}$Ni reactions, and in turn, the strength of the NiCu nucleosynthesis cycle, which is predicted to significantly impact the modeling of type I x-ray burst light curves and the composition of the burst ashes. Detailed theoretical calculations, Monte Carlo simulations, and performance tests with radioactive sources have been conducted to validate the feasibility of employing LIBRA for the ${}^{60}$Ga experiment. LIBRA can be utilized to measure most essential ingredients needed for charged-particle reaction rate calculations in a single experiment, in the absence of direct measurements, which are often impractical for radioactive reactants.

   ↳ physics.ins-detastro-ph.IMnucl-ex4 citations
3. 03*

   Double $\varphi$ Production in $\bar{p}p$ Reactions Near Threshold

   Dayoung Lee🇰🇷 · Jung Keun Ann🇰🇷 · Seung-il Nam🇰🇷

   We employ an effective Lagrangian approach to investigate double $\varphi$ production in the $\bar{p}p$ reaction near the threshold and describe a notable violation of the Okubo-Zweig-Iizuka (OZI) rule in this reaction process through hadronic degrees of freedom, using the currently available theoretical and experimental information. The ground-state nucleon and its $s$-wave resonances, i.e., $N^{\ast }(1535,1650,1895)$, are taken into account in the $t$- and $u$-channel tree-level diagrams. The pentaquark-like nucleon resonance $P_s(2071,3/2^{-})$ is also considered. In the $s$-channel diagrams, scalar and tensor mesons are incorporated, specifically $f_0(2020,2100,2200)$ and $f_2(1950,2010,2150)$, respectively, along with the pseudoscalar meson $\eta (2225)$. Our calculations suggest that contributions from the $N$ and $N^{\ast }$ resonances significantly enhance the cross-section near the threshold. At the same time, those from the $f_0$ and $f_2$ mesons produce distinctive peak structures around $W=2.2$ GeV, qualitatively reproducing the JETSET experimental data. The openings of the $\bar{\Lambda }\Lambda$ and $\bar{\Sigma }\Sigma$ channels lead to the cusp structures, which can explain the nontrivial structures in the cross-section at $W\approx 2M_{\Lambda }$ and $2M_{\Sigma }$ observed in the data. It turns out that contributions from the $\eta$ and $P_s$ resonances are almost negligible. Additionally, polarization observables such as the spin density matrix element (SDME) provide crucial insights into the individual hadronic processes involved in this reaction.

   ↳ hep-phhep-exnucl-exnucl-thPLB(2025)·1 citation
4. 04*

   Coupled-channel analysis of the near-threshold $e^{+}{e}^{-}\to N\bar{N}$ cross sections

   Zhao-Sai Jia🇨🇳 · Zhen-Hua Zhang🇨🇳 · Feng-Kun Guo🇨🇳 · Gang Li🇨🇳

   The possible existence of nucleon-antinucleon bound states has been studied for decades. We investigate the $e^{+}{e}^{-}\to p\bar{p}$ and $e^{+}{e}^{-}\to n\bar{n}$ cross sections in the nonrelativistic effective field theory framework. The proton-antiproton and neutron-antineutron coupled-channel final state interactions are considered and found responsible for near-threshold enhancements. Both the proton-neutron mass difference and the Coulomb interaction between $p$ and $\bar{p}$ are considered, and the $N\bar{N}$ strong interactions are taken into account through a short-distance optical potential. By fitting the low energy constants in the amplitudes to the data for the near-threshold $e^{+}{e}^{-}\to N\bar{N}$ cross sections from the BESIII and SND Collaborations, a $N\bar{N}$ quasi-bound state is found just above the $p\bar{p}$ threshold, and another $N\bar{N}$ pole is found on the unphysical Riemann sheet, farther away from the threshold. The constructed coupled-channel amplitude with Coulomb effects also offers a framework that can be used directly in experimental analyses on fine structures near the $N\bar{N}$ thresholds.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2025)·7 citations
5. 05*

   Ion manipulation from liquid Xe to vacuum: Ba-tagging for a nEXO upgrade and future $0\nu \beta \beta$ experiments

   Dwaipayan Ray🇨🇦 · Robert Collister🇨🇦 · Hussain Rasiwala · Lucas Backes🇨🇦 · Ali V. Balbuena🇺🇸 · Thomas Brunner🇨🇦 · Iroise Casandjian🇨🇦 · Chris Chambers🇨🇦 · Megan Cvitan🇨🇦 · Tim Daniels🇺🇸 · Jens Dilling🇨🇦 · Ryan Elmansali🇨🇦 and 18 other authors

   Neutrinoless double beta decay {($0\nu \beta \beta$)} provides a way to probe physics beyond the Standard Model of particle physics. The upcoming nEXO experiment will search for $0\nu \beta \beta$ decay in ${}^{136}$Xe with a projected half-life sensitivity exceeding $10^{28}$ years at the 90\% confidence level using a liquid xenon (LXe) Time Projection Chamber (TPC) filled with 5 tonnes of Xe enriched to $\sim$90\% in the {$\beta \beta$}-decaying isotope ${}^{136}$Xe. In parallel, a potential future upgrade to nEXO is being investigated with the aim to further suppress radioactive backgrounds and to confirm $\beta \beta$-decay events. This technique, known as Ba-tagging, comprises extracting and identifying the $\beta \beta$-decay daughter ${}^{136}$Ba ion. One tagging approach being pursued involves extracting a small volume of LXe in the vicinity of a potential $\beta \beta$-decay using a capillary tube and facilitating a liquid-to-gas phase transition by heating the capillary exit. The Ba ion is then separated from the accompanying Xe gas using a radio-frequency (RF) carpet and RF funnel, conclusively identifying the ion as ${}^{136}$Ba via laser-fluorescence spectroscopy and mass spectrometry. Simultaneously, an accelerator-driven Ba ion source is being developed to validate and optimize this technique. The motivation for the project, the development of the different aspects, along with the current status and results, are discussed here.

   ↳ physics.ins-detnucl-exAtoms(2024)·4 citations
6. 06*

   Development and commissioning of ion-optical elements for ion and antiproton beams with energies up to 5 keV

   Clara Klink🇩🇪 · Moritz Schlaich🇩🇪 · Jonas Fischer🇩🇪 · Alexandre Obertelli🇩🇪 · Alexander Schmidt🇩🇪 · Frank Wienholtz🇩🇪

   In nuclear and atomic physics experiments, charged ion beams often need to be guided from the ion production to the experimental site. In the PUMA experiment, an ion source beamline was developed, which can be operated with up to \SI{5}{\kilo\electronvolt} beam energy at a base pressure of $10^{-9}$\,mbar or better. In this paper, a low-energy pulsed drift tube for beam energy modification, a hybrid einzel lens assembly for beam focusing and steering and an iris shutter assembly for separating beamline sections with different vacuum requirements are described with their design principles and performances.

   ↳ physics.acc-phnucl-exJINST(2024)·5 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.