Thu·Sep 15, 2022Thursday·September 15, 2022

1. 01*

   E2 Rotational Invariants of $0_1^{+}$ and $2_1^{+}$ states for ${}^{106}$Cd: the Emergence of Collective Rotation

   T. J. Gray🇺🇸 · J. M. Allmond🇺🇸 · R. V. F. Janssens🇺🇸 · W. Korten🇫🇷 · A. E. Stuchbery🇦🇺 · J. L. Wood🇺🇸 · A. D. Ayangeakaa🇺🇸 · S. Bottoni🇺🇸 · B. M. Bucher🇺🇸 · C. M. Campbell🇺🇸 · M. P. Carpenter🇺🇸 · H. L. Crawford🇺🇸 and 20 other authors

   The collective structure of ${}^{106}$Cd is elucidated by multi-step Coulomb excitation of a 3.849 MeV/$A$ beam of ${}^{106}$Cd on a 1.1 mg/cm${}^2$ ${}^{208}$Pb target using GRETINA-CHICO2 at ATLAS. Fourteen $E2$ matrix elements were obtained. The nucleus ${}^{106}$Cd is a prime example of emergent collectivity that possesses a simple structure: it is free of complexity caused by shape coexistence and has a small, but collectively active number of valence nucleons. This work follows in a long and currently active quest to answer the fundamental question of the origin of nuclear collectivity and deformation, notably in the cadmium isotopes. The results are discussed in terms of phenomenological models, the shell model, and Kumar-Cline sums of $E2$ matrix elements. The $⟨0_2^{+}||E2||2_1^{+}⟩$ matrix element is determined for the first time, providing a total, converged measure of the electric quadrupole strength, $⟨Q^2⟩$, of the first-excited $2_1^{+}$ level relative to the $0_1^{+}$ ground state, which does not show an increase as expected of harmonic and anharmonic vibrations. Strong evidence for triaxial shapes in weakly collective nuclei is indicated; collective vibrations are excluded. This is contrary to the only other cadmium result of this kind in ${}^{114}$Cd by C. Fahlander et al., Nucl. Phys. A485, 327 (1988), which is complicated by low-lying shape coexistence near midshell.

   nucl-exnucl-thPLB(2022)·9 citations
2. 02*

   Direct measurement of resonances in ${}^7$Be($\alpha ,\gamma$)${}^{11}$C relevant to $\nu p$-process nucleosynthesis

   A. Psaltis🇨🇦 · A.A. Chen🇺🇸 · R. Longland🇺🇸 · D.S. Connolly🇨🇦 · C.R. Brune🇺🇸 · B. Davids🇨🇦 · J. Fallis · R. Giri🇺🇸 · U Greife🇺🇸 · D.A. Hutcheon · L. Kroll · A. Lennarz🇨🇦 and 9 other authors

   We have performed the first direct measurement of two resonances of the ${}^7$Be($\alpha ,\gamma$)${}^{11}$C reaction with unknown strengths using an intense radioactive ${}^7$Be beam and the DRAGON recoil separator. We report on the first measurement of the 1155 and 1110 keV resonance strengths of $1.73\pm 0.25(stat.)\pm 0.40(syst.)$ eV and $125_{-25}^{+27}(stat.)\pm 15(syst.)$ meV, respectively. The present results have reduced the uncertainty in the ${}^7$Be($\alpha ,\gamma$)${}^{11}$C reaction rate to $\sim$ 9.4-10.7% over T = 1.5-3 GK, which is relevant for nucleosynthesis in the neutrino-driven outflows of core-collapse supernovae ($\nu p$-process). We find no effect of the new, constrained reaction rate on $\nu p$-process nucleosynthesis.

   nucl-exastro-ph.HE0 citations
3. 03*

   First inverse kinematics measurement of resonances in ${}^7$Be($\alpha ,\gamma$)${}^{11}$C relevant to neutrino-driven wind nucleosynthesis using DRAGON

   A. Psaltis🇨🇦 · A.A. Chen🇹🇼 · R. Longland🇺🇸 · D.S. Connolly🇨🇦 · C.R. Brune🇺🇸 · B. Davids🇨🇦 · J. Fallis · R. Giri🇺🇸 · U Greife🇺🇸 · D.A. Hutcheon · L. Kroll · A. Lennarz🇨🇦 and 9 other authors

   A possible mechanism to explain the origin of the light $p$-nuclei in the Galaxy is the nucleosynthesis in the proton-rich neutrino-driven wind ejecta of core-collapse supernovae via the $\nu p$-process. However this production scenario is very sensitive to the underlying supernova dynamics and the nuclear physics input. As far as the nuclear uncertainties are concerned, the breakout from the $pp$-chains via the ${}^7$Be($\alpha ,\gamma$)${}^{11}$C reaction has been identified as an important link which can influence the nuclear flow and therefore the efficiency of the $\nu p$-process. However its reaction rate is poorly known over the relevant temperature range, T = 1.5-3 GK. We report on the first direct measurement of two resonances of the ${}^7$Be($\alpha ,\gamma$)${}^{11}$C reaction with previously unknown strengths using an intense radioactive ${}^7$Be beam from the ISAC facility and the DRAGON recoil separator in inverse kinematics. We have decreased the ${}^7$Be($\alpha ,\gamma$)${}^{11}$C reaction rate uncertainty to $\sim$ 9.4-10.7% over the relevant temperature region.

   nucl-exastro-ph.HEPRC(2022)·4 citations
4. 04*

   Measuring dilepton and heavy quark production at large ${\mu }_{\mathrm{B}}$: the NA60+ experiment at the CERN SPS

   Enrico Scomparin · NA60+ Collaboration

   The high-${\mu }_{\mathrm{B}}$ region of the QCD phase diagram has become the object of several studies, focused on the investigation of the order of the phase transition and the search for the critical point. Accessing rare probes is experimentally challenging as it requires large integrated luminosities, and a fixed-target environment represents an ideal solution for these studies. The CERN SPS covers, with large beam intensity, the collision energy region $5<\sqrt{s_{\mathrm{NN}}}<17$ GeV. A future experiment, NA60+, is being proposed to access this region and perform accurate measurements of the dimuon spectrum from threshold up to the charmonium mass region, and of hadronic decays of charm and strange hadrons. The experiment, which is also part of the Physics Beyond Colliders CERN initiative, aims at taking its first data with Pb and proton beams around 2029.

   nucl-exActa Phys.Polon.Supp.(2023)·2 citations
5. 05*

   Probing $\Xi N$ interaction through inversion of spin-doublets in $\Xi N\alpha \alpha$ nuclei

   E. Hiyama🇯🇵 · M. Isaka🇯🇵 · T. Doi🇯🇵 · T. Hatsuda🇯🇵

   A new way to study the spin-isospin dependence of the $\Xi N$ interaction is explored through the energy levels of $\Xi N\alpha$ and $\Xi N\alpha \alpha$ systems with $\alpha$ being a spectator to attract the $\Xi N$ pair without changing its spin-isospin structure. By using the Gaussian expansion method (GEM) with the state-of-the-art $\Xi N$ potential obtained from lattice QCD calculations, it is found that $\Xi N\alpha \alpha$ has spin-doublet bound states with $J^{\pi }=1^{-}$ and $2^{-}$ in both isospin triplet and singlet channels. The inversion of the $1^{-}$-$2^{-}$ spin-doublet between the iso-triplet and the iso-singlet is found to be strongly correlated with the relative strengths of the $\Xi N$ interaction in the ${}^{11}{\mathrm{S}}_0{,}^{13}{\mathrm{S}}_1{,}^{31}{\mathrm{S}}_0$ and ${}^{33}{\mathrm{S}}_1$ channels. The $(K^{-},K^{+})$ and $(K^{-},K^0)$ reactions on the ${}^{10}$B target are proposed to produce those bound states.

   ↳ nucl-thnucl-exPRC(2022)·20 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.