Tue·Jan 12, 2021Tuesday·January 12, 2021

1. 01*

   Determination of the ${}^{60}$Zn level density from neutron evaporation spectra

   D. Soltesz🇺🇸 · M. A. A. Mamun🇺🇸 · A. V. Voinov🇺🇸 · Z. Meisel🇺🇸 · B. A. Brown🇺🇸 · C. R. Brune🇺🇸 · S. M. Grimes🇺🇸 · H. Hadizadeh🇺🇸 · M. Hornish🇺🇸 · T. N. Massey🇺🇸 · J. E. O'Donnell🇺🇸 · W. E. Ormand🇺🇸

   Nuclear reactions of interest for astrophysics and applications often rely on statistical model calculations for nuclear reaction rates, particularly for nuclei far from $\beta$-stability. However, statistical model parameters are often poorly constrained, where experimental constraints are particularly sparse for exotic nuclides. For example, our understanding of the breakout from the NiCu cycle in the astrophysical rp-process is currently limited by uncertainties in the statistical properties of the proton-rich nucleus ${}^{60}$Zn. We have determined the nuclear level density of ${}^{60}$Zn using neutron evaporation spectra from ${}^{58}$Ni(${}^3$He, n) measured at the Edwards Accelerator Laboratory. We compare our results to a number of theoretical predictions, including phenomenological, microscopic, and shell model based approaches. Notably, we find the ${}^{60}$Zn level density is somewhat lower than expected for excitation energies populated in the ${}^{59}$Cu(p,$\gamma$)${}^{60}$Zn reaction under rp-process conditions. This includes a level density plateau from roughly 5-6 MeV excitation energy, which is counter to the usual expectation of exponential growth and all theoretical predictions that we explore. A determination of the spin-distribution at the relevant excitation energies in ${}^{60}$Zn is needed to confirm that the Hauser-Feshbach formalism is appropriate for the ${}^{59}$Cu(p,$\gamma$)${}^{60}$Zn reaction rate at X-ray burst temperatures.

   nucl-exPRC(2021)·8 citations
2. 02*

   $\beta$-decay of ${}^{61}$V and its Role in Cooling Accreted Neutron Star Crusts

   W.-J. Ong🇺🇸 · E. F. Brown🇺🇸 · J. Browne🇺🇸 · S. Ahn🇺🇸 · K. Childers🇺🇸 · B. P. Crider🇺🇸 · A. C. Dombos🇺🇸 · S. S. Gupta🇮🇳 · G. W. Hitt🇺🇸 · C. Langer🇩🇪 · R. Lewis🇺🇸 · S. N. Liddick🇺🇸 and 11 other authors

   The interpretation of observations of cooling neutron star crusts in quasi-persistent X-ray transients is affected by predictions of the strength of neutrino cooling via crust Urca processes. The strength of crust Urca neutrino cooling depends sensitively on the electron-capture and $\beta$-decay ground-state to ground-state transition strengths of neutron-rich rare isotopes. Nuclei with mass number $A=61$ are predicted to be among the most abundant in accreted crusts, and the last remaining experimentally undetermined ground-state to ground-state transition strength was the $\beta$-decay of ${}^{61}$V. This work reports the first experimental determination of this transition strength, a ground-state branching of 8.1${}_{-2.0}^{+2.2}\%$, corresponding to a log $ft$ value of 5.5${}_{-0.2}^{+0.2}$. This result was achieved through the measurement of the $\beta$-delayed $\gamma$ rays using the total absorption spectrometer SuN and the measurement of the $\beta$-delayed neutron branch using the neutron long counter system NERO at the National Superconducting Cyclotron Laboratory at Michigan State University. This method helps to mitigate the impact of the Pandemonium effect in extremely neutron-rich nuclei on experimental results. The result implies that $A=61$ nuclei do not provide the strongest cooling in accreted neutron star crusts as expected by some predictions, but that their cooling is still larger compared to most other mass numbers. Only nuclei with mass numbers 31, 33, and 55 are predicted to be cooling more strongly. However, the theoretical predictions for the transition strengths of these nuclei are not consistently accurate enough to draw conclusions on crust cooling. With the experimental approach developed in this work all relevant transitions are within reach to be studied in the future.

   nucl-exPRL(2020)·14 citations
3. 03*

   Precision measurements of differential cross sections and analyzing powers in elastic deuteron-deuteron scattering at 65 MeV/nucleon

   R. Ramazani-Sharifabadi🇮🇷 · A. Ramazani-Moghaddam-Arani🇮🇷 · H.R. Amir-Ahmadi🇳🇱 · C. D. Bailey🇺🇸 · A. Deltuva🇱🇹 · M. Eslami-Kalantari🇮🇷 · N. Kalantar-Nayestanaki🇳🇱 · St. Kistryn🇵🇱 · A. Kozela🇵🇱 · M. Mahjour-Shafiei🇮🇷 · H. Mardanpour🇳🇱 · J.G. Messchendorp🇳🇱 and 4 other authors

   We present measurements of differential cross sections and analyzing powers for the elastic 2H(~d; d)d scattering process. The data were obtained using a 130 MeV polarized deuteron beam. Cross sections and spin observables of the elastic scattering process were measured at the AGOR facility at KVI using two independent setups, namely BINA and BBS. The data harvest at setups are in excellent agreement with each other and allowed us to carry out a thorough systematic analysis to provide the most accurate data in elastic deuteron-deuteron scattering at intermediate energies. The results can be used to confront upcoming state-of-the-art calculations in the four-nucleon scattering domain, and will, thereby, provide further insights in the dynamics of three- and four-nucleon forces in few-nucleon systems.

   nucl-exEPJA(2021)·1 citation
4. 04*

   Measurement of quarkonium production in ALICE

   Victor Feuillard (for the ALICE collaboration)🇩🇪

   ALICE is designated to study the quark-gluon plasma (QGP), a state of matter where, due to high temperature and density, quarks and gluons are deconfined. One of the probes used to investigate this state of matter is quarkonium states, bound states of either a charm and anti-charm quark pair (charmonia) or a bottom and anti-bottom quark pair (bottomonia). The presence of the QGP is expected to modify the quarkonium production yields in a very specific way due to a balance between medium-induced suppression, and a recombination mechanism or a hadronization mechanism. To understand the the properties of the QGP in nucleus-nucleus collisions, it is essential to measure the quarkonium differential yields in proton-proton collisions, as it provides a reference and allows the investigation of quarkonium production mechanisms, as well as in proton-nucleus collisions to understand the cold nuclear matter effects that appear. In this contribution, the latest results for quarkonium production measured with the ALICE detector in pp collisions at different collision energies are reported. The measurements of the nuclear modification factor and anisotropic flow in Pb-Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV and in p-Pb at $\sqrt{s_{NN}}=8.16$ TeV at mid- and forward rapidity are also reported. All measurements are compared to various theoretical predictions.

   nucl-exhep-exNucl.Part.Phys.Proc.(2021)·0 citations
5. 05*

   Experimental evidence of (M1+E2) mixed character of the 9.2 keV transition in ${}^{227}$Th and its consequence for spin-interpretation of low-lying levels

   A. Kovalík (1 and 2) · A. Kh. Inoyatov (1 and 3) · L. L. Perevoshchikov (1) · M. Ryšavý (2). D. V. Filosofov (1) · P. Alexa (4) · J. Kvasil (5) ((1) JINR Dubna, (2) NPI Řež near Prague, (3) Institute of Applied Physics, Tashkent, (4) Technical University, Ostrava, (5) Institute of Particle and Nuclear Physics, Prague)

   The 9.2 keV nuclear transition in ${}^{227}$Th populated in the $\beta$-decay of ${}^{227}$Ac was studied by means of the internal conversion electron spectroscopy. Its multipolarity was proved to be of mixed character M1+E2 and the spectroscopic admixture parameter ${\delta }^2$(E2/M1)=0.695 $\pm$ 0.248 (|$\delta$(E2/M1)|=0.834 $\pm$ 0.210) was determined. Nonzero value of $\delta$(E2/M1) raises a question about the existing theoretical interpretation of low-lying levels of ${}^{227}$Th.

   nucl-exnucl-thPLB(2021)·3 citations
6. 06*

   Implications of PREX-II on the equation of state of neutron-rich matter

   Brendan T. Reed🇺🇸 · F. J. Fattoyev🇺🇸 · C. J. Horowitz🇺🇸 · J. Piekarewicz🇺🇸

   Laboratory experiments sensitive to the equation of state of neutron rich matter in the vicinity of nuclear saturation density provide the first rung in a "density ladder" that connects terrestrial experiments to astronomical observations. In this context, the neutron skin thickness of 208Pb (Rskin) provides a stringent laboratory constraint on the density dependence of the symmetry energy. In turn, an improved value of Rskin has been reported recently by the PREX collaboration. Exploiting the strong correlation between Rskin and the slope of the symmetry energy L within a specific class of relativistic energy density functionals, we report a value of L=(106 +/- 37)MeV -- that systematically overestimates current limits based on both theoretical approaches and experimental measurements. The impact of such a stiff symmetry energy on some critical neutron-star observables is also examined.

   ↳ nucl-thastro-ph.SRnucl-exPRL(2021)·574 citations
7. 07*

   Response of undoped cryogenic CsI to low-energy nuclear recoils

   C.M. Lewis🇺🇸 · J.I. Collar🇺🇸

   The bright scintillation of pure CsI operated at liquid-nitrogen temperature makes of this material a promising dark matter and neutrino detector. We present the first measurement of its quenching factor for nuclear recoils. Our findings indicate it is indistinguishable from that for sodium-doped CsI at room temperature. Additional properties such as light yield, afterglow, scintillation decay properties for electron and nuclear recoils, and energy proportionality are studied over the \mbox{108-165 K} temperature range, confirming the vast potential of this medium for rare-event searches.

   ↳ physics.ins-detastro-ph.IMhep-exhep-ph+1PRC(2021)·21 citations
8. 08*

   Influence of {\alpha}-particles irradiation on the performance and defect levels structure of Al/SiO2/p-type Si surface barrier detector

   S.V. Bakhlanov🇷🇺 · N.V. Bazlov · D.V. Danilov · A.V. Derbin🇷🇺 · I.S. Drachnev🇷🇺 · I.M. Kotina🇷🇺 · O.I. Konkov · A.M. Kuzmichev · M.S. Mikulich🇷🇺 · V.N. Muratova🇷🇺 · M.V. Trushin🇷🇺 · E.V. Unzhakov🇷🇺

   Deterioration of the operation parameters of Al/SiO2/p-type Si surface barrier detector upon irradiation with alpha-particles at room temperature was investigated. As a result of 40-days irradiation with a total fluence of 8*10^9 {\alpha}-particles, an increase of {\alpha}-peak FWHM from 70 keV to 100 keV was observed and explained by increase of the detector reverse current due to formation of a high concentration of near mid-gap defect levels. Performed CV measurements revealed the appearance of at least 6*10^12 cm-3 radiation-induced acceptors at the depths where according to the TRIM simulations the highest concentration of vacancy-interstitial pairs was created by the incoming {\alpha}-particles. The studies carried out by current-DLTS technique allowed to associate the observed increase of the acceptor concentration with the near mid-gap acceptor level at EV+0.56 eV. This level can be apparently associated with V2O defects recognized previously to be responsible for the space charge sign inversion in the irradiated n-type Si detectors.

   ↳ physics.ins-detcond-mat.mtrl-scinucl-ex0 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.