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The lifetime of the 11/21+ state in the Sb131 nucleus was measured at the LOHENGRIN spectrometer of the Institut Laue-Langevin via neutron-induced fission of U235 using γ-ray fast-timing techniques. The obtained value of T1/2=3(2) ps, at the edge of the sensitivity of the experimental method, is the first result for the 11/21+ state half-life in neutron-rich Sb isotopes. The corresponding quadrupole reduced transition probability to the ground state is B(E2)=1.4-0.6+1.5W.u., indicating a noncollective nature of this state. Realistic shell-model calculations performed in a large valence space reproduce well the experimental value and point to a dominant 2+(Sn130) - πg7/2 configuration for the 11/21+ state, as expected in a weak-coupling scenario. At the same time, the sum of the quadrupole strength of the multiplet states is predicted to exceed the one of the Sn130 core as a consequence of the equal contribution of the proton and the proton-neutron quadrupole matrix elements, pointing to possible development of collectivity already in the close neighborhood of Sn132.

The decay of the 21.47-MeV stretched resonance in $^{13}$C, arising from p3/2→d5/2 nucleon excitation coupled to maximum spin, was investigated in a (p,p′) experiment at 135 MeV proton bombarding energy, performed at the Cyclotron Centre Bronowice (CCB) at IFJ PAN in Krakow. First experimental information on the proton and neutron decay branches from this state was obtained by using coincidence measurement of protons inelastically scattered on a $^{13}$C target and γ rays from daughter nuclei, namely, $^{12}$B (proton decay) and $^{12}$C (neutron decay). The main branches lead to the Jπ=2+, first-excited state at 0.953 MeV in $^{12}$B, and to the Jπ=1+, T=1 level at 15.110 MeV in $^{12}$C. The results were compared with predictions from the Gamow Shell Model (GSM), which was used to describe the stretched resonance in terms of its energy, width, electromagnetic transition strengths and decay pattern. A very good agreement was obtained between the measured and calculated properties of the 21.47-MeV stretched resonance in $^{13}$C, demonstrating the high-quality and precision of the GSM wave function calculations, which include coupling to the resonant and non-resonant particle continuum.

We report the first (in)elastic scattering measurement of 25Al+p with the capability to select and measure in a broad energy range the proton resonances in 26Si contributing to the 22Mg(α,p) reaction at type I x-ray burst energies. We measured spin-parities of four resonances above the α threshold of 26Si that are found to strongly impact the 22Mg(α,p) rate. The new rate advances a state-of-the-art model to remarkably reproduce lightcurves of the GS 1826-24 clocked burster with mean deviation

The triple alpha reaction is one of the most important reactions in the nuclear astrophysics. However, its reaction rate in high temperature environments at T₉>2 was still uncertain. One of the major origins of the uncertainty was that the radiative-decay probability of the 3⁻₁ state in ¹²C was unknown. In the present work, we have determined the radiative-decay probability of the 3⁻₁ state to be 1.3[+1.2][-1.1] × 10⁻⁶ by measuring the ¹H(¹²C, ¹²Cp) reaction for the first time, and derived the triple alpha reaction rate in high temperature environments from the measured radiative-decay probability. The present result suggests that the 3⁻₁ state noticeably enhances the triple alpha reaction rate although the contribution from the 3⁻₁ state had been assumed to be small.

The triple alpha reaction is one of the most important reactions in the nuclear astrophysics. However, its reaction rate in high temperature environments at T9> 2 was still uncertain. One of the major origins of the uncertainty was that the radiative-decay probability of the 31− state in $^{12}$C was unknown. In the present work, we have determined the radiative-decay probability of the 31− state to be 1.3−1.1+1.2×10−6 by measuring the $^{1}$H($^{12}$C,$^{12}$Cp) reaction for the first time, and derived the triple alpha reaction rate in high temperature environments from the measured radiative-decay probability. The present result suggests that the 31− state noticeably enhances the triple alpha reaction rate although the contribution from the 31− state had been assumed to be small.

International audience; Detailed studies of the low-spin structures of neutron-rich Ni isotopes may help shedding light on the shape coexistence phenomenon. Of particular interest is the 65Ni nucleus, since it lies between 64Ni and 66Ni, where shape coexistence has been reported earlier. A spectroscopic investigation of 65Ni has been performed at Institut Laue-Langevin via the reaction64Ni(n,γ) 65Ni, using the FIPPS HPGe array. Several new gamma transitions have been observed and angular correlation analyses have been performed. A comparison with Monte Carlo shell-model calculations pointed to a dominance of spherical states up to 1.5 MeV excitation energy, together with the appearance of two states of oblate character.

The low-spin structure of the semimagic ^{64}Ni nucleus has been considerably expanded: combining four experiments, several 0^{+} and 2^{+} excited states were identified below 4.5 MeV, and their properties established. The Monte Carlo shell model accounts for the results and unveils an unexpectedly complex landscape of coexisting shapes: a prolate 0^{+} excitation is located at a surprisingly high energy (3463 keV), with a collective 2^{+} state 286 keV above it, the first such observation in Ni isotopes. The evolution in excitation energy of the prolate minimum across the neutron N=40 subshell gap highlights the impact of the monopole interaction and its variation in strength with N. ispartof: PHYSICAL REVIEW LETTERS vol:125 issue:10 ispartof: location:United States status: published

A systematic investigation of the shape coexistence phenomenon in the Ni isotopic chain, from A = 62 to A = 66, is being performed by using gamma-ray spectroscopy and employing sub-Coulomb barrier transfer reactions. The aim is to shed light on the microscopic origin of nuclear deformation along the Ni isotopic chain. The experiments were performed at the Tandem Accelerator Laboratory in Bucharest and IPN-Orsay, following the first observation of a shape-isomer-like structure at spin zero in 66 Ni. The study has been inspired by various mean-field theoretical approaches as well as by the state-of-the-art Monte Carlo Shell Model (MCSM) calculations, all pointing to 66 Ni as the lightest nucleus with a pronounced secondary prolate minimum in the nuclear potential energy surface, at spin zero, although other examples of shape isomerism in this mass region are not excluded. Preliminary results are discussed for 64 Ni, in comparison with MCSM predictions, together with perspectives for similar searches in 62 Ni., SCOPUS: cp.j, info:eu-repo/semantics/published

The neutron-rich nucleus \nucleus{200}{Pt} is investigated via in-beam \gamma-ray spectroscopy in order to study the shape evolution in the neutron-rich platinum isotopes towards the N = 126 shell closure. The two-neutron transfer reaction \nucleus{198}{Pt}(\nucleus{82}{Se}, \nucleus{80}{Se})\nucleus{200}{Pt} is used to populate excited states of \nucleus{200}{Pt}. The Advanced Gamma Ray Tracking Array (AGATA) demonstrator coupled with the PRISMA spectrometer detects \gamma rays coincident with the \nucleus{80}{Se} recoils, the binary partner of \nucleus{200}{Pt}. The binary partner method is applied to extract the \gamma-ray transitions and build the level scheme of \nucleus{200}{Pt}. The level at 1884\,keV reported by Yates et. al [Phys. Rev. C 37, 1889] was confirmed to be at 1882.1\,keV and assigned as the (6^+_1) state. An additional \gamma ray was found and it presumably de-excites the (8^+_1) state. The results are compared with state-of-the-art beyond mean-field calculations, performed for the even-even \nucleus{190-204}{Pt} isotopes, revealing that \nucleus{200}{Pt} marks the transition from the \gamma-unstable behaviour of lighter Pt nuclei towards a more spherical one when approaching the N=126 shell closure.

The neutron-rich nucleus Pt-200 is investigated via in-beam gamma-ray spectroscopy to study the shape evolution in the neutron-rich platinum isotopes towards the N = 126 shell closure. The two-neutron transfer reaction Pt-198(Se-82, Se-80)Pt-200 is used to populate excited states of Pt-200. The Advanced Gamma Ray Tracking Array (AGATA) demonstrator coupled with the PRISMA spectrometer detects gamma rays coincident with the Se-80 recoils, the binary partner of Pt-200. The binary partner method is applied to extract the gamma-ray transitions and build the level scheme of Pt-200. The level at 1884 keV reported by Yates et al. [S. W. Yates, E. M. Baum, E. A. Henry, L. G. Mann, N. Roy, A. Aprahamian, R. A. Meyer, and R. Estep, Phys. Rev. C 37, 1889 (1988)] was confirmed to be at 1882.1 keV and assigned as the (6(1)(+)) state. An additional gamma ray was found and it presumably deexcites the (8(1)(+)) state. The results are compared with state-of-the-art beyond mean-field calculations, performed for the even-even Pt190-204 isotopes, revealing that Pt-200 marks the transition from the gamma-unstable behavior of lighter Pt nuclei towards a more spherical one when approaching the N = 126 shell closure.

International audience; The neutron-rich nucleus Pt200 is investigated via in-beam γ-ray spectroscopy to study the shape evolution in the neutron-rich platinum isotopes towards the N=126 shell closure. The two-neutron transfer reaction Pt198(Se82, Se80)Pt200 is used to populate excited states of Pt200. The Advanced Gamma Ray Tracking Array (AGATA) demonstrator coupled with the PRISMA spectrometer detects γ rays coincident with the Se80 recoils, the binary partner of Pt200. The binary partner method is applied to extract the γ-ray transitions and build the level scheme of Pt200. The level at 1884 keV reported by Yates et al. [S. W. Yates, E. M. Baum, E. A. Henry, L. G. Mann, N. Roy, A. Aprahamian, R. A. Meyer, and R. Estep, Phys. Rev. C 37, 1889 (1988)] was confirmed to be at 1882.1 keV and assigned as the (61+) state. An additional γ ray was found and it presumably deexcites the (81+) state. The results are compared with state-of-the-art beyond mean-field calculations, performed for the even-even 190−204Pt isotopes, revealing that Pt200 marks the transition from the γ-unstable behavior of lighter Pt nuclei towards a more spherical one when approaching the N=126 shell closure.