Magnetic susceptibility of vanadium carbide

Magnetic susceptibility of vanadium carbide from 77 to 300 K measured by magnetomete

Gamma-widths, lifetimes and fluctuations in the nuclear quasi-continuum

Statistical $\gamma$-decay from highly excited states is determined by the nuclear level density (NLD) and the $\gamma$-ray strength function ($\gamma$SF). These average quantities have been measured for several nuclei using the Oslo method. For the first time, we exploit the NLD and $\gamma$SF to evaluate the $\gamma$-width in the energy region below the neutron binding energy, often called the quasi-continuum region. The lifetimes of states in the quasi-continuum are important benchmarks for a theoretical description of nuclear structure and dynamics at high temperature. The lifetimes may also have impact on reaction rates for the rapid neutron-capture process, now demonstrated to take place in neutron star mergers.Comment: CGS16, Shanghai 2017, Proceedings, 5 pages, 3 figure

Completing the nuclear reaction puzzle of the nucleosynthesis of 92Mo

One of the greatest questions for modern physics to address is how elements heavier than iron are created in extreme, astrophysical environments. A particularly challenging part of that question is the creation of the so-called p-nuclei, which are believed to be mainly produced in some types of supernovae. The lack of needed nuclear data presents an obstacle in nailing down the precise site and astrophysical conditions. In this work, we present for the first time measurements on the nuclear level density and average strength function of $^{92}$Mo. State-of-the-art p-process calculations systematically underestimate the observed solar abundance of this isotope. Our data provide stringent constraints on the $^{91}$Nb$(p,{\gamma})^{92}$Mo reaction rate, which is the last unmeasured reaction in the nucleosynthesis puzzle of $^{92}$Mo. Based on our results, we conclude that the $^{92}$Mo abundance anomaly is not due to the nuclear physics input to astrophysical model calculations.Comment: Submitted to PR

Scissors resonance in the quasi-continuum of Th, Pa and U isotopes

The gamma-ray strength function in the quasi-continuum has been measured for 231-233Th, 232,233Pa and 237-239U using the Oslo method. All eight nuclei show a pronounced increase in gamma strength at omega_SR approx 2.4 MeV, which is interpreted as the low-energy M1 scissors resonance (SR). The total strength is found to be B_SR = 9-11 mu_N^2 when integrated over the 1 - 4 MeV gamma-energy region. The SR displays a double-hump structure that is theoretically not understood. Our results are compared with data from (gamma, gamma') experiments and theoretical sum-rule estimates for a nuclear rigid-body moment of inertia.Comment: 11 pages, 9 figure

Statistical properties of 243^{243}Pu, and 242^{242}Pu(n,γ\gamma) cross section calculation

The level density and gamma-ray strength function (gammaSF) of 243Pu have been measured in the quasi-continuum using the Oslo method. Excited states in 243Pu were populated using the 242Pu(d,p) reaction. The level density closely follows the constant-temperature level density formula for excitation energies above the pairing gap. The gammaSF displays a double-humped resonance at low energy as also seen in previous investigations of actinide isotopes. The structure is interpreted as the scissors resonance and has a centroid of omega_{SR}=2.42(5)MeV and a total strength of B_{SR}=10.1(15)mu_N^2, which is in excellent agreement with sum-rule estimates. The measured level density and gammaSF were used to calculate the 242Pu(n,gamma) cross section in a neutron energy range for which there were previously no measured data.Comment: 9 pages, 8 figure