States in52Cr Research Articles

Shell model study of 52V and 52Cr and gamma decay of isobaric analogue states in 52Cr

The spectrum of 52V is studied with the Kuo-Brown (KB) renormalized interaction and with Vervier's interactions. Wave functions of isobaric analogue states (IAS) in 52Cr are generated from 52V wave functions. Wave functions of low-lying levels of 52Cr are obtained by a shell model calculation with the KB interaction and with the phenomenological effective interaction of Lips and McEllistrem. Electromagnetic decay of IAS to low-lying states via the isovector part of the transition operator is considered. Transition rates are first calculated by assuming that the final state configurations do have the proper isospin. A projection operator is defined in isospace to construct basis states having the proper isospin, starting with excited configurations of 52Cr which do not have well-defined isospin. Two methods — diagonalization after projection and projection after diagonalization — are developed in which the definite isospin of basis states can be handled.

High-spin states in 52Cr populated via the 50Ti( α, 2n γ) reaction

The decay scheme of 52Cr has been studied by γ-ray spectroscopy with the 50Ti( α, 2n γ) reaction. Spin and parity assignments were made on the basis of coincidence measurements, angular distributions, excitation functions and DSAM lifetime measurements. Six new high-energy levels with spins up to 9 were established.

Study of analogue states in52Cr through proton capture by51V

γ-Ray yield function has been studied for the proton capture by vanadium in the proton energy range 720–1300 keV. Isobaric analogues of low lying states in52V have been identified. At two resonances theγ-decay andγ-ray angular distributions have been obtained and the branching ratios and the multipole mixing ratios have been deduced. The analogue-antianalogue M1 transition in52Cr is found to be strongly hindered as in other f7/2 nuclei. TheQ-value obtained for this reaction is (10500±2.8) keV and the Coulomb displacement energy is (8.06±0.01) MeV. An upper limit of 2 meV has been obtained for theα- decay strength of the 11.395 MeV state in52Cr.

The γ-ray decay properties of analogue states in 52Cr via the reaction 51V(p, γ) 52Cr

The γ-ray spectra emitted following proton capture by 51V were measured as a function of incident proton energy. The γ-ray decay of the states was observed and angular distributions were measured. The measured branching ratios and excitation energies suggest these states in 52Cr are analogues of low-lying states in 52V. Assuming these states to be analogues, the measured mixing ratios, branching ratios and normalized decay rates are compared with shell model calculations. Qualitative agreement with the mixing and branching ratios is obtained but the inclusion of 2 p 1 2 and 1 f 5 2 neutron excitations appears essential if the decay rates are to be described.

A study of the low-lying isobaric analogue states in52Cr from (p, γ) and (p, n) reactions in51V

A study of the low-lying isobaric analogue states in52Cr from (p, γ) and (p, n) reactions in51V

A study of the low-lying isobaric analogue states in52Cr from (p, γ) and (p, n) reactions in51V

A study of the low-lying isobaric analogue states in52Cr from (p, γ) and (p, n) reactions in51V

Doppler-shift lifetime measurements in 46Ti and 50Cr

Abstract The lifetimes of nine states in 46Ti and fourteen states in 50Cr have been measured through the Doppler-shift attenuation method. The states were populated by the 46Ti(p, p′γ) and 50Cr(p, p′γ) reactions at Ep = 7 MeV. Thick targets (≈ 300 keV) were used to provide adequate averaging over many compound-nucleus levels. Singles γ-ray spectra were obtained with 33 and 55 cm3 Ge(Li) detectors at θγ = 0°, 90° and ≈ 160°, and lifetimes were extracted from the observed centroid shifts. An alternative method of analysis, involving a simulation of profiles of Doppler-shifted peaks with six free parameters gave considerably more accurate results. Both methods were tested by measuring known lifetimes in 58Ni. In addition, the lifetimes of three states in 52Cr were determined. A comparison of the energy spectra and electromagnetic decay properties of these nuclei to shell-model calculations revealed the failure of the simple ( f 7 2 ) 6 picture. A startling example of this failure is the fact that the 22+(E2)21+ rate in 46Ti appears to be a factor of ⪆ 25 faster than that in the cross-conjugate nucleus 50Cr.

Isobaric analogue states in52Cr from (p, γ) and (p, n) reactions in51V

Isobaric analogue states in52Cr from (p, γ) and (p, n) reactions in51V

(α, t) reaction on medium-weight odd-mass nuclei (I). 51V and 55Mn

The (α, t) reactions on 51V and 55Mn have been studied at an incident alpha energy of 29.0 MeV using an E− ΔE semiconductor detector telescope. Angular distributions were obtained and analysed by the DWBA theory. Zero-range DWBA calculations without radial cut-offs gave a reasonable fit to the data with depths of the real parts of the alpha and triton potentials of 183.7 and 149.0 MeV, respectively. The l-values and spectroscopic factors were deduced from the transitions leading to 15 low-lying states of 52Cr and 56Fe. The results are compared with the seniority scheme and the sum rule of the j− j coupling shell model and give information about the (1 f 7 2 ) n proton states in 52Cr and 56Fe.

Absolute level densities from neutron inelastic scattering

The spectra of neutrons inelastically scattered from Na, Al, K, Cr, Fe, 58Ni and 60Ni have been measured for 7 MeV incident neutrons. For the nuclei 56Fe and 60Ni, statistical-model calculations were made to predict the complete spectrum of scattering to the known discrete levels below about 3.5 MeV together with a continuum of higher levels described by the level density formula ω( U) = KU −2 exp 2√ aU. By fitting the theoretical spectrum to the experimental one, the constants K and a were both obtained, thus determining the absolute level density in the continuum in addition to its variation with excitation energy. The results indicate that the nuclear moments of inertia of 56Fe and 60Ni have approximately the rigid-body value. Evidence is also presented for strong direct components in the scattering to the first levels in 23Na and 27Al and to the first 2 + level and 3 − collective states in 52Cr, 56Fe, 58Ni and 60Ni.