Investigation of the 47,49Ti(n, γ)48,50 reactions

Abstract The γ-radiation produced by thermal neutron capture in enriched 47 Ti and 49 Ti targets has been investigated. In the analysis 57 excited states of 48 Ti and 31 of 50 Ti have been identified. The Q -value of the 47 Ti(n, γ) reaction, 11 626.66(4) keV, is in agreement with previous data. The present value for 49 Ti, 10 939.20(4) keV, differs by five standard deviations from a previous result. The nature of the neutron-capture mechanism has been investigated by comparing the present results with those from previous (d, p) work. It appears that in 47 Ti capture proceeds through a doorway state and that the potential capture formalism is valid for 49 Ti. Yet the 49 Ti cross section for transitions to p-states is predicted low by a factor of 4. The Fermi gas model gives a good representation of the nuclear level density in both nuclei. The combination of nuclear orientation measurements and circular polarization measurements has yielded the unambiguous determination of the spins of one 48 Ti state and of five 50 Ti states. Further spin and parity determinations for six 48 Ti and for five 50 Ti states have been obtained from the analysis of the identified branches together with the results of previous experiments. Shell-model calculations, which yielded excitation energies, branching ratios, lifetimes and (d, p) spectroscopic factors, give a good representation of the experimental data for the low-lying states in both nuclei.