Energy distribution of the E 1-transition strengths in the 46 Ti nucleus
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CLEI Experiment
Energy Distribution of the E1-Transition Strengths in the
46
Тi Nucleus
I. D. Fedorets* and S. S. Ratkevich Karazin Kharkiv National University, pl. Svobody 4, 61077 Kharkiv, Ukraine Received August 1, 2007; in final form, January 21, 2008
Abstract—The structure of levels of the 46 Тi nucleus is studied by means of the nonselective reaction 45 Sc(p, γ) at proton energies ranging between 1.2 and 3.1 MeV. Spin–parity assignments for 46 Тi states of excitation energies up to 5.5 MeV are obtained by using the method of averaged resonances. Radiative strength functions for E1 transitions populating these states are determined. The resulting data are compared with predictions of various models. PACS numbers: 25.40.Lw, 23.20.Lv, 27.40.+z DOI: 10.1134/S1063778808080024
1. INTRODUCTION The results of investigations recently launched in order to explore systematically the collective character of rotational degrees of freedom in the 1f7/2 -shell nuclei revealed that the 46 Тi nucleus, as the most strongly deformed among even–even titanium isotopes [1], is a convenient object for studying shape variations [2], backbending, and processes associated with the termination of rotational bands [1, 3–5]. So far, experimental and theoretical studies have been focused primarily on exploring the yrast sequence of levels in 46 Тi up to the termination of the band in n and 1d−1 ⊗ 1f n−1 configuration spaces for, the 1f7/2 3/2 7/2 respectively, positive and negative parities. However, experimental data on the properties of nonyrast levels characterized by moderate spin values are required for confirming the theoretical prediction that, along with rotational degrees of freedom, other degrees of freedom may exist in nuclei associated with the filling of the middle of the 1f7/2 shell and for studying this coexistence. Previously, such states of the 46 Тi nucleus were investigated in beta decay and in reactions induced by various light particles. The results of those investigations published before 2000 were systematized by Wu [6]. Methods currently used to excite 46 Тi nuclei are very diverse, but data on the properties of many identified nonyrast levels of 46 Тi come from earlier studies and therefore remain incomplete and insufficiently reliable. The radiative capture of low-energy neutrons or protons is one of the main sources of information about the properties of low-spin states of the *
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f p-shell nuclei in the excitation-energy region from the ground state to the nucleon binding energy. The primary-gamma-transition intensities averaged over the resonances of the compound nucleus formed upon neutron (proton) capture depend on the transition energy and on the spin–parity of the final state for the transition being considered. Knowing the energy dependence of such averaged intensities, one can determine unknown spin–parities of final states. In the case where the quantum numbers of the final state are known, it is possible to invert the procedure and to determine thereby, from the the m
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