Nuclear level densities and γ-ray strength functions inSc44,45

Abstract

The scandium isotopes 44,45 Sc have been studied with the 45 Sc( 3 He,αγ) 44 Sc and 45 Sc( 3 He, 3 He ′ γ) 45 Sc reactions, respectively. The nuclear level densities and γ-ray strength functions have been extracted using the Oslo method. The experimental level densities are compared to calculated level densities obtained from a microscopic model based on BCS quasiparticles within the Nilsson level scheme. This model also gives information about the parity distribution and the number of broken Cooper pairs as a function of excitation energy. The experimental γ-ray strength functions are compared to theoretical models of the E1, M1, and E2 strength, and to data from (γ,n) and (γ,p) experiments. The strength functions show an enhancement at low γ energies that cannot be explained by the present, standard models.

Level Densities andγStrength Functions in Light Sc and Ti Isotopes

“…Figure 1 shows the preliminary level density distribution for 43 Sc. It is apparent that the level density is lower by a factor 2-3 compared to the A + 2 neighbour 45 Sc [5]. While at higher energies this could be understood to be due to the larger number of particles outside the 40 Ca core, it is not yet clear how to explain the observed effect for lower energies.…”

“…Figure 1 also shows the preliminary γ-ray strength function for 43 Sc. For comparison, the strength function for 45 Sc [5] is reproduced in the same figure. Although the two curves have been obtained in very different reactions -(p, α) and ( 3 He, 3 He') -the obtained curves are very similar.…”

“…As such data are not available for 43 Sc, the normalisation has been done using the average neutron resonance width of 46 Sc (cf. [5]). Figure 1 also shows the preliminary γ-ray strength function for 43 Sc.…”

Soft structures ofγ-ray strength functions studied with the Oslo method

“…In this work we present recent results on the γ-ray strength functions of the nuclei 44,45 Sc [1], 50,51 V [2], 93−98 Mo [3], and 116−119 Sn [4,5].…”

Properties of warm nuclei in the quasi-continuum

“…The BSFG model has proven to describe level densities throughout the periodic table. An example from experiments at the Oslo Cyclotron Laboratory [3] is shown in Fig. 1.…”