Statistical Properties of Excited Nuclei in the Mass Range 47≤A≤59

B.V Zhuravlev,N.N Titarenko,A.A Lychagin,V.I Trykova,V.G Demenkov

doi:10.1051/epjconf/20122105003

B.V Zhuravlev, N.N Titarenko + Show 3 more

Open Access

https://doi.org/10.1051/epjconf/20122105003

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Abstract

Level densities and their energy dependences for nuclei in the mass range 47≤A≤59 have been determined from the measurements of neutron evaporation spectra in (p,n) reaction. Neutron spectra from (p,n) reaction on nuclei of 47Ti, 48Ti, 49Ti, 53Cr, 54Cr, 57Fe, 59Co have been measured at proton energies between 7 and 11 MeV. The measurements of neutron spectra were performed by time-of-flight fast neutron spectrometer on the pulsed tandem accelerator EGP-15 of IPPE. The high resolution and stability of time-of-flight spectrometer allowed identify reliably the discrete low-lying levels together with continuum part of neutron spectra. Analyses of the measured data have been carried out in the framework of statistical equilibrium and pre-equilibrium models of nuclear reactions. The calculations are done with use of the exact formalism of the statistical theory as given by Hauser-Feshbach with the generalized superfluid model of nucleus, the back-shifted Fermi-gas model and the composite formula of Gilbert-Cameron for nuclear level density. The nuclear level densities of 47V, 48V, 49V, 53Mn, 54Mn, 57Co, 59Ni and their energy dependences have been determined. The obtained results have been discussed in totality with existing experimental and model systematic data.

Highlights

The basic statistical function of excited nuclei is the nuclear level density
The calculations are done with use of the exact formalism of the statistical theory as given by Hauser-Feshbach with the generalized superfluid model of nucleus, the back-shifted Fermi-gas model and the composite formula of Gilbert-Cameron for nuclear level density
The general features of nuclear level density are known, but there are considerable uncertainties of its functional forms conditioned by the unhomogeneity of a single-particle state spectrum, residual interaction, effects of collective nature et al The required accuracy of level density knowledge for nuclear cross-section calculation problems is ~ 10 % in a wide range of excitation energy from 0.1 MeV to 20 MeV, and the existing data are often differed in 1.5 times

Summary

Introduction

The basic statistical function of excited nuclei is the nuclear level density. Knowledge of the level density values and their functional peculiarities is very important for the creation of consistent theoretical description of excited nucleus statistical properties and in making nuclear reaction cross-section calculations in the framework of statistical model. One of the information sources on nuclear level density in a range between the discrete states and the neutron binding energy with accuracy comparable with resonance capture data are the spectra of particles emitted in nuclear reactions. In this case the type of reaction and the energy of incident particles should be chosen so that the contribution of non-equilibrium. Typical angle-integrated neutron emission spectra from (p,n) reaction on 49Ti are presented in fig. 1

Data analysis

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Conclusion