Investigation of the50Cr(n, ?)47Ti reaction atE n =14.1 MeV

Abstract

The energy and angular distribution of the e-particles from the 5~ ~) reaction for 14.1 MeV incident neutron energy was measured by means of a multitelescope system. The results are compared with calculations based on the statistical model of nuclear reactions including precompound processes. This comparison indicates that there is somewhat more emission of high energy ~particles than predicted from the conventional precompound model suggesting direct excitation of the lowest excited states of 47Ti. No indication is found for a reduction of the effective moment of inertia below the rigid body value. From the shape of the e-spectrum in the backward hemisphere and the known total number of levels below U = 3 MeV the level density parameters of 47Ti were determined as a=5.4+_0.3MeV 1 and A=-I.9_+0.2MeV in the framework of the back-shifted Fermi-Gas model.

Fast-neutron induced pre-equilibrium reactions on 55Mn and 63,65Cu at energies up to 40 MeV

“…However, the present case of the 63,65 Cu nuclei comes in addition of those mentioned in Ref. [2], at variance with Yamamuro's statement.…”

“…These potentials were used also for the calculation of the collective inelastic scattering cross sections by means of the direct-interaction distorted-wave Born approximation (DWBA) method and a local version of the computer code DWUCK4 [42]. The weak coupling model was adopted in this respect for the odd nuclei 55 Mn and 63,65 Cu using the collective state parameters of Kalbach [27]. Typical ratios of the direct inelastic scattering to the total reaction cross sections in the energy range from few to 60 MeV decrease from ∼11 to 5%, for the 55 Mn nucleus, and from ∼8 to 3% for the Cu isotopes.…”

“…The larger amount of data existing for the (n,2n) and (n,p) reactions on 65 Cu have been involved in this respect as it is shown in Fig. 9.…”

“…As part of a general investigation [1,2,3,4] of the reaction mechanisms of fast neutrons at low and medium energies, we have analyzed the activation cross sections of the odd-mass isotopes 55 Mn and 63,65 Cu in the excitation-energy range up to 50 MeV.…”

“…Moreover, a systematic analysis by Mills et al [9] in the same mass range highlighted that some of the discrepancies observed in the yields of nuclides with closed or nearly-closed nucleon shells may not affect the inherent validity of the relevant model but follow the use of incorrect, e.g., average model parameters for certain nuclei involved in the decay process. Thus, in order to gain insight into this problem, we have analyzed the activation cross sections of 55 Mn and 63,65 Cu isotopes using the parameter databases obtained previously by global optimization within the computer codes TALYS [10] and EMPIRE-II [11], as well as a local parameter set within the STAPRE-H code [12]. No fine tuning was done to optimize the description of the nucleon emission for all the cases, but for STAPRE-H a consistent set of local parameters has previously been established or validated on the basis of independent experimental information of, e.g., neutron total cross sections, proton reaction cross sections, low-lying level and resonance data, and γ-ray strength functions based on neutron-capture data.…”