Investigation of the reactions Li6(t,n), Li7(t,n), Li7(He3, n), Be9(t,n)B11, and Be9(He3, n)C11

Neutron yields have been measured in the bombardment of thin targets containing Li⁶, Li⁷, and Be⁹, by tritium and He³ ions, the energies of the accelerated particles ranging as high as 1.4 Mev. The neutron yield from the reactions Li⁶(t, n) and Be⁹(t, n) is proportional to the penetrability of the Coulomb barrier. In the reactions Li⁷(t, n) and Li⁷(He³, n), when the kinetic energies of the accelerated particles are small resonances are detected, corresponding to levels of the component nuclei near the threshold of these reactions. The thresholds for formation of slow neutrons have been investigated in the interaction of tritons with Li⁶, Li⁷, and Be⁹ nuclei. In the reactions Li⁶(t, n)Be⁸ and Li⁷(t, n)Be⁹ slow neutrons are detected, corresponding to the formation of the Be⁸ nucleus in excited states with energies of 16.08, 16.66, and 16.94 Mev and the Be⁹ nucleus in a state with energy 10.50 Mev. In the reaction Be⁹(t, n)B¹¹ no slow neutron thresholds were observed.The nuclear photoemulsion method was used to measure the neutron spectra in all of the investigated reactions at zero angle of incidence. The neutron spectra are in agreement with the established data [1] on the energy levels of the Be⁸, Be⁹, Be⁹, B¹¹, and C¹¹ nuclei.The authors are grateful to all these comrades for their contribution.     

Nondestructive Evaluation of Changes in Local Density of Compressed Components from Composite Materials

The paper analyzes improvements in the gamma-method for nondestructive evaluation of density of constant-thickness components fabricated from highly filled composite materials. A facility designed for such measurements is described. The parameters of the radiation source and detecting instrument required to guarantee the high precision of the method are determined. Results of tests of the experimental facility are given.