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The ~4N(n,p)~4C reaction cross section has been measured for thermal neutrons, making use of the neutron beam of the IBR-30 pulsed booster of the JINR, Dubna. Thermal neutrons were identified by a time-offlight method. Solid adenin targets were utilized. An ionization chamber was used for detecting the charged particles. The cross section was found to be O-tnhv = (1.83 _+ 0.07) b.

The 24.5 keV neutrons induced reaction with the 7Be radioactive nucleus was studied. The value of a,p= (18 ___ 4)b was obtained for the 7Be(n, p)7Li reaction cross section. 25.40.Fq; 95.30.Cq For astrophysics it is of much importance to study the 7Be(n,p) TLi reaction at star temperatures (from 0.3.109 ~ to 1.109 ~ corresponding to the neutron energy range from 20 keV to 80 keV. The investigations of this reaction had been carried out at Dubna and Los Alamos [1,2], but at lower energies. Therefore, this study with 24.5 keV neutrons is of much interest. PACS:The experiment reported here had been performed on the beam of filtered neutrons from the reactor in Kiev. A truncated cone from 56Fe, 390 mm long, was used as a filter. It allowed one to have neutrons with the average energy E,=24.5 keV at an energy spread of 2 keV. In the measurement there was used an ionization chamber with two grids [3] (for separating charged particles of different types) and the 7Be target of 7.5.107 Bq activity on tantalum backing. The background was determined as in [4]. Protons from the beryllium target were registered through a cone of 70 o around the direction of the neutron beam.The cross section for the 7Be(n, p)VLi reaction at the neutron energy E,=24.5 keV was determined in two ways.The first way is based on the comparison of it with the cross section of the 6Li(n, e)3H reaction measured in the same conditions. This, however, results in rather a large error (30%), caused, in principle, by not accurate enough determination of the proton registration efficiency in the thick target, due to the fact that target

The reaction 2ZNa(n,p)2ZNe has been investigated at a neutron energy up to 1,000eV by the time-of-flight method at the reaction IBR-30 of JINR. A neutron resonance was found in the reaction cross section. By fit, the parameters assigned to the resonance were E o = 145 _+ 11 eV; F, ~ = 1.6 + 0.2 eV; Fpl = 114 _+ 20 eV. The presence of this resonance explains the large values for the thermal cross section of this reaction.