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On the context of the Cern n_TOF collaboration the 232Th(n,2n)231Th reaction cross section has been measured relative to the 56Fe(n,p)56Mn and 27Al(n,a)24Na reaction cross sections by the activation method for neutron energies up to 11 MeV. The neutrons were produced via the 2H(d,n) reaction using a deuterium filled gas-cell, at the 5.5MV TANDEM Accelerator of NCSR "Demokritos". In addition to the experimental work, theoretical Statistical model calculations have been performed using the computer code STAPRE/F. The code STAPRE is designed to calculate energy averaged cross sections for particle induced nuclear reactions with several emitted particles and gamma rays under the assumption of sequential evaporation. For the first evaporation step preequilibrium emission is taken into account while population of states resulting from the first equilibrium evaporation step is calculated using the Hauser-Feschbach theory. Fission process competition is also taken into account in the evaporation steps. Sensitive parameters for the calculation, like level density parameters, have been adopted after fitting experimental data for the competing (n,f) reaction. The results are being compared to the experimental data.

The neutron flux and energy distribution of the neutrons produced in a gas cell were measured using a silicon semiconductor detector. The energy spectra produced by the borbardment of the silicon detector with neutrons were simulated using Monte Carlo techniques and were compared with the measured spectra

The 232 Th(n,2n) 231 Th reaction cross-section was measured relative to the 56 Fe(n,p) 56 Mn and 27 Al(n,a) 24 Na reaction cross-sections with the activation method for neutron energies up to 11 MeV. Neutrons were produced by the 2 H(d,n) reaction in the 5.5 MV Tandem accelerator of the NCSR ‘‘Demokritos’’. The characteristic g lines of the product nuclei 231 Th (25.646 keV) and 56 Mn (846.771 keV) or 24 Na (1368 keV) were measured with an 80 mm 2 Si(Li) and a 20% reverseelectrode coaxial germanium detector, respectively. The results indicate that our values are in agreement with the JEF2 and BROND2 database values up to 9 MeV and slightly higher than those from all the libraries for higher energies. r 2003 Elsevier Science B.V. All rights reserved.

A new technique for measurements of total neutron cross sections is presented. This method has been applied to measurements of the excitation function for the "B + n system at E = 7.2 - 8.5 MeV, in order to obtain the 8Li(n , 1 B thermonuclear reaction rate. 1. INTRODUCTION In this work, we present a system for transmission measurements of total neutronaoss sectionsusing two silicon semiconductor detectors. One detector is placed in front of the target and monitors the incident neutron flux. The second detector is placed behind the target and measures the attenuation of the incident neutrons as well as their energy.This system has been used to measure the excitation function of the "B(ri. x) reaction , where x is either a neutron or an alpha, and at incident neutron energies between 7.2 and 8.5 MeV.The parameters of the resonances observed in this reaction together with those observed in the previously measured "B(n, a)8 Li reaction2 were used to derive the stellar rate for the 8L i(a, ri)1' B

Cross sections and angular distributions for the 26 Mg(p, n) 26 Al and 23 Na(α, n) 26 Al reactions, populating the ground state and the first three excited states in 26 Al, have been measured between 5.3 and 7.0 MeV proton bombarding energy and between 3.9 and 5.9 MeV alpha bombarding energy, using the neutron time-of-flight technique. The measured total cross sections were used to derive the cross sections for the astrophysically interesting reactions 26 Al(n, p 0 ) 26 Mg and 26 Al(n, α 0 ) 23 Na. The 26 Mg(p, p′) 26 Mg and 26 Mg(p, α) 23 Na cross sections were also measured at E p = 5.3–6.1 MeV. A resonance analysis of the measured 26 Mg+p excitation functions is used to obtain information on cross sections for the 26 Al(n, p') 26 Mg reaction.

The 96Mo(p, n) and 96Mo(p, nγ) reactions have been studied for proton energies between 3.8 and 5.5 MeV. Energy levels in 96Tc up to 632 keV excitation energy have been determined. Possible spin and parity assignments are given for several levels based on the neutron enhancement and angular distributions observed on and off resonance of the 5 2 >+ isobaric analog state in 97Tc, as well as the observed γ-yields. The first excited state reported at 34 keV was found to be a close doublet only 0.8 keV apart. The observation of this doublet in the (p, n) reaction was used to determine the ground state Q-value Q = − 3.760±0.010 MeV.

Energy and angular distributions of neutrons, protons, and alpha particles were measured in coincidence with the projectilelike fragment in deep inelastic collisions of $^{16}\mathrm{O}$ on $^{40,44,48}\mathrm{Ca}$ at 102 and 142 MeV. Using an event-by-event analysis which takes into account particle emission from both fragments and the recoil correction due to light particle emission, we show that our data are consistent with the assumption that the light particles are evaporated in the rest frame of the fully accelerated projectilelike and targetlike fragments. This conclusion is based on the results for neutrons and alpha particles. But because of kinematic limitations which affect the alpha particle data, the conclusions based on the latter are less definitive.