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The neutron facility at the 5.5 MV tandem T11/25 Accelerator of NCSR “Demokritos” can deliver monoenergetic neutron beams in the energy range from thermal to 450 keV, 4–11.5 MeV and 16–20.5 MeV via the 7Li(p,n), 2H(d,n) and 3H(d,n) reactions, respectively. The flux variation of the neutron beam is monitored by using a BF3 counter and a liquid scintillator BC501A detector. The 232Th(n,2n)231Th and 241Am(n,2n)240Am as well as (n,2n), (n,p) and (n,α) reactions on natural Ge and Hf isotopes, have been investigated from threshold up to 11.5 MeV, by using the activation method. The cross section values have been determined relative to the 197Au(n,2n)196Au, 27Al(n,α)24Na and 93Nb(n,2n) reference reaction cross sections. [ABSTRACT FROM AUTHOR]

The measurement of the cross section of the reaction 241Am(n,2n)240Am has been performed at neutron energies from 8.8 to 11.1 MeV, implementing the activation technique. The neutron beam was produced at the TANDEM accelerator of NCSR “Demokritos” by the 2H(d,n)3He reaction, using a deuterium gas target. During the 5-day long irradiation, the neutron beam fluctuations were monitored in 100 seconds intervals by a BF3 counter connected with a multiscaling unit. The radioactive target consisted of a 37 GBq 241Am source enclosed in a Pb container. A natural Au foil, a 27Al foil and a 93Nb foil were used as reference materials for the neutron flux determination. After the end of the irradiation the activity induced at the target and the reference foils, was measured off-line by a 56% HPGe detector. [ABSTRACT FROM AUTHOR]