Transmutation of [sup 99]Tc in a low lethargy medium as a function of the neutron energy

In the TARC experiment the differential neutron flux φ(E,r⃗) of a spallation of 2.5 and 3.5 GeV/c proton in large lead block is measured in the range between 0.1 eV and 1.5 MeV. A new technique, using small quantities (less than 0.1 gram) of material, is used for measuring the transmutation rate as a function of neutron energy in the range between 0.1 eV up to a few keV. The method is applied to a target of 86 mg (99Tc) mixed with 1.7 g of Aluminum. From these measurements the energy profile of the capture cross section can be extracted.