We summarize here the results of the TARC experiment whose main purpose is to demonstrate the possibility of using Adiabatic Resonance Crossing (ARC) to destroy efficiently Long-Lived Fission Fragments (LLFFs) in accelerator-driven systems and to validate a new simulation developed in the framework of the Energy Amplifier programme. An experimental set-up was installed in a CERN PS proton beam line to study how neutrons produced by spallation at relatively high energy ( E n ≥ 1 MeV) slow down quasi adiabatically with almost flat isolethargic energy distribution and reach the capture resonance energy of an element to be transmuted where they will have a high probability of being captured. Precision measurements of energy and space distributions of spallation neutrons (using 2.5 GeV/ c and 3.5 GeV/ c protons) slowing down in a 3.3 m × 3.3 m × 3 m lead volume and of neutron capture rates on LLFFs 99 Tc, 129 I, and several other elements were performed. An appropriate formalism and appropriate computational tools necessary for the analysis and understanding of the data were developed and validated in detail. Our direct experimental observation of ARC demonstrates the possibility to destroy, in a parasitic mode, outside the Energy Amplifier core, large amounts of 99 Tc or 129 I at a rate exceeding the production rate, thereby making it practical to reduce correspondingly the existing stockpile of LLFFs. In addition, TARC opens up new possibilities for radioactive isotope production as an alternative to nuclear reactors, in particular for medical applications, as well as new possibilities for neutron research and industrial applications.

Energy and space distributions of spallation neutrons (from 2.5 and 3.57 GeV/c CERN proton beams)

Thermal treatment of LiF:Mg, Cu, P in the range 80 - performed after typical annealing at for 10 min causes important modifications to the glow-curve structure and to the behaviour of the individual glow-peaks. The maximum glow-peak temperatures and the activation energies obtained by a glow-curve de-convolution procedure are varied as a function of pre-irradiation annealing at temperatures below . Initial rise measurements support the results obtained by the glow-curve de-convolution concerning the high values of the activation energy of glow-peak 4, as well as its variation as a function of the pre-irradiation annealing. The `prompt' isothermal decay of glow-peak 4 at temperatures just below the maximum peak temperature consists of three components instead of one, which would be expected from the kinetic models. The second component corresponds to glow-peak 4 and also presents very high E and s values. The third one corresponds to a glow-peak at the high-temperature tail of peak 4. The first component was attributed to a mechanism competitive to the mechanism responsible for the main peak 4.

Energy and space distributions of spallation neutrons (from 2.5 and 3.57 GeV/c CERN proton beams)

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