No abstract

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)

No abstract

Abstract-It is usually difficult to compare different designs of Positron Emission Tomography (PET) small-animal scanners because of the disparity of measurements protocols. In this work we compare two commercial PET scanners installed at ClEMAT (Madrid, Spain): the ClearPET and the rPET-I, using an assessment procedure that fulfilled the recommendations of the new NEMA NU 4-2008 standard to evaluate small animal PET systems, including spatial resolution, sensitivity, scatter fraction and count losses studies. The scanners evaluated have significant geometrical differences, like the axial field of view (110 mm on ClearPET versus 45.6 mm on rPET-l), the configuration of the detectors (one pair of planar blocks on rPET-I, versus whole ring detectors on ClearPET) and the use of an axial shift between ClearPET module detectors. Our experiments showed a FWHM (FOV center, averaged over the three axes) of 1.98 mm for the rPET-1 and 2.15 rom for the ClearPET, with a small variation across the transverse axis on both scanners «1 rom). The absolute sensitivity was 1.0% per detector pair for rPET-I and 4.70/0 for ClearPET. Regarding count losses studies, the obtained peak NEC rate is 73.4 kcps at 0.51 MBq/ml for the ClearPET and 29.2 kcps at 1.35 MBq/ml for the rPET-1, considering a NEMA mouse-like phantom.

A new instrument to assess neutron ambient doses has been designed and constructed. In its design, spectrometric capabilities have been implemented that allow to take into account the energy spectrum of the neutron field in the evaluation of the operational magnitude, ambient dose equivalent, H*(10). This dosemeter is based on the moderation-absorption technique and can be employed over a wide range of energies from thermal to 20 MeV. It consists of a spherical shaped polyethylene moderator with a set of thermoluminescence dosemeters (TLDs) inserted in different positions of its interior to evaluate the external neutron energy spectrum. At this moment the system uses pairs 6LiF:Mg,Ti (TLD-600) and 7LiF:Mg,Ti (TLD-700) thermoluminescence dosemeters for a better gamma discrimination. The dosemeter response matrix was calculated using the MCNP4C Monte Carlo code (MC). The viability of the dosemeter for area dosemetry has been examined experimentally showing its capabilities over a wide range of energies.

No abstract

No abstract