Search

Decommissioning is the last step in the life cycle of a nuclear facility. After the evacuation of the facility components, the remaining structures such as concrete walls and floors must be controlled to ensure that no residual contamination remains. As it is a costly and time consuming activity, CEA develops fast measurement methods allowing a complete scanning of very large areas (hundreds of thousands of square meters) in legacy uranium enrichment plants based on gas diffusion, at Pierrelatte nuclear site, France. After fast alpha and beta measurements, HPGe and NaI gamma-spectroscopy detectors are used to characterize more precisely uranium contamination. HPGe has excellent energy resolution but requires very long acquisition times. On the contrary, NaI(Tl) detectors enable rapid measurement, but extracting the contamination signal from the natural background is difficult due to their low resolution. Using an innovative approach based on energy bands of the NaI spectra, contamination activity and enrichment are consistent with that measured with HPGe but in only 15 min vs. 65 h, and with a sufficiently low relative uncertainty of about 15 % and 20 %, respectively, on activity and enrichment. Large area NaI(Tl) detectors will allow cost-effective scanning of the Gaseous Diffusion Plant (UDG) nuclear site (hundreds of thousands of squared meters) within practical times, in complement to alpha and beta contamination detectors. [ABSTRACT FROM AUTHOR]

Abstract: Front-end electronics for future high-energy physics experiments are driven primarily by systems considerations. Minimizing material is a key aspect in both the ILC and sLHC upgrades. This requires minimizing power dissipation in the front-end electronics, as this can reduce material in the cabling and cooling systems. Various techniques to reduce power dissipation and material are discussed. Current systems, however, have developed successful technologies for large-scale highly segmented detectors that are being applied to other applications such as electron microscopy and high-rate X-ray imaging. In closing, the paper discusses multiplexing technologies for large-scale cryogenic bolometer arrays as could be applied to precision gamma spectroscopy. Current frequency-domain multiplexers are operating reliably, but the challenges associated with SQUID front-ends are discussed and a more robust alternative is presented. [ABSTRACT FROM AUTHOR]