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Cutting Edge Radiation detector highlights risk


DEMOLITION engineers working on nuclear decommissioning projects could soon be able to differentiate accurately between potentially dangerous sources of radiation and naturally occurring ones.

Intended for use by nuclear inspectors, scientists at the National Institute of Standards and Technology have designed a gamma ray detector that they claim has 10 times the accuracy of conventional sensors and could be used by engineers to determine the level and type of radiation.

Tests showed the 1 sq mm prototype detector can pinpoint the gamma ray emission signatures of specific atoms, and now plans are afoot to build a 100 sensor array that could be used on site.

This array would measure 1 sq cm and could be used by engineers to determine if materials are dangerous or merely radium.

NIST scientist Joel Ullom said: 'The system is intended for detailed analysis of material flagged by other detectors that have a larger collection area but less measurement accuracy.' The detector borrows heavily on sensors developed by NIST to analyse x-rays and infrared light.

Temperature change s caused by the sensors absorbing minute amounts of radiation ensures they can accurately track the source and type of material.

Cold-sensitive Cryogenic sensors absorb individual photons and measure the energy based on the temperature increase.

The rise is measured by a layer of molybdenum superconducting metal that changes its resistance to electricity in response to heat from the radiation.