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Neutron dosimetry system
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Neutron dosimetry system

TASLImage™ Neutron Dosimetry System
See also our TASLImage™ systems page

NVLAP accredited in the USA and HSE accredited in the UK

Our neutron dosimetry system is a complete system for measuring fast neutrons, comprising the TASLImage microscope-based analysis system, etch tank, trays and a 64-bit Windows™ 10 Dell computer running the analysis software. From the moment detectors are returned for analysis, they can be mounted in a tray which can be used for keeping them in place during the etching and afterwards be placed on the TASLImage system for subsequent analysis.

Our neutron dosimetry system can measure doses from 0.1 mSv and has been calibrated up to 600 mSv, showing a linear relationship between exposure and measured dose. Neutrons with energies from 200 KeV to 14 MeV (fast neutrons) can be reliably detected using our TASTRAK™ polyallyl diglycol carbonate (PADC) plastic detector by means of detecting the knock-on protons. For thermal- and epithermal neutrons, an additional converter can be used with the PADC. Etching of the plastics will reveal conically-shaped tracks in the detectors which can be analysed for dose determination. The size of the etch-tracks in the detector is dependent on the detector sensitivity and the subsequent etch conditions, which our system takes into account via a self-calibration procedure. This automatic procedure calibrates the plastics, allowing for a variation in sensitivity of between 150 to 750 tracks per mSv.

Etch-tracks from recoil protons are typically 3-15 microns in size. The track sizes overlap with the alpha particle region at large track sizes, where shape differences are used to discriminate particle species. At the small track sizes, efficient discrimination between noise (primarily dust on the surface) and genuine tracks is achieved with the measurement of 26 track parameters, including a variety of size and shape characterisations. These allow discrimination of tracks against backgrounds of up to 2000 non-track features per cm2 without compromising the measurement accuracy. Even a low energy fast neutron signal (~200 keV), which is almost identical to that of the background, is distinguishable by use of a variety of complex shape-detection algorithms. This enables the system to work in normal laboratory environments, including the presence of a high radon atmosphere.

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