X-ray dosimetry during low-intensity femtosecond laser ablation of molybdenum in ambient conditions

Title X-ray dosimetry during low-intensity femtosecond laser ablation of molybdenum in ambient conditions
Author
Abstract

The absorbed X-ray dose was measured during 35 fs pulsed laser ablation of a high purity molybdenum target in ambient conditions for optical intensities from 1.8 × 10 14 to 1.6 × 10 15 W/cm 2 (0.5-4.5 mJ per pulse) at a repetition rate of 1 kHz. During 1 s of ablation, at a distance of 6 cm from the source, appreciable X-ray dose was observed at all optical intensities, ranging from 0.08 μGy, at the minimum intensity, to 0.97 μGy at the maximum intensity, corresponding to equivalent dose rates of 0.3-3.5 mSv/h. At the highest optical intensity, an absorbed dose of 0.29 μGy was measured at a distance of 12 cm from the source, corresponding to an equivalent dose rate of 1.1 mSv/h. Characterization of the laser plasma emissions showed X-rays with energies approaching 20 keV at higher laser pulse energies. In Canada, the annual equivalent dose limit for nonradiation workers is 1 mSv. Our findings suggest that under certain conditions it is possible to exceed this dosage in as little as an hour of fs-laser material processing in ambient conditions. As such, workers in these environments may need to be trained in radiation safety, equipped with personal dosimeters, and provided proper radiation shielding.

Year of Publication
2017
Journal
IEEE Transactions on Nuclear Science
Volume
64
Start Page
2519-2522
Issue
9
URL
https://ieeexplore.ieee.org/abstract/document/8010306
DOI
10.1109/TNS.2017.2739156
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