Radiological characterisation of photon radiation from ultra-high-intensity laser–plasma and nuclear interactions

Abstract

With the increasing number of multi-terawatt (10(12) W) and petawatt (10(15) W) laser interaction facilities being built, the need for a detailed understanding of the potential radiological hazards is required and their impact on personnel is of major concern. Experiments at a number of facilities are being undertaken to achieve this aim. This paper describes the recent work completed on the Vulcan petawatt laser system at the CCLRC Rutherford Appleton Laboratory, where photon doses of up to 43 mSv at 1 m per shot have been measured during commissioning studies. It also overviews the shielding in place on the facility in order to comply with the Ionising Radiation Regulations 1999 (IRR99), maintaining a dose to personnel of less than 1 mSv yr(-1) and as low as reasonably practicable (ALARP).

Measurements of Ionizing Radiation Doses Induced by High Irradiance Laser on Targets in LCLS MEC Instrument

“…Considering the large uncertainties in the irradiance measurements, the measurements agree well with the calculations at 1.0x10 17 [7,11,12] in the figure:…”

“…The RP measurements outside the LLNL Titan chamber (1x10 20 to 6x10 20 W/cm 2 , 1.053 µm laser wavelength, 0.7-1 ps, 50-400 J per pulse, a few mg/cm 2 of hydrocarbon foam followed by 1-mm-gold target, 1.5"-thick Al target chamber), 2. The measurement results at Vulcan [11] (4x10 19 to 4x10 20 W/cm 2 , 1 ps, ~230 J per pulse, a few mm Au, Cu, or Al targets, 2-cm-thick Al target chamber), and 3. At LULI [12] (1x10 19 to 3x10 19 W/cm 2 , 1.057 µm laser wavelength, 300 fs, 5-20 J per pulse, < 1-mm-thick Au, Al or teflon targets, 1-cm-thick steel target chamber).…”

“…At irradiances > 10 19 W/cm 2 , the RPD model gives an estimate that is conservative by a factor of 3-5. Figure 32 compares the photon dose yield (mSv/J at 1 m without shielding) calculated by the RPD model with the measurements of electron doses at MEC (maximum at 180-degree and minimum at 0-degree) and the neutron doses measured at MEC and LULI [11]; the latter is ~1% of the LULI measured photon doses (also shown). …”

Evaluating laser-driven Bremsstrahlung radiation sources for imaging and analysis of nuclear waste packages

“…High-power laser-matter interactions are also capable of generating x-ray beams with the ideal spectral output and have favourable beam and operational qualities for this imaging challenge. Namely, laserdriven sources can generate bright, ultra-short bursts (at 1m: 43mGy/pulse, 26Gy/min at 10Hz) [18] of high-energy (>500keV) x-rays from a small source area (<0.5mm). Furthermore, the laser-driven concept also benefits from the option of generating an in situ, bright, short-pulsed, fast-neutron beamline (>1MeV neutron energy, 10 8 neutrons/pulse), thus enabling a versatile multimodal probing system for the characterisation of nuclear waste containers.…”

“…tantalum and gold) will result in a particularly high peak intensity and energy of Bremsstrahlung radiation, thus generating a large flux of high-energy x-rays. Dose measurements made during gold target irradiation with the Vulcan laser, at the Science and Technology Facilities Councils Rutherford Appleton Laboratory, show a total beam dose of 43mGy/pulse at 1m [18]. Finally, a review by Giuletti and Gizzi[19] provides a detailed introduction to x-ray emission from laser produced plasmas.…”