A Polarised-Film Radiation Dosimeter: Computed Dose Response, Minimum Detectable Dose and Range of a Spin-Polarised Film Badge

Radiation dose in a polarised material leaves a permanent record: ionising events destroy polarisation in proportion to dose, and a polarimetric readout afterwards recovers the accumulated exposure. This paper specifies a badge dosimeter on that principle and computes its dosimetric characteristics. With a depolarisation constant of 0.35 per gray and a polarimeter readout precision of 1.0e-4 in polarisation fraction, the minimum detectable dose is 0.29 milligray; the response stays within ten per cent of linear to 0.29 gray; and saturation at ninety-eight per cent depolarisation gives an upper range of 11.2 gray, a dynamic range of 3.91e+04. Fading is specified at 1.5 per cent per month at room temperature. SIMULATED, NOT MEASURED: the badge is specified and its response computed from the stated calibration constant; no film has been irradiated.