Radiation detector, 'Smart Ion', plastic / metal, made by Mini Instruments Inc, Burnham-on-Crouch, Essex, England, 2000-2005
These various radiation meters were originally procured and/or used by the NSW government agencies including the former State Pollution Control Commission (SPCC), the Environment Protection Authority (EPA), the NSW Department of Environment and Conservation (DEC), and possibly the NSW Department of Health. These agencies, collectively over the years regulated the use of radiation apparatus (for example x-ray machines used in medical diagnostics) and radioactive substances (for example cobalt-60 used in industrial gauging applications).
The equipment was used to measure the type and intensity of radiation and it exemplifies one of the many aspects of regulation administered by government health departments and augments the Museum's collection of measuring instruments and workplace health and safety material.
Written by Erika Dicker
Assistant Curator, 2007.
Radiation detector made by Mini Instruments Inc in Burnham-on-Crouch, Essex, England, between 2000-2005
The Smart Ion is a micro computer based instrument of advanced design for the measurement of gamma, beta and x-ray radiation. It provides functions previously not available in meters of this type, including data logging, dose rate alarm, remote calibration and security features. Operation is simple, reliable and maintenance free, and the instrument is housed in a robust plastic case of attractive appearance.
The meter employs an ion chamber for detecting gamma radiation and beta particles. A potential applied between a central electrode and the chamber wall attracts the positive and negative parts of the ionised particle. The resulting current flow generates a voltage that is detected and amplified to give an indication of radiation intensity. The meter always measures gamma radiation that penetrates the case from any angle. Beta radiation however is subject to considerable attenuation through the case. Beta radiation is measured through the thin window in the base of the meter. A shield can be slid across this window to exclude beta particles; while this cover is closed, the meter is only sensitive to gamma radiation.