Radiation detector, 'Mini-monitor', metal / plastic, made by Mini Instruments Inc, Burnham-on-Crouch, Essex, England, 1963-2005
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 1980-2005
Mini Instruments was developed in 1963 and currently (as of 2007) Thermo Scientific are the producers of 'Mini Instruments'.
The mini monitor is well established in teaching, research, hospital and industrial laboratories as a reliable, convenient, and inexpensive contamination meter. The machine has a large logarithmically scaled meter with an open scale at the lower end to show background levels of radiation while displaying high levels without switching. There is also a speaker to give an audible estimation of radiation intensity. There is an alarm which can be set to trip at any level on the scale. The unit can be battery or mains operated.
Geiger counters are used to detect ionizing radiation, usually alpha and beta radiation, but other types of radiation as well. The sensor is a Geiger-Müller tube, a gas-filled tube (usually helium, neon or argon with halogens added) that briefly conducts electricity when a particle or photon of radiation temporarily makes the gas conductive. The tube amplifies this conduction by a cascade effect and outputs a current pulse, which is indicated by a needle or lamp and/or audible clicks. Modern instruments can report radioactivity over several orders of magnitude.