Radiation Detection and Measurement

Radiation detectors are devices for detecting and measuring ionizing radiation. Radiation dosimeters are a subset of radiation detectors and are designed to measure absorbed dose, i.e. the amount of energy deposited by radiation in matter and especially living tissue. Radiation detectors and dosimeters can be divided into two broad categories: active detectors and passive detectors. The EVBRPL is involved in the development and use of both types of detector.

 

Active Detectors

Active detectors are radiation detectors that require electrical power to operate and which can detect or measure radiation as a function of time. Active detectors are also often equipped with a meter or electronic display that provides absorbed dose and related information in real time. Examples of active radiation detectors include Geiger-Müller counters and other survey meters often used in health physics and radiation protection, scintillation-based detectors such as Sodium Iodide and semiconductor-based detectors such as high purity germanium, both used in gamma ray spectroscopy. The EVBRPL is currently developing tissue equivalent, gas-filled radiation detectors including ionization chambers and proportional counters for use in dosimetry aboard spacecraft and for measuring the dose from proton and heavy ion beams used in cancer radiotherapy.

 

Passive Detectors

Passive detectors do not require electrical power to operate and tend to be considerably smaller and lighter-weight than active detectors. Passive detectors usually operate in a cumulative mode: exposure to radiation causes the accumulation of a signal that is stored in the detector. After the exposure period, the detector is processed and the stored signal is read-out. Examples of passive detectors include x-ray film badges, photographic nuclear emulsions, and thermoluminescence and optically stimulated luminescence detectors. The EVBRPL specializes in the use of CR-39 plastic nuclear track detector (PNTD), a type of passive detector widely used in space radiation dosimetry and neutron dosimetry, and that can also be employed in nuclear physics and cosmic ray experiments.