Radiation detectors are useful tools that aid in our understanding, discovery, and assessment of the radiation present.
- Area Monitors are detectors used, mounted on a wall, or on a benchtop, sometimes with external detectors to relay a signal to the observer location where the meter face is.
- Dose Measurements (Gamma) are detectors that readout in tissue equivalent units of mrem, rem, mrem/hr, or rem/hr. Ionization chambers fall into this category where they measure a current that is related to the flow of electrons on the detector anode resulting from an ionization within the fill gas. If the ionization chamber has a sliding, removable attenuator, this is most likely a deep dose/ shallow dose attenuator. With this attenuator open, the signal is relative to deep dose (dose penetrating at/beyond the 1cm depth of tissue) as well as shallow dose (dose penetrating at the 0.007cm depth of tissue). With the attenuator in place, the resultant dose is just deep dose, which is used to quantify whole body dose and rates (radiation area, etc.). In some cases Geiger counters can be calibrated to dose, please note that these detectors are primarily for the radiation they are calibrated to (e.g. on campus most detectors are calibrated to Cs-137). Bare Geiger's also have a energy response dependency that results in a varying reading dependent on the energy of the photon present. some manufacturers sell/include a cap or cover that may resolve this.
- Neutron Meters are to be used in areas where neutrons are present. These detectors operate in many configurations, most commonly is when one slows the neutrons down (neutrons present may be a spectrum or mono-energetic) to a thermal energy 0.025eV so a resultant reaction can create an ionization within the detector fill gas and that signal can be equated to neutron dose rate if calibrated correctly.
- Survey Meters are used commonly to asses areas of local contamination in units of counts per minute. These meters typically consist of a survey meter and a radiation probe. The meter contains the display to relate information to the user while the probe is what measures the radiation. Each probe has its limitations for example the type of radiation, efficiency of said radiation, etc.)
- Radiation Probes are meant to be connected to some sort of meter (e.g. survey meter) and if this probe is chosen correctly, can aid in your identification of radiation activity present (contamination limit posting, tool clearance, etc.). Below is a rough example, please contact radiation safety to help you determine the best probe(s) for your application.
- Gamma fields use a Sodium Iodide (higher energy photons use a thicker crystal);
- high energy Beta, use Geiger
- low energy beta (depending on the energy) gas proportional
- Alphas use Zinc Sulfide, Air proportional counter, or gas proportional