IAEA Post Graduate Educational Course Radiation Protection and

IAEA Post Graduate Educational Course Radiation Protection and Safe Use of Radiation Sources Part IIQuantities and Measurements Module 3 Principles of Radiation Detection and Measurements Session 14 Other Detectors IAEA International Atomic Energy Agency

Overview • Various kinds of radiation detectors will be discussed and their principles of operation explained • Students will learn about Electrets; selfpowered detectors; thermally stimulated exoelectron emission (TSEE); and radiophotoluminescent detectors (RPLD) IAEA 2

Content • Electrets • Self-powered detectors • Thermally stimulated exoelectron emission (TSEE) • Radiophotoluminescent detectors (RPLD) IAEA 3

Electrets ü Semi-permanently electrically charged material ü Usually a type of plastic insulator ü Requires a special reader and the use of calibration factors specific to each type ü Electrets most often used for measurement of radon, both short- and long-term, and surface alpha detection IAEA 4

Radon Electret IAEA 5

E-PERM Alpha Surface Monitor (Electret) IAEA 6

Electret Voltage Reader IAEA 7

E-PERM Electret Voltage Reader IAEA 8

Two Sizes of Electrets IAEA 9

Electret Microprocessor IAEA 10

Self-Powered Radiation Detectors • Two examples will be given: • Self-powered neutron detectors used in nuclear power stations • Self-powered Geiger counters IAEA 11

Self-Powered Neutron Detectors IAEA 12

Self-Powered Geiger Counters IAEA 13

Self-Powered Geiger Counters IAEA 14

Test Source for Self-Powered Geiger Counters IAEA 15

Thermally Stimulated Exoelectron Emission (TSEE) • Refers to heating of a material after it has been exposed to radiation • Irradiation leaves the material in an excited state (i. e. a state of disequilibrium) • Heating the material stimulates electron emission, which produces a current which can be measured and related to the dose IAEA 16

Thermally Stimulated Exoelectron Emission (TSEE) • A French-German cooperative project developed a TSEE counting system for exoelectron research • System uses Be. O thin film detectors, a heater and a geiger counter to measure the electrons released • Dose range is from 10 -3 c. Gy to above 10 c. Gy IAEA 17

Thermally Stimulated Exoelectron Emission (TSEE) • Thin aluminum layers have been used for TSEE detection of alpha and beta particles • Method can be applied to monitoring of alpha emitters, contamination control of tritium, and to skin dosimetry of high LET radiations IAEA 18

Thermally Stimulated Exoelectron Emission (TSEE) • TSEE has been applied to personal beta dosimetry • Dosimeters have been developed using TSEE from Li. F • Sensitivity of this method ranges as low as 30 Gy IAEA 19

Radiophotoluminescence (RPLD) • Radiophotoluminescence is the property of certain glasses (e. g. silver-activated phosphate glass) to store the energy from radiation until the glass is exposed to ultraviolet light, at which time the energy is released in the form of orange light. • A fluorimeter is used to measure the light output. IAEA 20

Summary • Various kinds of radiation detectors were discussed and their principles of operation explained • Students learned about Electrets; selfpowered detectors; thermally stimulated exoelectron emission (TSEE); and radiophotoluminescent detectors (RPLD) IAEA 21