Quartz fiber dosimeter

A quartz fiber dosimeter, sometimes called a self indicating pocket dosimeter (SIPD) or self reading pocket dosimeter (SRPD), is a type of radiation dosimeter, a pen-like device that measures the cumulative dose of ionizing radiation received by the device. It is usually clipped to a person's clothing and worn to measure one's actual exposure to radiation.

As with other types of personal radiation dosimeter, it is worn by workers who are occupationally exposed to radiation, so their employers can keep a record of their exposure, to verify that it is below legally prescribed limits. It works by measuring the decrease in electrostatic charge on a metal conductor in an ionization chamber, due to ionization of the air in the chamber by radiation. It was invented in 1937 by Charles Lauritsen.

The dosimeter must be periodically recharged. It is usually read before it is charged, and the dose is logged, to chart one's exposure. In many organizations, possession of the recharger is limited to health physicists to prevent falsification of exposures. Magnifying lenses (a low-power microscope) and an illumination lens allow one to directly read the dose at any time by aiming the illumination lens at a light source and looking into the device.

The device is mainly sensitive to gamma and x-rays, but it also detects beta radiation above 1 MeV. Neutron sensitive versions have been made.

Quartz fiber dosimeters are made in different ranges. Peace-time occupational exposure ranges usually measure up to 500 mrem (5 mSv), which exceeds the normal US yearly dose of 360 mrem (3.6 mSv). War-time fallout meters measure up to 500 rem (5 Sv), roughly the lethal dose.

The quartz fiber device is an older dosimeter design. It suffers from these disadvantages:

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