Quartz fiber dosimeter

In some organizations, possession of the recharging device is limited to health physicists to ensure accurate recording of exposures.

War-time fallout meters measure up to 500 rem (5 Sv), roughly the lethal dose.

It suffers from these disadvantages:[3] Susceptibility to moisture is dealt with by separating the charging pin from the ion chamber by a small gap.

The device is pushed firmly onto the charger, closing the gap and allowing the dosimeter to be reset.

Releasing the dosimeter disconnects the charger pin from the ion chamber but does induce a small change in the zero which is relatively unpredictable.

The quartz fiber dosimeter is a rugged form of a device called a Lauritsen electroscope.

Recharging restores the charge that was lost and returns the fiber to its original deflected position.

[1] This consisted of a simple ionization chamber with an electrode running down the center, but no electroscope for reading.

These had the advantage that they were simpler, more rugged, and cheaper than the electrometer type, but had the disadvantage (considered desirable in some military applications) that the exposure couldn't be read by the wearer without the electrometer/charger.

The rate meter has two internal scales that read the radiation flux directly in rems for each period.

Quartz fiber radiation dosimeter, showing clip for securing it to clothing; normally a breast pocket.
Display of quartz fiber dosimeter, in units of roentgen . Viewing is by holding the instrument towards an external light source and looking through the magnifying eyepiece. [ 1 ]
Gold leaf electroscope showing principle of fiber dosimeter. When ionizing radiation penetrates the inner gas of the electroscope, ions are created. Since the gold leaves are charged positive, the negative ions are attracted to it and neutralize some of the charge , thus causing the gold leaves to close together.