The invention relates to a pocket type digital radiation dosemeter comprising
of a detector, which converts the ionisation in the detector caused by the incidence
of ionising radiation of certain energy range into electrical impulses, a low power
pulse amplifier, that amplifies the electrical pulses from the detector to detectable
amplitudes, a discriminator circuit, that is used to reject pulses of origin other
than those caused by the ionising radiation, a programmable divider circuit for
calibrating the dosemeter, an electronic counting circuit and a six digit LCD display.
The sensitivity of the dosemeter is 1 count per Sv (micro Sievert) and the
accuracy is within 15% from 60 keV to 1.25 Mev of X or Gamma radiation. A
metallic energy compensation filter and a discriminator threshold modulation circuit
are used to provide uniform response within 15% from 60 KeV to 1.25 MeV.
The Digital display indicates at any instant the total X or Gamma radiation dose,
in Sv, received by the dosemeter since the time at which the dosemeter was
switched on. The dosemeter is designed for very low power consumption and is powered
by two coin type Li batteries (Type CR2320). It is capable of over 500 hours of
continuous operation before having to replace the batteries. A blinking LED indicates
low battery condition when 8 hours of battery life is still left. The entire circuitry
and the battery holder are mounted on a single printed circuit board. Surface mount
components are used to make the unit compact. The dosemeter is compact (110 mm
L30 mm W14 mm H excluding Clip) and light in weight (60 gm).