EPD/HB/40521/000
ISSUE 5
EPD TECHNICAL HANDBOOK Page 1
SECTION 1
INTRODUCTION
This handbook is for the Thermo Electron Electronic Personal Dosemeter (EPD) -
EPD Mk2. The EPD Mk2 is lighter and slimmer than the original Thermo Electron
EPD and has new micro-circuitry, case design and software. The EPD Mk2 also has
a number of enhanced dosimetry features and user functions. To simplify
nomenclature the term EPD has been used throughout this handbook. The term EPD
should be read to signify the EPD Mk2.
1.1 General
The EPD is a personal radiation monitor that detects and measures beta and gamma
radiation. Radiation that is detected by the EPD is processed to give an indication of
penetrating dose, superficial dose and the dose rates. This information is displayed
to the user via an LCD display on the top of the EPD.
The EPD contains three silicon diode detectors. Each detector feeds a chain of
dedicated amplifiers and counter circuits to measure soft gamma, hard gamma and
beta radiation. The outputs from each detector chain are processed to calculate and
display penetrating and superficial dose and dose rate. Other functions include:
EEPROM storage of detected radiation, annunciation of alarm conditions (LED and
sounder), Infra-red (IR) communication and a user interface comprising an LCD
display and button. Each of the above functions is described in detail in this
handbook.
1.2 EPD Major Characteristics
Major Characteristics relating to the EPD are listed in Table 1.1.
Table 1.1 - EPD Major Characteristics
Item Characteristic
Power One AA battery, either a standard Alkaline (1.5 V) battery or
high energy Lithium Thionyl Chloride (LTC) (3.6 V).
Weight 95 gms (including LTC battery and clip).
Dimensions 86 x 62 x 18.5 mm (excluding clip).
Alarm sounder 98 - 101 dB.
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