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The new Beta Secondary Standard (BSS2) is a complete irradiation
facility including beta sources, mechanics, electronics, sensors
for air pressure, temperature and humidity, and a personal
computer to control all irradiation parameters and to deliver
the desired dose to the instrument under test.
The main features of the new facility are:
• Dosimeters can be positioned easily at the
calibrated point in the radiation field
• Irradiation table rotates in 5 degree steps for measuring
polar response
• High activity Pm-147, Kr-85 and Sr-90 sources - dose
rate from 7µGy/s to
38 µGy/s with beam flattening filters
• Sr-90 source also calibrated without filter for source-detector
distances
of 11, 30 and 50cm
• Each source contained in an individual shield with
built-in shutter -
reduced operator dose, no special handling equipment needed
• Low activity Tl-204 source replaced by high activity
Kr-85 source
For quality assurance purposes and to deliver the required
dose to the dosimeter, the computer automatically records
the following parameters:
1. Radionuclide and source identification number
2. Type of beam flattening filter
3. Distance between source and dosimeter
4. Angle of incidence of radiation
5. Temperature and air pressure
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