“Monoblock Gamma” detection module (“Monoblock”) is a device designed to measure ambient equivalent dose rate (ADER) of gamma radiation by converting it into output electrical pulses with average counting rate depending on the measured value. The unit employs “Gamma‑6” Geiger-Mueller counter.
The ADER value can be calculated by using the following formula:
Ḣ = (f-f0)/(S∙(1-τ∙f)), (1)
where Ḣ — the ADER value to be measured, μSv/h;
f — mean counting rate, cps;
f0 — detector intrinsic background, cps;
S — detector sensitivity, cps/(μSv/h);
τ — detector dead time, sec.
Measurement range — 0.1 μSv/h to 30 mSv/h.
Relative intrinsic error when using formula (1) provided with optimal values of its parameters — within ±15%.
Note — The error of calculations with formula (1) depends on proper choice of ADER level for calibration of the dead time parameter.
Energy range — 50 KeV до 3 MeV.
Energy dependence of sensitivity in 60 KeV до 1.25 MeV range, relative to 137Cs — ±25%.
Operating temperature — minus 40°C to +55°C.
Response variation due to environmental temperature change — less then ±5% per 10°C.
Sensitivity to gamma radiation of 137Cs —3.6 to 5.3 cps/(μSv/h).
Typical dead time value — 16 to 18 μsec.
Typical intrinsic background — 0.2 cps.
Power supply — 5 VDC.
Power consumption — depends on ADER:
- 1 μSv/h — 1.5mA (max),
- 30 mSv/h — 60 to 80mA.
Output pulses:
- levels — CMOS;
- polarity — positive;
- width — 9±2 μsec.
Control input:
- high level — enables operation,
- low level — disables operation.
Dimensions — Ø64 × 36 mm.
Cable length — 130 mm.