The Monitor 4 and Monitor 4EC are compact, general purpose survey meters capable of detecting gamma, and x-rays over 3 selectable ranges. A red count light flashes and a beep sounds with each event detected. The Monitor 4EC, (energy compensated) offers a more accurate linear reading for gamma and x-rays above 40 keV. Gamma sensitivity is typical of a G-M detector: 1000 CPM/mR/hr, referenced to Cs-137. Energy Sensitivity for the 4EC is the same as Monitor 4, but the energy response for gamma and x-rays through the detector sidewall is flat within +61% or -26% ov
Monitor 4 Survey Meter Specifications:
Monitor 4: Halogen-quenched uncompensated GM tube with thin mica window 1.5-2.0 mg/cm2 thick.
Monitor 4EC: Halogen-quenched GM tube, energy compensated sidewall 2mm tin filter. Thin mica window 1.5-2.0 mg/cm2 thick.
Effective diameter of window is 9.1 mm (.36 in.).
Analog Meter Scale.
Monitor 4 Energy Sensitivity
Detects alpha down to 2.5 MeV; typical detection efficiency at 3.6 MeV is
greater than 80%.
Detects beta at 50 keV with typical 35% detection efficiency.
Detects beta at 150 keV with 75% typical detection efficiency.
Detects gamma and x-rays down to 10 keV typical through the window, 40 keV minimum through the sidewall of the detector.
Normal background is approximately 10-20 CPM.
1000 CPM/mR/hr (referenced to Cs-137)
Monitor 4EC Energy Sensitivity
Energy Sensitivity for the 4EC is the Same as Monitor 4 except the energy response for gamma and x-rays through the detector sidewall is flat within +61% or -26% over the range of 40 keV to 100 keV, and within +35% or -17% over the range of 100 keV to 1.3 MeV.
0-.5, 0-5, 0-50 mR/hr
0-500, 0-5,000, 0-50,000 CPM or 0-500 µSv/hr
X1, X10, X100, Battery Check.
±15% of full scale (referenced to Cs-137)
Monitor 4 Response Curve
Monitor 4EC Response Curve
Internally mounted beeper (can be switched off for silent operation).
Meter will hold at full scale in fields as high as 100 times the maximum reading.
One 9-volt alkaline battery. Battery life is up to 2,000 hours at normal background radiation levels
-20° C to 55° C (-4° F to 131° F).
Monitor 4: 178 grams (6.3 oz.) without battery
Monitor 4EC: 198.1 grams (7 oz.) without battery
145 x 72 x 38 mm (5.7 x 2.8 x 1.5 in.)
1 year limited warranty
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