Detector
Monitor 4:
Halogen-quenched uncompensated GM tube with thin mica window 1.5-2.0 mg/cm2 thick.Effective diameter of window is 9.1 mm (.36 in.).
Monitor 4EC:
Halogen-quenched GM tube, energy compensated sidewall 2mm thin filter. Thin mica window 1.5-2.0 mg/cm2thick. Effective diameter of window is 9.1 mm (.36 in.).Operating Range
0-.5, 0-5, 0-50 mR/hr 0-500, 0-5,000, 0-50,000 CPM or 0-5, 0-50, 0-500 μSv/hr (SI Scale Meter Option)Energy Sensitivity
1000 CPM/mR/hr (Cs137). M4EC is the same as M4 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. M4 & M4EC meter scales shown below.Both Detect beta at 50 keV with typical 35% detection efficiency and beta at 150 keV with typical 75% detection efficiency.
Accuracy
Typically ±15% of reading (Cs137)
 |
 |
|---|---|
| Monitor 4: Detects alpha down to 2.5 MeV; typical detection efficiency at 3.6 MeV is greater than 80%. Detects gamma and x-rays down to 10 keV typical through the window, 40 keV minimum through the case. | Monitor 4EC: Detects alpha down to 2.5 MeV; typical detection efficiency at 3.6 MeV is greater than 80%. Detects gamma and x-rays down to 10 keV typical through the window (non-compensated), 40 keV through the sidewall. |
Range Switch
X1, X10, X100, Battery Check.
Display
Analog Meter holds full scale in fields as high as 100X maximum reading. CPM & mR/hr scale. Optional SI Scale Meter AvailableAudio Indicator
Internally mounted beeper (can be turned off for silent operation).Power Requirements
9-volt alkaline battery. Approx. 2,000 hrs. at normal backgroundTemperature Range
-20° to 55°C (-4° to 131°F)Weight
M4: 200 g (7.1 oz) M4EC: 224 g (7.9 oz)Outputs
3.5 mm jack with pulse out.Size
209 x 71 x 50 mm (8.2 x 2.8 x 1.9 in.)Includes
Carrying Case w/ Belt ClipOptions
SI Meter Option, Observer SoftwareLimited Warranty
1 year limited warrantyMonitor 4 Kits
Build your own Monitor 4! Learn about how a geiger counter works!
