The M4 and M4EC are compact, ergonomic, general purpose survey meters capable of detecting alpha, beta, gamma, and x-rays over 3 selectable ranges. A red count light flashes and a beep sounds with each event detected. The Monitor 4EC offers a more linear reading for gamma and x-rays (above 40 keV). Monitor 4 & 4EC Quick Specs PDF
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/cm2 thick. Effective diameter of window is 9.1 mm (.36 in.).
Operating Range0-.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 Sensitivity1000 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.
AccuracyTypically ±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 SwitchX1, X10, X100, Battery Check.
DisplayAnalog Meter holds full scale in fields as high as 100X maximum reading. CPM & mR/hr scale. Optional SI Scale Meter Available
Audio IndicatorInternally mounted beeper (can be turned off for silent operation).
Power Requirements9-volt alkaline battery. Approx. 2,000 hrs. at normal background
Temperature Range-20° to 55°C (-4° to 131°F)
WeightM4: 200 g (7.1 oz) M4EC: 224 g (7.9 oz)
Outputs3.5 mm jack with pulse out.
Size209 x 71 x 50 mm (8.2 x 2.8 x 1.9 in.)
IncludesCarrying Case w/ Belt Clip
OptionsSI Meter Option, Observer Software
Limited Warranty1 year limited warranty
Monitor 4 Kits
Build your own Monitor 4! Learn about how a geiger counter works!
Frequently Asked Questions about the Monitor 4 & Monitor 4EC
What are the differences between the Original Monitor 4 and the new ergonomic Monitor 4 models?
Both models share the same specifications of operating range, meter face, count light and audio clicks, however the new ergonomic Monitor 4 comes with a standard 3.5mm pulse output jack where as with the original Monitor 4 that option was a special order item. The new Monitor 4 and Monitor 4EC also comes with a mini USB and Observer USB Software option.
Are there any efficiencies available for the Monitor 4?
The two efficiencies we have on file are:
Radium 226 @ 1 CM - %0.575
Cobalt 57 @ 1 CM - %0.017