Monitor 4 & 4EC Handheld Radiation Alert® Detector

Same Monitor 4. New ergonomic design. The M4 and M4EC are compact, 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). Click here for Original Monitor 4.

Specifications

Detector

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.

Display

Analog Meter holds full scale in fields as high as 100X maximum reading.

Monitor 4 Energy Sensitivity

M4: Detects alpha down to 2.5 MeV; typical detection efficiency at 3.6 MeV > 80%. Detects beta at 50 keV with 35% efficiency. Detects beta at 150 keV with 75% efficiency. Detects gamma and x-rays down to 10 keV through the window, 40 keV minimum through the sidewall. Normal background is approximately 10-20 CPM.

M4EC: 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.

Gamma Sensitivity:

1000 CPM/mR/hr (referenced to Cs-137)

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.

Operating Range

0-.5, 0-5, 0-50 mR/hr 

0-500, 0-5,000, 0-50,000 CPM or 0-500 µSv/hr 

0-50 mR/hr.

Range Switch

X1, X10, X100, Battery Check.

Accuracy

Typically ±15% of reading (referenced to Cs-137)

Audio

Internally mounted beeper (can be turned 

off for silent operation).

Power Requirements

9-volt alkaline battery up to 2,000 hrs at 

normal background

Temperature Range

-20° C to 55° C (-4° F to 131° F). 

Weight

M4: 223.9 grams (7.9 oz) without battery

M4EC: 245.7 grams (8.7 oz) without battery

Outputs

3.5 mm headphone jack with pulse out.

Size

210 x 70 x 48 mm (8.25 x 2.75 x 1.875 in.)

Accessories

Carrying Case, Observer Software, USB Option, SI Meter Option

Warranty

1 year limited warranty

Monitor 4 Kits

Build your own Monitor 4! Learn about how a geiger counter works!