Radiation ALERT Monitor 4

The Radiation Alert Monitor 4 is a hand-held radiation detector with an analog display over three selectable operational ranges for detecting potentially harmful ionizing alpha and beta particles, and gamma and x-ray radiation. This meter has a dual-scale, analog, needle-point display of counts per minute (CPM), and milliRoentgen (mR) per hour. It detects the four main types of ionizing radiation: alpha and beta particles, and gamma rays and x-rays. It has three selectable operational ranges (X1, X10, or X100) to be adjusted when the meter face peaks at the highest mR level.

The Monitor 4 has a red, flashing counter and a beeping noise to indicate each ionizing radiation event. It has a halogen-quenched Geiger Mueller (GM) tube with a thin, mica end window for sensing ionizing radiation. It is used to check radiation levels in the environment and objects, such as particle accelerators, x-ray shielding, and industrial gauges. An audio indicator with an internally mounted beeper can be turned off for silent operation.

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.

Energy Sensitivity
1000 CPM/mR/hr (Cs137). 4EC 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.

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)

Typically ±15% of reading (Cs137)

Analog Meter holds full scale in fields as high as 100X
maximum reading. CPM & mR/hr scale. Optional SI
Scale Meter Available

Audio Indicator
Internally mounted beeper

Power Requirements
9-volt alkaline (included)
Approx. 2,000 hrs at background

Temperature Range
-20° to 55°C (-4° to 131°F)

Humidity Range
10% to 70% Non-Condensing

M4: 200 g (7.1 oz)
M4EC: 224 g (7.9 oz)

Headphone 3.5mm jack to count to computer or

209 x 71 x 50 mm (8.2 x 2.8 x 1.9 in.)

Carrying Case w/ Belt Clip
SI Meter Option, Observer Software,
NIST Calibration
Limited Warranty
1 year limited warranty