The Monitor 4 is compact, analog radiation detector. A general purpose survey meter capable of detecting alpha, beta, gamma, and x-rays over 3 selectable ranges. Proven and reliable over decades of use in the industry, the Monitor 4 has evolved into one of the best analog radiation detectors of today. Simple and ergonomic , a red count light flashes and a beep sounds with each count detected. Battery check and silent operation with the flick of your thumb.
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.).
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 and beta at 150 keV with typical 75% detection efficiency. Detects gamma and x-rays down to 10 keV typical through the window, 40 keV minimum through the case.
For more info: https://www.zabdiresources.com/monitor-4-analog-radiation-detector
