GAMMA PROBE for Argus 2000 & 3000 Systems
Probe Type	MC74L - low intrinsic background, energy compensated, environmental gamma probe.
Incorporates:
US manufactured LND Geiger Muller halogen quenched gamma detector:  78017
Integral EHT power supply and output pulse conditioning circuits. 
Overall weatherproof tubular aluminium enclosure.	
Probe Manufacturer	Thermo Electron Corporation	
Overall Probe dimensions	Length  507 mm. 
External diameter 31.6 mm.	
		
Maximum Doserate  for 137Cs	1 mSv/Hour, 0.83 mGy/Hour	
Fixed electronic dead time	200 µS.
Note: The GM dead time will reduce at higher dose rates.	
GM Detector effective dimensions	Length 240 mm.
Diameter 19.8 mm 	
		
Compensated GM detector - Sample response factors:		
Normalised for 60Cs.
The detector’s response was tested at 60 and 148 keV at five orientations for each energy. The detector’s response was also tested on phantom.
Centre of the detector was test reference point. 
Radiation beam normal to detector’s major axis.
Estimated uncertainty 10% at 95% confidence level.	Measured by National Radiological Protection Board UK, Report No. 10208. Equipment calibration directly traceable to National Physical Laboratories or NAMAS accredited calibration facilities. 
(Measurements made on the compensated LND78017 detector excluded the aluminium weatherproof enclosure of the MC74 assembly)	
		
     Gamma Radiation Quality:	Response Factor	
     60Co   (1250 keV)	1.25	
     137Cs   (662 keV)	1.00	
     X-radiation ISO Low Series:		
     248 keV	0.78	
     211 keV	0.83	
     185 keV	0.91	
     148 keV	1.05	
     109 keV	1.16	
     87 keV	1.13	
     60 keV	0.90 	
     48 keV	0.50