Scintillation Monitors for
Contamination Control

Series 900

The mini monitor is well established in teaching, research, hospital and industrial laboratories as a reliable, convenient and inexpensive contamination meter.

FEATURES:
• A large logarithmically scaled meter with an open scale at the lower end to
show background levels of contamination while displaying high levels
without switching
• A speaker to give an audible estimate of radiation intensity
• An alarm which can be set to trip at any level on the scale
• Battery or mains operation using a separate power unit. Included is an
internal constant current charger for rechargeable batteries
• Lightweight aluminum case
• A comprehensive manual containing tables and curves of response to
different radiation's and other useful information
• The monitor conforms to the requirements of the International
Technical Commission publication 325




PHYSICAL CHARACTERISTICS 2
Weight: 1.0 kg without probe
Size: 180w by 110d by 165h mm overall
Batteries: 6 type AA cells, alkaline (IEC LR6) or rechargeable (IEC KR15/51).
Battery Life: Approximately 120 hours at 4 hours/day.
Meter Range: 0.5 to 5000 counts s-1
Paralysis Time: Scale corrected to give true count rate.
Ratemeter Integration Time: 1 to 4 seconds set to match count rate
Radiation Detector: Most portable scintillation probes having a single cable termination are suitable
HV Supply: 600-1500 volts set internally
Overload Protection: Provision to indicate excess tube current
Main Power: 12-18 volts DC from mains unit
ELECTRICAL CHARACTERISTICS PH
Socket Outlet: Single PET 100 series for single output + H.V. supply
Dynode Chain: approximately 55Mohms
Preamplifier: sealed unit giving a maximum of 1 volt negative pulse into a minimum load of 1000 ohms
Pulse Decay Time: 2.5µs in above load
Current Consumption: Approximately 17µA at 1000 volts

 


Below is the range of Mini Instruments scintillation probes suitable for use
with the 900 scintillation monitor.

 

　

　

　

　
Gamma Scintillation Probe Type 41
Sodium iodide crystal 19mm dia by 25mm thick. Suitable for energies from 25keV upwards. A lead cylinder surrounds the crystal giving the probe directional properties as well as reducing background. Diameter 40mm, length 210mm.
Sensitivity
10µSv h-1 (1mR/h) 137Cs approx 1000 counts s-1 / 3.7kBq (0.1µCi) of 99mTc at 20mm approx. 130 counts s-1
Background 3-8 counts s-1 depending on locale.


Gamma Scintillation Probe Type 41S
Similar to type 41 but without lead shielding and has a larger sodium iodide crystal (25mm dia by 38mm thick) for increased sensitivity. Suitable for energies from 25keV upwards. The probe is essentially omni directional for medium and high energy gamma radiation. Diameter 38mm, length 217mm.
Sensitivity
10µSv h-1 (1mR/h) 137Cs approx 3500 counts s-1
Background 20-30 counts s-1 depending on locale.


X-Ray Scintillation Probe Type 42A
Sodium iodide crystal 23mm dia by 1mm thick with a 14mg cm-2 aluminum window. This probe has a higher sensitivity than the type 41 for y energies below 60keV to a minimum of 10-15keV. An integral lead collimator makes it particularly useful for 125 I thyroid monitoring and deep vein thrombosis location. Diameter 40mm, length 187mm.
Sensitivity
3.7kBq (0.1µCi) of 125I at 20mm approx. 330 counts s-1
Background 2-3 counts s-1 depending on locale.


X-Ray Scintillation Probe Type 42B
This probe is the berylium window version of the above and detects very low y energies down to 5keV. The response above 15keV is almost identical to the 42A. Window weight 47mg cm-2.


Scintillation Probe Type 44A
Sodium iodide crystal (32mm dia by 25m thick) is mounted on the front surface of the probe to facilitate monitoring of large contaminated areas. It is suitable for a range of energies from approximately 15keV to 250keV. It is also ß sensitive for energies above 500keV. Diameter 50mm, length 180mm. Aluminum window weight 14mg cm-2.
Sensitivity
3.8, 1.6 & 1.4 counts s-1 for 1 Bq cm-2 (2.7 x 10-5 µCi cm-2) of 125 I, 99mTc,57Co respectively.
Background 4-8 counts s-1 depending on locale.


Scintillation Probe Type 44B
This probe is the beryllium window version of the above and extends the sensitivity down to approx. 5keV making it useful for 55Fe.3.7kBq (0.1µCi) of 55Fe at 10mm approx 180 counts s-1. Window weight 47mg cm-2.

Unless otherwise stated none of these probes are suitable for the detection of alpha or beta radiation.