Sentec GmbH - Strahlenmesssysteme

                  Nukleare Messtechnik

Qualität und Erfahrung seit über 20 Jahren!



on Geiger-Mueller basis

o Long Term Temperature up to 75oC

o Short Term Temperature up to 110oC

o Waterproof up to 95% without dewing

o Shock proofed

o Logic Signal

o Driver stage for signal transmission up to 400 m

o Ruggedized Housing

o Simple Handling

o Special selected components



* Radiation monitoring of condensors (beta- and gamma monitoring)

* Monitoring of nuclear cooling systems

* General radiation and activity monitoring


The system GM110/B-G is designed as measuring device

for betas (version “B”) and gammas (version “G”) at elevated environmental temperature.

A compact design of the detector head and of the succeeding electronics is coupled with transmission distances for the logic signals across up to 400 m.

Therefore these systems are suited for inaccessible, hot and/or contaminated areas. The resulting signals can be directly input into counter/timer electronics.

The measuring devices GM110 consists of an integrated

combination of detector head and electronics.

For the beta version (type: GM110-B) the counter tube lies open between small steel rods and for the gamma version (type: GM110-G) the counter tube is covered with an aluminum shield.

The detector part consists of a highly qualified and special selected Geiger-Mueller counting tube.

The electronics comprises a first amplification stage (current sensitive amplifier), a pulse shaping unit an a driver stage.

In interaction with the counting gas inside the Geiger-Mueller-tube the gammas and betas produce electrons which are multiplied by secondary ionisation and which produce voltage pulses when unloading to the anode. These pulses are available at the signal output of the measuring device.

A) Systemconstruction

1. Beta-Gamma-Vesion GM110-B

   -Counter tube SBM13 uncapsuled

   -Variable adapter counter tube - preamplifier  

   -Preamplifier in stainless steel housing

2. Gamma-Vesion GM110-G

   -Counter tube SBM13 in stainless steel housing

   -Variable adapter counter tube - preamplifier  

   -Preamplifier in stainless steel housing

3. Options

The versions -B and -G are available in variable length

of the adapter counter tube - preamplifier from 20 to

100 mm. Classification as



with XYZ=length of adapter in mm

4. Cable for Signal/High voltage supply/Power supply

to secondary electronics

(not part of the system)

Cable:                shielded cable with 2 coax and 4 trip lines

Mantle diameter: 9.1-10.5 mm

Max. length: 400 m

Cable impedance: 50 ohms

Connector:         Fischer SE 105 A 096-12

B) Electrical Data

1. Input High Voltage/Supply Voltage

High Voltage/Max:                      1400 V positive

High Voltage/Operation Voltage:1250 V positive

Power Consumption/Max.:         0.25 W when counter tube is shorted

Supply Voltage:                          + 15 V to + 22 V

Power Consumption (typ.):         2*30 mA  

2. Signal Output

Amplitude:                                  5.5 + 0.5 V in 50 ohms 

Pulsewidth:                                 10 + 5 μs (FWHM) 

Risetime:                                    5-100 ns (10% - 90%) 

Pulseshape:                                rectangular

Polarity:                                      positive or negative (upon request)

Max. load:                                   20 nF 


3. Radioscreening                     acc. VDE 0847

4. Electrical protection             IP 65 acc. DIN 40050

C. Operating conditions

1. Background

Background countrate without shielding

( at 0,1 " 0,05 μSvh-1)                 < 2.0 cps (15 B 110oC)

2. Operation parameters

Operating voltage:                      1250 " 10 V

Region of plateau (minimum):    1200 B 1300 V

Slope of plateau:                        < 10% pro 100 V

3. Sensitivity (effective cross section)

Beta radiation                Sr-90/Y-90        > 1 cm2 *)

Cs-137              > 1 cm2 *)

Gamma radiation           Co-60                > 0,15 cm2 **)

Cs-137              > 0,08 cm2 **)

*) deduction from theory

**) from measurements with encapsulated detector GM175

4. Temperature dependance of the countrate

Max. changes in countrate            < 5% for 15oC # T # 110oC

C. Environmental parameters

1. Storage and transportation

Temperature:    10 - 60oC

humidity:           <50%

Shock (acc. DIN 40046): 30 g, 11 ms in packaging


2. Operating conditions

Temperature:    15 B 110oC without limitation

pressure:           0,7 - 1,2 * 105 Pa absolute

humidity:           100 % with dewing in whole temperature range                         with connected cables

radiation:           max. 109 counts für counter tube SBM13



D.Mechanical Assembly

- Housing for electronics: stainless steel

- Detectorhead covered by aluminum tube (version -G only)

- Geiger-Mueller counter tube SBM13


Total Length:     341.5 + l mm (adapter length l = 20 - 100 mm)

Max. diameter:  70 mm

Weight:             about 0.9 kg



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