Sentec GmbH - Strahlenmesssysteme

                  Nukleare Messtechnik

Qualität und Erfahrung seit über 20 Jahren!


High Activity Beta Measuring Device

with Ion Implanted Silicon Detector

for Activities up to 4*1012 Bq/m3

- Qualified according to the German KTA 1503

- Ion implanted silicon detector

- Logic Signal & Analog Signal

- Discriminator

- Long term temperature range up to 50oC

- Short term temperature range up to 55oC

- Humidity up to 100% with dewing

- Vibration/Shock proofed

- Driver for signal transmission up to 400 meters

- Internal stabilisation against voltage drifts

- Binary signal on interrupt of high voltage, supply voltage

or exceeding temperature

- Direct connection to secondary electronics for pulse processing


Measuring of concentrations of radioactive gases in stack monitoring

 for concentrations from 4*107 to 1*1013 Bq/m3

Far distance monitoring

Overview and principle of measurements

The system PIA55 is typicalle used for measurements of beta activities in the range from 107 to 10-13 at elevated temperatures up to 55oC.

The system consists of an ionimplanted silicon detector and a charge sensitive preamplifier built into an extremely ruggedized housing from stainless steel.

The active area of the detector is limited by a collimator. The detector is protected against contamination and light. The housing can be directly coupled to a calibration container with inlets for the monitored gas.

The electronic part comprises amplifying and discriminator circuits, an internal high voltage generator and voltage control, a temperature control unit including voltage shutdown, a pulse shaping circuit, a baseline restorer and a driver circuit.

The signals can be used for countrate measurements or spectroscopy.

Beta particles passing the collimator are producing charge carriers within the active region of the detector. The resulting charge is amplified by a charge sensitive preamplifier and processed through filter/discriminator stages to the driver which enables signal transmission across distances up to 400 meters.


Technical Data

High Voltage/Maximum:             150 V (generated internally)


Input supply voltage

Preamplifier supply voltage:       18 - 30 V (typ. 24 V) positive

Current:                                      typ. 250 mA + 10% at 24 V

Power consumption/typical:        6,5 W at 24 V

Power consumption/maximum:  7,2 W at 18 V

Socket: Fischer DBEE 105 A 096-11



Output "Device Interrupt"

Collective binary signal for          - high voltage failure

                                                   - supply voltage failure

                                                   - exceeding of temperature limit

Socket: Fischer DBEE 105 A 096-11



Output/Logic signal

Amplitude:                     6.0 + 0.6 V in 75 Ohm 

Pulsewidth:                    550 + 100 ns (FWHM) 

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

Pulseshape:                   rectangular 

Polarity:                         positive or negative 

Impedance:                   75 + 10 ohms  

Sockets:                         Fischer DBEE 105 A 005-11 


Output/Analog signal

Amplitude:                     0 - 5.0 V 

Pulsewidth:                    about 0.75 + 0.25 μs (FWHM) 

Risetime:                       0.5 + 0.2 μs (10% - 90%)

Pulseshape:                   Gaussian

Polarity:                         positive

Impedance:                   75 + 10 ohms  

Sockets:                         Fischer DBEE 103 A 002-11



Controls (internal)

Conversionfactor:          5.3 + 0.5 mV/keV

Lower discriminator:     factory set on request



Operation conditions

Long term temperature range                  10 - 50oC

Short term temperature range                 50 - 55oC

Pressure resistance                                 0.5 - 1.5 * 105 Pa

Long term humidity in medium                80% without dewing

Long term humidity in environment         100% with dewing 

Background countrate (at 0,1 μSv/h)       < 0.3 cps

Max. beta resolution (for Ba-133)            about 10 keV (for detector)

Max. alpha resolution (for Am-241)        about 15 keV (for detector)

Dynamic range                                        better than 5 decades

Doserate sensitivity                                 about 1,1 ips/μSv*h (with

                                                                measuring device)


Vibration proof

1.4g, 5-35 s-1, 1 oct/min for all components of the system


Shock proof

30g, 11ms for all components of the system


Magnetic Shielding

Influence of the magnetic earth field is negligible for all directions


Radioscreening            acc. VDE 0847


Electrical protection    IP 65 acc. DIN 40050



Mechanical Assembly

Housing for detector and electronic from stainless steel:

Length:                          380 mm

Max. diameter:        140 mm

Weight:                          about 7 kg


Calibration container from stainless steel:

Height:                           about 60 mm

Max. diameter:               about 140 mm (incl. gas flanges)

Weight:                          about 7 kg



Possible connections to secondary electronics

(not part of the system; testcable optional)


Signal cable

(Connection signal output - secondary electronics)

Cable:                            shielded coaxial cable

Mantle diameter:            10.2 + 0.3 mm

Max. length:                   400 m

Impedance:                    75 Ohm

Connector to preamplifier: Fischer SE 105 A 005-11


Supply cable

(Connection supply input - secondary electronics)

Cable:                            shielded coax with 7 lines

Mantle diameter:            10.2 + 0.3 mm

Max. length:                   400 m

Connector to preamplifier: Fischer SE 105 A 096-12


Test cable PK1

(Connection signal output - testing device)

Cable:                            BNC-Coaxial cable 75 Ohm

Mantle diameter:            6.2 + 0.3 mm

Max. length:                   max. 10 m

Connectors:Fischer SE 105 A005-11 to BNC


Test cable PK2

(Connection test output - testing device e.g. MCA)

Cable:                            BNC-Coaxial cable 75 Ohm

Mantle diameter:            6.2 + 0.3 mm

Max. length:                   max. 10 m

Connectors:                   Fischer SE 103 A002-11 to BNC




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