LB 124 B (Xenon) contamination monitor for β-γ-Measurement

The contamination monitor LB 124 B is a versatile and flexible instrument for practical radiation protection based on well proven Xenon filled proportional counter technology. It can be employed wherever contamination caused by radioactive substances is encountered and has to be monitored.

The LB 124 B has a high sensitivity for beta particles and for gamma and it is especially suited for measurement of photon emitting radionuclides.



The beta-gamma contamination monitor LB 124 B for the measurement of radioactive contamination on surfaces is based on the well proven Xenon filled proportional counter technology. This detection technique provides extremely high sensitivity for beta particles and also for gamma radiation. The instrument, therefore, is ideally suited for the measurement of photon emitting radionuclides as widely used in nuclear medicine as well as in other laboratories and environments.

•      Calibration factors for more than 50 nuclides

•      Calibration selectable according to ISO 7503-1 or related to activity
        on 100 cm2 area

•      Protection grid with high transmission

•      Adjustable alarm thresholds

•      Acoustic alarm

•      RS232 Interface



The contamination monitor LB 124 B is a portable battery operated instrument with a sensitive area of 150 cm2. It comprises a sealed Xenon filled proportional counter tube, a microprocessor board with display unit, as well as an amplifier and discriminator module with high voltage supply for signal processing. There are guides to mount an additional grating for better detector protection or to use a sample holder with drawer for activity measurement of small samples.

The LB 124 B has an attractive and ergonomic design and due to its low weight it is easy to handle. Even under adverse conditions, the measured results can be read easily on a large high-resolution display with background lighting.

A few directly accessible function keys suffice to operate the LB 124 B. The instrument’s surfaces can be easily decontaminated. Different user profiles with different levels of complexity and access rights can be selected: Less experienced users may use the instrument as a simple, clearly structured system. For experienced users the software offers numerous functions and utilities, measurement modes and access to all parameters. Profiles can be configured password-protected and are pre-defined as EASY, STANDARD and EXPERT. The instrument has a large data memory and supports bidirectional communication via RS232. Program download and data transfer to a PC or printer are possible.

DisplayMonochrome LCD 192 x 64 pixel
Electro-luminescence illumination
Radiation detectorsealed proportional counter tube with Xenon filling
Measurement modesratemeter, scaler-timer-mode, clearance measurement, half-life measurement, survey mode
Entrance window’s dimensions100 mm × 150 mm
Sensitive area150 cm²
Entrance window’s material10 μm titanium (5 mg/cm²)
Protective Grid80 % Transmission
External dimensions240 mm × 140 mm × 110 mm (L x W x H)
Weight1620 g (with batteries)
AlarmAcoustic with adjustable alarm thresholds
Data memory1000 measured values with date & time
Serial interfaceRS232
Power supply

3 × C size batteries LR14 alkaline 1.5 V or
NiMH (HR-14) batteries 1.2 V,
rechargeable by plug type power supply or alternatively in the wall mounting bracket

Max. operating time (without illumination)

> 100 h with alkaline batteries 7.8 Ah
> 50 h with NiMH batteries 4.5 Ah


Ambient Conditions
Temperature range-15 °C to +50 °C (operation)
-20 °C to +70 °C (storage)
Relative humidity0 % to 80 % (no condensation)
External pressure500 to 1300 hPa (operation)
100 to 1300 hPa (storage/transport)
Protection classIP 64 (according to IEC 60529)


Efficiency (related to the activity of a source with an area of 100 cm²)
14C2 % 
18F17 % 
36Cl24 % 
60Co26 % 
99mTc2.6 % 
131I17 % 
137Cs20 % 
241Am11 % 
Background                         approx. 10 cps 


Order Information and AccessoriesIdent. No.
Contamination MonitorLB 124 B36516-10
Test source200 Bq 90Sr41872
Aluminum caseLB 124-KB38164
Power supplyMultirange58067
Wall bracketfor LB 124 B38789
Additional protection gridfor LB 124 B45355
Data cableD-Sub cable 3 m26204
Rechargeable batteries3 x NiMH 1.2V/4.5 AH40650
Floor trolleyfor LB 124 B41028
Sample holder with drawerfor LB 124 B40927



The contamination monitor LB 124 B is a versatile and flexible instrument for practical radiation protection. It can be employed wherever contamination caused by radioactive substances is encountered and has to be monitored:

  • nuclear medicine
  • research
  • nuclear power plants
  • decommissioning of nuclear facilities
  • disposal of nuclear waste
  • environmental monitoring

The instrument is used to measure radioactive beta-gamma contaminations on surfaces such as floors, walls, desks, objects, clothing or skin.

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LB 124 B en PDF 255.51 KB