LB 790 10-Channel α-β Low-Level Counter with PC-Software AMS

The 10-Channel Low-Level Counter - LB 790 allows simultaneous and separate measurements of low activities for alpha and beta radiation emitting radionuclides with a detection limit of approx. 12 mBq for Alpha (Am-241) and approx. 22 mBq for Beta (Sr-90) (according to ISO 11929; 1 h measuring time)1).






Detection limit is calculated regardless of spillover and calibration uncertainty.

Measuring times (sample = background), 5% error probability, background value of 0.1 cpm for Alpha and 1 cpm for Beta.

For Am-241 an efficiency of 34% and for Sr-90 an efficiency of 50% is used.




  • Simultaneous α and β measurement (10-fold sample drawer for planchets up to Ø 60 mm)
  • Guard counter directly above measuring counters to suppress cosmic ray (anticoincidence)
  • 10 cm lead shielding in all directions for optimal low background performance
  • Modular sample detector construction (2 detectors per module)
  • Easy servicing concerning maintenance and repair
  • Detectors and sample drawer are one unit
  • Preamplifiers integrated in the detector
  • New PC Windows-Program AMS (Activity-Measuring-System for Data Acquisition)

The planchets (Ø 60 mm) are arranged in 2 rows on, 5 planchets each, a tray made of copper. The 10 ultra-flat flow-through proportional counter tubes are located directly above the planchets and their entrance window is protected by a thin foil. On the rear side all counters are capped by a large-area flow-through counter tube acting as a common guard counter. This guard counter operates in anticoincidence with the measuring counters to suppress the cosmic radiation.

The tray and counter tubes are surrounded by a shielding, 10 cm thick, made of standard lead bricks, for reduction of the environmental radiation (Total weight: approx. 1200 kg).

The detector unit is connected with the interface LB 5330 for registration, preprocessing of the count rates, transfer of the measured values to a PC via USB port and supply of the high voltage.

PC Software AMS

  • Simultaneous measurement of 10 samples - Alpha and Beta radioactivity in freely selectable units
  • Parallel connection of several detector systems simultaneously (up to 4 systems). This depends on the number of USB ports in your PC and the unblocking of the dongle (licence)
  • Definition of the measuring time: either by entering the preset time or the statistical accuracy
  • Automatic background subtraction after storage of the measured background in the user protocol
  • Nuclide chart with parameters and additional chart for calibration and quality assurance
  • Automatic half-life correction independently adjustable for Alpha and Beta channels
  • Live display of the detected activities, cpm values, statistical uncertainties for Alpha and Beta channels during the measurement, with different categories for measurement ranges
  • Statistical screening of the measured values concerning outliers. Outliers are displayed colourized
  • Stored measurements can be displayed on the monitor and evaluated at any time
  • Data analysis: Storing of measurements (Background, Calibration and Performance Check) in a history file with graphical display of the process. Possibility to show the changes in a defined time period, for example trend of background values
  • Graphical representation of measuring cycles in a time diagram
  • Compilation of test reports (e.g. Excel, Word or Access)
  • Data transfer of sample parameters from an input data file (e.g. generated by LIMS) and data output via Excel-Sheet for data processing in LIMS or reports [LIMS – Laboratory Information Management System]


Mechanical Data
External dimensions
(with lead shielding)
850 x 545 x 320 (L x W x H in mm)
Weight (with lead shielding)approx. 1200 kg
Dimension detector unit with
sample drawer and electronics
590 x 520 x 120 (L x W x H in mm)
Weight detector unit37.5 kg
Dimensions dual-detector module262 x 92 x 30 (L x B x H in mm)
Weight dual-detector module1.55 kg
Material detector moduleCathode copper
Material guard counterAluminium
LB 5330
Power Supply             90 – 260 VAC 50/60 Hz

1 A,T at 230 VAC
2 A,T at 110 VAC


Physical & Electrical Data
Power supply electronics+15/-15 V via LB 5330
Total current consumption250 mA
Current consumption of amplifiers+15 V = 8 mA/ -15 V = 6 mA
Connector                                            25 pol. SUB-D for signals and power supply
Operating point with P-10 (typical)1450 V
Counting gasArCH4 (90/10) or
ArCO2 (82/18) / ArCO2 (90/10)
PurityArCH4:Argon 4.8 
Methane 3.5
99.998 %
99.95 %
 ArCO2:Argon 5.0 
CO2 4.5 
99.9990 %
99.995 %
Detector window1.5 µm Hostafan foil (0.21 mg/cm²)
Metrological Data (P-10)
Typical background            < 0.1 cpm (Alpha)          
< 1.0 cpm (Beta)
Typical efficienciesAlpha radiation241Am
Beta radiation14
Ambient Conditions
Operating temperature                   0 °C to 50 °C
Relative humidity10 to 80 %, no condensing
Protection degreeIP50 (according to DIN IEC 60529)   



  • Environmental monitoring
  • Water treatment plants
  • Nuclear Facilities
  • Radiation Protection
  • Radiochemistry
  • Nuclear Physics
Format Size
LB 790 en PDF 617.78 KB