LB 150 D-R α-β Fixed Filter Monitor

The α-β-particulates monitor LB 150 D-R uses a fixed filter and is a true real time monitor while collection, detection and evaluation are done simultaneously.

The very high sampling rate of 40 m³/h ensures a representative sampling for both stack monitoring with isokinetic extraction as well as room or workplace air monitoring.




  • Simultaneous Measurement of artificial α- and β-particulates
  • Compensation and measurement of natural radioactivity (Rn/Tn daughters)
  • 3-fold large surface proportional counter with high α- and β-efficiency
  • Prompt measurement of the activity deposited on the collection unit
  • High sample air flow for representative sampling
  • Collection of airborne particulates on a 200 mm Ø glass fiber filter
  • Continuous measurement and alarm threshold monitoring while sampling
  • Isokinetic air flow, known particulates loss factors taken into account
  • Measuring principle independent of particulates energy
  • Independent of pressure or temperature fluctuations, minor influence of filter loading
  • Independent of Radon/Thoron ratio
  • Minor influence equilibrium state of the Radon/Thoron progeny (depends on in situ conditions – geological, meteorological)
  • Data collection and evaluation unit LB 9000 with ABPD/AERD application program to set parameters and visualise Measurement results. Utility programs for service and maintenance: calibration, plateau take-up, background measurement, recurrent testing, etc.

The α-β-particulates monitor LB 150 D-R uses a ficed filter and is a true real time monitor while collection, detection and evaluation are done simultaneously.


The very high sampling rate of 40 m³/h ensures a representative sampling for both stack monitoring with isokinetic extraction as well as room or workplace air monitoring.

Particulates collection and detector

The sampled air is drawn through an S-class glass fiber filter with 200 mm Ø. The detector, a large surface proportional counter with thin entrance window, is located directly above the collection area at a distance of 7 mm and measures the radiation intensity from α and β decays. The airtight particulates collection unit can be constructed in stainless steel or in teflon depending on the application.

Air flow regulation

By means of a frequency regulator the sample air flow can be regulated proportional to a stack flow or be kept constant i.e. independent of the dust loading on the filter. To keep the air sample flow constant the air flow through the system is required. The flow rate information is obtained by means of a Vortex flow meter, which operates to the Karmann vortex principle, independent of pressure or temperature fluctuations. This flow measurement principle has no mechanical moving parts and is therefore almost maintenance free.

Evaluation electronics

The versatile multi-counter Electronics LB 9000 with 12” TFT touch screen display and trackball keyboard is used as data logger electronics. It serves as data processing and evaluation unit with ABPD/AERD application program (Alpha-Beta Pseudo-coincidence Difference method / Alpha Energy Range Discrimination) for parameter entry and visualisation of the measurement results. 

Status monitoring functions

The system is equipped with self-monitoring functions for the critical operating parameters which will report any Alarm threshold breaching or failure condition.

  • Monitoring of pump function
  • Monitoring of filter Loading
  • Monitoring of the frequency regulator unit
  • Monitoring of the collection unit
  • Monitoring for detector failure of α, β and γ detector
  • Breaching of pre-alarm thresholds
  • Breaching of alarm thresholds for α and β


Technical Data
Pump                                     Silent Turbine Pump
Type SV 5.130/2 max. 40 m³/h flow rate
Type SV 5.90/2 max. 20 m³/h flow rate (optional)
Filter disk          Glas fiber filter; S-class No. 8, Schleicher & Schüll, Ø 200 mm or equivalent


Ambient Conditions
Ambient temperature            0 to + 50 °C
Sample air temperatureup to 85 °C
Relative humiditymax. 95 %
Sample air pressure0.7 to 1.2 bar absolute                                      








Type                                                      3-fold proportional counter tube GFDZ 200 in sandwichconstruction
Lead shield   4 pi 2 cm (5 cm optional)
Counting gas Methane, Natural Gas, Propane P-10 or Ar-CO2 90/10
Gas consumptionapprox. 2 l/h




approx. 0.2 cps

approx. 2.5 cps with Antico-Stage

approx. 6.0 cps

Measuring range   

approx. 200 000 cps with Antico-stage
Effectiveness ABPD/AERD-compansation up to approx. 500 Bq/Filter, beyond this integral α- and β measurement up to 5 E+5 Bq/Filter




23% (Cal. Factor kf = 4.4 Bq/cps)

16% (Cal. Factor kf = 6.3 Bq/cps)





21% (Cal. Factor kf = 4.8 Bq/cps)

11% (Cal. Factor kf = 9.1 Bq/cps)

11% (Cal. Factor kf = 9.1 Bq/cps)

(Measured with 200 mm Ø flat surface emission sources)
Noble Gas influence
85Kr       24.8 kBq/m³/cps
133Xe  69.0 kBq/m³/cps
(Data from KFA-Jülich, Germany)
Particulates Losses
Collection Unit 

Particle Ø in µm

2 neutral 

2 (3000 µ+/part.)

4 neutral

10 neutral

Loss in %





 (Data from CEA-IPSN, Paris - France)

Detection Limits

Instrument background 

At 10 Bq/m³ nat. Activity      


0.003 Bq/m³

0.17 Bq/m³ 


0.012 Bq/m³    

0.35 Bq/m³

 (MDC in accordance to DIN 25482 with a measuring time of 1 h and k1-α = k1-β = 1,645)





The Alpha-Beta-particulates monitor LB 150 D-R can be deployed for the measurement of airborne artificial Alpha and Beta activity in

  • Nuclear facilities in the Nuclear fuel cycle and Fission product production
  • Storage and processing of Nuclear waste products
  • Hot Cell Labs
  • Monitoring of Alpha emitting (transuranic) substances



Product Information
Format Size
LB 150 D-R en PDF 465.03 KB