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( For measuring gross beta activity / contamination)
Technical Data

Low Background Beta counting system LB615 is primarily designed for the measurement of gross Beta activity / contamination in water and other environmental samples . It is highly recommended for Radio analytical Labs and environmental survey labs at Nuclear power stations for this application.

Counting of samples having very low specific beta activity becomes difficult with conventional G.M. Counters having high background and low efficiency. A thin plastic scintillation detector based beta counting system has twin advantage of low background and high efficiency when compared. This system uses thin plastic scintillation detector based main counter and another wide area plastic scintillator based guard counter. System works on the principle of anticoincidence. The detector assembly is provided with a 3” lead shield to reduce background.

Applications : This system is highly recommended for the estimation of gross Beta activity in Environmental samples, including air, water (river, lake, pond, ground & sea waters), soil, vegetation & biological sample.

System can be used by testing labs, Environmental survey labs at Nuclear Plants, in normal or in a Nuclear disaster scenario.

  • Measures gross Beta activity / contamination in water and other environmental samples. Including Air, Water, Soil, Vegetation & Biological samples. Suggested products for Environmental Survey labs.
  • Highly recommended for low beta counting of environmental samples at environmental survey labs / Nuclear power stations.
  • Adequate Lead shielding has been provided to minimize background.
  • Modular in construction.
  • Stable high voltage continuously adjustable from 0V to 2000V.
  • Uses coincidence technique. Gives out both COIN & ANTI-COIN output.
  • Outputs on Dual Counter/Timer with two channels.

The Low Background Beta counting systems (PC based) manufactured by NUCLEONIX essentially consist of the following constituent units.

• Mini Bin MB403 & Power supply PS401
• High Voltage Units (Two Nos) HV 502
• Coincidence Analyzer - CA570
• Dual Counter Timer- CT542A
• Plastic scintillator based main & guard counter.
• Lead Shielding Enclosure

Two High Voltage Units of this counting system are used for biasing the Guard counter and Main counter respectively. Outputs from these counters are routed through paralysis time units. These output signals from paralysis time units are then fed to the coincidence unit for obtaining both coincidence and Anti-Coincidence outputs which are inturn fed to the Dual counter timer unit.

This system is very useful in estimating gross beta activity in environmental samples and samples of low specific beta activity. The twin advantages of low background and high efficiency offers excellent sensitivity for this counting system.

Brief specifications of individual constituent units are given as follows.

1. Mini Bin (MB 403) :
MINIM INSTRUMENTATION BIN is a standard Minibin designed to power Standard Nuclear Instrumentation Modules with 24-pin type of power connectors.
It provides mounting space for 8 standard module widths of the 8 ¾ inch high type. The eight corresponding module connectors are provided with necessary wiring for distribution of all standard power supply voltages, +/-12V & +/-24V DC.

2. Power supply (PS 401) :
Operating Voltage : 230V AC, 50Hz
Out put Voltage : +12V @1A, -12V@1A, + 24V@0.5A
Regulation (Line & Load) : + 0.5% from no load to full load.
Ripple : Less than 10mV (rms) peak to peak at full load.

3. High Voltage Unit (HV 502):
Output Voltage : 0V to 2000V continuously variable by a ten turn helipot provided on front panel. (All specifications are valid from 10V to 2000V).
Output Current : It can deliver upto a maximum of 1mA.
Line & Load Regulation : Better than 0.05% of full scale.

4. Coincidence Analyzer (CA570) :
This unit is a two bit module which receives the output pulses from both guard and main counters converts these signals to TTL levels and checks for coincidence and anti-co-incidence condition to give both outputs i.e., anti-co-incidence output is released if there is output due to main counter only and there is no guard counter output with in 50 m sec on its occurance. Also if guard counter output comes first, then further upto 50 m sec any output coming from the main counter will be treated as co-incidence event. Output(s) from this unit are counted in a Dual counter timer.

5. Dual Counter Timer (CT542A) :
Count Input(s) IN1 & IN2 : 100mV to 10V, unipolar or positive bipolar semi-gaussian pulse
Pulse Width : 1µsec (min)
Polarity : Positive or Negative
Input Impedance : 5.0 K ohms
Input Counts Capacity : 999999 counts
Input Frequency (max) : 1 MHz
Pulse Height Discrimination : 100mV - 10V by a trimpot provided (inside) on PCB
Counts Indication : 16 x 2 dotmatrix LCD display

Modes of Data Acquisition :
a. Counts for a preset time
b. CPS
c. CPM

TIMER: Preset Time Setting : Programmable through tactile switch control buttons

Control Buttons : START, STOP, PROG, STORE, INC, DEC

Preset Time / Elapsed Time Indication: On 16 x 2 LCD Dot matrix display

Preset Time Range : 1 to 9999
Printer Port : Built-in
Serial Port : RS 232C built-in

Additional Options:(at extra cost) :
a. Data communication Software for down loading of data can be given at extra cost.
b. Printer.

Module connector :
Amphenol Connector Type : 26-159-24P-H (24 Pin Type) or NIM Standard as per AEC specifications TID 20893 (Rev) Type : AMP 204186-5

6. Plastic scintillator based Beta Counter
Main Counter :

Operating Voltage : 900 - 1000V
Sensitive Area : 28mm Ø
Energy range : 50keV to 3 MeV
Calibration Accuracy : +/- 15% with Sr90

7. Background (with 80mm shielding) : < 2 CPM (Auto-coincidence mode)
Guard Counter:

Operating Voltage : 900 - 1000V
Sensitive Area : 50mm Ø
Energy range: 50keV to 3 MeV
Calibration Accuracy: +/- 15% with Sr90
Guard Counter:
Operating Voltage: 900 - 1000V
Sensitive Area: 50mm Ø
Background (Inside the shield) : < 50 cpm

Background (with 80mm shielding): < 2 CPM (Anti-coincidence mode)


8. Efficiency : Better than 40% with Sr90

9. MDL (as measured with Background in Hyderabad at our works): 0.00000151085µCi (0.0559016Bq)
NOTE: MDL vary in your place depending upon the background at your place.

10. Lead Castle:

This lead castle facilitate the user to insert the sample tray and also provides good shielding with 80mm thickness lead shield, so as to achieve very low background of the order of less than 2CPM in Anti co-incidence mode

Accessories: SS and aluminium planchets are required, to place the prepared environmental samples for counting. These planchets are of 25mm dia & have a depth of 2mm. These are designed to fit into the sample / source holder / drawer of the detector assembly.

Plot No.162 A & B, Phase-II, IDA, Cherlapally, Hyderabad-500051 India Phone: +91-7207034546, +91-7331104481, 7331104482, Fax : 040 - 29706486.
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