Radiation Counting System with Alpha probe for measurement of gross alpha activity/contamination

Radiation Counting System with Alpha probe for measurement of gross alpha activity/contamination [ TYPE : RC 605A ]

Technical Data

RC605A is Highly recommended for gross alpha activity / contamination measurement (in water & other environmental samples) with alpha probe AP165 connected, for Radio analytical labs, Health physic counting labs and Environmental survey labs at Nuclear power stations.

Radiation Counting System essentially has a processor card and other electronic circuits to generate continuously variable HV upto 1500V to be applied to scintillation detector Probes ( α , β , Γ ) or End window G.M.Tube, amplify the detector output and convert them to digital pulses for counting and displaying the recorded counts for a preset time.

Microcontroller design facilitates programmability for background, standard and sample counting. The data can be downloaded into PC or printed directly onto a printer.

System facilitates counting of samples either on planchets or filter paper.

Applications : This system will find applications for counting of air activity, wipe, environmental samples, including air, water (river, lake, pond, ground & sea waters).

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

P.M. Input (From alpha, beta,
gamma scintillation detector probe)
(a) Polarity : Negative
(b) Amplitude : -100 mV (min)
G.M. Input (From G.M.Counter) : (a) Polarity : Negative
(b) Amplitude : -500 mV (min)
(c) Built-in load resistor : 4.7 or 3.3M Ohms
HV Output : HV (0-1500V) @1mA continuously variable through front panel keypad in steps of 1 volt, ripple less than 20mV, line & load regulation better than 0.05%.
HV indication : On LCD dotmatrix provided.
Display : 20 x 2 LCD dotmatrix display has been provided to indicate data counts, Elapsed Time and HV.
Counts Capacity 999999 counts
Preset time 1min to 24 hrs (HH : MM) format
Preset cycles / Iterations : 1 to 10
Command Buttons: START, STOP, PROG, STORE, INC & DEC command buttons have been provided on the front panel key pad.
Paralysis Time : A choice of three paralysis times 250, 350 and 550 micro sec plus OFF position selected through PROG key.
Programmability : Includes selection of Preset Time, Storing / Recalling of data, starting and stopping of acquisition, label assignment for data counts BG (Background), ST (Standard) & SP (sample) etc,.
RTC : Built in RTC provides real time clock information which is stamped in the activity report when printed. Built in Real time clock facillitates the user to generate sample analysis reports with RTC stamping. Both date month & time in hrs and minutes are printed.
Scintillation detector probe socket : This is a UHF socket for connecting to a, b or g scintillation Probe.
G.M. Socket : UHF connector for connecting to G.M. Detector
Printer Port : Built-in centronics port facilitates connection to a printer for direct data printing selectively.
Data Communication Software : (Optional at extra cost) Can be provided for serial transfer of data readings into PC.
PCB Edge Connector : EURO Type.
Inter PCB Connections : Through Mother Board.
Power : Unit is powered through a detachable mains cord. It will draw about 250 mA at 230 volts AC at 50 Hz.
Operating Temperature: 0 to 50oC
Relative Humidity : Upto 90%
Compliance : Instrument will meet all requirements applicable
(a) Manufactured confirming to ANSI N 42.17.
(b) Complies to IS -9000 part III & V, for climatic test.
(c) Complies to Interference test as per IEC61000 or equ. .
Mechanical Dimensions : 250mm(W) X135mm(H)X325mm(D) Approx.

BGD CPM : 0000

CPM OF STD : 00092

DPM OF STD : 00265

EFF. OF STD : 034.7

*FLOW RATE : 01.00

PTIME (BG):0300

PTIME (ST):0300

PTIME (SP) : 0300

0001 BG 11:43 06-09 0000CPM 000180
0002 STD 11:52 06/09 000160CPM 000060 0010dps 26.56% Eff
0003 SP1 11:47 06/09 000196 000060 0000 ml- 0000.00Bq/ml– 01
0004 SP2 11:48 06/09 000180 000060 0001ml– 0009.03Bq/ml– 01
0005 SP3 11:50 06-09 000187 000060 0001ml– 0000.93Bq/ml– 01

Applications:This system can be used for counting α, β or Γ samples on a 25mm dia planchet or 47/50mm dia filter paper obtained from air samplers, or continuous air monitors in a Nuclear facility. System can also used for wipe sample counting in nuclear counting lab of a Nuclear power plant or similar facility. Also this system can be used in a University for teaching lab experiments in a physics department.


Alpha Probe type AP165 manufactured by NUCLEONIX is meant to be used along with Radiation Counting System model RC 605A for counting alpha samples. Radiation Counting System along with Alpha Probe essentially works as an Alpha Counting System.

Alpha Probe of NUCLEONIX make is essentially an integration of ZnS (Ag) scintillator screen, optically coupled to a 2” PMT & covered by a pin hole free aluminized mylar foil to provide, sealing against ambient light. Scintillations received by PMT because of Alpha particles will be converted to electrical charge and inturn to voltage pulses. Each of these events after amplification in the RCS will be counted. The required high voltage is applied (which is typically 900V) through RCS to the Alpha Probe.

Probe has a drawer assembly which facilitates sample placement on sample tray for counting applications. The counting samples are usually deposited on planchets of 25mm diameter or filter paper upto 38mm diameter.

Detector material : Zns (Ag) Screen covered with Aluminized mylar foil.
Density : 10mg/cm 2
Efficiency : 25%
Background counts / 1 Hour: Less than 7 to 8 counts
Photomultiplier tube : PMT of ETL or Hamamatsu make or its equivalent.
Size : 50.8 dia (2″)
Operating Voltage Range : 700 to 900V
Drawer Assembly : Holds both 25mm dia SS planchets or 50mm dia filter paper.

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.


Am241 alpha standard source can be supplied as an optional item. This is an electro deposited source on an SS planchet. Typical activity is in the range of 3000 to 5000 dpm.


(i) Count Net – RS485 based networking software (for multiple systems network).

(ii) Data Communication Software : for data downloading from a single system.

(iii) Dot Matrix Printer : Radiation Counting System has a built-in centronics printer port, it can be directly connected to a printer. Data readings stored in the unit can be downloaded onto the printer (Care should be taken while choosing the printers not all printers are compatible. Please cosult Nucleonix systems for choosing your printer).

MDA=BG (cpm) + {(3*(BG)1/2 )/t}
Where t is the time in minutes
MINIMUM DETECTABLE ACTIVITY (MDA) CALCULATIONS : Minimum Detectable Activity (MDA) calculations for Radiation Counting System (RC605A): For Counting samples:

Example (1) :
What is the MDA for a counter with background of 7 counts in 1 hour?
MDA = {0.1166+ {(3*(7)1/2)/60}
=0.1166+ {(3*2.645)/60}
=0.2488 CPM
=0.004146 CPS.
Thus any gross alpha counts over 0.2488CPM can be considered to be due to radioactivity. That is to say any gross counts above 15 counts per hour can be considered to be due to radioactivity.

To calculate the MDA in terms of Bq, divide by the efficiency of the detector The lower the MDA, the more accurately the activity of samples with low counting rates can be determined. This can be statistically achieved by increasing the counting time and /or by decreasing the BG

Example (2) :
What is the MDA (in Bq) for a counter with background of 7 counts in 60 minutes and an efficiency of 26% for the nuclide of interest?
MDA = {(3*(7)1/2)/60} =0.1322 CPM
=0.1322/0.26 (efficiency) =0.5084 DPM
0.5084 DPM=0.00847 DPS or 0.00847Bq