This document summarizes a seminar presentation on detecting radon concentration using an air flow meter. It includes: - An introduction to radon and its health effects - The aim of determining radon progeny concentration in the atmosphere - A description of how an air flow meter works to draw air through a filter paper at a known rate - The procedure of collecting aerosols on the filter paper and measuring alpha particle emissions - Calculations using the Tsivoglou method to determine radon progeny concentrations from counting rates - Results showing progeny concentrations increased with humidity

1. SEMINAR ON
DETECTION OF RADON
CONCENTRATION USING AIR FLOW
METER
Presented by,
Priya H.P
2nd M.Sc, 4th semester
Department of Studies in Physics,
Manasagangotri
Mysore

2. CONTENTS
 INTRODUCTION
 AIM
 AIR FLOW METER
 WORKING
 PROCEDURE
 INSTRUMENTATION
 MEASUREMENTS AND CALCULATIONS
 RESULTS
 REFERENCES

3. INTRODUCTION
 There is a wide range of sources of natural radiation
for which we are being continuously exposed.
 Radon was discovered in 1900 by Friedrich. E. Dorn
in Eastern Pennsylvania.
 It was named ‘niton’ in 1908 by Ramsay and Gray
because of its luminosity.
 Concentration of radon in an area is governed by the
radium content in the minerals, radon emanating
power in the materials, permeability of the soil and
the underlying rock, and moisture content of the soil .
 Radon and its progeny are responsible for about 45 %
of radiation exposure received by the world
population from natural sources.

4. AIM
Determination of Radon progeny concentration
in the atmosphere

5. AIR FLOW METER
 Air flow meter consists of 15 cm long and 1 cm
diameter tube made up of Perspex.
 The tube is embedded in a Perspex block of
square cross section of side 3 cm.
 A scale is marked on the block to enable the flow
rate – reading in units of liters per minute.
 At one end of the tube a metallic device is
provided for fixing the filter paper and a means
to control the air flow.
 At the other end there is a provision for
connecting an air pump.
 A steel ball is placed inside the tube. The
position of the ball indicates the air flow rate.

6. Air flow rate
Indicator
Air Sucking by vacuum
pump
Filter paper
Holder
Flow rate
Adjustment
Screw
SCHEMATIC REPRESENTATION OF AIR FLOW
METER

7. MEASUREMENTS
 In this method we collect the aerosols which are
attached, at a height of one meter from the earth
surface on a filter paper.
 A glass microfibre filter paper (Whatmann, 2000,
2.5 cm diameter) is fixed to the holder of the air
flow meter
 A vacuum pump is connected to the top end of the
tube.
 The air is drawn through a glass fiber filter paper
by means of suction pump at known flow rate for a
period of 30 min.
 Here we have considered the flow rate to be 40 ltrs
per minute.

9. WORKING
 The radon progeny which are metallic ions present in
the atmospheric air gets attached to the aerosol particles.
 When air is sucked through a glass fiber micro filter
paper at a known flow rate for a typical period they are
retained on the filter paper.
 These radon progeny are also radioactive and emit alpha
particles and their activities are counted using Alpha
scintillation counter

10. INSTRUMENTATION
 A number of organic and inorganic substances have
found wide use as scintillations.
 Here ZnS (Ag) phosphor is used for alpha radiation.
 In this study, the alpha counting system (ACS 4004),
made by Electronic Corporation of India Limited
with Alpha Probe SP647A was used to measure the
alpha activity in the environmental samples.
 The measurement of concentrations of radon and its
progeny depends on the detection of alpha particles
emitted by them.
 As such an alpha counting system is an integral
part of measuring devices of radon and its progeny.

11. ALPHA
SCINTILLATION
DETECTOR
E. H. T. PRE-
AMPLIFIER
Pulse
shaper
scaler
gate,
timer
Block diagram of Alpha counting system.

13. CALCULATIONS
 Several methods have been developed for the
measurement of radon daughters such as two
filter method, Tsivoglou method, Thomas
method, Kusnetz’s method (using active devices)
and twin cup dosimeter method employing
SSNTD technique (passive devices).
 Here we are using Tsivoglou method.
 Tsivoglou method was done by Thomas and
LeClarec (1970).
 In our work radon progeny concentrations in
atmosphere have been estimated by the modified
Tsivoglou method (Raghavayya, 1998).

14. Activities of RaA, RaB and RaC are calculated using
the modified equations,
)m(Bq
)(949949.1)(062417.2)(249019.4 3321 

VE
CCC
RaA
(mWL)
)(037053.0)(019335.0)(048445.0 321
VE
CCC
Rd


)m(Bq
)(502945.0)(371319.0)(215175.0 3321 

VE
CCC
RaC
)m(Bq
)(240618.0)(006232.0)(355129.0 3321 

VE
CCC
RaB
Where,
C1, C2 and C3 are the gross counts during the three
counting intervals
E is the efficiency of alpha counting system (30%)
V is the sampling rate in liters per minute (LPM)
Rd is the concentration of radon progeny (mWL)

15. TIME RnA RnB RnC mWL HUMIDITY
7.30-8.30AM 0.623±0.000 0.446±0.004 0.458±0.009 0.056±0.01 79%
9.00-10.00AM 0.646±0.000 0.235±0.005 0.271±0.010 0.033±0.001 79%
12.30-1.30PM 0.407±0.000 0.243±0.005 0.386±0.011 0.026±0.001 92%
17-02-2013
02-03-2013
TIME RnA RnB RnC mWL HUMIDITY
10.30-
11.30AM
0.520±0.000 0.188±0.005 0.275±0.010 0.025±0.001 79%
100-2.00PM 5.294±0.061 0.091±0.004 0.082±0.008 0.132±0.001 94%
2.30-3.30PM 1.723±0.061 0.269±0.005 0.069±0.000 0.057±0.001 97.5%
8.17-9.17PM 21.442±0.047 0.285±0.003 0.000 0.438±0.001 94%

16. TIME RnA RnB RnC mWL
8.15 - 9.15 AM 0.870±0.049 1.257±0.003 1.491±0.008 0.214±0.001
1 PM – 2 PM 2.648±0.037 0.268±0.003 1.646±0.007 0.236±0.001
3.15 – 4.15 PM 1.678 ±0.041 0.334 ± 0.004 1.340 ± 0.008 0.169 ± 0.001
9.15–10.15 PM 3.774 ±0.043 0.258 ± 0.003 0.892 ± 0.007 0.213 ± 0.001
03.03..2013

17. RESULTS
It was observed that the concentration of Radon
progeny increased with meteorological changes
ie., increases with the increase in the humidity in
the atmosphere and vice versa.

18. REFERENCE
STUDIES ON NATURAL RADIOACTIVITY AND
ELECTRICAL PARAMETERS OF THE
ATMOSPHERE AT MYSORE by Mrs. RAGINI .N
(2010)

19. THANK YOU