Avg Count Increase (%)...tor detectors. •In addition to that, all scintillator detector rates...
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M EASUREMENT OF R ADON BY GRAPES-3 P LASTIC S CINTILLATOR D ETECTORS Meeran Zuberi on behalf of GRAPES-3 collaboration, Cosmic Ray Laboratory, Ooty T HE GRAPES–3 E XPERIMENT • Located at Ooty, India at 11.4 o N latitude, 76.7 o E longitude and an altitude of 2.2 km amsl. • 400 (1 m 2 ) plastic scintillation detectors with 8 m inter–detector separation. • Tracking muon telescope (560 m 2 ). • Total area covered 25,000 m 2 . • ∼3 million air shower events/day. 12 S EPTEMBER 2018 E VENT Time (min) 500 1000 Avg Count Increase (%) 2 - 0 2 4 Unfiltered Combined • During rain episode, a sudden in- crease is observed in all scintilla- tor detectors. • In addition to that, all scintillator detector rates undergo daily variations due to change in atmo- spheric temperature and pressure. • These daily variations (back- ground) are successfully modeled and removed by using higher order polynomial. 0 200 400 600 Avg Count Increase (%) 0 2 4 6 8 Time (min) 0 200 400 600 Rain (mm) 0 1 2 3 Set-1 Set-2 Set-3 Set-4 0 200 400 600 Avg Count Increase (%) 0 2 4 6 Time (min) 0 200 400 600 Rain (mm) 0 1 2 3 Cone Type Fiber Type 0 500 Total Counts Increase 0 2 4 6 Time (min) 0 500 Rain (mm) 0 1 2 3 Combined • Half-life(T 1 2 ) is calculated for dif- ferent combination of detectors by fitting it with exponential func- tion. • T 1 2 for four equal detector sets; Set-1 = 21.8 min, Set-2 = 28.1 min, Set-3 = 32.5 min, Set-4 = 25.3 min. • T 1 2 for different detector type ; Cone = 29.3 min, Fiber = 24.9 min. • T 1 2 for all detectors combined; Combined = 26.6 min. S CINTILLATOR D ETECTORS Cone Type Fiber Type R ADON D ECAY C HAIN • Radioactive decay is governed by N=N 0 e -λt λ (decay constant) = 0.693 T 1 2 S UMMARY • The observed half-life clearly indicates the presence of radon decay products such as lead and bismuth isotopes. • The observed data from both cone and fiber type detector show consistent results. However, the cone detector data show an extra feature during decay period of the event which is under investigation. • The study of more such events observed by GRAPES-3 plastic scintillator detectors could lead to a better understanding of radon decay products by using more realistic decay fitting models and hence they can be used as an inexpensive alternative to the inorganic crystal scintillators. R EFERENCES [1] S.K. Gupta et al., Nuclear Instruments and Methods in Physics Research A, 540, 311 (2005). [2] Y. Hayashi et al., Nuclear Instruments and Methods in Physics Research A, 545, 643 (2005). [3] P.K. Nayak et al., Astroparticle Physics, 32, 286 (2010). [4] P.K. Nayak et al., Astroparticle Physics, 72, 55 (2016).
Transcript of Avg Count Increase (%)...tor detectors. •In addition to that, all scintillator detector rates...
MEASUREMENT OF RADON BY GRAPES-3 PLASTIC SCINTILLATOR DETECTORS
Meeran Zuberion behalf of GRAPES-3 collaboration, Cosmic Ray Laboratory, Ooty
THE GRAPES–3 EXPERIMENT• Located at Ooty, India at 11.4oN latitude,
76.7oE longitude and an altitude of 2.2 kmamsl.
• 400 (1m2) plastic scintillation detectorswith 8 m inter–detector separation.
• Tracking muon telescope (560m2).
• Total area covered 25,000m2.
• ∼3 million air shower events/day.
12 SEPTEMBER 2018 EVENT
Time (min)
500 1000
Avg C
oun
t In
cre
ase (
%)
2 −
0
2
4
Unfiltered Combined
• During rain episode, a sudden in-crease is observed in all scintilla-tor detectors.
• In addition to that, all scintillatordetector rates undergo dailyvariations due to change in atmo-spheric temperature and pressure.
• These daily variations (back-ground) are successfully modeledand removed by using higherorder polynomial.
0 200 400 600
Avg
Co
un
t In
cre
ase
(%
)
0
2
4
6
8
Time (min)0 200 400 600
Ra
in (
mm
)
0
1
2
3
Set1
Set2
Set3Set4
0 200 400 600A
vg
Co
un
t In
cre
ase (
%)
0
2
4
6
Time (min)0 200 400 600
Ra
in (
mm
)
0
1
2
3
Cone Type
Fiber Type
0 500
Tota
l C
ounts
Incre
ase
0
2
4
6
Time (min)0 500
Rain
(m
m)
0
1
2
3
Combined
• Half-life(T 12
) is calculated for dif-ferent combination of detectors byfitting it with exponential func-tion.
• T 12
for four equal detector sets;Set-1 = 21.8 min, Set-2 = 28.1 min,Set-3 = 32.5 min, Set-4 = 25.3 min.
• T 12
for different detector type ;Cone = 29.3 min, Fiber = 24.9 min.
• T 12
for all detectors combined;Combined = 26.6 min.
SCINTILLATOR DETECTORS
Cone Type
Fiber Type
RADON DECAY CHAIN• Radioactive decay is governed by
N = N0 e−λt
λ (decay constant) = 0.693T 1
2
SUMMARY• The observed half-life clearly indicates the presence of radon decay products such as lead
and bismuth isotopes.
• The observed data from both cone and fiber type detector show consistent results. However,the cone detector data show an extra feature during decay period of the event which is underinvestigation.
• The study of more such events observed by GRAPES-3 plastic scintillator detectors couldlead to a better understanding of radon decay products by using more realistic decay fittingmodels and hence they can be used as an inexpensive alternative to the inorganic crystalscintillators.
REFERENCES
[1] S.K. Gupta et al., Nuclear Instruments and Methods in Physics Research A, 540, 311 (2005).
[2] Y. Hayashi et al., Nuclear Instruments and Methods in Physics Research A, 545, 643 (2005).
[3] P.K. Nayak et al., Astroparticle Physics, 32, 286 (2010).
[4] P.K. Nayak et al., Astroparticle Physics, 72, 55 (2016).
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