1. ATUL JAIN (CRL-TIFR, Ooty) on behalf of GRAPES-3 Collaboration
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2. Motivation
In past there have been reports of variation in the flux of g-rays during
the Total Solar Eclipse (TSE)
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3. g-ray flux during TSE of 24 October 1995 at Kolkata, India
100 cm3 NaI(Tl) detector
A. Bhattacharyya et al., Astrop. Space Sci. 250 (1997) 313
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4. g-ray flux during PSE of 11 August 1999, Istanbul, Turkey
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5. Constraints on Earlier Observations
Observations were based on measurements from a single detector experiments.
Instrumental errors and fluctuations could significantly influence the outcome.
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6. g-ray flux during TSE of 1 August 2008, Novosibirsk, Russia
Two Identical NaI(Tl) crystal detectors and signal processing instruments were used for g-ray flux measurements at Novosibirsk Russia.
Also carried out concurrent measurements of temperature and humidity.
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7. TSE experiment at BINP, Novosibrisk on 1 August, 2008
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8. Variation in g-ray flux before, during and after the eclipse
Integrals counts in the energy region
keV.
Excellent correlation.
Small statistical errors.
Just prior to eclipse, a drop in flux of
~4% with subsequent sudden
increase in flux of ~9%
Throughout eclipse, a steady decline
of flux of ~4 %
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9. Comparison with neutron monitor data
Neutron monitor data shows a flat
distribution, rms spread of ~0.4%.
Our data shows rms spread of ~1.5%
nearly 4 times larger
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10. 16 Dec, 2010
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11. Limitations of all past observations: Single location measurement.
Influence of atmospheric and local phenomenon could plays a significant role in generating observed variation.
Highlight of Present observation
For TSE 2009 measurements were carried out at two widely separated locations along the path of totality with identical detectors and signal processing equipment.
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12. Geomagnetic Cutoff rigidity (GV)
Eclipse of the Century
The Earth will not see such a long duration TSE in the next century.
The TSE began in India, passing through South Asia into China and reaching a maximum duration of 6 minutes and 39 seconds near Japan’s Ryukyu Islands.
City of India
Average cloud in July
(calc. in %ge)
Avg. Rainy Days in July
Duration of Totality
Geomagnetic Cutoff rigidity (GV)
Surat 78 19
194 s
18.77
Indore* 16
185 s
17.66
Bhopal 85 20
189 s
17.14
Varanasi 71
> 16
181 s
15.70
Patna 79
224 s
15.36
Siliguri* 84 24
227 s
14.59
Dibrugarh 86
215 s
13.67
Total solar eclipse on 22 July 2009
In view of accessibility and excellent infrastructure facilities at RRCAT, Indore and North Bengal University, Siliguri, it was decided to carry out this experiment at Indore and Siliguri
Criteria for selection of the experimental sites

13. 22 July 2009 TSE in India
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14. Experimental Set Up NaI Crystal PMT Pre-Amplifier Spectroscopic
LAPTOP
NaI Crystal
PMT
Pre-Amplifier
Spectroscopic
Amplifier
MCA
LAPTOP
NaI Crystal
PMT
Pre-Amplifier
Spectroscopic
Amplifier
MCA
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15. 16 Dec, 2010

16. Effect of lead shielding
40K
208Tl
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17. Charged Particle Measurements
Plastic Scintillator
coupled with PMT
through WLS
Discriminator
INTEGRATED
COINCIDENCE UNIT
AND
SCALER
Plastic Scintillator
coupled with PMT
through WLS
Discriminator
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18. Charged Particle Detectors & DAQ
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19. Complete experiment pic
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20. Independent measurements
15th July,2009
16th July,2009
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21. Calibration using Cs137, Co60
661KeV
1173KeV
1332KeV
2505KeV
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22. Daily on site Monitoring
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23. Variation in g-ray flux in three different days
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24. Variation in g-ray flux on 22nd July,2010
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25. 16 Dec, 2010
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26. Summary
g-ray flux measured during July 2009 at Indore and Siliguri including the day of TSE on 22 July 2009.
At each location measurements with two identical setup to ensure full redundancy.
1400 km distance between the two sites to exclude local effects
Rain just before and after TSE introduced severe g-ray flux variation making it difficult to detect variation due to TSE.
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27. THANKS
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