Tidal effect in the Radon-due neutron
flux from the Earth’s crust
Yuri Stenkin & Victor Alekseenko
for the Baksan group
Institute for Nuclear Research, Russian Academy of Sciences
E-mail: [email protected]
Let me start from A and B.
A. Starting hypotheses : There exists gravitational influence of Moon
on variation of Radon concentration in the crust (global crust
effect)
B.
Radon-due neutron production mechanism
Sun – Earth - Moon Gravitation tidal effect
A
!
Variation of Radon
concentration in
terrestrial crust
trigger mechanism
for EarthQuakes
B
?
variation of thermal neutron flux
Yu. V. Stenkin. TAUP’09, July 3,
2009
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Schematic picture of what we detect.
Radon-due neutron production mechanism
Yu. V. Stenkin. TAUP’09, July 3,
n-detector 2009
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Detector of thermal neutrons.
From 2003 year, INR RAS
•! Nuclear reaction in use:
6Li + n ! 3H + ! + 4.78 Mev
6LiF+ZnS(Ag)
~160000 light photons
per a capture
•! Resulting particles produce in ZnS
(Ag) scintillations which are
recorded by PMT of 6” diameter.
•! Counting Rate on surface ~0.5 / sec
•! 5-min CR points, day after day, during
months..
Yu. V. Stenkin. TAUP’09, July 3,
2009
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Advantages
•! The detector measures thermal and epithermal neutrons
•! Due to thin scintillator its efficiency follows " ~1/v law
•! Measured flux F = Cv" ~ C, where C is the neutron concentration
and v#2200 m/s is mean thermal neutron velocity
The detector is practically insensitive to radon concentration in air
and thus it is insensitive to ventilation of underground room where
it is working. It is sensitive to radon concentration in several meters
of rock outside the room.
It needs not any service while running and its stability depends only
on the HV stability. It is intended for long-term measurements.
Yu. V. Stenkin. TAUP’09, July 3,
2009
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Baksan experiment – where.
Experiment is going at Baksan Neutrino Observatory, INR RAS.
North Caucasus, Elbrus region, 43" N, ~ 1700 m a.s.l.
Yu. V. Stenkin. TAUP’09, July 3,
2009
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•! Measurements are carried out in two sites:
1). 2.5 m above ground level
2). ~400 m below ground level (~1000 m of w. e.)
Yu. V. Stenkin. TAUP’09, July 3,
2009
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It is naturally to expect - following the starting
gravitational hypothesis and the Radon-due-neutron
production mechanism - an existence of variations
of thermal neutron flux from terrestrial crust.
Hence, it was also naturally to apply a frequency
analysis (Fast Fourier Transformation )
to accumulated data to search for some well-known
periodicities arising from well developed theory of
Moon-Earth-Sun dynamics:
- semi-diurnal variations
- variations with moon month periods
--------------------------------------------------------------------Results of frequency analysis of thermal neutron flux above
ground level are following:
Yu. V. Stenkin. TAUP’09, July 3,
2009
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1). Lunar month periodicities (meteo corrected data)
Anomalistic, Ta = 27.55 d Draconic, Td = 27.21 d Synodic, Ts = 29.53 d
Yu. V. Stenkin. TAUP’09, July 3,
2009
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Semi-diurnal periodicities (not meteo corrected data)
S2 = 12.003±0.007 hour.
M2 = 12.384±0.007 hour, K2= 11.950±0.006 hour,
Yu. V. Stenkin. TAUP’09, July 3,
2009
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If observed semi-diurnal and month periodicities are really due to
gravitational influence of Moon, then
a question arises : is it possible to construct some adequate math
model for observed variations?
ADS model (V. Alekseenko)
An essence of model :
description of changing in time of gravitational forces
in terms of amplitudes and phases of fixed basic periods of Moon
rotation around Earth:
Anomalistic, Draconic, Synodic.
We fit the observed day-after-day variations of Counting Rate by
superposition of sinusoidal functionals corresponding to basic
periods:
CRmod(t) ~ (1+ A(t,#a)
)·(1+ D(t,#d) )·( 1+ S(t,#s) ) -1
Yu. V. Stenkin. TAUP’09, July 3,
2009
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Comparison of experiment with model fit
2004 year
R=0.80
2006 year
R=0.89
2004-06 yy
1.5 year
R=0.79
Large enough R-values makes us free with inference that observed long-term variations might
be in principle caused by gravitational tidal force.
Yu. V. Stenkin. TAUP’09, July 3,
2009
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Comparison of experiment with model fit (continued)
Yu. V. Stenkin. TAUP’09, July 3,
2009
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What could one expect when measuring
neutron flux/concentration underground?
$air # 100 ms; $rock # 1 ms
Yu. V. Stenkin. TAUP’09, July 3,
2009
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2). Underground (1000 m w.e.).
Crust effect : No atmospheric neutrons and No Meteorology.
Yu. V. Stenkin. TAUP’09, July 3,
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Seasonal effect
Yu. V. Stenkin. TAUP’09, July 3,
2009
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Yu. V. Stenkin. TAUP’09, July 3,
2009
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Diurnal variations
(superposed epoch analysis for the mean day waves)
Yu. V. Stenkin. TAUP’09, July 3,
2009
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Semi-diurnal variations
Yu. V. Stenkin. TAUP’09, July 3,
2009
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Absolutely another behaviour can be seen
in gamma-rays
E%>0.6 MeV
Yu. V. Stenkin. TAUP’09, July 3,
2009
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Solar day
Yu. V. Stenkin. TAUP’09, July 3,
2009
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Global crust effect.
4th harmonic of Synodic period for Radon emission and neutron flux
•!
Direct
measurements of
Radon
concentration
Russia, Far East,
Kamchatka
Long = 160° E
Baksan Neutrino
Observatory
thermal neutron flux
North Caucasus
Long = 43° E
Yu. V. Stenkin. TAUP’09, July 3,
2009
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Variation of thermal neutron flux vs seismic activity
So, if we adopt and combine together three premises :
i) tidal effect results in variation of concentration of Radon in
the crust
ii) Radon-due neutron flux does exist
iii) tidal trigger mechanism for EQs works
then ought to be correlation between thermal neutron flux and
seismic activity.
Yu. V. Stenkin. TAUP’09, July 3,
2009
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Abnormal behavior of neutron flux on May 2, 2004.
Local North Caucasus seismic activity and full Moon
Yu. V. Stenkin. TAUP’09, July 3,
2009
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Conclusion
1. A novel experimental approach to record variations of Radon
concentration is presented. The method is based on the
recording of thermal neutron flux from the crust.
2. For the first time the experimental evidence of thermal
neutron flux variations connected with Moon periods (Radondue neutron tidal waves) has been established.
3.The methods may be used in:
•!
applied geophysical researches as a part component of the
seismic station net, for Radon-neutron monitoring of environment
and of global Radon-neutron Earth’s field.
•! low background experiments
•! environmental radiation monitoring.
4. The neutron background flux deep underground has
seasonal, diurnal and even tidal variations.
Thank you !
Yu. V. Stenkin. TAUP’09, July 3,
2009
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Yu. V. Stenkin. TAUP’09, July 3,
2009
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Where the topic came from.
Kuzhevskij B.M., Nechaev O.Yu., Panasyuk M.I. et al.
Studies of the distribution of neutral and charged cosmic ray components in the
atmosphere of the Earth. Preprint INP MSU 91-38/242, 1991.
And also :
- Phenomenon of Neutron Intencity Bursts duiring New and Full Moons.
N.N.Volodichev, B.M.Kuzhevskij et al.
Cosmic research Vol.35, No 2, 1997, pp. 135-143.
- Neutron flux variations near the Earth’s crust. A possible tectonic activity detection.
B.M.Kuzhevsky et al.
Natural Hazards and earth System Sciences (2003) 3: 637 – 645.
- On the Relationship of the Time Variation of Surface Radon (222Rn)
and Hidrogen to Seismicity in Kamchatka in July-August 2004.
P.P. Firstov et al.
Vulcanologia i Seismologia, 2006, No. 4, pp. 1- 11.
Yu. V. Stenkin. TAUP’09, July 3,
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