Transcript High Energy Neutron Detector for Martian Odyssey 2001

Numerical
modeling of neutron
spectra above the Martian
surface
(preliminary results)
Krylov A.R., Shvetsov V.N.,
Timoshenko G.N.
141980, JINR, Dubna, Russia
WS HEND2002
“The First year of HEND
operation
Soil model
• Four elements: Si, O, Fe, H
• Elements percentage [i]:
– O – 56.7 w. %
– Si – 26.6 w. % + H2O
– Fe – 16.7 w. %
Joseph Masarik and Robert C. Reedy Journal of Geophysical
Research, vol.101, No. E8, p.p. 18,891-18,912, August 25,
1996.
WS HEND2002
“The First year of HEND
operation
Soil X-sessions
Mean free path, cm
Neutron mean free pathes for soil and water
10
1
10
0
10
-1
Soil
H2O
10
-10
10
-9
10
-8
10
-7
10
-6
10
-5
10
-4
10
-3
10
-2
10
-1
10
0
10
Е, MeV
Soil & water densities = 1 g/cm3
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“The First year of HEND
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1
GCR
Astroparticle Physics,
16(2001), 13-46
RUNJOB
Collaboration
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“The First year of HEND
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GCR
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Computer Codes
• LAHET (Los Alamos High
Energy Transport), Bertini
model for intranuclear
cascade
+
• MCNP4B (Monte Carlo NParticle)
WS HEND2002
“The First year of HEND
operation
Neutron Spectra on 400 km
Orbit
Neutron spectral flux density on 400 rm orbit
1000000
1000000
Water 0%
Water 5%
Water 50%
Water 100%
100000
-2
Neutron spectra, cm *MeV
-1
10000
100000
10000
1000
1000
100
100
10
10
1
1
0,1
0,1
per 1 incident GCR proton
0,01
0,01
1E-3
1E-9
1E-3
1E-8
1E-7
1E-6
1E-5
1E-4
1E-3
0,01
Neutron energy, MeV
WS HEND2002
“The First year of HEND
operation
0,1
1
10
Neutron Spectra on 400
km Orbit
Number of neutrons in energy bins & HEND Sensitivity
0,1
0,01
2
1
1E-3
1E-4
1E-5
1E-6
1E-9
1E-8
1E-7
1E-6
1E-5
1E-4
1E-3
0,01
Neutron energy, MeV
WS HEND2002
0,1
MD
SC
Water 0%
Water 5%
Water 50%
Water 100%
“The First year of HEND
operation
0,1
1
10
Sensitivity, cm
Number of neutrons in energy bin
On 400 km orbit, per 1 incident GCR proton
Neutron Spectra on 400
km Orbit
HEND sensors count rates (calculated)
Count rate, a.u.
0,1
SC
LD
MD
SD
0,01
1E-3
0
20
40
60
Water content, w %
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“The First year of HEND
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80
100
Neutron Spectra on 400
km Orbit
HEND sensors count rates ratios (calculated)
Count rates ratio
1
0,1
MD/SC
SD/SC
MD/LD
SD/MD
0,01
0
20
40
60
Water content, w %
WS HEND2002
“The First year of HEND
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80
100
CONCLUSION, PERSPECTIVES
• Taking into account the modulation of
GCR flux due to Solar activity
• Comparison of the results, obtained
with different computer codes
(different models) & data libraries
• Soil content specification
• Importance of the “Ratio’s”
information
WS HEND2002
“The First year of HEND
operation