1. INTEGRAL Satellite on Oct 28th 2003

2. INTEGRAL Satellite on Oct 28th 2003

3. Tsumeb, Namibia 17.6E, 19.1S, 1240m, Air mass : 890 g/cm2
Conditions at the event time
　・ Zenith angle : 9.5°
　・ Air mass : 902 g/cm2

4. Tsumeb Neutron Monitor on Oct 28th 2003
6.4σ
Excesses were seen between 11:05 – 11:15UT.
The statistical significance for 10 minutes is 6.4σ.
Assuming that the solar neutrons were produced at 11:05UT, the energy of solar neutrons were >100MeV.
Calculate the energy spectrum of solar neutrons (solar surface)
・ Attenuation : Shibata Program (Shibata et al., 1994)
・ Detection Efficiency of NM : Clem & Dorman (2000)

5. solar neutrons (>100MeV) : 3.1×1025 [erg/sr]
Neutron Spectrum
on Oct 28th 2003
(Tsumeb NM)
Power index
= – 3.6 ± 0.3
100MeV
= (3.1 ± 1.0)×1027
[/MeV/sr]
Total energy flux of
solar neutrons (>100MeV) : 3.1×1025 [erg/sr]

6. Solar neutrons were produced at
INTEGRAL Satellite
on Nov 4th 2003
Peaked at 19:45UT ⇒
Solar neutrons were produced at
19:45UT

7. Haleakala, Hawaii 2003/11/4 19:45UT ・ Zenith angle : 50.5°
203.7E, 20.7N, 3030m, 707 g/cm2
18m2 Neutron Monitor
2003/11/4 19:45UT
・ Zenith angle : 50.5°
・ Air mass : 1112 g/cm2
Mexico City, Mexico
260.8E, 19.3N, 2274m, 780 g/cm2
4m2 Solar Neutron Telescope
2003/11/4 19:45UT
・ Zenith angle : 40.5°
・ Air mass : 1026 g/cm2

8. Neutron Monitor on Nov 4th 2003
5.3σ
Clear excesses were seen between
19:46 – 20:01 UT
7.5σ
Clear excesses were seen between
19:45 – 20:00 UT
3.3σ
5.2σ

9. Haleakala Neutron Monitor on Nov 4th 2003
5.3σ
Clear excesses were seen between 19:46 – 20:01UT.
The statistical significance for 15 minutes is 7.5σ.
Assuming that the solar neutrons were produced at 19:45UT, the energy of solar neutrons were 59 – 913MeV.
Assuming that the solar neutrons were produced at 19:45UT, the energy of solar neutrons were 59 – 913MeV.
Solar neutrons in this energy range can penetrate to the ground through the earth’s atmosphere.
From the time profile of the neutrons, we have calculated the energy spectrum of solar neutrons at the solar surface using Shibata program and the efficiency of neutron monitor calculated by Clem.
Calculate the energy spectrum of solar neutrons (solar surface)
・ Attenuation : Shibata program (Shibata et al., 1994)
・ Detection Efficiency of NM : Clem & Dorman (2000)

10. Neutron Spectrum on Nov 4th 2003 (Haleakala NM) Power index
= – 3.9 ± 0.5
Flux at 100MeV
= (1.5 ± 0.6)×1028
[/MeV/sr]
(χ2/dof = 0.92/3 = 0.31)
Assuming that solar neutrons were produced at 19:45UT, the energy spectrum of solar neutrons produced at the solar surface is well fitted by a power law with index –3.9.
(The total energy flux of solar neutrons detected between 59 and 913MeV is 3.4 times 10 to the 26 erg/sr.)
This power index is typical value for solar neutron events observed thus far.
In this calculation, we assumed that solar neutrons were produced at the peak time of gamma-rays, however, gamma-rays were emitted for 4 minutes.
Thus we simulated the time profile of solar neutrons at the neutron monitors assuming that solar neutrons were produced with the same time profile as the gamma-ray emission.
Total energy flux of
solar neutrons
(59 – 913MeV) :
3.4×1026 [erg/sr]

11. Neutron Time Profile on Nov 4th 2003 Power index = – 3.9 ± 0.5
Haleakala NM
Power index
= – 3.9 ± 0.5
Flux at 100MeV
= (1.5 ± 0.6)
×1028[/MeV/sr]
Mexico NM
・ Attenuation :
Shibata program
・ Efficiency of NM :
Clem & Dorman
・ Efficiency of SNT :
GEANT3
FLUKA-COLOR
Hawaii SNT