A New Solar Neutron Telescope working at the International Space Station K. Koga, T. Goka (PI), H. Matsumoto, T. Obara, O. Okudaira (JAXA) Y. Muraki (Nagoya) and T. Yamamoto (Konan) The SEDA-AP has been on-board Japan Experimental Module on 16 th July 2009 by the space shuttle Endeavor, and started to take the data from 25th, August. Maybe we have detected solar neutrons from M3.7 flare on 2011 March 7 th at 20:04:54UT (the first detection of solar neutrons by the M-class flares) Paper #370 submitted for the 32 nd China, on August 16 th

contents 1. Scientific purpose of the experiment 2. Detector details 3. Flares on March 7-10 th, Results of the analysis SEDA-AP

1. The scientific purposes of measurement of neutrons at the International Space Station Evaluation of the risk of cosmic rays to the astronauts (Radiation Physics ） (lack on neutron information) Prediction of arrival of the dangerous radiation from the Sun in association with large solar flares (space weather forecast ） Establishment of the acceleration process of solar cosmic rays (solar physics, cosmic ray physics ）

The advantage of neutrons Physics aim is to confirm particle acceleration model at the solar surface. How and When? How are particles accelerated? When are particles accelerated? What is the highest energy of SCR? up to 100GeV? 1TeV? Pure information on the process of proton scceleration at the solar surface We may aboe to confirm the acceleration theory together with the set of other data. Sun Earth Neutron Proton, Ion Magnetic field

2. The details of new neutron detector The energy must be measured for the separation between the impulsive production and the gradual production of protons. The arrival direction must be measured

FIB detector in the Space Environment monitor SEDA The FIB detector can measure the energy and the direction of incoming neutrons by the scintillation fibers. The BBD detector can measure the low energy neutrons less than 30 MeV

3. Flare on Mar.7 th 2011

Fermi-LAT satellite sees the peak at 20:02:30UT

RHESSI data on March 7 th, 2011

4. Results of the analysis We have searched for solar neutrons in association with the M-class flares on March 7 th – 10 th, We have found some increase of neutral events at the peak time of FERMI-LAT satellite and RHESSI satellite hard X-ray and soft gamma-ray emission. We have checked the direction of the tracks, being based on the directional information of the scintillating bar detector They are consistent with protons induced by neutrons from the Sun.

2011/3/7 19:00-22:00 total count Date Begin Max End Class GOES data 07 Mar M3.7 a bump Used as the background study 90 minutes later Event number UT

Satellite Date Begin Max End Class GOES 07 Mar 1:943 20:12 20:58 UT M3.7 RHESSI 19:40 20:05 20:08 FERMI-LAT (20:02) 20:02 20:40 Slightly increase ？ Hard X-ray peaks March 7 20:05UT RHESSI Fermi Event number UT

4-1. Results of the analysis for solar neutrons Search for solar neutrons in association with the M-class flare of the solar flares on March 7 th – 10 th, 2011 We have found some increase of events 4 minutes after the peak time of FERMI-LAT and 2 minutes after RHESSI hard X-ray and soft gamma-ray emissions. We have checked the direction of the tracks, being based on the directional information of the scintillating bar detector They are consistent with protons induced by neutrons from the Sun.

Comparison with flare maximum time and 90 minutes later background Preliminary

4-2. Results of the analysis for solar neutrons Search for solar neutrons in association with the M-class flare of the solar flares on March 7 th – 10 th, 2011 We have found some increase of neutral events at the peak time of FERMI-LAT satellite and RHESSI satellite hard X-ray and soft gamma-ray emission. We have checked the direction of the tracks, being based on the directional information of the scintillating bar detector They are consistent with protons induced by neutrons from the Sun. Statistical significance is 6σ(=46events/√46+17) by Li-Ma statistics.

Summary of the events around 20:04UT of March 7 th, 2011 In asociation with the M3.7 flare of March 7 th, 2011, the SEDA-AP seems to have detected solar neutrons around 20:08 – 20:11UT. E n ~400MeV – 120MeV The statsistical significance is not enough, ( though 6σ by Li-Ma ) We should regard that this event represnts our limit of observation. Therfore we had better wait the next large solar flare in association with GLE.

We are waiting large solar flares and SGRs!!! Thank you for your attention!

Expected Event Rate by Kyoko Watanabe Expected background (for middle latitude) 0.047Hz normal region 1.7Hz over SAA

The counting rate of one orbit

Principle of measurement The energy of neutrons can be measured by the range method. The green box corresponds to the observation target energy (30-100MeV)