1. Search for solar neutrons associated with proton flares in solar cycle 23 Yutaka Matsubara (presenter) Solar-Terrestrial Environment Laboratory, Nagoya University August, 2005, Pune 29th International Cosmic Ray Conference

2. Authors Y. Matsubara 1, Y. Muraki 1, T. Sako 1, K. Watanabe 1, S. Masuda 1, T. Sakai 2, S. Shibata 3, E. Flückiger 4, R. Bütikofer 4, A. Chilingarian 5, G. Hovsepyan 5, Y. H. Tan 6, T. Yuda 7, M. Ohnishi 7, H. Tsuchiya 8, Y. Katayose 9, R. Ogasawara 10, Y. Mizumoto 10, M. Nakagiri 10, A. Miyashita 10, A. Velarde 11, R. Ticona 11, and N. Martinic 11 (1)Solar-Terrestrial Environment Laboratory, Nagoya University (2) College of Industrial Technologies, Nihon University (3) College of Engineering, Chubu University (4) Physikalisches Institut, University of Bern (5) Yerevan Physics Institute (6) Institute of High Energy Physics, Chinese Academy of Science (7) Institute for Cosmic Ray Research, University of Tokyo (8) RIKEN (9) Facaulty of Engineering, Yokohama National University (10) National Astronomical Observatory of Japan (11) Institoto de Investigaciones Fisicas, Universidad Mayor de San Andres

3. Contents 1. Motivation 2. Solar neutron telescopes 3. Solar neutrons associated with proton flares 4. Summary

4. 1. Motivation

5. Soft X-rays versus Protons S12W83 X-class proto n Aug1 7 Aug1 8 Aug1 9 Apr1 0 Apr1 1 Apr1 2 2004 S14W47

6. Soft X-rays versus Protons Jul2 6 Jul2 7 Jul28 2005 East limb Where do these protons come from ?

7. X-class flares without protons 971127 1259 X 2.6 2B N17E63 8113 980818 2210 X 4.9 1B N33E87 8307 010825 1623 X 5.3 3B S17E34 9591 011213 1420 X 6.2 3B N16E 9 9733 020520 1521 X 2.1 2N S21E65 9961 020703 208 X 1.5 1B S20W51 17 020723 18 X 4.8 2B S13E72 39 020830 1247 X 1.5 SN N15E74 95 030611 2001 X 1.6 1N N14W59 375 031103 943 X 3.9 2F N 8W77 488 040716 1349 X 3.6 3B S11E35 649 040818 1729 X 1.8 SF S12W83 656

8. What do we search for ? To detect solar neutrons: in the past →We investigated large flares in X-rays To detect solar neutrons: in this work →We investigate proton flares

9. 2. Solar neutron telescopes

10. World-wide Solar Neutron Telescopes

11. Summary of solar neutron telescopes Solar neutron telescopes are at good places to observe high energy protons !

12. Typical Solar Neutron Telescope n p

13. 3. Solar neutrons associated with proton flares

14. GLE: April 2001 Oulu: April 2001 Counting rate increase (%) 40 0

15. April 18, 2001 GOE S Soft-X >10MeV >50MeV>100MeV 3 days Proton Apr1 7 Apr1 8 Apr19 X-class

16. Oulu: 010418 >10% increase around 3 UT

17. GOES Proton vs Neutron Monitor: 010418 39 － 82MeV Oulu (0.8GV ) 84 － 200MeV 110 － 500MeV Higher energy channels increase more rapidly than lower energy channels !

18. Position of the Sun 010418 3:30 UT

19. Norikura vs Tibet: 010418 Norikura >20MeV Tibet >40MeV Both increse around the same time as Oulu

20. Norikura vs Oulu vs Goes-p: 010418 Norikura (>20MeV) Oulu (0.8GV ) GOES-p(110 － 500MeV) Norikura increased later than others

21. [ Expected ] neutron>Oulu>GOES-proton [ Obtained ] Oulu>GOES-proton>neutron The Gornergrat and Aragats stations (night) also show increases !!!

22. 010418 (Norikura, Tibet, Gornergra, Aragats) Norikura >20MeV Tibet >40MeV Gornergrat >40MeV Armenia >40MeV

23. 4. Summary

24. Several solar neutron telescopes show similar time profiles of counting rates on ・ March 31, 2001 ・ April 15, 2001 (GLE event) ・ April 18, 2001 (GLE event) ・ October 29, 2003 (GLE event) ・・・・・・ At the moment, no indication of solar neutrons has been detected, but ……

25. Summary ・ Solar neutrons have been searched for associated with proton flares by using solar neutron telescopes. (also high energy protons) ・ So far, only indications of high energy protons have been accumulated. This study is in progress for events obtained during Solar Cycle 23.

26. End Thank you very much for your attention !

28. List of Ground Level Enhancement November 6, 1997 X9.4 May 2, 1998 X1.1 August 24, 1998 X1.0 June 14, 2000 X5.7 April 15, 2001 X14.0 April 18, 2001 M1.3??? November 4, 2001 X1.0 December 26, 2001 M7.1 August 24, 2002 X3.1 October 28, 2003 X17.0 October 29, 2003 X10.0 January 20, 2005 X7.1 by Oulu NM

29. Neutrons are attenuated in the air 1. Solar neutron telescopes should be at high mountains. near the equator. for charged particles: opposite 2. Solar neutron telescopes should be operated at different longitudes.

30. Location of neutron monitors 1 10 1

31. Solar neutron telescope can 1. measure energy of neutrons (nm: weak) 2. measure direction of neutrons (nm: never) 3. discriminate neutrons from protons (nm: never)

32. Understanding from solar neutron telescopes Time and duration of neutron production Total energy of high energy neutrons Relation between neutron observation and flare position Acceleration time of ions Efficiency of acceleration Direction of acceleration Directly connected with ion acceleration Observation Acceleration model

33. Ground Level Enhancement: 000714 15% July 2000 14 日

34. July 14, 2000 GOE S Soft-X Proton >10MeV X5.7 >50MeV >100MeV 3 days Jul13Jul14Jul15 X-class

35. GOES X-ray vs Proton 40 － 80MeV X-ray 80 － 165MeV 165 － 500MeV Soft X-rays started earlier than protons

36. GOES Proton vs Neutron Monitor 40 － 80MeV NM: Apatity (0.65GV ) 80 － 165MeV 165 － 500MeV Higher energy channels increase more rapidly than lower energy channels

37. GOES vs Neutron Monitor: 000714 X-ray Apatity 165 － 500MeV Start time of increase of counting rate: (1) X (2) NM (3) GOES-proton

38. March 31, 2001 GOE S Soft-X >10MeV >50MeV >100MeV 3 days Proton Mar3 0 Mar3 1 Apr1 X-class

39. Norikura vs Tibet vs Goes-p: 010331 Norikura (>20MeV) GOES-p(10 － 40MeV) Norikura & Tibet increase later than GOES-p Tibet (>40MeV)

40. 010331 (Norikura, Tibet, Gornergra, Aragats) Norikura >20MeVTibet >40MeV Gornergrat >40MeV Armenia >40MeV

41. April 15, 2001 GOE S Soft-X >10MeV >50MeV >100MeV 3 days Proton Apr1 4 Apr1 5 Apr1 6 X-class

42. Gornergrat vs Oulu vs Goes-p: 010415 Oulu(0.8GV) GOES-p(84 － 200MeV) Gornergrat increased most rapidly Gornergrat (>40MeV)

43. 010415 (Norikura, Gornergrat, Aragats) Norikura >20MeV Gornergrat >40MeV Armenia >40MeV

44. June 18, 2003 GOE S Soft-X >10MeV >50MeV >100MeV 3 days Proton Jun1 7 Jun1 8 Jun1 9 X-class

45. Oct 29, 2003 GOE S Soft-X >10MeV >50MeV >100MeV 3 days Proton Oct2 8 Oct2 9 Oct3 0 X-class

46. Gorner. vs Nor. vs Oulu vs Goes-p: 031029 Oulu(0.8GV) GOES-p (15-40MeV) Gornergrat and GOES-p behave similarly Gornergrat (>40MeV) Norikura >20MeV

47. 031029 (Norikura, Tibet, Gornergrat, Aragats) Norikura >20MeV Gornergrat >40MeV Armenia >40MeV Tibet >40MeV

48. List of >M flare around 010418 010409 1520 M 7.9 2B S21W04 9415 010410 0506 X 2.3 3B S23W09 9415 010411 1256 M 2.3 1F S22W27 9415 010412 0256 M 1.3 1N S22W38 9415 010412 0939 X 2.0 SF S19W43 9415 010414 1715 M 1.0 SF S16W71 9415 010415 1319 X 14.0 2B S20W85 9415 010420 0501 M 1.0 1F N16E63 9433 010420 1951 M 4.1 1F N15E55 9433 010422 2037 M 3.2 1N N14E18 9433 010423 0119 M 1.0 1F N18E18 9433 010423 2015 M 4.0 2N N14E23 9433 010424 0533 M 2.1 1N N18E01 9433