Search for solar neutrons associated with proton flares in solar cycl

e 23

Yutaka Matsubara (presenter)Solar-Terrestrial Environment Laboratory,

Nagoya University

August, 2005, Pune29th International Cosmic Ray Conference

Authors

Y. Matsubara1, Y. Muraki1, T. Sako1, K. Watanabe1, S. Masuda1, T. Sakai2, S. Shibata3, E. Flückiger4, R. Bütikofer4, A. Chilingarian5, G. Hovsepyan5, Y. H. Tan6, T. Yuda7, M. Ohnishi7, H. Tsuchiya8, Y. Katayose9, R. Ogasawara10, Y. Mizumoto10, M. Nakagiri10, A. Miyashita10, A. Velarde11, R. Ticona11, and N. Martinic11

(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 Scienc

e(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

Contents

1. Motivation

2. Solar neutron telescopes

3. Solar neutrons associated

with proton flares

4. Summary

1. Motivation

Soft X-rays versus Protons

S12W83X-class

proton

Aug17 Aug18 Aug19 Apr10 Apr11 Apr12

2004

S14W47

Soft X-rays versus Protons

Jul26 Jul27 Jul28

2005

East limb

Where do these protons come from ?

X-class flares without protons

971127 1259 X 2.6 2B N17E63 8113980818 2210 X 4.9 1B N33E87 8307010825 1623 X 5.3 3B S17E34 9591011213 1420 X 6.2 3B N16E 9 9733020520 1521 X 2.1 2N S21E65 9961020703 208 X 1.5 1B S20W51 17020723 18 X 4.8 2B S13E72 39020830 1247 X 1.5 SN N15E74 95030611 2001 X 1.6 1N N14W59 375031103 943 X 3.9 2F N 8W77 488040716 1349 X 3.6 3B S11E35 649040818 1729 X 1.8 SF S12W83 656

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

2. Solar neutron telescopes

World-wide Solar Neutron Telescopes

Summary of solar neutron telescopes

Solar neutron telescopes are at good places to observe high energy protons !

Typical Solar Neutron Telescope

n

p

3. Solar neutrons associated with proton flares

GLE: April 2001

Oulu: April 2001

Cou

nti

ng

rate

incr

ease

(%

)

40

0

April 18, 2001

GOES Soft-X

>10MeV

>50MeV >100MeV

3 days

Proton

Apr17 Apr18 Apr19

X-class

Oulu: 010418

>10% increase around 3 UT

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 !

Positionof the Sun

0104183:30 UT

Norikura vs Tibet: 010418

Norikura >20MeV

Tibet >40MeV

Both increse around the same time as Oulu

Norikura vs Oulu vs Goes-p: 010418

Norikura (>20MeV)

Oulu(0.8GV)

GOES-p(110 － 500MeV)

Norikura increased later than others

[ Expected ]

neutron>Oulu>GOES-proton

[ Obtained ]

Oulu>GOES-proton>neutron

The Gornergrat and Aragats stations (night) also show increases !!!

010418 (Norikura, Tibet, Gornergra, Aragats)

Norikura >20MeV Tibet >40MeV

Gornergrat >40MeV Armenia >40MeV

4. Summary

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……

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.

EndEnd

Thank you very much for your attention !Thank you very much for your attention !

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

byOulu NM

Neutrons are attenuated in the air1. 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.

Location of neutron monitors

1

10

1

10

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)

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

Ground Level Enhancement: 000714

15%

July 2000

14 日

July 14, 2000

GOESSoft-X

Proton>10MeV

X5.7

>50MeV

>100MeV

3 days

Jul13 Jul14 Jul15

X-class

GOES X-ray vs Proton

40 － 80MeVX-ray

80 － 165MeV

165 － 500MeV

Soft X-rays started earlier than protons

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

GOES vs Neutron Monitor: 000714

X-ray

Apatity

165 － 500MeV

Start time of increase of counting rate:(1) X (2) NM (3) GOES-proton

March 31, 2001

GOESSoft-X

>10MeV

>50MeV

>100MeV3 days

Proton

Mar30 Mar31 Apr1

X-class

Norikura vs Tibet vs Goes-p: 010331

Norikura (>20MeV)

GOES-p(10 － 40MeV)

Norikura & Tibet increase later than GOES-p

Tibet (>40MeV)

010331 (Norikura, Tibet, Gornergra, Aragats)

Norikura >20MeV Tibet >40MeV

Gornergrat >40MeV Armenia >40MeV

April 15, 2001

GOES

Soft-X

>10MeV

>50MeV >100MeV

3 days

Proton

Apr14 Apr15 Apr16

X-class

Gornergrat vs Oulu vs Goes-p: 010415

Oulu(0.8GV)

GOES-p(84 － 200MeV)

Gornergrat increased most rapidly

Gornergrat(>40MeV)

010415 (Norikura, Gornergrat, Aragats)

Norikura >20MeV

Gornergrat >40MeV Armenia >40MeV

June 18, 2003

GOES

Soft-X

>10MeV>50MeV

>100MeV3 days

Proton

Jun17 Jun18 Jun19

X-class

Oct 29, 2003

GOES

Soft-X

>10MeV>50MeV

>100MeV

3 days

Proton

Oct28 Oct29 Oct30

X-class

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

031029 (Norikura, Tibet, Gornergrat, Aragats)

Norikura >20MeV

Gornergrat >40MeV Armenia >40MeV

Tibet >40MeV

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