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Kaz. Munakata 1 , C. Kato 1 , S. Yasue 1 , J. W. Bieber 2 , P. Evenson 2 , T. Kuwabara 2 ,

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Muon Detector Workshop (17 October, [email protected] Petite Rouge)

GlobalMuonDetectorNetwork

(GMDN)

Kaz. Munakata1, C. Kato1, S. Yasue1, J. W. Bieber2, P. Evenson 2, T. Kuwabara 2,

M. R. DaSilva 3, A. Dal Lago 3, N. J. Schuch 4, M. Tokumaru 5, M. L. Duldig 6, J. E. Humble 6,

I. Sabbah 7,8, H. K. Al Jassar 9, M. M. Sharma 9

GMDN collaboration

1 Shinshu University, JAPAN

2 Bartol Research Institute, USA

3 INPE, BRAZIL

4 CRS/INPE, BRAZIL

5 STE Laboratory, JAPAN

6 University of Tasmania, AUSTRALIA

7 College of Health Science, KUWAIT

8 Alexandria University, EGYPT

9 Kuwait University, KUWAIT

15 people from 9 institutes in 6 countries

working with 4 muon detectors in operation at…

Nagoya,Hobart,São Martinho,Kuwait

(36 m2)(16 m2)(28 m2)(9 m2)

- Ground-based detectors measure byproducts of the interaction of primary Galactic Cosmic Rays (GCRs: predominantly protons and helium nuclei) with Earth’s atmosphere.
- Two types of observation:
- Neutron Monitors
Typical energy of primary:

~1 GeV for solar CRs (GLEs),

~10 GeVfor GCRs

ommidirectional

- Muon Detectors
Typical energy of primary:

~50 GeVfor GCRs

(surface muon detector)

multi-directional

- Neutron Monitors

Energy responses of NM and GMDN

to primary GCRs

Differential response fn. (solar min.)

Integral response fn. (solar min.)

14.5

59.4

Rigidity of primary GCRs (GV)

- ☆indicates the location of the detector.
- ○□△display the asymptotic viewing directions of median energy cosmic rays corrected for the geomagnetic bending.
- Thin lines indicate the spread of viewing direction for the central 80 % of the energy response to primary CRs.

Deriving anisotropy vector

: pressure corrected count rate in the j th directional channel of the i th detector

We derive which minimize ….

Nagoya,Hobart,São Martinho

Kuwait

Four horizontal layers of

Proportional Counter tubes

1 hour data (2006 12/14 09:30UT)

- Useful when analyzing local-structure like the “loss-cone”.
- Applied to the GMDN data (Fushishita et al., ApJ, 715, 2010).

N

Pitch angle from

the sunward nominal IMF

S

W

E

GCR transport equation (Parker 1965)

: GCR density

(omnidirectional intensity)

SW convection

diffusion

Adiabatic cooling

: streaming

: anisotropy

- Anisotropy () tells us the spatial gradient ( )
- which reflects the magnetic field geometry

- GCR density decrease (Forbush Decrease).
- Strong GCR streaming (wind) is associated.
- Need to measure density & streaming separately.
- Only global network can make such a precise measurement .

(%)

Muon count rates in 3 vertical telescopes

2001

Can deduce 3D distribution from the GCR gradient (G) from the anisotropy

G

Detector orbit

GCR depleted region

Single telescope tells us only 1D distribution along the orbit

What does GMDN tell us?

http://neutronm.bartol.udel.edu/

Testing the drift model

A > 0

A < 0

Away

Toward

Drift model prediction by

Kota and Jokipii (1983)

Toward

Away

7.5 excursion of the Earth may cause the seasonal variation in the gradient.

ICME

doy

CR density

CR anisotropy

- GCR depleted region is formed in an expanding MFR into which GCRs can penetrate only through the cross-filed diffusion.
- GCR density gradient G pointing away from the MFR can be deduced from the diamagnetic drift streaming.
- We deduce MFR geometry from the GCR density gradient by assuming an infinite straight cylinder.

GCR depleted region

(Forbush decrease)

G

G(t)

CRs

2R(t)

Cross-field diffusion

Adiabatic cooling

CR diffusion into MFR

CRs can penetrate into MFR

only by the cross-field diffusion

k can be evaluated from CR data during MFR

Self-similar expansion of MFR

Dimensionless parameter k0 determines k

- k0 appropriate to the observed
- FD is 10 ~ 50.
- f (x) rapidly becomes stationary, much earlier than the 1st contact of Earth with MFR at t=1.

Stationary solution

f(x) is given by a polynomial expression….

Use polynomial f(x)（n≦6） for best-fitting to the data

Best-fitting at k0=18

k = k0v0R0 = 1.61021 (cm2/s)

(v0=0.21 AU/day, R0=0.17 AU)

k// ~ 3.01023 (cm2/s) for muon

(Munakata et al., 2002)

k/ k ~ 0.005 for muon

Z

Y

X

Z

Y

X

cosmic ray

ACE B&V

IPS

STEL

SMEI

(Tokumaru et al., 2006)

(Kuwabara et al., 2007)

Loss cone

(deficit)

Magnetic flux rope

CR cylinder

Shock reflection

(excess)

Munakata et al. (JGR, 105, 2000)

Leerungnavarat et al. (ApJ, 593, 2003)

- CRs behind the shock travel to the upstream Earth with the speed of light overtaking the shock ahead.
- The precursor is seen as the deficit intensity of CRs arriving from the sunward IMF.
- loss-cone (LC) precursor
- CRs reflected and accelerated by the approaching shock are also observed as an excess intensity.
- precursory excess

(sunward)

distance from the shock (mfp)

pitch angle cosine

(anti-sunward)

Sunward IMF direction

X3.4 flare onset 02:38UT on 12/13

VSW

~3% FD @~30 GeV

Flare onset

SSC

B

CME ejecta

Kp

No additional disturbances

GMDN: CR density

average VSW = 1160 km/s

12/13

12/14

12/15

12/16

12/17

GSE-x

GSE-y

GSE-z

Liu et al., ApJ 689, 2008