Cosmic Ray Composition
in the Knee Region
H. Tanaka
GRAPES-3 Collaboration
1
Cosmic Rays
TeV
PeV
EeV
ZeV
High Energy Particle from
outside of the Earth


107~1020eV
Power Low Spectrum E－γ
Particle Type

Electron, Proton ~ Iron
Origin

Energy Spectrum
SNR?
2
Knee in Energy Spectrum
1015eV
H
Fe
?
Fe
H
What is the cause of knee ?
Limit of Acceleration
Leakage from the Galaxy
or others
Measurement of nuclear
composition and their
energy spectrum could be
one of the key to the
solution.
3
Air Shower Experiments
GRAPES-3
KASCADE
Tibet AS
Obs. Height
2200m
100m
4300m
Density of
Particle Detector
1det / 55m2
1.8%
1det / 167m2
1.3%
1det / 56m2
0.9%
Other
Observations
560m2 Muon Det.
80m2 Burst Det.
Features
Larger Statistics
Lower E Threshold
800m2 Muon Array
300m2 Hadron Det.
128m2 MTT etc.
Larger Statistics
Lower E Threshold
Tibet ASγ
KASCADE
GRAPES-3
GRAPES-3 has both of dens
array and large muon detector
at the high altitude.
4
GRAPES-3 Experiment
Location:
Tamil nadu, Ooty
2,200m (800g/cm2)
SC
Charged Particle
(electron) Detector:
Plastic Scintillator
1m2, 5cm thick
x400 (8m separations)
MU
Muon Detector:
16 detectors (>1GeV)
total 560m2
Observation:
The number of electrons
and the number of 5muons
Shower Size
LOG
N2.5dI/dN [m-2sr-1s-1N1.5]
LOG
Size Spectrum
Energy? Composition?
 MC, muon
6
Particle Type and Energy Estimated
from Observations (MC)
6
Fe 1016eV
LOG10(Nμ)
Air Shower
5
Simulation
Energy
Fe 1015eV
H 1016eV
4
Fe 1014eV
H 1015eV
3
H 1014eV
Nuclear Number
2
γ 1016eV
15
γ 10 eV
Hadronic Interaction Model
* SYBILL 2.1
* QGSJET01
γ 1014eV
1
3
4
5
LOG10(Ne)
6
7
Estimation of primary energy and nuclear mass number
from the numbers of electrons and muons
Model dependency for HE-Hadronic interaction
8
7
<number of detected muons>
N- Ne diagram (M.C.)
M.C. simulation

CORSIKA
QGSJET01, SIBYLL2.1,
QGSJET-II

５ nucleous

Proton, He, N, Al,Fe
 Observation

8
Multiplicity Distribution
Al / Fe is fixed to
0.8
Ne: 105.0 - 105.2
marker




Good sensitivity of
cosmic ray mass


Proton 0.3
He
0.4
N
0.3
Al
0.02
Fe
0.03
Observation
9
Energy Spectra Analysis
dI/dE・E2.5
QGSJET
Log(E)
1000
ALL
H
He
N
Al
Fe
dI/dNexNe2.5
100
10
Log10(E/TeV)
MC
1
4
5
6
Log10(Ne)
7
10
Log10(Ne）
All-particle Spectrum
11
Proton Spectrum
Comparing with direct measurements is possible
12
Other Spectra
He
Al
N
Fe
13
Mean Mass Number
Fe
Al
N
He
H
Lower threshold enables data to compare with direct measurements.
14
Summary
GRAPES-3 can get energy spectra of five
groups utilizing muon multiplicity
distribution.
Change in proton spectrum and increase
in mean mass with energy observed
The results with SIBYLL and QGSJET-II
agree with direct and KASCADE
measurements.
Extend spectrum to higher energy
15
THANK YOU
16
17
Air Shower Experiments
KASCADE
Tibet ASγ
GRAPES-3
SPASE-2
BASJE
18
Method of EAS Observation
BASJE


Bolivia (550g/cm2)
46 SDs (1 or 0.83 m2
each)

12 SDs (4 m2 each)
SPASE-2


South Pole (695g/cm2)
30 SDs (0.8m2 each)
KASCADE
Karlsruhe (1020g/cm2)
252 SDs
Central Detector
Muon Tracking
Detector
Tibet Asγ
Tibet (606g/cm2)
500 SDs (0.5m2 each)
Emulsion chamber
Burst detector
19
Method of EAS Observation
Location
EAS Array
GRAPES-3
Ooty
800g/cm2
400 SDs
(1m2)
BASJE
Chacaltaya
550g/cm2
46SDs(1m2)
12SDs(3m2)
SPASE-2
South Pole
695/cm2
30 SDs
(0.8m2)
KASCADE
Karlsruhe
1020g/cm2
252 SDs
(3.2m2)
Tibet ASγ
Yangbajing
606g/cm2
789 SDs
(0.5m2)
20
Low Flux of Cosmic Ray around Knee
Low Flux



1 particle in 1m2 in a year
(>1015eV)
Poor statistics in Direct
Method
Air Shower Observation
above 1015eV
21
Important Matters in Observing
Cosmic Ray around Knee
To get enough statistics (Lower flux for higher cosmic rays)

1 particle in 1m2 in a year
 Air Shower Observation above 1015eV
Sensitivity of Cosmic Ray Mass

The number of Muon
 Large Area Muon detector
Solve the Uncertainty of Monte Carlo (high energy
phenomena)

Compare the observation with direct measurements
 Density Shower Array for lower threshold energy
GRAPES-3 Experiment
22
The First Report of Knee
“On the Size Spectrum
of Extensive Air Showers”
G.V. Kulikov and G.B. Khristiansen
Journal of Experiment and Theoretical Physics, 1958
Break of size spectrum was reported between 106 – 107.
The cause of knee is not yet clear for 50 years.
 How are Recent Observations?
23
Energy Spectrum
24
Air Shower
Observation
Low Energy Particle
60GeV
High Energy Particle
>1013eV
Primary particle
ATMOSPHERE
, e

MC


GROUND
Muon Detector
Particle Detector Array
Observation
25
Direct
Measurements
JACEE

Japanese American
Cooperative Emulsion
Experiment

Balloon Experiment



1 - 1000 TeV
The Antarctic
Emulsion Chamber


X-ray film
Lead Plate
RUNJOB

RUssia Nippon JOint
Balloon experiment

Balloon Experiment

JACEE

10 - 1000 TeV
Kamchatka to Moskva
26
Mean Mass
Number
Much difference
among them!
27
Important Matters in Observing
Cosmic Ray around Knee
To get enough statistics
(Lower flux for higher cosmic rays)
Sensitivity of Cosmic Ray Mass
Solve the Uncertainty of Monte Carlo
(high energy phenomena)
28
x = -11.8m
y = 27.3m
s = 0.91
LOG
検出粒子数
検出粒子数
サイズ推定（横方向フィット）
コアからの距離(m)
シャワーサイズ
1.82×105
r 
 r    
 rm 
s  2.0

r 
1  
 rm 
NKG関数
29
s  4.5
ミューオントラック検出装置
検出装置

1層58 本の比例計数管
(6m×10cm×10cm)


4 layers

交互に組まれた4層で
トラックを識別
合計16台(560m2)
E>1GeV
58 counters
6m
30
Observation
EAS Data



2000 – 2001 (560days)
Shower Number 6×108
Shower Rate
13Hz
Shower Selection


Core Location (>80m)
Zenithal Angle θ < 25o
Monte Carlo Simulation

CORSIKA




QGSJET-II (CORSIKA6.50)
SIBYLL 2.1 (CORSIKA6.50)
QGSJET01 (CORSIKA6.02)
Primaries
Proton, He, N, Al and Fe
31
Expanded GRAPES Collaboration
(1)
TIFR, Mumbai: H.M. Antia, S.K. Gupta, P.K. Manoharan, P.K. Mohanty,
P.K. Nayak, H. Tanaka, S.C. Tonwar
(2) Osaka City University, Japan: S. Kawakami, Y. Hayashi, S. Ogio, A. Oshima
(3) Aligarh Muslim University, Aligarh: Shakeel Ahmad, Badruddin, R. Hasan
(4) APS University, Rewa: A.P. Mishra, P.K. Shrivastava
(5) BARC, Mumbai: R. Koul, G.N. Shah
(6) J.C. Bose Institute, Kolkata: S. Ghosh, P. Joarder, S. Raha, S. Saha
(7) Gauhati University: R. Baishya, A.G. Baruah, K. Boruah, P.K. Boruah, P. Datta,
J. Saikia
(8) IIA Bangalore: D. Banerjee, P. Subramanian
(9) North Bengal University: A. Bhadra
(10) R.D. University, Jabalpur: R. Agarwal, S.K. Dubey, Santosh Kumar
END
Thanks for your kind attention!
32
The Number of Electron and Muon
33
Target for present experiment


getting the size spectrum and muon multiplicity
distribution
Using M.C., energy spectrum of nucleus can
be deduced from these results
To achieve this, compact array (high density SD)
and muon detectors with large area are
required.
In this experiment our energy range is overlapping
with direct measurement (Balloon exp.). It
means we have an anchor point, even though
our results are totally M.C. dependent.
34
Location of GRAPES-3
Ooty Air Shower Experiment
•日
印
:共
/
/同
i
n研
d
i究
a
-(
t
oO
u
rC
i
sU
m
.,
h
t
t
p
•Location
Mt. Ooty, South India
E 76.7° N 11.4°
2,230m a.s.l. (800g/cm2)
35
Future Expansion Plans
to observe higher energy cosmic rays
Shower Array
Muon Detector
New Muon Detector
100m2 Hadron Calorimeter
Radio Array (30-70MHz)
Neutron Monitor
Radio Telescope
(326MHz)
1km2 Array
36
空気シャワーシミュレーション
CORSIKA
ハドロン相互作用モデル

DPMJET

ミューオン数

HDPM



110m a.s.l.
2-D Half maximum
D.Heck et al., Proc. ICRC27, 233, 2001


GRT + minijet
空気シャワー向け
SIBYLL

電子数
GRT + minijet
QGSJET


現象論的モデル
neXus


GRT + minijet
minijet
空気シャワー向け
VENUS

GRT（Gribov-Regge Theory）
37
ハドロンモデルの影響
1 PeV 鉄
電子数
ミューオン数
両者とも ~１０％ 程度の違い
38
<検出ミューオン数>
ハドロンモデル依存性
QGSJET Fe
QGSJET Proton
CORSIKA

SIBYLL Fe

OBS
QGSJET
SIBYLL
SIBYLL Proton
Log(サイズ）
39
Knee のモデル
加速
1.超新星残骸での加速
2.超新星衝撃による加速
3.斜め衝撃波による加速
4.多様な超新星による加速
5.単一の超新星残骸での加速
6.銀河風での再加速
7.火の玉モデル
伝播
8.銀河からの漏れ出し
9.銀河からの異常拡散
10.銀河磁場中の拡散と漂流
11.乱流銀河磁場中の移流拡散
12.拡散漂流モデル
相互作用
13.光分裂と拡散
14.ニュートリノとの相互作用
40
Shower Cascade in the Atmosphere
Air Shower Phenomena
Primary particle
Nuclear Cascade
p, n, , 0, K, K0, …
[decay]
 0   + 
[8×10-17sec]
    + () [3×10-8sec]

air
Observation


High Energy:
Low Energy:
COLLISION
DECAY
Electromagnetic Cascade


Pair Creation
 e+ + eBremsstrahlung ee + 
41
個々の成分の比較
個々の成分で比較できる！
42
シャワー到来方向
検出器へ粒子の入射する時間差から
到来方向を推定する
ガンマ線点源の観測時の際は重要
43
時間差 (nsec)
シャワー到来方向推定
（ｍ）
44
Observation
EAS Data



2000 – 2001 (560days)
Shower Number 6×108
Shower Rate
13Hz
Shower Selection


Core Location (>80m)
Zenithal Angle θ < 25o
Monte Carlo Simulation

CORSIKA




QGSJET-II (CORSIKA6.50)
SIBYLL 2.1 (CORSIKA6.50)
QGSJET01 (CORSIKA6.02)
Primaries
Proton, He, N, Al and Fe
The Number of Electron and Muon