Based on the air shower data, the chemical composition of the primary cosmic rays in the energy range 10 to the 15th power - 10 to the 17th power eV was obtained. The method is based on a well known N sub e-N sub mu and N sub e-N sub gamma. The simulation is calibrated by the CERN SPS pp collider results

Muraki, Y.

English

NASA Technical Reports Server

178 OG 5.1-12
Cosmic Ray Composition between 1015to 1017 eV obtained by
_ir Shower Experiments
Y. Muraki
Inst. for Cosmic Rays, Univ. of Tokyo, Tanashi, Tokyo 188
abstract
Based on the air shower data, the chemical composition
of the primary cosmic rays in the energy range 1015-1017eV
has been obtained. The method is nased on a well known
Ne-N u and Ne-N Y. Our simulation is calibrated by the
CERN SPS pp collider results and very reliable.
I. Introduction and Model
When the first pp collider results from _ERN has reported
in the end of 1981, we have started a Monte Carlo calculation
with the use of the data on thenuclear nuclear interaction.
The first result has been already published in a proceeding
of the Bagalore conference and the simulation model is described
in detail therin I) , however, here we describe briefly the
simulation model : <n> _ EI/6 (in/_) 2 K/_ 0 15s o ' _tot _ ' " '
<P_ _O.4 GeV/c and no energy dependency. The effect of
geo-magnetic field add the scattering in the air have been
taken account of.
2. Transition Curve
The transition curve of the electron number N is shown
e
in Fig. 1 as a function of the altitude. • and X represent
the proton and iron primaries respectively with the same
incident energy Eo= 2 x 1016eV. The error bar implies
the region of 90% air shower involved, while • and X represent
the mean value.
78 OG S.1-12 
Cosmic Ray Composition between 101Sto 1017 eV obtained by 
Air Shower xperiments 
. uraki 
Inst. for Cosmic Rays, niv. of Tokyo, Tanashi, Tokyo 188 
stract 
ased on t e ir sho er ata, t e chemical composition 
of the pri ary cos ic rays i  the energy range 101S_1017eV 
as een tained. he ethod  ased   ell own 
N -N and N -N . 
e 1.1   Our simulation is calibrated by the 
E N SPS pp llider r sults and ery r liable. 
1. troduction d odel 
hen t e first pp llider r sults fro  C~RN has reported 
  d f 81, e ave t rted  onte arlo alculation 
ith  se f e ata  . nuclear uclear teraction. 
he first r sult as been already ublished i  a r ceeding 
f the agalore conference and the si ulation odel is described 
in detail therin l ), however, here we describe briefly the 
si ulation odel: n  ~ l / 6 , crt t~ (l jS) , K/TI~ O.lS, 
 0 0 
<P.r ~0·.4 GeV/c and no energy dependency. The effect of 
eo-magnetic i ld a,nd t  attering i  t  ir ave een 
en count f. 
. rans tion urve 
he nsition rve f  l ctron ber e  n 
i  ig. 1 as a f nction f t e ltit de. • and  re resent 
t e r ton and ir n ri aries respectively ith t e sa e 
incident energy Eo= 2 x 1016ev . The error bar implies 
t e r ion f 90  ir s wer i olved, hile. a d  r present 
e ean alue. 
• 
https://ntrs.nasa.gov/search.jsp?R=19850025740 2020-03-20T18:01:46+00:00Z
OG 5.1-12
179
Fig. 1 Transition curve for proton(o) and iron(X)
Ne ....
10 7
10 6
200 400 600 800 i000
or
3. Ne._ plot and Triqger Bias
It is interesting to compare present result with the
previous calculation by Jogo 2). Our result of proton_ ....)
primary fits well with the result based on CKP model for
proton promaries rather than sac.Ling model with iron primaries
calculated by Jogo. However we must take account of the
trigger bias involved in the data taking. As shown in Fig.
3, even if the composition of primary cosmic rays could be
90% iron(x) nad 10% proton(e) beyond 1015eV, it is identified
as proton dominant by the Ne trigger. To avoid such a
misunderstanding, N trigger is preffered.U
• Fig.. 2 N-N plot Fig. 3 Trigger bias (e)P,(x)F
_0_ e }..1 ,," e
CKP(1/_) Fe._ o N j
_ EI>I GeV ._/_/." p
odata
20/o/_ " - --- present
I I I i , I , J
,,, 10s 10° 10? 108
Ne 105 N
e
G 2 
9 
Fig. 1 Transition curve for proton(o) and iron(X) 
    1  
r 
~~ plot and Trigger Bias 
t  teresting  pare resent sult ith t e 
revious alculation  J go ) • ur r sult f roton(----) 
pri ary fits ell ith t e r sult ased on P odel f r 
r ton romaries rather than sacling odel ith iron rimaries 
alculated y go. ow ver e ust t e ccount f t e 
rigger ias nvolved n he ata aking. s shown in ig. 
, even if the comp sition f rimary cosmic rays could e 
 iron(x) ad  r ton (e) eyond 015ev , t is identified 
as proton dominant by the Ne trigger. To avoid such a 
isunderstanding,  trigger is pr ffered. 
1.1 
Fig. 2 N -N plot 
1 6  r 
CKP(1/4) 
E >1 GeV 
1.1 
o data 
- Jl5go 
- resent 
Ne 
Fig. 3 Trigger bias (e)P, (x)F 
e 
 
 
N 
P 
180 0'G 5.1-12
4. N -N Trigger Data
--p---e
Fig. 4 represents Ne-N p contour plot by Ne trigger.
In a range of Ne2 107, no trigger bias is observed even if the
data have been taken by Ne trigger 3) .
In the same N -N plot of Fig.4, we draw the line with
e }1
the same incident energy for various kind of primaries (Fig. 5).
The highest peak of the contour corresponds to the size s=l.1.
The corresponding size for each primary is s=1.0-1.2 for proton
, s=1.2-1.3 for He, s=1.3-1.4 for CNO, and s--1.4-1.5 for iron
................................................................................................... in 900 grams(Akeno).
I I ,' IO J¢l I
I ! , ,I
I III I t
i I.I ill Ii i
. .1 Iiiiii i
" ......... Fig. 4 N-N plotI ! '_sl_,*fl*ll I I
N_ ¢ ..................................., Itl't.)5}Ai1&klil_)I-1...................I .................I|11111._|ass11. ,,,_n_)| 111 I I
..........._!, ,, ,,,,,,I,,, ,, ,, a,b,c corresponds the
, . 1! _ti_t_s- I , o I
. I _ I11111 I I I
. I
_ I ,,,,-,,,, _ I. I I number f eve t :
_ .................... _ . 101 1 2
................................................................ " "
o,, ....,, , , 0_10
.... ............ , 01.2_l,,, .(,c ,,. ""' ' '"-".....--" 1 4
.....(_a'_ .......... '....,,., b : 1 0
'.....................'-"_'"_!,,,-""" i ...._ '.... ¢:', c : 101"4-101"6
t ....... ii I I11111) ............................ _...... I................... I................... I
' ' ' (d_ta from Ref 2)_- I ' • ' n u *
I I I I
, '',' , ' ' '. real number means real
' ' " ' ' ' '" population
N e _1¢. Se*,_,r pl._, ,, v, _p
Fig. 5 Contour plot
._,.. ,, the same incident energyI I
j_ "'_I'_ line is dragon by line. .
_ _']/"_'_'"_ the same age is repre-
_;0'7 sented by the dotted_o6 +
S_ '": _ ,o_ lines__ " / , "/ / . _.:!7',7:_X "E
• L: ' "" _i_'"! ":: ....
' "f _:::_]:_:!:!::.ii:::i'_/:.i.: :iT!__]!ii_::_2:_ Note added: above logic .
""" --; .:--ill/-_i holds even if the primary
I ; [ _ :" 1 " : " _ I _ _ _ "&_ . : ..... composition is 90% F +
e .
_°_ _°_ _°_ "" _ I0 % P. We assumed peak
corresponds to proton.
.  -  rigger ata 
--p.--e --
0 O'G .1  
Fig. 4 represents N -N 
7  11 
contour plot by N trigger. 
 
In a 
data 
range of N ? 10 , no trigger bias 
e 3) 
have been taken by Ne trigger . 
is observed even if the 
I  t e sa e  -  lot f ig.4, e draw t e line ith 
e p 
the sa e incident energy for various kind of primaries (Fig. 5) 
he ighest eak f t e ontour rresponds t  t e ize =l.l. 
The corresponding size for each primary is s=1.0-1.2 for proton 
s 1.2-1.3 for e, s=1.3-1.4 for , a d s=1.4-1.5 for iron 
in 900 grams (Akeno) • 
ig. 4  -N lot p e 
a,b,c corresponds 
ber f ents 
101. 0 _101. 2 a 
 
101 • 2 _101. 4 
101 . 4_10 1 . 6 
( tita fr  ef. 2) 
the 
al umber eans al 
opulation 
Fig. 5 contour plot 
the same incident energy 
line is dra\~n by line. 
the same age is repre-
sented by the dotted 
lines. 
(data from Ref. 3) 
Note added: above logic 
holds even if the primary 
composition is 90% F + 
e 
10 % P. We assumed peak 
corresponds to proton. 
181 OG 5.1-12
Fi 9 . 7 events
1000 200 50
2X _IG _× 16 . _7
,.T_ooucT,o.T T.EC*.^CT,CCO_"C_^D'^'m_ lOeV 7 10eV 2x10 eV
o........ 1½,_.__ 500 100F q_
; . _.4_. ""
" h', -q l
';l,, P He C Fe P HeC Fe P HeC Fe
tt\ It a N N
lllJl. _ O O 0
'II Fig. 6 Primary composition
|_7 ,o. ,o. \ The number of events which
_nzcago has the same energy(Eo) and the
same size has been counted from
JACEE _ Fig. 4 and 5. The distributionresults_ is given in Fig. 6.
l(r'I
,_f 5. Conc ius ion
!i_iI "_i"'_'L_ It is interesting to plot
_G_ present result on the differntial
_. spectrum obtained lower energy
" experiments (Fig. 7) . From Figs.
___._' . ' 6 and 7, we conclude the comD-
IPresent _i_'_ " osition of primaries in the range
- Lanalysi s
F6 of energy 2 XI016eV and 2 Xl017 eV,
-I_ the iron component does not become
dominant.
Re ferences
I) Y. Muraki,A.Okada; 18thICRC
,o. ,6,-_&,.,_. _,b ,6.",
- _ _ at Bangalore, 7 (1983), 54.| 2) N. Jogo; PHD thesis to Tokyo
o .,.15 Univ. ( in English) (1981_
3) Akeno group; 18thICRC,ll(83)281.
Fig. 7 
INTRODUcrlON TO THE CALAcrlC COSMIC MlllATION 
,0" 
{
Present --A 
analysis 
event  
100  
500 
1 
00 
100 
.6 7X10eV 
OG 5.1-12 
50 
2Xld7eV 
   e 
N 
  C 
 
o 
 e  
 
o 
e" 
. P 
cHe. 
JJ 
6-
o 
fig. 6 Primary composition 
The number of events which 
has the same energy(E ) and the 
o 
e e s en unted ro  
Fig. 4 and 5. The distribution 
is given in Fig. 6. 
5.Conclusion 
It is interesting to plot 
present result on the differntial 
spectrum obtained lower energy 
experiments (Fig. 7). From Figs. 
6 and 7, we conclude the comp-
osition of primaries in the range 
of energy 2 Xl016ev and 2 Xl0 17 eV, 
the iron component does not become 
omi ant. 


Cosmic ray composition between 10 to the 15th power - 10 to the 17th power eV obtained by air shower experiments

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server