The cosmic ray interactions in the energy region 10 to the 13th power to 10 to the 17th power eV were studied by emulsion chambers exposed at Chacaltaya, 5220 m above sea-level. The chambers have a two-storied structure, and the events observed in both chambers give important informations on these phenomena. The first Centauro event was detected as a small shower at the bottom of the upper chamber and as a big fraction of energy deposit in the lower chamber, which indicates a high contribution of hadronic showers. Results of the events with continuation in the rather low energy region are described

Amato, N. M.

Arata, N.

Maldonado, R. H. C.

English

NASA Technical Reports Server

292
HE 3.3-7
Atmospheric Interactions detected in both the
Upper and the Lower Chambers at Chacaltaya
W * WW
N.M.Amato, N.Arata and R.H.C.Maldonado
• Centro Brasileiro de Pesquisas Ffsicas
Rua Dr. Xavier Sigaud 150
22290 Rio de Janeiro, RJ, Brasil
•* Instituto de Ffsica
Universidade Federal Fluminense
Niteroi, RJ, Brasil
I. Introduction
Brasil-Japan Collaboration has been studying the cosmic
ray interactions in the energy region 1013 - 1017 eV by
means of emulsion chambers exposed at Chacaltaya, 5220 m
above sea-level, Bolivia[I]. The recent chambers hav_ a two-
storied structure, and the events which are observed_oth
chambers have given us important informations on the pheno-
mena. For example, the first Centauro event was detected as
a small shower at the bottom of the upper chamber and as a
big fraction of energy deposit in the lower chamber, which
indicated a high contribution of hadronic showers[l].
We are almost finishing the complete analysis of the
events of atmospheric interactions with such continuation for
the Rio part of the 19th chamber. In this paper, we describe
some results of the events with continuation in the rather
low energy region which are often eliminated in the discuss-
ion only because of their low energy.
\ Fig. 1 The integral distri\ -1.3
100_ # xx _ \ _(ZE) butions of total visible
x_\ energy. (x) for all the
x\ events and (.) for the eve
-×\. nts with continuation.
IX x
• • K=6
^10 1 s
d
= H
\\ 0 , , I , , , , x ,0 I000
• eventswithconiinuotion I <£'_R*> GeV.m
I _" I Fiq.2 The histogram ofI i , i b , <E_R*>, where K=6 GeV.m is
10 lo0 used for decascading.
Z E TeV
https://ntrs.nasa.gov/search.jsp?R=19850027612 2020-03-20T17:20:27+00:00Z
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HE3.3-7
CH19 S56 136A
I I I I i I I I I I I I
CH19S56 136A
I cm 1.0 ._.._..i;....._..,
c(_.2) ....._ ' "'.,
OO e'" "
S(9.4) D(1,1) A .:/
• e :,
A(19.0) ."
1.0 _"
Fig. 3 The target diagram _ S "..........
of CH19 $56 I36 A. The , .."" o '...
and energy of each _ . ""._..name
core is shown. _ 1.o ..
lFig.4 The transition ofdarkness D with slit dia- _ c .-"........"'.D. •meter 225 _ for 4 cores in _ ....• ••S56 I36 A. The fitting ..." """..
curves are also shown. 1.0- :" • '" -
2. Experiment D
The 19th chamber is
two-storied, and for the
whole upper and lower 0.1 .o...." '...
I | I I I I I I I I I
chambers, nuclear emulsion 0 4 6 8 10 12 3 4 5 6 8 10 12
plates were inserted in Upper Chamber Lair Ch. (C.U.)
sandwiches of lead plates
together with X-ray films. The exposure time was 677 days.
The upper chamber has total area of 44.2 m 2 and the lower
chamber 32.4 m 2 . They are formed by unit blocks of dimension
40 x 50 cm2; in Rio de Janeiro have been analyzed 59 blocks
of the upper chamber and 48 blocks of the lower chamber.
We must observe at least two penetrative shower cores
in both the upper and the lower chambers, in order to deter-
mine the relative geometrical position of all the showers in
" both chambers. We have observed 21 events with such continua-
tion. Fig.1 shows the integral distributions of the total
energy visible in the form of. electro-magnetic cascade
, showers for all the events and for the events with continua-
tion. We notice _h_t the distribution for all the events
obeys o_( Z E ) -..o, which is consistent with the previous
measurements [I].
Fig.2 shows the distribution of average energy-weighted
lateral spread, <E'R*>, for the 21 events, where the so-
called decascading constant K = 6 GeV.m was chosen [2]. We
usually have a larger interest in the region of large ER,
but in the following we describe three events in the small
ER region.
3. Results
We have two events with continuation in the interval of
294
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CH19 S56 136B
CH19 $56 [36 B , . , , , ' ' , . . ' '
1.0- -
I cm
I
2a,b _"e"'°'t .....i' 9
• (16.0) _ ...'"' "" ",
• _ _'II ""
I (10.1) _ 1.0 - ._... -
o 2 a+b ._.. ......
Fig.5 The target diagram _ •"..... ".....
of CH19 $56 I36 B _ ."• C
'.
Fig.6 The transition of D _ 0.1 ...._"_'".......
for 2 spots in $56 I36 B. •
I I I I I I I I I i i I
<E'R*} less than 100 GeV.m. 0 4 6 8 10 12 34 56 8 10 12
The names of the events Upper Chamber Lower Ch, (C.U.)
are CH19 $56 I36 A and CH
19 $56 I36 B; it is a coincidence that these two events were
observed in the same blocks•
CH19 $56 I36 A Fig.3 shows the target diagram of this
event• The event consists of only four shower spots with the
total visible energy 33.7 TeV. Fig.4 shows the transition of
darkness D on the N-type X-ray films for the four spots of
the event• The slit size is 225 _ in diameter. The depth of
lead is indicated by the cascade unit of each chamber.
#A starts to be observed at the very deep layer, 8 cu
on the emulsion plate and 10 cu on the X-ray film, as a
sharply collimated shower core. #B starts to be observed at
8 cu and we can not find any track on the corresponding
position at 6 cu. #C starts to be observed at 12 cu. #D is
observed only in the lower chamber as a diffused small shower•
Down to 6 cu in the upper chamber, this event does not
appear for detection, and the cores B, A, C and D start to
appear, one by one, to form the event.
We can identify all the four cores as hadronic because
of their deep penetration• This event is lacking in electro- "
magnetic components at the entrance of the chamber within
the limit of detection threshold (-I TeV).
CH19 $56 I36 B Fig.5 shows the target diagram of this
event. The event consists of two spots (#I and #2) with the
total visible energy 26.1TeV. #2 consists of two constitu-
ent cores (a and b) with the very short mutual distance 33
Both the two spots continue into the lower chamber.
Fig.6 shows the transition of spot darkness on the N-
type X-ray films• #I starts to appear at 12 cu in the upper
chamber as a collimated core and in the lower chamber as
multi-cores. #2 starts to be observed at 6 cu and the
spacing effect of air-gap between the upper and the lower
chambers is clearly seen in Fig.6.
We can identify #I as a hadronic core, but we can not
judge whether #2 contains hadronic nature.
295
HE3.3-7
CH19 $83 #200 This event is observed
only in the upper chamber. Fig.7 shows CH19 583 @200
the target diagram of this event• The
event consists of two spots (#I and #2) _cm
with the total visible energy -30 TeV.
#I consists of two constituent cores (a • la,b
and b) with the mutual distance 175 _/. (~27)
Fig.8 shows the transition of 2(> 2)
electron number counted on the nuclear
emulsion plates in the area 78 x 78 _m 2. Fig.7 The target#la appears as a normal shower, but
#Ib starts to appear at 8 cu and grows diagram of $83#200.
up remarkably down to 12 cu. #2 is CH19 S83 _200
observed only at 12 cu in the upper ....
chambe r. 103
We can identify #1a and #2 as _::.
hadronic cores. We can not judge #Ib as ..........:_
a hadronic core. _ la ......
i'
4 Discussions _ ; •
• 102 ' "We have encountered interesting _ / ..."
(exotic) events in the high energy reg _ .. 2
ion, ZE > 80- 100 TeV [I ,3] . But as z ."
shown in the previous section, we can
pick up some events with an impressive Ib :
character even in the lower energy
region I0 , , , :', , ," 2 4 6 8 10 12
In the energy interval, 25- 35 TeV, Upper Ch. (C.U.)
we have analyzed 18 events, among which
3 events showed a hadron-rich nature. Fig.8 The transition
If we use the power fit of (7. E) -1.3 in of electron number
Fig.l, these 3 events are in the un- inside the counting
biased sample of ~40 events in that area 78 x 78 )_m2.
energy interval.
More details on the events with continuation will be
presented at the Conference.
, 5. Acknowledgement
The authors wish to acknowledge all the members of the
Brasil-Japan Collaboration for their kind support. They are
grateful to Profs. F.M. Oliveira Castro and H.M. Portella
for their continuous encouragement. They also thank
T.T.Villar, N.Miranda and I.A.Lopez in CBPF for their help
in scanning work. Thanks are also due to the CNPq, Brasil,
for a financial support•
Re ferences
[I] C.M.G.Lattes, Y.Fujimoto and S.Hasegawa, Phys.Rep. 65
(I980) 15_1 and references therein•
[2] H.Semba, Supplement of Prog.Theor. Phys. 76 (1983) 111.
[3] Brasil-Japan Collaboration, AIP Conference Proceedings,
85 (1981) 500.


Atmospheric interactions detected in both the upper and the lower chambers at Chacaltaya

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