A cosmic-ray induced nuclear event is presented, which is of clear binocular-type and contains several exotic features through its passage in the atmosphere and the emulsion chamber

Amato, N. M.

Arata, N.

Maldonado, R. H. C.

English

NASA Technical Reports Server

324 HE 3.4-6
A Binocular-type Atmospheric Interaction
Generating Sequential Exotic Features
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 Fleminense
Niteroi, RJ, BRASIL
Abstract A cosmic-ray induced nuclear event is presented,
which is of clear binocular-type and contains several exotic
features through its passage in the atmosphere and the
emulsion chamber.
I. Introduction
Brasil-Japan Collaboration has observed some exotic
events (Centauro family) in the high-energy cosmic-ray inter-
actions, and they are classified into four categories as
(original-) Centauro, Mini-Centauro, Geminion and Chiron
according to their multiplicity and average pT./I,2/ Their
common feature is a lack of _-ray emission in their inter-
actions, and they are regarded as phenomena quite distinct
from the normal pion production.
In this paper, we present a very special event which
shows several exotic features in three generations of inter-
actions.
2. Experiment
The event was observed in the 19th emulsion chamber at
Chacaltaya. The chamber is two-storied, which consists of an
upper chamber, a lower chamber and a target layer in-between.
The chamber is multi-layered sandwiches of lead plates and
photo-sensitive materials. In the unit block where the
present event was detected, nuclear emulsion plates were
inserted with N-type X-ray films at 6,8 and 12 cu in the
upper chamber and 3,4,5,6,10 and 12 cu in the lower chamber.
At 4 and 10 cu in the upper chamber and at 8 cu in the lower
chamber, only X-ray films were inserted. Thanks to the high
spatial resolution of nuclear emulsion, we can study a fine
structure of shower cores in detail which is quite powerful
to pick up and examine the exotic features.
3. Results
As the event was observed in the unit block 109 in the
upper chamber and in the block 69 in the lower chamber, we
name this event as CH19 $109 I69. In the following, the
results corrected on the incident zenith angle (15 degrees)
will be presented.
Fig.1 shows the target diagram of the event, which
already visualizes the first impressive feature, i.e., a
clear double-core structure. In the group A, 83.7 TeV is
observed in the form of electro-magnetic cascade showers,and
https://ntrs.nasa.gov/search.jsp?R=19850027621 2020-03-20T17:20:41+00:00Z
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HE 3.4-6
51.3 TeV in the group B. CH19 SI09 I69
The relative distance bet
ween A and B is 22 cm,and
the value _(A,B) = R(A,B) • I •
_(A)E(B) is 1440 TeV.cm.
We notice how large the 2 cm • 3
spread of this event is,
comparing the average 2 •
value -650 TeV. cm of the
binocular-type events
observed by the Brasil- Group A
Japan Collaboration./1,2/
3-I. Group A The group A
contains 3 high energy
hadrons and 4 low energy
showers as shown in Fig.1 Group B
and Table I. O
(#AI) _AI has two cores
in the upper chamber (10.5 Fig.1 The target diagram
TeV and 5.8 TeV with the of the event CH19 S109169.
relative distance 152 _),
and continues into the
lower chamber where five Energy(TeV) Comments
weak and diffused showers AI 16.3 A-jet
and one very new core are A2 31.5 Pb-jet-upper
observed inside the radius A3 20.0 Pb-jet-lower
-400 _. Thus we can know A4-7 15.9 A-jet
that one of the two cores B 51.3 A-jet
observed in the upper
chamber or another hadron Table I Groups A and B.
interacted to produce the
showers observed in the lower chamber.
(#A2) _A2 starts to appear at 12 cu in the upper chamber
as a very collimated core which can be realized only in the
emulsion plate, and appears in the lower chamber as a multi-
. core event inside the radius 114 _. The energy was determined
for each of the 7 cores, and _°-coupling confirms that they
were born in a normal pion production at the lower part of
the upper chamber. Outside the multi-cores, one new core of
8 TeV starts to appear at 10 cu in the lower chamber, its
distance from the multi-cores being 187 _. But we can not
test whether it came from the emission point of the multi-
cores or from the atmosphere. In case of the former, the
electro-magnetic component of PT of this hadron with respect
to the emitted direction of the multi-cores is 0.80 MeV/c.
(#A3) #A3 starts to appear at 3 cu in the lower chamber
as a single core, but at 4,5 and 6 cu as double cores, their
energies being 17 TeV and 3 TeV. The relative distance bet-
ween the two cores increases gradually at the deeper layers
as shown in Fig.2. The convergence shows that #A3 is an
interaction in lead plate in the lower chamber, and that the
326
HE3.4-6
3O
" Group B " 5 8=L _ A3 i •
" | / 3.
o 20 " "
/ 29 1.7
I/ 6.0 "
0.5.e/ 6 cu •
4 /5 •2.4 3.6
_ I0
> +/ e6 5 +0 8/ I 0 " "4J
/ ee 5.4
/ , 500/ 4
0 i i i I t0 I 2 3 4 5
Vertical Depth (cm) Fig.3 The target dia-
Fig.2 Variation of relative dis gram of B. + standsm
tances in #A3 at 4,5 and 6 cu. for a hadron.
opening angle is (7.6 + 1.8). 10 -4 rad.. Their invariant mass
is calculated only for the electro-magnetic component to be
5.4 GeV/c 2 .
(_A4-7) #A4-7 are observed in the upper chamber as normal
low energy showers.
The triangulation method was applied to determine the
interaction height of the group A by measuring the relative
distances between the higher energy core of #A3 and one of
the multi-cores of _A2 at 3,4,5,6 and I0 cu in the lower
chamber and between the higher energy core of _A3 and the
new core of _AI at 4 and 5 cu in the lower chamber. Within
the error, the measurements on both pairs are consistent with
parallelism, so we can say that the interaction height of
the group A is higher than the limit of accuracy on the
height determination, -500 m above the chamber.
3-2. Group B The group B contains 13 shower cores with a
quite small lateral spread; the average spread is 745 _ which
is -I % of the average of atmospheric interactions. The tar-
get diagram of B is shown in Fig.3. One core indicated by the
cross in Fig.3 appears at 6 cu as a very collimated shower
core whose starting-point of cascade is estimated to be 2.2
cm. Pb, which is identified as a hadron.
4. Discussions and Conclusion
The event $I09 I69 is of clear binocular-type consisting
of two groups of particles well separated to each other. In
the view-point of Centauro family, this event can be a
Geminion-type. Using the average mass of Geminion (k_M - 5
GeV/c 2 ), the production height is calculated to be -3 km.
In the group A, the fraction of the energy sum of hadrons
over the total visible energy is 81%. This large fraction
satisfies the criteria/3/ that the event can be of Mini-
Centauro type. Using the average PT of Mini-Centauro (k_p T ~
327 HE 3.4-6
0.35 GeV/c),the interaction height is calculated as -I km.
#AI is an atmospheric interaction. If we assume that the
two cores observed are decay-products of _%2_ , the height is
8.8 m. If we assume that they are from mini-cluster/2,4/ with
PT = 20 MeV/c, the height is -30 m above the chamber.
#A2 is an interaction in the upper chamber. If the had-
ronic core came from the same emission point of the multi-
cores, #A2 can be a normal pion production in the chamber.
If the hadronic core came from the atmosphere with another
hadron producing the multi-cores, _A2 can be of mini-cluster.
Using PT = 20 MeV/c, the height is ~60 m.
#A3 is an interaction in the lower chamber, in which
two cores are well separated with a very large transverse
momentum (k_p T ~ 1.9 GeV/c). #A3 can be a Geminion.
_A4-7 may be products of normal pion production in the
atmosphere.
The group B is an atmospheric interaction very near the
chamber. If we assume that the interaction is of normal pion
production with <PT_> = 200 MeV/c, the height is 15 m. If we
assume a mini-cluster, the height is 150 m.
Summarizing the results and discussions on the event
CH19 $109 I69 whose total visible energy is 135 TeV, our
conclusion is as follows:
AI (Mini-cluster, 30 m or
Group A -- Pion Production, 8.8 m)
I (Mini- A2 (Pion Production, 0 m or
SI09 169 -- Mini-cluster 60 m)
(Geminion) Centauro)
-3 km ~I km 3 Gem nion, 0 m)4-7 -500 m)Group B
(Mini-cluster, 150 m or
Pion Production, 15 m)
Sequential appearance of exotic features in this event can be
well understood by the hypothesis on genetic relation/4/ that
an exotic interaction is generated by an exotic particle
produced out of the exotic interactions.
5. Acknowledgement The authors wish to acknowledge all
the members of the Brasil-Japan Collaboration for their kind
and continuous support. Thanks are due to the CNPq, Brasil,
for their financial support.
References (PIS=Proc.of Internat. Symposium on Cosmic Rays
and Particle Physics, Tokyo, 1984; CFL=Contribution to a
Festschrift for Prof.C.M.G.Lattes)
/I/ C.M.G.Lattes et al., Phys. Rep.65 (1980) 152.
/2/ Brasil-Japan Col., AIP Conf.Proceedings, 85 (1981) 500.
/3/ A.S.Borisov et al., PIS, 1984, p.248.
/4/ S.Hasegawa, PIS, 1984, p.718 and CFL, 1984,vol.1,p.71.
Brasil-J_apan Col., CFL, 1984, vol.1, p.62.


A binocular-type atmospheric interaction generating sequential exotic features

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