Scaling, mean P sub t, high P sub t jets and others at energies over 1000 TeV are discussed on the basis of gamma-family data with sigma E sub gamma  100 TeV, observed at Mt. Fuji (3750 m). These quantities were examined in connection with the primary composition

Amenomori, M.

Hotta, N.

Kasahara, K.

Kobayashi, T.

Konishi, E.

Mikumo, E.

Mizutani, K.

Nanjo, H.

Sato, K.

Yuda, T.

English

NASA Technical Reports Server

HE3.5-I
348
PARTICLE INTERACTIONS AT ENERGIES OVER I000 TeV INFERRED
FROM GAMMA-FAMILIES OBSERVED AT Mt. FUJI
Mr. Fuji Collaboration
Amenomori,M., Nanjo,H. and Konishi,E.
Hirosaki University, Hirosaki, Aomori
Hotta,N.
Utsunomiya University, Utsunomiya, Tochigi
Mizutani,K.
Saitama University, Urawa, Saitama
Kasahara,K., Kobayashi,T., Mikumo,E., Sato,K. and Yuda,T.
ICR, University of Tokyo, Tanashi, Tokyo
Mito,I.
Shibaura Institute of Technology, Shibaura, Tokyo
Shibata,M.
Yokohama National University, Yokohama, Kanagawa
Shirai,T., Taira,T., Tateyama,N. and Torii,S.
Kanagawa University, Yokohama, Kanagawa
Sugimoto,H. and Ta%ra,K.
Sagami Institute of Technology_ Fujisawa, Kanagawa
Scaling, mean P , high P jets and others at
energies over i000 T_V tare discussed on the basis
of gamma-family data with Z Ey > lO0 TeV, observed
at Mt. Fuji (3750 m). These quantities are
examined in connection with the primary composition.
I. Introduction.
At present, an observation of cosmic ray phenomena is a
unique source to get a dire_ information about particle
interactions at energies over IO-- eV. Among these, emulsion
chamber experiments produce fruitful results for this purpose.
Since 1970, the large-scale emulsion chamber experiments have
been continued at Mt. Fuji (3750 m, 650 glcm_). Now, the total
exposure of chambers reaches about i000 m .y and about 200 family
events with ZE > I00 TeV have been observed. Also we have
reliable data about particle interactions at energies up to 150
TeV and this energy will go higher at Felmilab in very near
future. So, within one or two years, we may give a definite
answer to the alternative of I) scaling break in the
fragmentation region and proton dominant primary or 2) scaling
and heavy enriched primary, which have been repeatedly discussed
for a long time.
16 this report, we discuss general features of particle
interactions expected from the Mt.Fuji experiment,comparing with
the Monte Carlo results, and also describe some characters of
https://ntrs.nasa.gov/search.jsp?R=19850027627 2020-03-20T17:20:03+00:00Z
HE3.5-1
349
super-families.
2. Problem of the Feynman scaling in the fragmentation region.
It is well confirmed that the absolute flux of gamma-ray
families at mountain altitude is the most sensitive to the energy
spectra of particles in the fragmentation region, inelastic cross
sections and also primary composition, I).
In Fig.l we compare our data
with the Monte Carlo results
which are simulated on the basis
of the conventional model of ! Fig. I.
the interaction and primary.
The symbols used for classifying
the model are : P means the _ _"
proton primary , M the mixed ._ %composition (heavy dominant), S _ 10_the scaling, F the fire-ballmodel (normalized to SPS data at150 TeV), Q the QCD-jet, I the
i_c_asing cross section as %
E-'-- and T the transverse i0-= usa,(tooo)
momest_ increasing with energy
as E " . The bending energy
(Eb in TeV) of primary proton is _kMsa,(_oo)
denoted in the blacker (spectral z , , I ,_ ,10= I0J
index changes from 1.7 to 2.0) EET(TeV)
and other nuclei also become
steeper at Z*Eb. The absolute
intensity of assumed total spectruT5 is normalized to the
Grigorov's one at energies around iO eV. Details of the
simulation will be found in the other paper, 2).
It can be understood that the scaling with heavy enriched
primary is compatible with the experimental data. In this case,
the& proton component should become steeper at energies around
IO-- eV. Of_course, a strong scaling break and proton dominant5
primary (Eb~lO TeV) can also explain our data, but the fr_tion
of protons to the total would not exceed 50 % at around iO eV
(bending energy of proton spectrum).
w
3. Mean Pt at high energies.
Fig. 2
The lateral spreads of
• constituent gamma-rays in _ Em = 4 TeV
the families give a >
measure of the mean P _ 50
of secondaries a_ ^ _+_._,_
the respective energy 10 _ ( )
range, with the Monte , , , I , , I_
Carlo results. In the IOz 10=' 10"
acccelerator energy EE;(TeV)
region, the mean P neart
HE3.5-1
sso
EO.04the central region seems to increase with energy as . If
this increasing rate is hold up to higher energies, it takes
about 450 MeV/c at I000 TeV. However, as learned from this
comparison, our data do not favour to increasing P (Here we
discuss the P in the small Pt region. Note that t_e QCD jets
are specious_y taken into account in the simulation.). This
result may suggest that the mean _t depends very weakly on the
primary energy, if any, or remalns almost constant, since the
family phenomena are very sensitive to the fragmentation region.
4. High Pt phenomena. I°-'I,
Fig. 3
In order to enhance the ZE_IOOTeV
effect of high Pt' a
clustering method is
applied to the family \
phenomena. This method is _ \
already described in the I0" _\\
paper, 3) Here we present \
• ' ' \ MSQIT
the frequency of double- \\
core events. In order to \PFI
I I I MSOI
pick up such events, first 2oo 4oo soo eoo
we clusterize the gamma- Xlz (TeV.cm)
families with EE_ >i00 TeV,
then impose the _ollowing conditions : El+E2 > 0.8 ZE_ and EI,E2>
I0 TeV ; RI2 > 5 max(rl,r2), where El(E2) and rl(r_) is the
energy and lateral spread of cluster 1(2) and RI2 the distance
between two clusters. In Fig.3 we show our data together with
the Monte Carlo results. The frequency of double-core events
with XI2(=RI2VEI-I.---_.E) > I00 TeV.cm is about 7 %. This figure
teaches us that such events are within the scope of expectation
of the model based on the scal_ng with QCD-jets, and also a rapid
energy dissipation model such as fire-ball is incompatible with
the data.
Concerning to high P jets, we should note here that thet
peculiar event "TITAN", observed in 1977 and composed of 6 very
high energy showers with E > IO0 TeV, 4), is by no means produced
by the conventinal interaction models according to our Monte
Carlo simulation.
5. Super-families.
Here, we describe some features of super-families with E
I000 TeV. The primary energy [_sponsible for generating such
families would mostly exceed i0 eV. A general feature of
these super-families is expected to bring us _6new c_e for the
study of particle interactions at energies i0 - i0 eV. A
remarkable structure is that the majority of super-families is
accompanied by a halo. In Fig. 4, we show the flux of gamma-
families with ZE_ > i000 TeV (E =4 TeV) and halo events at
Mt.Fuji. Here, the energy of _alos is estimated by using a
relation of E=C*Z_ where Zois the total track length and C the
"conversion factor of I0 MeV/c.u.. As discussed in other paper,
the flux of halo events can also be explained by the model
.mentioned above, 5).
HE3.5-I
361
At present, we have 6 halo I'|x\xx_ Fig. 4
events with energy exceeding
i000 TeV. The biggest event
is the FC-31 with energy of
about 9000 TeV. Two patterns _ IO" _, I",
• \
re found about halo struc u e, _ o \o
i.e., single and axial- "o" _o \\ J
symmetric core or multi-cores, z _ _,
Examples of the event, FH-89 -_ x\HALO
\
(2500 TeV) and FC-I04(4000 TeV) o
are shown in Fig. 5 and 6. _.I _i_I_I
Three among 6 events have a IO-_ mity
single-core structure. In \
I
._. . 10_ 104
,, Fig. 5 E(TeV)
_"° ,., Fig. 6
"Z x-_,s ,,.'
Fig. 5 -" FI{-89 (36 c.u.), Fig. 6 : FC-I04 (14 c.u.)." x__ _.._.. -'-
Density map of X-ray film measured by photometer.
Area • 24x24 n_n2, Sllt size ."300 microns, Z-axis '.
Density from 0-3.0.
particular, no high energy showers are found in the outskirts of
the halo of the event FH-89 , strikingly different from other
two, as noticed from Fig. 5. According to the Monte Carlo
simulation, such type of events are possibly produced by protons
deep in the atmosphere and the structure of the event FH-89 may
suggest a look of very high multiplicity. We need more events
to reach some conclusive resul_s.
i) Akashi, M. et al, Phys. Rev., D24, p2353 (1981).
2) Ding, L. K. et al, Prc Int. Symp. on Cosmic Rays and
Particle Physics, p142 (1984, ICR, Univ. of Tokyo). _.
3) Amenomori, M. et al, Phys. Rev., D25, p2807 (1982).
4) Akashi, M. et al, 15th ICRC, Vol.7, p184 (1977, Plovdiv) ;
Amenomori, M. et al, Proc. Int. Symp. on Cosmic Rays and
Particle Physics, p382 (1984).
5) Ren, J. R. et al, HE3.4- 9, in this volume.


Particle interactions at energies over 1000 TeV inferred from gamma-families observed at Mount Fuji

Particle interactions at energies over 1000 TeV inferred from gamma-families observed at Mount Fuji

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