It is shown that the Tien-Shan effect can be explained as a consequence of charmed particle production with a sufficiently high production cross-section (about 5 mb/nucleon at 100 TeV)

Dremin, I. M.

Efimenko, L. A.

Golubnichy, P. I.

Madigozhin, D. T.

Saakjan, V. A.

Savchenko, R. T.

Serdukov, A. D.

Yakovlev, V. I.

English

NASA Technical Reports Server

314 HE 6.2-17
TIEN-SHAN _FECT AND CHAR_I_ PARTICLES.
I .M.Dremin ,D.T.Madigozhio ,V.AoSaakjan ,A.D.Serdukov,
_..I._akovlev - P°NoLebedev Physical Imstitute,Mesccw
117924, Leninsky Prospect 53, USSR,
P.I.Golubnichy, L.A.Efimenks, R.T.Savchenko -
Voroshilovgrad Mashinery Building Institute, USSR°
Abstract
It is shown that the Tien-Shan effect of long-flying
component can be explained as a consequence of char-
med particles production with high enough production
cross-section (about 5 mb/nucleon at 100 TeV)o
The investigation of attenuation peculiarities of
EAS hadronic component energy flux in the calorimeter with
lead absorber has shown /1,2/ that energy dependence of
hadronic component energy attenuation length L(E) has a
peak-type behaviour (see figol in /I/). This phenomenon,
named as "Tien-Shan effect", we _l account for as a conse-
quence of generation and following decay ef particles with
charmed quarks. The most important conclusion from the com_
parison of theory and experiment is that charmed particles
have to be produced in the fragmentational _egion and the-
ir production cross-section at energies about 100 TeV must
be equal (5+2) mb/nucleon.
For a qualitative analisis ef influence of particles
with heavy quarks on the hadronic cascade we use as the
first approach only one sort of particles called conventi-
onally as charmed ones. It simplifies the system of kine-
tic,equations for proqesses investigated:
wiJ_itial cenditions
Here S - are the fractions of primary,ener.gy transferred
into charmed (C), nucleon (N) and pion (_7 $) components)
https://ntrs.nasa.gov/search.jsp?R=19850027840 2020-03-20T17:09:55+00:00Z
315
HE 6.2-17
Z is the coordinate along the axis of cascade developing;
_ c/ _ N -is a probability of charmed particle producti-
on. Eqs (q) show energy variation of charmed, nucleo_ and
pion components because of their decay and interaction.
in are
Coefficients (I_ : _ Kc , _= _ -S
where _ i' _i are mean free paths and inelasticities of
i-th component. B is the e.ergy fractioz transferred
into pioos by the particle decay into nucleons and pions
(kaoos have ipteractio, properties close to those of pi-
ons). The complete solution of the system of equations
is give. in /3/. I. particular case B = I; K = I, the to-
tal e_ergy of pions is written in the form :
It is see. that "the standard cascade" exp(-_z) acqu-
ires additional co.tributio, from the charmed component.
At the small depths it is negative that corresponds to ca R
cade damping because some eoergy is kept by charmed parti-
cles. After decay of those particles the energy is added
to the cascade so that at the depth Zo=(1._/o_)/(_-_)
the transferred into pioms energy becomes just the same as
- the energy i_ sta.dard cascade. The maximum contribution
from the charmed particles is achieved at the depth Zmax =
= 2 Zo, after that the cascade decreases along the same
expo.ent as a standard one, but with an enlarged coeffici-
ent. So the charmed particles in the beginning of cascade
start to "eat up" the standard cascade, then supply the a_
" ditional "bump" which transforms i_to the usual decrease
at the tail of the cascade.
More comprehensive system of kinetic equations for
distributions of particle multiplicity Fi (index i means
the particle s sort) of energyEE along depth Z :
(_Z ' 4 o , , I
fl'/_ _ -.-- .0 ..
The dump of particles i _ecau_e of imteraction ( _ i) and
316 HE 6.2.17
decay ( _i ) is compensated by their production in the
lastic interactions (Wij) and decays (Rij) of particles j.
The pion production spectrum has been chosen of CKP type,
but for A c it was admitted to be independent of X /4,5/
with X = 0,5. The D meson s spectrum is soft, but harde_
for primary pions to take into account the leading effect.
Mean free paths have been taken as _N=192 g/cm2; _W_h =
210 g/cm 2 /7/, and inelasticities are equal to KN=0,63;
K_± = 0,7 /7/; Kc=0,1 /8/. The hadrenic mode of decay on-
ly has been taken into account° Charmed particles produc-
tion cross-section is assumed to increase starting from
FNAL energy, passiog through ISR energy and achieving the
constant value at an energy 100 TeV. Cascade curves in
the depth _ interval 374-924 g/cm 2 (as io experiment) were
fitted by exponents, which determined attenuation lengths
of cascades. The results are shown in fig.1. L(E) depend_
rice for a standard cascade is shown by a dotted line. Num-
bers mark corresponding asympthotical cross-section values
equal 1,2,5,10 mb at 100 TeV. One can see that 5 mb value
corresponds to the best agreement with the experiment. The
energy fraction carried out of the calorimeter by charmed
particles grows with a primary energy (fig.2). It means
that we use in the experiment another energy scale becau-
se we group all events according to the energy released
in the calorimeter. Accounting this fact leads us to the
unexpected effect i.e. narrowing of peaks and moving them
to lower energies (fig_3).
For a detailed comparison with the experiment we
b
are performing now the Monte-Carlo calculations.
Thus sufficiently effective charmed particles produ_
tion in the fragmentational region leads to the energy de-
pendence of cascade _ attenuation lengths with clear maxi-
ma. It describes well qualitatively the main peculiarities
of the Tieo-Shan effect.
REF_ENCES:
I. Zakovlev V.I. et.al., Proc 18 ICRC,Bangaler 1983,v.5,102
317
HE 6.2-17
L(_) ,g/cm2
2000 Flour e 1) / \/ •
/ /7" ' "
_ooo _._'/'/ ............ _._/. _.'_..-._.--............ -;-
____u_o_c_- - -
_" 30 100 3000 1000 Eo ,TeVI I ,, I , I I
Eout/ Eo
_'(_')' f'_ #'k/ X \
-o,, ,_..+..,<>___,ooI/ \ o
Fi_u_ e 5.
300 1000 Eo,TeV __00 500 1000 E,TeV
• I I I,,, i, " _ ,, I
2.Xakovlev V.I et.al.Proc.16 IORO,Kyoto 1979,v.6,p.59.
" 3,Dremim I.M. et,al. Yadernaya Phisika,1985 in print°
.Basile M.et.si.Let.Nuovo Chim. 30,_87,1981.
5.Hwa R.O. Phys.Rev. D27, 653, 1983o
6. Bodek A.et.sl.Phys.Lett.126 b,#99,1983.
7,Bszarov EoV. Prepr.FIAN,102, 1981.
8.Hodzhamirjan A.Xu. Vopros_ Atomz.Nauki i Tehniki,
seriya phys. experiment ,3,112/,1@,1982.


Tien-Shan effect and charmed particles

Tien-Shan effect and charmed particles

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