Experimental data on the interaction mean free path of hadrons with energy E  20 TeV in lead obtained with multilayer X-ray emulsion chambers(XEC) are compared with results of simulation of nuclear-electromagnetic cascades in lead chamber. It is shown that, to explain experimental data, the value of the inelasticity coefficients,  K  .8 should be assumed

Kanevsky, B. L.

Mikhailova, I. A.

Rakobolskaya, I. V.

Sveshnikova, L. G.

English

NASA Technical Reports Server

HE 1.1-9
81
ESTIMATION OF THE TOTAL INELASTICITY COEFFICIENT
IN INTERACTION OF_ 20 TeV HADRONS WITH LEAD
KanevskyB,L., MikhailcvaI,A.,
Rakobolskaya I.V., Sveshnlkova L.G.
Institute of Nuclear Physics, Moscow State University,
Moscow 119899, USSR
Experimental data on the interaction mean free path of
hadrons with energy Eo_20 TeV in lead obtained with multi-
layer X-ray emulsion chambers(XEC) are compared with results
of simulation of nuclear-electromagnetic cascades in lead
chamber. It is shown that, to explain experimental data, the
value of the total inelasticity coefficient, < K>_.8 should
be assumed.
Multilayer XEC allow determination of gamma-ray and
__ _o_n _ad _ _n_g_ _ r_s_ into the- 'ca e C a n clear in er-
action, and the origin depth _ t of an electron-photon cas-
cade induced in a chamber by gamma-rays, electrons, and
hadrons. The experimental procedure and chamber design
have been described in detail in /1/.
In paper /2/ of the "Pamir" Collaboration, tie results
have been presented of measurement of the hadron interac-
tion mean free path, _ meas, in lead chambers obtained by
analysing the hadron flux(about 700 events) over an area of
140 mL. After efficiency of hadron registration in chambers
of different thickness has been allowed for more accurately,
the authors of /2/ obtained the following results:
2 . fcJ .
_ =185+40 g/cm for energy Eh=5 10 TeV,
meas-21-3__24g/cm 22for energy E_#_IO TeV,
meas-197+29 /cm for energy E_ _20 TeV.
A meas- - g
The measured value of _ meas can be seen to be independent
of EhI_)within errors and A meas=207±17 g/cm2.
The measured value of _ mea- concerns the summary flux
•of nucleons and charged plons w[th energies Eo 20 TeV.The
pion fraction in this flux can be estimated based on calcu-
lations in terms of quasiscaling models, e.g., from /3/.
This magnitude is almost independent of a model and, on
average, pions present ~30% and nucleon_ _ 70% in the total
hadron flux at the given depth(596 g/cm ).
. The value of _ meas may differ from the proper interac-
tion mean free path for hedrons in lead, 2 prop_ due to
the following causes:
° A. The influence of an admixture of electron-photon
component
https://ntrs.nasa.gov/search.jsp?R=19850027544 2020-03-20T17:22:02+00:00Z
3= HE 1.1-9
When determining /_meas, cascades wlth_ t _ 8 C.u. were
taEen Into account. _The number of EPC induced by gamma-rays
and electrons at depth 8-10 c.u. •from the chamber boundar_
was less than 2% of the hadron-induced cascades.
B. The influence of the boundary effects.
Usln_ the angular distributions •of cosO 5"3 for hadrons
and cos6 •6 for gamma-rays and the power law _nergy spect-
rum with the differential power •index 3 ,obtained in /4/,
the procedure of hadron and gamma-ray registration in a
2mx5m chamber (a standard size •of lead chambers in the
"Pamir" Collaboration) was Monte-Carlo simulated, The cas-
cades interacting in a chamber and leaving its volume and
additional cascades arriving from air, when taken into
account, change the value of 2 meas by less than 3%.
C. Allowance for secondary interactions•
The impossibility to follow entirely the hadron cascad-
es in a chamber due to a high registration threshold =leada
to appearing the hadron, induced cascades for which we mea-
sure _ t of the second and subsequent interactions instead
of the first one. So, there exist cascades in which in first
interaction the energy E_ lower than threshold Was ....._elae sad
while the energE released in one of subsequent interactions
exceeds the threshold. There are also the cascades with
energy released in the first and second interactions being
higher than the threshold and the second interaction occur-
es at a point of 15-20 c.u. far from the first one. So, the
second interaction was mistaken as the first one of another
hadron. ....
The existence of these cascades leads to overestimation
of _ meas compared with Apron, Monte-Carlo simulations were
performed to eliminate the distortions of _ meas. The scheme
of simulations used is presented in /5/, Energy Eo of %he
primary protons inducing in a chamber nuclear-electromagne-
tic cascades was simulated with respect to the spectrum
with the differential •power index 5 . The point of the
first interaction in a chamber was compute_ with _ prop=
190 E/on 2. Random stars imitating nuclear interaction were
simulated according to /6/. ......
In the first version of simulations, the difference in
inelastic interaction of incident hadron!; with protons and
nuclei was neglected, leading particles being simulated in
the x-presentation with respect tO the inclusive spectrum
from /7/, and the mean value <K>being equal to .5. In the
second version of simulations, use_was made of the data on
the inclusive spectrum of leading particles obtained in
terms of an additive quark model regarding the atomic num-
ber of the target-nucleus in /8/, the mean value being .
K > =.8. The electromagnetic cascades resulting from the
decay. Qf _ _-meson for particles with energy E_ > E_tr (E_=
•5-10l_eV) were also _onte-O_rlo simulated al_ov_Ing for'_he
processes of pair production, bremsstrahlung radiation, and
B_therford scattering. To obtain the electron number and
33 HE 1.1-9
the optical density of X-ray film wlthin a circle of given
radius(Rut40 urn) caused at an observation level by the ini-
tial gamma-rays and electrons(wlth energies E_<E_) use was
made of the averaged cascade curves calculate_ tb-_he core
approximation, Optical densities in X-ray film produced by
simulated cascades at various depths in lead were processed
by the same program as experimental ones /I/. ....
f_j_or each version of calculations, _ 1OOO events with
E_4 TeV and 8 c.u, _ to64 o.u. were Si_lated, The
meas-values obtained for the two versions of calculations
are listed in Table I together with the Corresponding values
of A prop deduced from the experimental values of A _===
and from ratios of A prop and _ meas obtained in difT_nt
versions of calculations. ..........
Table I. Ratios of _ crop and _ meas obtained when analys-
ing simulatea cascades
....... J I _J ,J ............. . .... ,.... ...... ,__
, calculation experiment .....
' , glcmz glcm2....
"<K> =_o.5 190 34o_3o 207+_17 115+_E2,..........
_:K > =0.8 230+_20
. ..... .
The contribution of the pion component allowed for do
not practically change the obtained ratios of _ meas and
urou. In the energy-region _ 200 GeV an_ inelastic cross
se_ti6n _e_ in the 7?*Pb interaction is by a factor of
1.1-1.3 le_ _han in the pPb-interact_on that may lead to
an increase in _ _r^_ for the total hadron flux by less
than 5%. _ inel o_ _e pion and nucleon interactions on
lead are expected to come closer with increasing energy/9/.
< K> in the _ Pb-interactlon is larger than in the pPb-
interaction, leading to a less diversity of _ from
u:_ou in the _ Pb,lnteraction, meas
EXperimental data obtained a% accelerators and _n cos-
mic rays for the hPb-interactlon_ows that up to energies
of several TeV) an Increase: _n _ within errors is absent
and_-1800 mb/lO/.Por highe_ _Interactionl energies, in 19/.,
usinl the_Glauber model, the following .v_lues have_been_
tained._=1900 mb that corres]2onds to._t_=180 g/cm and _¢ =
17]_ mb that corresponds to_=19_ glcm for Eo=20-100 TeV.
Thus, the experimental value _ meas=207+_17 g/cm _ for
the s_ry hadron _lux is consistent with the expected
value _$_;_=180 g/cm = for Eo > 20 TeV for the total inelasti-
city coefficient <K>_.8 only.
References
I. Bayburina S.G. et al. Trudy PIAN, 1984, v.154.
2. Borisov A.S. et al. Prec. of Intern. Syrup. on'CosmicRays and Particle Physics, Tokyo, 1984, 426 430.
3. Erlikin A.D., Kuzuma N.P., Preprint N 95 PIAN, 1980.
34
HE 1,1-9
4. Bayburina S.A. et al. Prec. 18th ICRC, 1983, 7, 420-423.
5. Belyaev A.A. et al. EPC in cosmic rays at superhigh
energies, Moscow, "Nauka", 1981.
6. Astafiev V.A. et al. Prec. 14th ICRC, 1975, 7, 2593.
7. Eilten et el., Nucl. Phys., B44, 333, 1972.
8. Anisevieh V.V., #raun Yu._., Shabelsky Yu.M., Yadernaya
Fizika, 1984, 39, vyp.4, 934-946.
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vyp..7 •
10. Garyaka A.P. et al. Izv. AN Arm. SSR, 78, vyp.1, 1983,
66-78.


Estimation of the total inelasticity coefficient in interaction of greater than or equal to 20 TeV hadrons with lead

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