On the nature of the Cosmic Ray penetrating hadronic component. A.S. Borisov1, V.G. Denisova1, V.I. Galkin2, Z.M. Guseva1, E.A. Kanevskaya1, M.G. Kogan1, A.E. Morozov1, R.A. Mukhamedshin3, S.I. Nazarov2, V.S. Puchkov1, S.E.Pyatovsky1, M.D. Smirnova1, A.V. Vargasov1 1 P.N.Lebedev Physical Institute of RAS, Moscow, Russia 2 M.V.Lomonosov Moscow State University, Moscow, Russia 3 Institute for Nuclear Research of RAS, Moscow, Russia 19th ISVHECRI, 22-27 August 2016, LPI, Moscow

Tien Shan High Mountain Station at 3340 m

15 layers of ionization chambers in total Large ionization calorimeter within EAS array at the Tien Shans in 1973 - 1974 Historical layout h = 2.85 m (850 g/cm2) 15 layers of ionization chambers in total

Tien Shan effect: ‘Long-Flying’ CR component Tien Shan effect: ‘Long-Flying’ CR component !!! Evidence of abnormally weakly absorbed EAS cores in lead !!! Eh ≥ 40 TeV * – Ne=1.8 - 3.2·105  – Ne=1.8 - 3.2·106 □ – Ne=3.2 - 5.6·106  – Ne=5.6 - 10 ·106 → → E0 ~ 10 PeV Attenuation length L(E) of hadronic component in EAS cores observed with ionization calorimeter: cross-circles – experiment, solid circles – Monte Carlo without charm, crossed squares – Monte Carlo with charm. Absorption curve of e-h cascades in the calorimeter normalized to EAS size when the showers are grouped by energy release Eh.

Long-Flying component at Tien Shan High Mountain Station I.V.Dremin & V.I.Yakovlev (LPI RAS) introduced two possible explanations of the effect: considerable contribution of charm particles (D0, Lc); (note: production cross sections scprod at √s < 20 GeV were quite small, i.e., scprod 10 μb). manifestation of quark strange matter existence of (strangelets). Both candidates can carry effectively the energy deep through the lead absorber.

Penetrating hadrons with abnormal absorption in lead (1980-ies) In the range of 070 rad. lengths, the absorption curve obeys the standard exponential law with index (1)abs=(2005) g/cm2. However, at larger depths (>70 c.u.), the absorption length of hadrons in lead changes and becomes as high as (2)abs=(34080) g/cm2. This unusual phenomenon seems to be similar to that discovered earlier at the Tien Shan Mountain Station when absorption of EAS hadron cores in a hadron calorimeter was studied (a hypothesis of long-flying component of cosmic rays introduced by V.I.Yakovlev). Distribution of the cascade origin points for hadrons with Eh(γ) 6.3 TeV obtained in the Pamir experiment by means of homogeneous Pb-chambers 110 cm thick.

A design of 2-tired XREC for testing of the charmed origin of penetrating particles Hypothesis: Excessive cascades are initiated by charm particles /Feinberg, Dremin, Yakovlev/ (  3 mb/nucleon at EL ≥ 20 TeV, xlab  0,1 ) , A Lay-out of a 2-storied XREC with 2,5 m air-gap Distribution of cascade origin points in deep uniform lead chamber and in 2-storied XREC with 2,5 m air-gap  2.5 m

RHIC experiments (STAR, PHENIX) STAR: 1,40,20,4 mb; PHENIX: 0,920,150,54 mb at = 200 GeV in d-Au collisions

RHIC experiments (STAR, PHENIX) STAR: 1,40,20,4 mb; PHENIX: 0,920,150,54 mb

Two-storey X-ray emulsion chamber with air gap at the Tien Shan Mountain Station (3340 m a.s.l.) A section view of ionization-neutron calorimeter with 2-storied X-ray emulsion chamber at the top of it (project).

Upper storey of XREC with 2.2 m air gap at TSMRS (assembled in 2004)

Lower storey of XREC with 2.2 m air gap at TSMRS

Foundation of the Pamir-Chacaltaya ISRC Foundation of the Pamir-Chacaltaya ISRC . New stage of CR researches at the Pamirs. Pamir-Chacaltaya ISRC is an international intergovernmental organization opened for joining by any other state or scientific institution.

Exotic Phenomena study with 2-storey XREC at the Pamirs The envisaged goals of the experiment: origin of penetrating hadronic particles (strangelets or charm hadrons); search for Centauros; study of coplanarity phenomenon.

Experimental data from 1-year exposition of 2-tired XREC at TSS Preliminary Preliminary Number of darkness spots produced by hadron cascades as a function of lead depth t (experiment and simula- tion according to FANSY code with different options for scprod and accounting for chamber response with ECSim2.0 based on GEANT 3.21) A layout of 2-tired XREC at TSS Supper = 48 m2, Slower= 32 m2, Egth  5 TeV

Simulation of 2-storey XREC response with ECSim 2. 0+FANSY 1 Simulation of 2-storey XREC response with ECSim 2.0+FANSY 1.0 code accounting for charm production MC code FANSY 1.0 (developed by R.A. Mukhamedshin of INR RAS) represents a phenomenological hadronic interaction model implementing quark-gluon string theoretical approaches and assuming various charm production cross section parameters (in many features close to QGSGETII model except for the x-spectra of secondary particles including charmed ones: they appeared to be too soft as compared to the LHC data). MC code ECSim 2.0 is based on GEANT 3.21 and allows to calculate the detector response for XREC of a given design taking into account the exact experimental technique used in the ‘Pamir’ experiment.

Simulation of 2-storey XREC response with ECSim 2. 0+FANSY 1 Simulation of 2-storey XREC response with ECSim 2.0+FANSY 1.0 code accounting for charm production p+Pb p+Pb (a) (b) Distribution of darkness spots produced by incident protons (a) and pions (b) in 2-storied XREC in the case of conventional charm production cross section and abnormally high one (dс= / = 0.4÷0.5 , s pp→cc ~ 8 mb at EL  75 TeV)

Analysis of data obtained with homogeneous lead XREC 110 cm depth Distribution of darkness spots produced in homogeneous lead XREC if scprod  5 mb/nucl. (a) or if scprod  8 mb/nucl. (b) at xlab ≥ 0.1 on assumption that the fractions of nucleons and pions among incident particles are 70% and 30 %, respectively.

Recent RHIC and LHC results The total charm production cross section at =2.76 and at 7 TeV was evaluated by extrapolating from the central rapidity range to the full phase space. Simulations: perturbative-QCD calculations accounting for Next-to-Leading Order corrections Pamir 2014 =7 TeV

Important note. Due to the high energy threshold (Eth ≥ 4 TeV), XREC experiments observe production of the most forward particles, i.e., they can study the kinematic fragmentation region of a projectile particle: !!! XREC experiments should be considered as complementary ones to collider experiments !!!

σ pp→charm ~ 8 mb/nucleon Conclusions The on-going CR experiment with 2-storey XREC is appeared to be rather sensitive to the charm production in forward cone. Charmed particle production cross section in the forward kinematic region (xlab ≥ 0.1) is as high as σ pp→charm ~ 8 mb/nucleon Note: accounting for more realistic and hard x-spectra may decrease this value Excess of hadronic cascades in the depth of lead calorimeters can be accounted for by contribution of charmed particles.

Thank you for attention!