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Nuclear g -Radiation in Peripheral HIC at LHC

Nuclear radiation. g `. Nuclear g -Radiation in Peripheral HIC at LHC. V.L.Korotkikh, L.I. Sarycheva Moscow State University, Scobeltsyn Institute of Nuclear Physics CMS meeting, December 2001. Two photon physics in AA collisions

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Nuclear g -Radiation in Peripheral HIC at LHC

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  1. Nuclear radiation g` Nuclear g-Radiation in Peripheral HIC at LHC V.L.Korotkikh, L.I. Sarycheva Moscow State University, Scobeltsyn Institute of Nuclear Physics CMS meeting, December 2001 • Two photon physics in AA collisions • Comparison** , *A and AA in the peripheral processes, pT - cut • - radiation of discrete nuclear levels • Two-stage process of nuclear excitation • Nuclear beam monitoring at LHC • Conclusions

  2. g*g *-Luminosity for AA collisions at LHC Effective g* g* -Luminosity for AA at LHC, LEP200 and a future NLC/PLC with photons from laser backscattering G.Baur, K, Hencken, CMS Note, 2000.060; J.Phys.G24,1998 C.Bertulani, nucl-th/0104059, 2001

  3. Advantages: Large photon=photon energy in center mass system  s () < 300 GeV at LHC Large electromagnetic cross-section of particle productionEM ~ Z4 EM(PbPb) 200Kbarn EM(CaCa) 3Kbarn Small background from the strong AA interactions Program: Resonance production in * * -fusion a)Quark content, Г** ~ Q4, Q - quark charge, Gluebal is forbidden to first order b) Meson size, on threshold * rM r c)Expectation of Higgs meson production at small background from strong interactions Exotic meson production * + *  Hybrids (q, anti q, gluon) * + Pomeron  Hybrids , Glueball Pomeron + Pomeron  Hybrids , Gluebal Lepton pair production * + *  e e (control QED, unitarity) * + *      Vector meson production * + *      , * + *  0 + A Peripheral Heavy Ion Collisions (b > RA1 + RA2 )

  4. S.Klein(STAR, RHIC, 130AGeV), nucl-ex/0108018 Au +Au    X , Au +Au ,  X 2 tracks pT < 100 Mev Charge sum = 0 signal Charge sum  0 background One or more neutrons in ZDC First experimental Result of Peripheral - Meson Production 0 e+e

  5. Equivalent Photon Spectra Fig.1. Geometry of two photon interaction. Beam direction is perpendicular to the picture plane. b1 and b2 are the distances from the nuclear centers to the photon interaction points P.

  6. g* g*-Luminosity for PbPb collisions at LHC qTdependence of equivalent photon spectrum for w = 10 GeV. Solid line is for Gauissian form factor, dott line for point charge. Vertical line is for qT=1/R g* g* -Luminosity for PbPb with A=2950 as a function of rapidaty y(g* g*) for different values of M G. Baur et al. CMS NOTE,2000/060

  7. Production of a single meson in * * fusion R  p 0 ,h, h,, ..., H

  8. Resonance Cross-Sections in * * fusion at LHC g g Meson cross-sections for fusion in PbPb and CaCa collisions at LHC CaCa  Resonance G. Baur et al. CMS NOTE,2000/060

  9. Nuclear radiation g` Three process of the resonance production in the peripheral AA collisions (b> R1 + R2) g* g* -fusion Bertulani, Baur, 1985, 1988 Kraus, Grener, Soft, 1997 Baur, Hencken, 1997, 1998, 1999 Klein, Nystrans, 1999 s (PbPb) 40 mbarn  s (PbPb) 7 barn  s (PbPb) 200 barn  AA - strong interactions in grazing collisions g* A - photonuclear desintegration Pshenichnov, Mishustin, 1999 RELDIS Anderson, Gustafson,Hong, FRITIOF

  10. Nuclear radiation g` p0 - rapidaty distribution for PbPb collisions at LHC 106 mbarn(incl), 36 mbarn(excl) K.A.Chikin, V,L. Korotkikh, A.P.Krykov,L.I.Sarycheva, I.A.Pshenichnov, J.P.Bondorf, I.M.Mishustin. Eur.Phys.J.A8(2000)537

  11. Our suggestion is to register the nuclear secondaryg’ radiation of HI after interaction How to select the peripheral collisions? Use the correlation of b and multiplicity n Use the correlation of b and transverse total energy Et Register the intact nuclei after interaction A+AA+A+M Use the small pt of produced particles Nuclear radiation g` Possible Signature of Peripheral AA collisions at LHC  But (AA A*A) 0.1 mbarn  @

  12. Nuclear radiation g` Kinematics of the Secondary g-radiation Dependence between the energy Eg and the polar qgof photon, emitted by the relativistic nucleus at LHC energy. Axis Z is along nuclear direction. The lines correspond to the discrete excited levels: Roman pots of TOTEM have 20 mrad < qg' < 150 mrad Energy of g'–radiation will be corresponded to the region 21 GeV < Eg' < 26 GeV

  13. Nuclear radiation g` Nuclear g-radiation and e+e production e+e production Huge cross-section: Pb Pb  Pb Pb + e+e (220 Kbarn) Ca Ca  Ca Ca + e+e (1.4 Kbarn) Baron, Baur. Phys. Rev. D46 (1992) R3695 Guclu et al. Phys. Rev. A51 (1995) 1836 Alscher et al. Phys. Rev. A55 (1997) 396 Properties of g'-radiation • Neutral radiation • High energy Eg' at LHC • Narrow collimation of g'-radiation • But the direct excitation of nucleus has a small cross-section

  14. Nuclear radiation g` Two-step mechanism of nuclear excitationV.Korotkikh, K.Chikin Preprint INPH MSU 2001-1/641 nucl-th/0103018, in press Discrete levels of Ca Endt et al. NPA633 (1998) 1. QED + Weizsacker-Williams 2. Ca + Ca a) L = (24)1030 cm-2 sec-1 b) Well famous form factors of discrete levels 3. e + Ca  e' + Ca*(lP, E0g') Gulkarov. Fis. Elem. Chast. at Nucl 19 (1998) 345 Ca + Ca  Ca + Ca*(lP) + e+ e sint = 5.1 barn  g' + Ca

  15. Nuclear radiation g` Main Formulae for Two Stage model Energy spectrum of   Angular distribution   Cross-section of two stage Cross-section convolution of two process

  16. Nuclear radiation g` Energy and Angular Distributions of g'-rays LHC, Ca + Ca  Ca + Ca*(3) + e+ e  g' + Ca Energy distribution of secondary photons. Numbers 1, 2, …, 5 correspond to discrete levels of 40Ca. Angular distribution of secondary photons for sum over all discrete levels Eg' = 0÷26 GeV (main contribution) Uniform distribution qg'  150 mrad eq = 0.35

  17. g` Nuclear radiation Comparison of g'-rays Distributions for Various Processes 1. Ca + Ca  Ca + Ca*(3) + e+ e 2. Ca + Ca  Ca + Ca*(3) 3. Ca + Ca  Ca + Ca + p0 Energy distribution of secondary photons. Numbers 1, 2, 3 correspond to three processes. Angular distribution of secondary photons for three processes.

  18. Nuclear radiation g` pp and Pure electromagnetic processes  EM(CaCa ) 3.0 barn @

  19. Large problem at LHC is a monitoring of nuclear beam luminosity What is necessary to solve the problem: Choice of a process for AA interaction Large cross-section of the process Effective detectors for registration of the process High accuracy of luminosity measurement g` Nuclear radiation Possibility of Nuclear Beam Monitoring at LHC by g-radiation of Nuclei Recoil

  20. g` Nuclear radiation Photon Registration Rate and Accuracy of Luminosity Monitoring TOTEM LHC Ca + Ca  Ca + Ca*(3) + e+e  g'+ Ca sint = 5 barn L = (24)1030 cm-2 sec-1 qg'= 20150 mrad jg'  0360 dL= 1%, dNg/dt = 106 photon/sec Dt = 10 msec Eg' = 25 GeV 4 radiation length eGeom 0.35

  21. Peripheral AA interactions are studied both theoretically and experimentally There are some good ways to select such kind of processes Two stage process A +A  A* + A + ee , A*  * + Ahas a large cross-section ( for CaCa ~ 5 barn) Nuclear*- radiation can be used for a)the signature of peripheral processes b)nuclear beam monitoring at LHC g` Nuclear radiation Conclusions

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