Electromagnetic and hadronic interactions of ultrarelativistic nuclei
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ELEMENTARY PARTICLES AND FIELDS Theory
Electromagnetic and Hadronic Interactions of Ultrarelativistic Nuclei* I. A. Pshenichnov1)** , E. V. Karpechev1)*** , A. B. Kurepin1) , and I. N. Mishustin2), 3) Received February 10, 2010; in final form, May 13, 2010
Abstract—Beam nuclei accelerated at the Large Hadron Collider (LHC) at CERN are lost due to interactions with the counter-rotating beam, residual gas, and accelerator elements. Proper modelling of the beam transport and radiation load on accelerator components requires reliable prediction of the yields of nuclear fragments produced in electromagnetic dissociation and hadronic fragmentation of beam nuclei. We investigate electromagnetic and hadronic fragmentation of lead nuclei in collisions with various nuclei and single electrons at the injection and collision energies of the LHC. The consideration is based on the RELDIS and abrasion–ablation models. Since this approach well describes Pb fragmentation data at 30 and 158 A GeV, its validity for Pb nuclei at the LHC collision energy is also expected. DOI: 10.1134/S1063778811010170
1. INTRODUCTION The advent of the Large Hadron Collider (LHC) at CERN puts forward new challenges to accelerator physics and theory of ion propagation in extended media. In particular, the interaction of the most energetic nuclei available on the Earth with the counter-rotating beam and various materials has to be understood and precisely simulated. It is expected that first lead nuclei with the design energy of 2.75 A TeV (2.75 TeV/nucleon) of each beam will collide in 2010–2011. Hadronic collisions of lead nuclei will be studied by means of various detectors built, in particular, by the ALICE Collaboration [1, 2]. Such collisions are characterized by an overlap of nuclear densities of colliding nuclei, intense hadron production in the mid-rapidity region and violent nuclear fragmentation. There exist several theoretical approaches which predict various characteristics of violent PbPb collisions and draw conclusions on the existence of new states of hadronic matter (quark–gluon plasma) during such collision events, see, e.g., [3]. Since the LHC is designed with the primary goal to collide protons, its collimator system is currently ∗
The text was submitted by the authors in English. Institute for Nuclear Research, Russian Academy of Sciences, Moscow. 2) Frankfurt Institute for Advanced Studies, J.-W. Goethe University, Frankfurt am Main, Germany. 3) Kurchatov Institute, Russian Research Center, Moscow. ** E-mail: [email protected] *** E-mail: [email protected] 1)
well tuned to clean proton beams, see, e.g., [4]. However, the same LHC collimator system, possibly with minor modifications, will also be used to accelerate and collide nuclei. In this operation mode very peripheral hadronic collisions and distant electromagnetic interactions of nuclei do not destroy projectile nuclei completely. In addition to a few hadrons, such collisions result in heavy fragments of beam nuclei propagating in very forward direction beyond the acceptance of the
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