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Proceedings of the Workshop on Physics at Future Accelerators CERN 87-07 Vol. I 4 June 1987 ORGANISATION EUROPÉENNE POUR LA RECHERCHE NUCLÉAIRE CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH PROCEEDINGS OF THE WORKSHOP ON PHYSICS AT FUTURE ACCELERATORS La Thuile (Italy) and Geneva (Switzerland) 7-13 January 1987 Vol. I GENEVA 1987 © Copyright CERN, Genève, 1987 Propriété littéraire et scientifique réservée pour Literary and scientific copyrights reserved in ail tous les pays du monde. Ce document ne peut countries of the world. This report, or any part of être reproduit ou traduit en tout ou en partie sans it, may not be reprinted or translated without l'autorisation écrite du Directeur général du written permission of the copyright holder, the CERN, titulaire du droit d'auteur. Dans les cas Director-General of CERN. However, permission appropriés, et s'il s'agit d'utiliser le document à will be freely granted for appropriate non• des fins non commerciales, cette autorisation commercial use. sera volontiers accordée. If any patentable invention or registrable design Le CERN ne revendique pas la propriété des is described in the report, CERN makes no claim inventions brevetables et dessins ou modèles to property rights in it but offers it for the free use susceptibles de dépôt qui pourraient être décrits of research institutions, manufacturers and dans le présent document; ceux-ci peuvent être others. CERN, however, may oppose any attempt librement utilisés par les instituts de recherche, by a user to claim any proprietary or patent rights les industriels et autres intéressés. Cependant, le in such inventions or designs as may be des• CERN se réserve le droit de s'opposer à toute cribed in the present document. revendication qu'un usager pourrait faire de la propriété scientifique ou industrielle de toute invention et tout dessin ou modèle décrits dans le présent document. CERN—Service d'Information scientifique — RD/737 -3000-juin 1987 - III - ABSTRACT A workshop took place at La Thuile and at CERN in January 1987 to study the physics potential of three types of particle collider with energies in the TeV region, together with the feasibility of experiments with them. The machines were: a Large Hadron Collider (LHC) placed in the LEP tunnel at CERN, with a total proton-proton centre-of-mass energy of about 16 TeV; an electron-proton collider, using the LHC and LEP, with a centre-of-mass energy in the range 1.3 TeV to 1.8 TeV; and an electron-positron linear collider with centre-of-mass energy about 2 TeV. This volume of the Proceedings contains summary talks given at CERN by the conveners of the study groups. They cover the possibilities for discovery of new phenomena anticipated in the energy region up to the order of a TeV in the centre of mass of colliding partons, or of the electron and positron. Also discussed are the limits of current technology in the construction of particle-detector systems suitable for use at these energies, and especially in the high event rates provided by a proton-proton collider of luminosity 1033 cm" 2 s~1 or more. - IV - Advisory Panel on the Physics Potential and the Feasibility of Experiments at Multi-TeV Energies G. Altarelli Rome J. Ellis CERN G. Flügge Aachen M. Holder Siegen P. Jenni CERN J. Mulvey (Chairman) Oxford F. Richard Orsay J. Sacton Brussels Organizing Committee for the La Thuile Workshop J. Ellis CERN M. Greco Rome P. Jenni CERN J. Mulvey Oxford C. Petit-Jean-Genaz (Secretary) CERN - v - PREFACE Under the auspices of CERN and ECFA, a 'Workshop on Physics at Future Accelerators' was held at La Thuile, in the Val d'Aosta, Italy, from 7 to 10 January 1987. On 12 and 13 January, the conclusions reached by the study groups were summarized by their conveners before a large audience at CERN. The papers contained in this volume are based on those summary talks. A second volume will publish contributions from individual participants, giving details of the studies carried out. I should like to take this opportunity, on behalf of the Workshop Organizing Committee, to thank all those who made the Workshop possible, and especially the conveners and members of the study groups whose hard work, both in the preceding months and during the days and nights at La Thuile, guaranteed its success. The Organizing Committee is greatly indebted to the Public Education Authority of the Autonomous Region of the Val d'Aosta and to René Faval, Minister of Education for the Region*', for the most generous financial assistance granted to the Workshop. We are also indebted to Professor Bruno Baschiera who was our very effective link with the Education Authority, and to the manager, Claudio Robba, and staff of the Hotel Planibel for their warm hospitality and readiness to make arrangements which would assist the progress of the Workshop. CERN and CERN staff helped in many ways. Christine Petit-Jean-Genaz (CERN-LEP), the secretary to the Organizing Committee, worked tirelessly on the preparations for the Workshop and during it, making sure everything was done which should properly be done. At La Thuile, Michelle Mazerand (CERN-EP) cheerfully helped with the continuous flow of physicists coming to the secretariat with questions to be answered and jobs to be done. We are very grateful to them both, and to their respective groups for releasing them from their normal duties. J.H. Mulvey, Oxford Editor. *) Assesseur à l'Instruction publique de la Région autonome de la Vallée d'Aoste. - VII - CONTENTS Page Preface v Introduction, J.H. Mulvey 1 The Large Hadron Collider in the LEP tunnel, G. Brianti 6 Linear e+e" colliders, K. Johnsen 16 Status of the Superconducting Super Collider, M. Gilchriese 30 The Standard Theory Group: General overview, G. Altarelli 36 Experimental studies, D. Froidevaux 61 Beyond the Standard Model, /. Ellis and F. Pauss 80 Large-cross-section processes, Z. Kunszt 123 Detection of jets with calorimeters at future accelerators, T. Äkesson 174 Vertex detection and tracking, D.H. Saxon 205 Particle identification at the TeV scale in pp, ep and ee colliders, F. Palmonari 233 Report from the Working Group on Triggering and Data Acquisition, J.R. Hansen 21A Design and layout of pp experimental areas at the LHC, W. Kienzle 295 ep interaction regions, W. Bartel 303 The CLIC interaction region, J. Augustin 310 The nature of beamstrahlung, P. Chen 314 Physics and detectors at the Large Hadron Collider and at the CERN Linear Collider, U. Amaldi 323 List of Participants 353 INTRODUCTION J.H. Mulvey, Nuclear Physics Laboratory, University of Oxford, UK. In June 1985 the CERN Council asked Professor Carlo Rubbia to chair a committee charged with exploring options for the long-range scientific future of CERN. The Long-Range Planning Committee (LRPC) in turn set up three Advisory Panels to assist it in its tasks. One, chaired by G. Brianti, continued the design studies which had already started for a Large Hadron Collider (LHC) in the LEP tunnel. Used in conjunction with LEP, this would also make it possible to study collisions between electrons and protons. Another Panel, under K. Johnsen, was given the challenging task of investigating the technical feasibility of an electron-positron linear collider in the TeV energy range (the CERN Linear Collider, or CLIC). The third Panel was commissioned to study 'the physics potential, experimental instrumentation, and other parameters' relating to the use of these particle colliders. Following the pattern set by similar studies in the past, the Panel was to engage members of the particle physics community as participants in the studies, and to form a link between the LRPC and ECFA. Study groups, listed in Table 1 with the names of their conveners, were formed in the first half of 1986. They each met several times later in the year to prepare for the four-day Workshop to be held at La Thuile from 7 to 10 January 1987. About 150 particle physicists took part in the study groups and 93 attended the Workshop. Summary reports from the study groups were presented at open meetings held at CERN on 12 and 13 January. Table 1 Study groups and conveners Topics Conveners 1. Physics of the Standard Model G. Altarelli Rome D. Froidevaux Orsay 2. Beyond the Standard Model J. Ellis CERN F. Pauss CERN 3. Large cross-section processes Z. Kunszt ETH, Zurich W. Scott Liverpool 4. Jet detection and calorimetry T. Ákesson CERN 5. Vertex detection and tracking D.Saxon RAL 6. Particle identification F. Palmonari Bologna 7. Triggering and data-acquisition J. Renner Hansen Copenhagen 8. Intersection regions, machine backgrounds, etc.: PP W. Kienzle CERN ep W. Bartel DESY e+e" J. Augustin Orsay Instead of structuring the studies according to the machines, it was decided that comparisons would be clearer if all three types of particle collider were considered in parallel by each study group. As Table 1 indicates, three - 2 - 'physics' groups analysed the machines in terms of their potential for 'discovery' in a selection of physics areas considered to be of the greatest importance for the development of our understanding. The third of these groups had the task of assessing the many processes with relatively large cross-sections which, as well as being of intrinsic interest, might be expected to be sources of backgrounds hampering identification of certain 'discovery' signals. The task given to the detector groups was to concentrate on the technical limitations in their area of responsibility rather than to accomplish designs of complete detector systems, with all the compromises such a step entails, and to identify directions for R&D. Over the past three years, several Workshops have been held in the USA to examine the physics possibilities of, and detector designs for, experiments at a 40 TeV centre-of-mass energy proton-proton collider—the Superconducting Super Collider (SSC).
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