Kjell Johnsen

The Large Hadron Collider (LHC) in the LEP tunnel

After the remarkable start-up of LEP, the installation of a Large Hadron Collider, LHC, in the LEP tunnel will open a new era for the High Energy Physics. This report summarizes the main LHC parameters and subsytems and describes the more recent studies and developments.

The CERN intersecting storage rings

Abstract The Intersecting Storage Rings (ISR) have been constructed to give very high centre-of-mass energies in proton-proton collisions by providing high-energy proton beams that collide head-on. By having 26 GeV protons in each beam one obtains 52 GeV centre-of-mass energies. In order to achieve similar energies with ordinary particle accelerators, energies of 1500 GeV would be needed. The main problem with such colliding beam devices is to accumulate sufficiently intense circulating beams that useful interaction rates are obtained. The design aim was a luminosity per intersection region of 4 × 10 30 cm −2 s −1 . This was reached by the end of 1972 and under good experimental conditions. After less than two years operation the ISR have therefore established themselves as an important high energy physics tool. The article describes the construction and the present performance with a few concluding remarks on the physics programme.

Design Concept for a 100 GeV E+-E- Storage Ring

A conceptual design of a 100 GeV e+-e- storage ring (LEP) being studied at CERN and some of the problems encountered are presented. The 20 GeV fastcycling injector synchrotron is studied at the Rutherford Laboratory.1 To obtain a luminosity L = 1 × 1032 cm-2 s-1 at 100 GeV, the product of bending radius ¿ and the RF power PB delivered to both beams must be PB ¿ = 136 GWm, assuming optimum coupling, a maximum permissible beam-beam tune shift ¿Q = 0.06, and a vertical amplitude function ßy* = 0.01 m at the crossings. The bending radius ¿ = 6.1 km was obtained by cost optimisation.2

Improvement in Luminosity, Background and Chamber Protection with Beam Scrapers in the ISR

The Intersecting Storage Rings (ISR) are equipped with beam scrapers used for various purposes such as improving luminosity, reducing background, beam diagnostics and for protection of machine components. A description is given of the different types of scrapers and of the results in the various applications obtained during the last year. In particular, the substantial improvements in luminosity and background by scraping are described.

An E-P Facility in the CERN SPS

A 25 GeV electron (or positron) storage ring installed in the SPS tunnel above the proton synchrotron would provide e-p collisions with a luminosity in the range of 10/sup 31/ to 10/sup 32/ cm/sup -2/ s/sup -1/. The collisions would normally take place at an intermediate plateau of the SPS-cycle up to 270 GeV, and could be followed by acceleration and extraction of the proton beam for fixed target experiments. The feasibility of such a facility is demonstrated and the essential features presented.

The Cern Storage Ring Project

CERN has carried out over a number of years a detailed study on the possibility of adding a set of Intersecting Storage Rings (ISR) to its 28 GeV Proton Synchrotron. The plans presented by CERN were accepted by the CERN Council at its meeting in June 1965 and the necessary funds for the construction were allocated in December of the same year. The ISR will consist of two concentric magnet rings of about 150 m mean radius. The two rings are slightly distorted so as to cross each other at 8 points, around which the colliding beam experimentation will take place. With about 20 A of stacked protons in each ring, the interaction rate will be about 1.5 × 105 interactions/sec. in each of the crossing points. The construction has started and the lecture will give a description of the project and its present status. It is hoped that the runningin of the facility will start in 1971.

Studies of 400 GeV superconducting proton storage rings

A study has been made of the feasibility of building Large Storage Rings (LSR) at CERN using superconducting dipoles and quadrupoles with the 400 GeV proton synchrotron, SPS, serving as injector. Proton-proton collisions at centre-of-mass energies of up to 800 GeV can be obtained in six interaction regions. Two of these provide luminosities exceeding 1033 cm−2 s−1 and would be dedicated to large-transverse-momentum physics. The other four p-p intersections offer much experimental flexibility at somewhat lower luminosity. Provision is made to add an electron storage ring of 20–25 GeV to obtain e-p collisions at up to 200 GeV centre-of-mass energy with a luminosity of 1032 cm−2 s−1 in each of two special e-p interaction regions. Antiproton-proton collisions could be obtained by a minor rearrangement of some elements in two of the interaction regions.

CERN 400 GeV Proton Storage Rings with Superconducting Magnets

A design is presented for 400 GeV proton-proton storage rings to be added to the CERN SPS. An electron (20-25 GeV) ring is also foreseen and possibilities for antiproton-proton collisions. Eight interaction regions are planned (six for p-p and two for e-p) with high luminosity and good flexibility for physics experiments.