Herwig Schopper

Measurement of inclusive neutron spectra from p-Be up to 24 GeV/c incident momentum

Abstract We present data on inclusive neutron spectra produced in an internal Be target of the CERN PS, for incident proton momenta between 8 and 24 GeV/ c at 0°, and for an incident proton momentum of 19 GeV/ c at 50 mrad.

LEP: A Historical Introduction [and Discussion]

On 13 August 1989, close to midnight, the electron and positron beams in LEP, the largest research device ever built, collided for the first time. Only ten minutes later the control-room telephone rang and one of the four experiments announced the detection of the first Z-event. This was the culmination of a project that had started 14 years ago had been brought to a full success thanks to the devotion and enthusiasm of physicist, engineers, technicians and administrators. The development of our field is so breath-taking that events of 10 years ago already are almost forgotten. Not only for the historical record but also for future projects it may be useful to report some of the experiences which were encountered during the realization of LEP.

Status of LEP and Its Experimental Programme

LEP is an electron-positron collider designed for 2×100 GeV. For an initial phase the RF power will be sufficient to produce collisions at 2 × 50 GeV at a luminosity of about 1.6 × 10-31 cm-2 s-1. The circumference of the ring is 26.7 km and will be installed 80 - 125 m underground. Electrons and positrons will first be accelerated in a linear accelerator LIL and accumulated in a new storage ring EPA. Subsequently, the existing machines, the PS and the SPS. will be used as pre-accelerators.

Elementary particle physics - where is it going?☆

Abstract The penetration into ever smaller dimensions is linked to higher energies put at the disposal of physicists by large accelerators and storage rings. the development of such devices is briefly reviewed and a short description of the most powerful tool presently available, the CERN proton-antiproton collider, is given. The most fundamental questions of elementary particle physics concern the ultimate constituents of matter and the forces acting between them. Our present knowledge and open problems are summarized.

CERN: From Birth to Success

A historical review is given of the development of CERN from its foundation to the present from the personal viewpoint of the author.

Elementarteilchen – oder woraus bestehen wir?

Ein effizientes Forschungssystem ist heute eine unverzichtbare Voraussetzung fur die wirtschaftliche, gesellschaftliche und kulturelle Entwicklung unseres Landes. Derzeit erleben wir weltweit die Transformation klassischer Industriegesellschaften zu Wissensgesellschaften. Die Erneuerung und Verbreiterung der Wissensbasis unserer Gesellschaft und ihre sinnvolle Nutzung sind ohne kontinuierliche Forschung und Entwicklung nicht denkbar, von der Grundlagenforschung bis zur Anwendung in Industrie und Dienstleistung. Dies begrundet gesamtstaatliche Aktivitaten im Bereich der Forderung von Forschung und die Schaffung von Rahmenbedingungen fur den Innovationsprozess. Zudem stehen Europa und auch Deutschland im Wettbewerb mit den USA und den sich rasch entwickelnden Staaten Asiens, insbesondere des Fernen Ostens. Die Lander der Europaischen Union hatten in Barcelona 2002 beschlossen, bis 2010 ihren Anteil der Forschungs- und Entwicklungsausgaben am Bruttoinlandprodukt (F- und E-Intensitat) auf 3% zu erhohen und damit den Anschluss an die Konkurrenten wieder herzustellen.

Thatcher and me

The interesting article by Gary Taubes about the discovery of the W and Z bosons 20 years ago (January pp23–28) reminded me of the following story. It began in the autumn of 1982 when the British Prime Minister Margaret Thatcher visited CERN. On her arrival, she asked me – as director-general of the lab at the time – to treat her as a fellow scientist and not as prime minister.

Hadron Sampling Total Absorption (STAC) Calorimeters

Sampling total absorption detectors for hadrons are an excellent example of the impressive development of particle detectors which has become an essential basis for the breathtaking progress in particle physics. For an energy measurement of hadrons, homogeneous blocks of scintillating or ionization measuring materials are, in contrast to electromagnetic showers, completely impractical since the large hadronic interaction length would lead to huge blocks of material. Hence materials with smaller interaction lengths interleaved with sampling detectors have to be employed. In the sixties, such sampling total absorption counters (STAC) were mostly considered to be useful only for specialized tasks such as neutron detection, and their use as a general purpose detector for hadronic energy measurement was almost laughed at. The advantages of such devices were recognized only in the seventies, where they played a major role, for example, in the collider experiments that discovered the W and Z. Today they have become an almost inevitable ingredient of most existing and planned experiments.

Physics at LEP

At the time this lecture was given the construction of LEP was approaching its end and first collisions were expected in Summer 1989. The four LEP experiments were very busy installing the final components and getting ready to take the first data. This exciting situation will be reflected in this report by concentrating on the physics that will be done in the near future. Therefore emphasis will be given to experiments that can be done with LEP 100 and in particular to the results which could be expected in 1989/90 [1]. In the meantime a first beam was injected into LEP as foreseen on 14 July 1989, a pilot run took place from 13 to 18 August 1989 with all four experiments taking data and within a few hours more than 50 Z0-events were accumulated as will be described later. The first physics run is foreseen to start in September 1989.

Criteria for Steps to Higher Energies

In discussing or proposing a new generation of high energy accelerators a number of arguments have to be taken into account. Physics motivation should, of course, be the main criteria, but machine technology is important and the development of detectors is getting an increasing weight. Financial boundaries cannot be neglected and political, ecological and sociological issues might also play a certain influence.