From the Preshower to the New Technologies for Supercolliders

The following sections are included:

• CONTENTS

• FOREWORD

The future plans for DESY, initiated by Prof. Dr. Björn Wiik, have been left unfinished with his untimely death in early 1999 and, in particular, the ongoing R&D work for the TESLA project. This project was conceived by him as an international, interdisciplinary centre for research at DESY, based on a superconducting linear collider with an integrated free electron laser. Following my appointment as Björn Wiik's successor and chairman of the DESY Board of Directors, DESY will continue this work in the framework of the international TESLA collaboration…

During many years, the dominant detector technology used in experimental subnuclear physics has been the bubble-chamber, which contributed to the discovery of many dozens of mesons and baryons in strong interaction physics and in later years to the first evidence of neutral currents in a neutrino experiment with the heavy liquid bubble chamber GARGAMELLE. The high rate of discovery of new particles focused the attention of a large fraction of the physics community on the physics of hadrons and neutrinos and on the bubble chamber detector technology.

The invention of the “preshower” method represents one of the most significant contributions to the progress of subnuclear physics. In fact, this technology has been applied to the search for new phenomena and new particles have been discovered, such as the J and the weak bosons.

This section contains the major contributions from its invention to its applications, together with the original papers on the “muon punch-through” studies and on the Lead-Scintillator Telescope technology.

The following sections are included:

• Introduction

• Description and Principle of Operation

• Calibration of the Telescope

• References

• Figure Captions

The following sections are included:

• The beam telescope

• The range telescope

• Experimental method

• Calculation of the results

• Acknowledgements

• REFERENCES

• Figure Captions

The range of highly relativistic muons has been measured. The results of the experiment are presented and compared with the theoretical expectations. The agreement between experiment and theory is estabilished to be within 2% up to a value af γ as high as 23.

An electron detector, which consists of five elements, each one being made of a lead layer followed by a plastic scintillation counter and a two-gap spark chamber, is described. The rejection power of this new detector against pions is of the order of 4 · 10⁻⁴, the efficiency for electron detection varies from 75% to 85%, and the energy resolution can be as good as 10%, in the energy range 1.1 GeV to 2.5 GeV.

A large electromagnetic shower detector which consists of nine layers, each one made of lead, spark-chamber and scintillation counter, is described. The rejection power against pions is of 6 × 10⁻⁴, the efficiency for electron detection varies from 68 % to 80 % and the energy resolution from 15 % to 10 % in the energy range 0.4 GeV to 1.1 GeV.

Un grand détecteur de gerbes électromagnétiques comprenant neuf couches – chacune faite de plomb, d'une chambre à etincelles et d'un compteur à scintillations – est décrit. La réjection contre les pions est de 6 x 10^-4, l'efficacité de détection des électrons varie de 68% à 80% et la résolutions en énergie de 15% à 10% dans la région d'énergie de 0.4 GeV à 1.1 GeV.

A large electromagnetic shower detector for identification and energy measurements of γ-rays (between 150 and 1600 MeV) and electrons (between 400 and 1100 MeV), in the presence of high pion background, is described.

The detector is based on the principle of simultaneous measurement of the spatial development of the electromagnetic cascade and of its energy release. It consists of 1) two six-gap thin-plate spark chambers for the reconstruction of the incoming particle trajectories; and 2) nine elements, each made of a lead foil, a spark chamber, and a plastic scintillator, all sandwiched together; here the shower development is studied. When used for γ-detection, a 0.5 cm Pb foil is placed in front of the thin-plate spark chambers, in order to allow the detection of the γ-corversion process and the identification of the γ-direction. The dimensions of the detector are 60 × 120 cm² front face, and 50 cm depth along the electromagnetic shower development.

A pion rejection power of the order of 5 × 10⁻⁴ between 400 and 1100 MeV, for electron efficiencies varying from 70% to 80%, is obtained. The pion rejection efficiency in the γ-case is highly improved by the anticoincidence efficiency factor, while the γ-detection efficiency depends on the precision required in the reconstruction of the γ-ray direction. The γ-ray and electron energy resolution is about ±15%.

The possibility to reach ± 70 psec time resolution allowed to open a new series of experimental investigations: i) the separation of antideuterons from other lighter negative particles via TOF measurements; ii) the position resolution in plastic scintillator counters, for fast kinematic reconstruction of charged particles; iii) the position resolution for neutrons in thick scintillating counters thus allowing neutron-missing-mass spectroscopy.

This section contains the reproduction of some original papers, where TOF technology was essential.

A beam of small production angle and large acceptance has been designed at the CERN Proton Synchrotron in order to yield partially separated, high-intensity beams of antiprotons and K-mesons. The new features of the beam are discussed together with the experimental results.

Note from Publisher: This article contains the abstract and Introduction only.

The results of an experiment which show the existence of antideuterons in the production process proton-beryllium are reported.

Note from Publisher: This article contains the abstract only.

Using the CDF technique for locating charged particles in plastic scintillator counters, it has been found that the accuracy in determining the position of an incident particle in the counter is essentially a function of the distance between the two photo-multipliers.

Moreover it has been shown that a position resolution of Δx = ±0.15 cm and a time resolution of Δt = ±0.07 nsec can be achieved in a simple way.

Finally it has been shown that it is possible to measure simultaneously the coordinates of an incident particle in two orthogonal directions. This would allow to measure particle trajectories in high rate beams, when spark chambers cannot be used.

The TOF technology developed at CERN in the sixties is an important component of the experiment to search for Antimatter in Space. The precision of ± 70 psec in time accuracy achieved at CERN is now made “space” resistant.

The following sections are included:

• OVERVIEW OF THE AMS APPARATUS

• THE TOF TECHNIQUE FOR LARGE SCINTILLATION COUNTERS

A large-acceptance and high-efficiency neutron detector is described. The sensitive surface and volume of the detector are 2.16 m² and 0.78 m³, respectively. The detector consists of twenty-four elements of plastic scintillator, each having dimensions (100 × 18 × 18) cm³. The large volume of scintillator, in the particular geometrical arrangement chosen, allows a mean detection efficiency of about 25% in the range (70÷390) MeV neutron kinetic energy for a laboratory solid angle of 0.14 sr at 4 m radial distance. With the techniques adopted, calibrations with charged particles can be easily performed in a few hours using a low beam intensity. An interesting feature of this instrument is the accuracy achieved in locating incident particles, which is ±1.4 cm for charged particles, and ±2.5 cm for neutrons. The accuracies achieved for the time-of-flight measurement are ±0.35 ns for charged particles and ±0.7 ns for neutrons. With these resolutions in the neutron time of flight and angle, the uncertainty in the missing mass is ±4 MeV for η, ±10 MeV for ω. and ±15 MeV for φ mesons.

A large (2 × 0.39 m³ plastic scintillator) neutron detector capable to measure with high accuracy the coordinates of the neutron interaction point as well as its time-of-flight is described. As a missing mass spectrometer, it allows to observe for example the η, meson with a mass resolution of ± 4.2 MeV.

Nous décrivous un détectcur de neutrons de grand volume sensible (2 x 0,39 m³ de scintillatcur plastique) capable de mesurer avec précision les coordonnées du point d'interaction du neutron détecté ainsi que son temp-de-vol. Employé comme spectrométre de masses manquantes, it permet d'observer par exemple le méson η avec une resolution de ± 4,2 MeY.

The following sections are included:

• DEDICATION

• Nomenclature

• Summary

• Introduction

• The MPNBC Setup
  • General Description
  • The Neutron Detectors
  • The EM Shower Detectors
    • π-e Discrimination

• Review of the Physics Results Obtained
  • Evidence Against the Existence of the S⁰ Meson [3]

The purpose of the LAA project was to prove, on the basis of prototypes, the feasibility of essential components for an ideal detector to operate in future multi-TeV hadron colliders, at the highest energy and luminosity. A brief summary and the reproduction of a review paper on this new venture in subnuclear physics technology are reported in this section, together with a list of all the published results.

The LAA Project was implemented at CERN in 1986 (ref. CERN Council Resolution, December 1986) and Prof. A. Zichichi presented its research and development programme in an open presentation at CERN in June 1987 and subsequently to the CERN Research Board…

The following sections are included:

• INTRODUCTION
  • General philosophy of the LAA Project
  • The basic data
  • The Physics at the new generation of Hadron Colliders
  • Present structure of the LAA project
  • Participants
  • The Main achievements of the LAA Project

• STATUS OF THE PROJECT
  • High Precision Tracking
    • Gaseous detectors
    • Scintillating fibres
    • Microstrip GaAs
  • CALORIMETRY
    • High precision electro-magnetic
    • Compact EM+Hadronic
    • “Perfect” Calorimetry
  • LARGE AREA DEVICES
    • Construction
    • Alignment
  • LEADING PARTICLE DETECTION
    • Radiation-hard technologies
  • DATA ACQUISITION AND ANALYSIS
  • SUPER COMPUTERS AND MONTE CARLO SIMULATIONS

• CONCLUSIONS

• References

This report describes the LAA Project from its origin to its present status. The results obtained during its first year of activity are described in detail.

Let me just remind that the LAA Project [1–4] is an intensive programme to develop new experimental techniques to operate in future Hadron Colliders…

The following sections are included:

• Highlights of the LAA project
  • Introduction

• LIST OF REFERENCES OF ALL LAA WORKS

The results obtained with the LAA project have been of great value for the detectors to be used at the LHC. A review illustrating the impact of the LAA results on the LHC detectors is reported in this section, together with a review of the role played by Italy with the ELN project in the framework of multi-TeV colliders in Europe.

In this chapter we discuss the impact of the LAA results on the LHC detectors and the role played by Italy in the ELN project within the framework of multi-TeV colliders in Europe…

Around mid-1980, most particle physicists in university institutes and the engineering staff of DESY and of CERN were fully engaged in constructing detectors for approved experiments and in preparing accelerator components together with industry for the electron-proton collider (HERA at DESY) and for the electron-positron collider (LEP at CERN). These projects left no room for new technological developments…

The progress in the understanding of the basic building blocks of matter and of the forces acting between them has been the result of a highly productive interaction between theorists, experimentalists and accelerator builders. In this way theoretical ideas could be confronted with experimental data, taken with high technology detectors at powerful accelerators. All this work has led to a surprisingly powerful and complete theory of the microscopic world, the Standard Model, which during recent years has been proved to describe the experimental data with unprecedented accuracy. We know however that this theory cannot be the final word. Physicists are therefore preparing for the next generation of experiments at accelerators of the highest energies, to prove theories which lead beyond the Standard Model…