R. D. Heuer

The Photon Collider at Tesla

High energy photon colliders (γγ,γe) are based on e-e- linear colliders where high energy photons are produced using Compton scattering of laser light on high energy electrons just before the interaction point. This paper is a part of the Technical Design Report of the linear collider TESLA.1 Physics program, possible parameters and some technical aspects of the photon collider at TESLA are discussed.

The trigger system of the OPAL experiment at LEP

Abstract A pretrigger system is described for running the OPAL detector at the LEP e + e − collider with more bunches than originally foreseen. A large number of low threshold pretrigger signals are formed by several independent components of the detector, and combined by a custom-built VME-based central pretrigger logic. Flexibility, high efficiency and high redundancy in all physics channels are all achieved with low additional deadtime, without any compromise to the trigger performance.

TESLA Technical Design Report, Part VI, Chapter 1: The Photon Collider at TESLA

High energy photon colliders (γγ,γe) are based on e-e- linear colliders where high energy photons are produced using Compton scattering of laser light on high energy electrons just before the interaction point. This paper is a part of the Technical Design Report of the linear collider TESLA.1 Physics program, possible parameters and some technical aspects of the photon collider at TESLA are discussed.

Results of wire chamber ageing tests with CH4− and DME-based gas mixtures

Abstract Results are presented of ageing tests performed on single-wire proportional counters under controlled conditions. The rate of the detector ageing with methane mixtures has been found to be independent of the anode and cathode materials used, and also of the purity of the gas. The rate of ageing for DME mixtures, on the other hand, appears to depend on the amount of gas used: it is small when the DME bottle is full, but increases as the cylinder empties. Addition of some water vapour to the Ar-DME mixture provided good lifetime, independently of the amount in the bottle. An explanation of this observation, based on assumptions on the fractional distillation of impurities, is provided.

Aging properties of straw proportional tubes with a XeCO2CF4 gas mixture

Abstract Studies of the behaviour of straw proportional tubes, 4 mm in diameter, under sustained irradiation were carried out with a XeCO 2 CF 4 [50-30-20] gas mixture. No observable gain drop has been found to affect the tubes up to reasonable doses ( ≤ 1 C/cm of wire). The chemical modification of the gas composition, causing the formation of electronegative, relatively stable species during the avalanche processes in a highly irradiated straw tube, is suggested to be responsible for a decrease of the pulse height in a second proportional counter (12.5 mm drift distance) operated with this (radical-enriched) gas mixture. Finally, we have observed that, for a straw tube operated at gain of a few times 10 4 , there is a contribution to the total collected charge coming from few, very large pulses, probably due to occasional transition to a limited streamer regime.

TESLA: The Superconducting electron positron linear collider with an integrated X-ray laser laboratory. Technical design report. Part 6. Appendices. Chapter 1. Photon collider at TESLA

High energy photon colliders (γγ,γe) are based on e-e- linear colliders where high energy photons are produced using Compton scattering of laser light on high energy electrons just before the interaction point. This paper is a part of the Technical Design Report of the linear collider TESLA.1 Physics program, possible parameters and some technical aspects of the photon collider at TESLA are discussed.