Electron-positron storage rings

The ideal tools for studying the spectroscopy of the new vector meson particles have undoubtedly been the various e e colliding beam machines SPEAR at SLAC, DORIS at DESY (Deutsches Elektronen Synchrotron), PETRA at DESY and, more recently, SLC at Stanford and LEP 1 at CERN though the actual discovery (Aubert et al, 1974 Herb et al, 1977 UAl, 1983 UA2, 1983) of some of these particles occurred on the proton machines (Brookhaven, Fermilab and CERN). 

The reason for the latter lies in the narrowness of these particles one can simply miss them as one varies the energy. On the other hand, once discovered, the fact that J/ (3097), T(9.46) and the Z are vector particles 1, and thus couple naturally to a virtual photon, makes an e+e  

it is rather difficult in an e e machine to sit right on top of one of these very narrow resonances whose width may be much smaller than the energy resolution of the machine itself. On the other hand, once the mass of a narrow resonance is known, an e e machine can be timed to the right energy to obtain an extremely large number of events. 

In a hadronic machine, the reaction not only does not proceed uniquely through the 1 channel, but the 1 states are produced together with a 

The role of e+e machines has been so important in the development of the new narrow resonance spectroscopy as to merit a short digression on their origin, their kinematics, some of their properties and some of their achievements. 

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An alternative and the most generally employed source of X rays for EXAFS experiments is that obtained from synchrotron sources based on electron (or positron) storage rings. 

No single development has influenced the field of EXAFS spectroscopy more than the development of synchrotron radiation sources, particularly those based on electron (or positron) storage rings. These provide a continuum of photon energies at intensities that can be from 103 to 106 higher than those obtained with X-ray tubes,... 

Secondly, the use of UHV/EHV systems is obviously desirable because of the extreme sensitivity of many materials and processes to residual gas. Work in this pressure range has allowed significant advances to be made in, for example, surface science and the exploitation in many areas of research of synchrotron radiation sources based on electron or positron storage rings. Relevant factors in the operation of these systems, such as adsorption and desorption (including diffusive outgassing), are examined in detail. 

G. Budker In Proc. Int. Symp. on Electron and Positron Storage Rings, ed. by H. Zyngier, E. Cremieux-Alcan (Presses Universitaire, Saclay 1966)... 

High-energy electrons are used in nuclear physics for the investigation of elementary and fundamental particles. Energies of the order of several GeV are sufficient to produce other elementary particles and antiparticles and to study their interactions. Collisions of electrons and positrons are investigated by use of storage rings. 

Figure 4.10 The time structure of the X-ray beam derives from that of the electrons (or positrons) in the storage ring. The electrons travel in the ring in bunches and thus the radiation is emitted in pulses. The values shown are for the Daresbury SRS in multibunch mode. In single bunch mode the light pulse occurs each orbital period of 0.321 jus.

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