Some of the problems associated with the monitoring of accelerator beams, particularly storage rings' beams, are reviewed along with their most common solutions. The various electrode structures used for the measurement of beam current, beam position, and the detection of the bunches' transverse oscillations, yield pulses with sub-nanosecond widths. The electronics for the processing of these short pulses involves wide band techniques and circuits usually not readily available from industry or the integrated circuit market: passive or active, successive integrations, linear gating, sample-and-hold circuits with nanosecond acquisition time, etc. This report also presents the work performed recently for monitoring the ultrashort beams of colliding linear accelerators or single-pass colliders. To minimize the beam emittance, the beam position must be measured with a high resolution, and digitized on a pulse-to-pulse basis. Experimental results obtained with the Stanford two-mile Linac single bunches are included.

Review of accelerator instrumentation

A new improved bunching system was designed in 1976 and installed in 1981 in the Argonne Electron Linac to replace the one installed in 1972. In the new bunching system, a spiral loaded double gap 12th subharmonic buncher is replacing the previous single gap 6th subharmonic buncher and a one wavelength fundamental frequency traveling wave prebuncher has replaced the previous two wavelength prebuncher. Individual pulses of picosecond (25 to 36) duration and up to 40 ? Coulomb in charge, with ?E/E < ± 0.5% at FWHM over the energy range of 4 to 22 MeV, and a repetition rate from one to 1000 p psec are available to the experimenter on a routine basis. The design and the microwave properties of the cavity are discussed along with the general design of the injector and the results achieved.

High Charge Picosecond Pulses with a Double Gap Subharmonic Buncher

Single S-band bunches of ~ 109 electrons have been used to study the characteristics of the SLAC linac in anticipation of its operation as a linear collider Emittance measurements have been made, the longitudinal charge distribution within single bunches has been determined and transverse emittance growth has been produced by deliberately missteering the beam New equipment is being installed and checked out, and the sensitivity of new traveling-wave beam position monitors has been measured

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Single Bunch Beam Measurements for the Proposed SLAC Linear Collider

Some of the problems associated with the monitoring of accelerator beams, particularly storage rings’ beams, are reviewed along with their most common solutions. The various electrode structures used for the measurement of beam current, beam position, and the detection of the bunches’ transverse oscillations, yield pulses with sub-nanosecond widths. The electronics for the processing of these short pulses involves wide band techniques and circuits usually not readily available from industry or the integrated circuit market: Passive or active, successive integrations, linear gating, sample-and-hold circuits with nanosecond acquisition time, etc. This report also presents the work performed recently for monitoring the ultrashort beams of colliding linear accelerators or single-pass colliders. To minimize the beam emittance, the beam position must be measured with a high resolution, and digitized on a pulse-to-pulse basis. Experimental results obtained with the Stanford two-mile Linac single bunches are included.

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A Review of Accelerator Instrumentation

Electron-beam energy spectral measurements were made on a tapered-wiggler free-electron laser amplifier. A 10 MeV electron beam from a traveling-wave linear accelerator interacted in a tapered-wiggler with an intense 10.6pm CO2 laser beam. The electron spectra show a 4 percent net energy loss and a 9 percent peak loss. Measurements of electron energy spectra, extraction efficiency as a function of electron-beam energy, and extraction efficiency as a function of optical power are presented and are consistent with theoretically predicted performance.© (1984) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Demonstration Of Large Electron-Beam Energy Extraction By A Tapered-Wiggler Free-Electron Laser

The 20 MeV electron linac at Argonne produces 5 × 1010 electrons in a single bunch. This amount of charge per bunch is required for the proposed single pass collider at SLAC. For this reason the characteristics of the beam from this machine are of interest. The longitudinal charge distribution has been measured by a new technique. The technique is a variation on the deduction of bunch shape from a spectrum measurement. Under favorable conditions a resolution of about 1° of phase is possible, which is considerably better than can be achieved with streak cameras. The bunch length at 4.5 × 1010e− per bunch was measured to be 15° FWHM. The transverse emittance has also been measured using standard techniques. The emittance is 16 mm-mrad at 17. 2 MeV.

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M. B. James

Papers

Beam measurements on Argonne linac for collider injector design