In this paper, we consider a klystron-like mechanism of amplification of parasitic density modulations in an electron bunch passing a magnetic bunch compressor. Analytical expressions are derived for the small-signal gain. The effect of wakefields in front of the bunch compressor is analyzed by using a model of linear compression which assumes linear correlated energy chirp and linear dependence of a path length on energy deviation. Analysis of the density modulation growth due to coherent synchrotron radiation inside bends of the magnetic bunch compressor is done for the simplified case of no correlated energy chirp (no compression). Analytical results of this paper can be used for benchmarking numerical simulation codes.

Klystron instability of a relativistic electron beam in a bunch compressor

A high-gradient-doping technique is applied to strained polarized photocathodes. A 5.0– 7.5 nm p-type surface layer doped to 5×10 19 cm −3 is found sufficient to overcome the surface charge limit while maintaining high beam polarization. This technique can be employed to meet the charge requirements of the Next Linear Collider with a polarization approaching 80%.

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A very high charge, high polarization gradient-doped strained GaAs photocathode

In this paper we consider a possible mechanism of strong distortions of longitudinal phase space due to collective effects in an electron bunch passing a bunch compressor. Analytical expressions are derived for the case of a linear compression. Estimates for the TESLA Test Facility at DESY are presented.

An analytical description of longitudinal phase space distortions in magnetic bunch compressors

We discuss options for future colliders at CERN, after the LHC, which should address the burning problems of particle physics: mass, flavour and unification. We give and comment upon parameter lists for linear e e colliders, colliders and future larger hadron colliders that are being studied in various places. We discuss how particle physics experiments can be carried out at these colliders. We make a number of observations how these colliders might be constructed on or near to the CERN site, and how the existing expertise and infra-structure might best be employed for their study. Finally, we formulate recommendations for action at CERN.

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Options for Future Colliders at CERN

https://www.slac.stanford.edu/grp/rd/pprc/publications/PLA282_309.pdf

Photovoltage effects in photoemission from thin GaAs layers

This Zeroth Order Design Report (ZDR) for the Next Linear Collider (NLC) has been completed as a feasibility study for a TeV-scale linear collider that incorporates a room-temperature accelerator powered by rf microwaves at 11.424 GHz--similar to that presently used in the SLC, but at four times the rf frequency. The purpose of this study is to examine the complete systems of such a collider, to understand how the parts fit together, and to make certain that every required piece has been included. The design presented here is not fully engineered in any sense, but to be assured that the NLC can be built, attention has been given to a number of critical components and issues that present special challenges. More engineering and development of a number of mechanical and electrical systems remain to be done, but the conclusion of this study is that indeed the NLC is technically feasible and can be expected to reach the performance levels required to perform research at the TeV energy scale. Volume one covers the following: the introduction; electron source; positron source; NLC damping rings; bunch compressors and prelinac; low-frequency linacs and compressors; main linacs; design and dynamics; and RF systems for main linacs.

/pdf/zeroth-order-design-report-for-the-next-linear-collider-31dw8rm0br.pdf

T.O. Raubenheimer

Papers

Zeroth-order design report for the next linear collider. Volume 1