A.300 GeV High Quality Electron and Pion Beam at the New Generation Proton Accelerators

Abstract

It is demonstrated that high quality secondary electron beams can be made available with intensities of 108 e/pulse at the new generation proton accelerators. A beam design is presented with the following qualities. 1) Large beam transport acceptance [9.5 μster % Δp/p (FW), with a momentul bite of ± 2%], 2) good momentum resolution [less than ± 0.3%], 3) good angular resolution [less than ± 0.1 mrad], 4) small final spot size [less than ± 3 mm horizontally and ± 6 mm vertically]; and 5) negligible pion contamination [less than 1 pion in 105 electrons]. All of these qualities are achieved while preserving the valuable electron intensities at production. Using standard beam transport magnets a 300 GeV/c transport system is designed with four focussing stages, the first two of which provide a beam spot of sufficient quality for tagged photon experiments. The optics design is based on a periodic cell structure which includes correction of second order aberrations by means of four weak sextupoles. The synchrotron radiation by electron throughout the transport system is used to advantage, to remove pion contamination at the final beam spot. Pion impurity is null at energies greater than 160 GeV. This high quality transport system can also be used to de} iver a high intensity pion beam [109 - 1010 π- per 1013 interacting protons], up to 300 GeV/c. Thus a very versatile facility can be provided for electron and pion experiments at the same installation.