538 research outputs found
Development of an intense positron source using a crystal--amorphous hybrid target for linear colliders
In a conventional positron source driven by a few GeV electron beam, a high
amount of heat is loaded into a positron converter target to generate intense
positrons required by linear colliders, and which would eventually damage the
converter target. A hybrid target, composed of a single crystal target as a
radiator of intense gamma--rays, and an amorphous converter target placed
downstream of the crystal, was proposed as a scheme which could overcome the
problem.This paper describes the development of an intense positron source with
the hybrid target. A series of experiments on positron generation with the
hybrid target has been carried out with a 8--GeV electron beam at the KEKB
linac. We observed that positron yield from the hybrid target increased when
the incident electron beam was aligned to the crystal axis and exceeded the one
from the conventional target with the converter target of the same thickness,
when its thickness is less than about 2 radiation length. The measurements in
the temperature rise of the amorphous converter target was successfully carried
out by use of thermocouples. These results lead to establishment to the
evaluation of the hybrid target as an intense positron source.Comment: 17pages, 10figure
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