We have performed an experiment of positron generation using a crystal target at an electron/positron linac at KEK. The target consists of a tungsten crystal to emit photons and an amorphous tungsten for pair creation, whose thicknesses are 0.5 and 2.0 radiation length, respectively. When the 〈1 1 1〉 crystal axis is oriented parallel to the 3 GeV incident electron beam, the positron yield is enhanced by 40% compared to values for the disoriented crystal. No effect of injecting intense ultra-short electron bunches on the crystalline structure is observed. The crystal orientation dependence of the positron yield as well as the enhancement factor can be explained by a simulation assuming a coherent bremsstrahlung process of the electron in the crystal.
|Number of pages||8|
|Journal||Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms|
|Publication status||Published - 1 Jan 2001|
ASJC Scopus subject areas
- Nuclear and High Energy Physics