We have measured the positron production efficiency from tungsten single-crystal targets using an 8 GeV electron beam. A single-bunch beam with a bunch width of 10 ps, a repetition rate of 2 Hz, and an intensity of 0.2 nC/bunch was incident on a target mounted on a precision goniometer. Positrons produced in the forward direction were detected by a magnetic spectrometer in the 10-20 MeV/c momentum range. Systematic data on the target-thickness dependence and the momentum distribution of the produced positrons were obtained for crystal targets. The results show that, when the crystal axis 〈111〉 is aligned to the electron beam direction, the positron yield increases compared to the amorphous case by factors of 6.5, 3.4 and 2.3 at 10 MeV/c for 2.2, 5.3 and 9.0 mm thick crystals, respectively. We observed that the positron yield from the 9.0 mm thick crystal is larger than the maximum yield attainable with 18-20 mm thick amorphous targets at 8 GeV.
|Журнал||Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms|
|Состояние||Опубликовано - 1 янв 2003|
|Событие||RREPS 2001 - Lake Aya, Российская Федерация|
Продолжительность: 1 сен 2001 → 1 сен 2001
ASJC Scopus subject areas
- Nuclear and High Energy Physics