Intense source of slow positrons from pulsed electron accelerators |
| |
Authors: | G Gräff R Ley A Osipowicz G Werth J Ahrens |
| |
Institution: | (1) Institut für Physik, Universität Mainz, D-6500 Mainz, Germany;(2) Max-Planck-Institut, D-6500 Mainz, Germany |
| |
Abstract: | A pulsed LINAC is used for pair production in a tantalum target of 2.5 radiation lengths in an energy range from 80 to 260 MeV. Several well-annealed tungsten vanes are placed immediately behind the target and thermalize a small fraction of the fast positrons. The slow positrons are extracted from the target region and magnetically guided over a distance of 17 m to the detector at the end of an S-shaped solenoid. Two Nal detectors with well-known detection efficiency are used to register the 511 keV annihilation-rays. To reduce pile-up effects 50 mm of Pb were placed in front of the detectors. At an average electron current of 1 A we could detect about 107 slow positrons per second. The positron yield is proportional to the electron current, and shows an increase with the electron energy for our target. The positron energy distribution has a FWHM of 1.8 eV. |
| |
Keywords: | 7 77 29 25 |
本文献已被 SpringerLink 等数据库收录! |
|