The Linear Accelerator
Electrons emitted from a heated filament are accelerated in a
special 30 meter long vacuum pipe under the action of a microwave
electric field. Positrons, the positively charged antiparticles of
the electron, do not normally occur in matter but are produced by
accelerating electrons up to 140 MeV at an intermediate point of the
linac where they strike a tungsten plate. A spray of electrons,
positrons and X-rays emerges from the plate. The positrons are
selected, focused, accelerated in the remaining length of the linac up
to the 200 MeV final energy, and injected into the
synchrotron.
MPEG clips:
- Prebuncher (1300 kbyte
MPEG) shows the beam as it comes out of the electron gun
and is compressed in the prebuncher.
- Converter (4300 kbyte
MPEG) shows the electron beam striking a heavy metal
target, and the collection and acceleration of the resulting
positrons.
- RF Accelerator Cutaway
(2500 kbyte MPEG) shows a cut away of one of the eight
Acceleration Cavities in the Linear Accelerator, where the
oscillation of the powerful electric field from a radio wave
accelerates the electron or positron beam.
dsr@lns598.lns.cornell.edu
$Id: linac.html,v 1.2 2002/08/29 17:57:39 dsr Exp $