The
Tandem
beams can be further boosted in energy by a superconducting
linac "booster". The main body of the Linac consists of 12 niobium
split-ring resonators, with a total active accelerating length of
3 meters. Our current average electric field is about 2.5 MV/m.
The resonators are a product of research by Ken Shepard, Lowell
Bollinger and the rest of the
ATLAS group at
Argonne National Laboratory .
Two other resonators act as bunchers. The first compresses the
Tandem beam to fit the Linac's acceptance. A typical time width for
an injected beam is around 150 picoseconds. The other resonator is the
last in the lattice and is used to tailor the beam characteristics
for delivery to the target.
Liquid helium cooling is provided to the Linac by a CCI
(now Cryo Technologies)
helium refrigeration plant. This refrigerator gives about 300 watts of
cooling without liquid nitrogen pre-cooling and about 600 watts
with LN2. This plant also supports
Cryebis operations.
We have completed
a major renovation of the He gas handling system, moving the noisy
compressor off the laboratory roof and into a dedicated structure.
The Linac is now available for experiments in either accel or decel
modes, with the unique decel capability attracting the most demand.
Beams of F 9+ have been decelerated from 36 MeV down to
about 10 MeV. The ultra-short pulses from the bunching system have
been used by investigators to probe
recoil-ion momentum distributions
in remarkable detail.
The Linac project is managed by
Kevin Carnes. The staff includes
Mike Wells,
Al Rankin
and
Vince Needham .
Electronics support is provided by Kevin Carnes and
Scott Chainey.