New SWIC Scanner/Controller System
W. Kissel, B Lublinsky, A. Frank, J. Smolucha
Fermilab
Since the early 70's Segmented Wire Ion Chambers (SWIC's) have been used in the
Fermilab Switchyard beam transport lines to measure beam profiles and
intensities. The Switchyard SWIC's as originally engineered have been
geographically multiplexed. There are 26 physical SWIC's and only 7
scanners/controllers and therefor all profile data cannot be collected in one
beam cycle. In the Main Ring era short cycle times (~10 seconds.) lessened the
impact of this limitation. Tevatron era operation of Switchyard uses both
SWIC's and BPM's. SWIC's will show profile information and have a much lower
beam intensity threshold as compared to BPM's. This is an advantage during
tune-up at low intensity especially when dealing with cryogenic transport
lines. Long Tevatron cycle times (~60 seconds.) coupled with the need to
sequence various SWIC's and their gains on a given controller, have proved to
increase startup/tuning time.
The new SWIC controller/scanner system has been designed to ease these
limitations. New cabling combined with a new scanner/processor system will
allow simultaneous data collection of all SWIC's. Each will have their own
specific data collection criteria (gain, sample duration, spill type, to name a
few). Existing "Automated Tuning" programs will be able to use either BPM or
SWIC position and intensity information.
Hardware as to the new SWIC system is implemented as a distributed system with
68060 based FE, connected via ARCNET to 80186 embedded processors - one per
SWIC. 186s are responsible for the actual data collection controller
manipulation. Collected data is then shipped to the FE, which is doing data
massaging and communications with the consoles. FE software is VxWorks based
system, running communications, finite state machines, defining measurements,
circular buffers of collected data and special calculations.