The instrumentation for the BAF beam line includes a number of different types of instruments to cover the full range of ion species and beam intensities. A list of the various instruments used can be found here, and a schematic view of their location in the beam line here. The main elements guiding the tuning of the beam line are the 6 FLAGS and the 5 Segmented Wire Ionization Chambers (SWIC's). The flags are tilted by 45 deg with respect to the beam direction and will be viewed through a port at 90 degree by cameras recessed into the tunnel shielding. The camera images will be processed by a frame grabber and image processor, see video. Three Ion Chambers (IC's) provide additional information about the integrated beam intensity along the beam line. Most of the instruments have to be retractable in order to be able to transport low energy Ion beam down to the target. For the same reason there is no window separating the Booster vacuum (~10-11 torr) from the BAF beam line vacuum. This requires the instrumentation to be mounted in UHV compatible boxes. The flag assembly is separated from the other instruments, since the flag itself is UHV compatible, and also because the flag requires more space along the beam direction due to the 45 degree tilt. The other three types of instruments, SWIC, IC and Scintillator, are housed in a UHV compatible instrument window box with machined aluminum windows, which separates the instruments from the beam line vacuum. Any instrument location along the beam line can house any combination of these three instruments, see here for a complete assembly in the sequence IC, SWIC, Scintillator. They are mounted on a flange which attaches to the instrument box to provide a seal for the chamber gas. The instrument box itself is mounted to the flange of a large diameter bellows with a travel of about 10", see the plunging instrument assembly.
The expected range of particle intensities covered by the various instruments can be found here. Beam intensities down to 103 ions per spill or even lower are being considered by future BAF users. At the low intensities it is not possible to see the beam profiles on the flags or SWIC's, but the integrated intensity can be monitored using Scintillators which can count individual ions. The low intensities can be achieved by closing the collimator upstream of the D6 septum in combination with the use of a vertical stripping wire instead of a stripping foil to define a small horizontal aperture.
The instrumentation electronics and controls will be located in Service Building 957 which also houses the beam line magnet power supplies.
Minutes of meetings related to instrumentation:
