Magnetic performance measurement
A magnetic performance measurement was carried out, in order to get values of the real screening performance of the septum YIN (23.12.1999). Therefore the septum pulser was connected to the magnet and the vacuum tank was vented with liquid nitrogen. Then the septum exit blind flange could be opened under nitrogen atmosphere. A translucent plastic bag, connected to a membrane pump and equipped with rubber gloves was used therefore.
Fig. 1: bag set-up (w/o magnetic field probe and pump)
With a specially prepared miniature magnetic field probe the main field and the leakage field have been measured subsequently, along the magnetic pole of the septum. It was found that the magnetic screening at the ends of the septum exceeded 1/1000. Over a distance of about 10mm the magnetic field increased up to 3/1000 of the main magnetic field in the center of the septum magnet.
Fig. 2: Additional CO-Netic screen at the septum entrance
Fig. 3: Two additional magnetic screens at the septum exit
Then custom made additional CO-Netic screens were added. Two screen pieces at the exit of the septum and one at the entrance improved the screening as is shown in Fig 4.
Fig. 4: Leakage Field with and without CO-Netic screen
