AA, closed orbit observation pickup

Electrostatic pickups around the circumference of the AA served for the measurement of the closed orbits across the wide momentum range of +- 3% to either side of central orbit. The pickups were of the "shoebox" type, with diagonal cuts, a horizontal and a vertical one mechanically coupled together. They were located where they would not require extra space. The small ones, like the one we see here, were inserted into the vacuum chamber of the BLG (long and narrow) bending magnets. Werner Sax contemplates his achievement. See also <a href="https://cds.cern.ch/record/969516">8001383</a>, <a href="https://cds.cern.ch/record/969690">8010042</a>, <a href="https://cds.cern.ch/record/969691">8010045</a>.