Today we began examining and modifying parts of the chamber shipped from CIRCE to Edinburgh.

The parts shipped were:

• Chamber Collar
• Central Lid
• Downstream Lid
• Two Metal Detector Masks
• Two Iris Mounts
• One Iris
• Two Actuators
• Pin Diode Mount

This morning we began piecing parts of the chamber one by one, starting with putting the lids on the collar and checking how easily the iris arms fit. We found whilst fitting together the chamber that the actuator used to control the downstream iris will need to be moved further away from the chamber than the current Al tubes allow. This is because currently the aperture arm hits the metal iris mount. By moving the actuator further away there will still be space for a thin wire to hook onto the iris arm.

Originally the S2 detector was intended to be mounted with the front strips facing downstream. We found in CIRCE during the recent February shifts that this was not possible, because the connectors on the detector PCB hit the lid.

Today Peter machined space for the downstream detector connector, so now the detector may be mounted as originally intended. We checked the vacuum feedthrough still fits too.

However, the ribbon cable between detector and feedthrough will still come between the actuator arm and the iris arm, so adjustment of the iris from outside the chamber is still not possible. We are still working on this.