1. MICE Target Report Video Conference 05/07/07 Chris Booth Sheffield 5 th July 2007

2. Chris BoothUniversity of Sheffield 2 As reported at Collaboration meeting: Major problem with wear on ceramic bearings (after few hundred thousand operations, bearings become eccentric, significant quantities of dust generated) Proposed solution – ruby-sapphire spherical bearings. Housing made, tests recommenced. After 80K operations, actuator dismantled and examined: Serious wear (and chips) to sapphire bearings, with scoring and pitting of titanium shaft.

3. Chris BoothUniversity of Sheffield 3 Discussion with local tribology expert: For non-lubricated bearings, we should use soft (not hard) “self-lubricating” material, and increase contact area (to reduce pressure) Recommended leaded bronze (up to 20% lead) Alternative is hard (steel) bearing with smooth self- lubricating surface (sputtered) –Diamond-like carbon (DLC) –Molybdenum disulphide All considered appropriate for UHV applications, but still trying to get information from ISIS vacuum experts. Leaded-bronze bearings being machined, will start tests tomorrow.

4. Chris BoothUniversity of Sheffield 4 Cause of off-axis force against bearings? Misalignment of coils or magnets? Discussion with electrical engineer (motor expert) says this is NOT likely. Probably cause deformation of shaft under load. Mechanical analysis of shaft underway – local engineer plus input from Wing Lau. Sputtered bearings would also probably need different shape. Ideas for different shaft – tubular, with different alignment mechanism. Would require joins (and could allow different target material, as suggested at CM). Needs proper analysis.

5. Chris BoothUniversity of Sheffield 5 New locations for control & power electronics (suggested at last CM) Would require longer cable run (for power cables). Will test as soon as bearings ready (tomorrow). Cables & fibre links to be finalised in few days (in consultation with RAL & DL). Alternative target geometry? Suggested at last CM. Depends on details of ISIS beam profile and stability, and relationship between energy loss and beam trapping. Will organise meeting with ISIS machine experts to try to reach conclusions very soon.