1. 18 December, 2007 Analysis PC 18 Dec 2007 1 PIDer’s Question of Friday 14 Dec: Dear John and Marco, would you be able to give us a first preliminary ball-park answer to the following question? Do you think MICE needs to map the (Kgauss or so) fringe fields upstream of the TOFI shielding cage? Is the knowledge of these field maps relevant to the measurement of cooling? The real question being : do we need to have the cage at Fermilab for magnetic measurements before we deliver it to RAL? Any wisdom will help. Already for the PID meeting today at 3.30 pm.... Best Vittorio

2. 18 December, 2007 Analysis PC 18 Dec 2007 2 EFFECT OF SHIELD ON OPTICS Shown at CM15 (Fermilab, June 06) Shield B z small beyond position of shield even without shield  Muons drift  Expect effect of shield on downstream optics to be very small, if not entirely negligible

3. 18 December, 2007 Analysis PC 18 Dec 2007 3 Since December 18.... H. Witte passed D.Phil viva Computed fields with 0, 1 & 2 shield plates –End coil #1 current adjusted for one plate –not readjusted for two plates ‘Good field region’ good (< +/- 1%) in all cases –Presence of 2nd plate unimportant in this region Very little difference in B z beyond 1st shield with 1 or 2 shields –Maximum is at z = -6.8m ~12% of 0.1T = 120 Gauss (next page) Shields start at z = -6.4m Good field region

4. 18 December, 2007 Analysis PC 18 Dec 2007 4 Ratio of axial fields in shield region with 0, 1, 2 shields 1st shield = 100mm thick Virostek disc –-6.5 < z < -6.4m 2nd shield = 50mm thick disc –-6.65 < z < -6.6m Outside shields effect of 1 or two shields is small No obvious need to measure with 2nd disc (or cage) Should be quite insensitive to precise material Should answer PIDers’ question Ratio of axial fields on axis