1. 1 OPTICS OF STAGE III Ulisse Bravar University of Oxford 6 October 2004

2. 2 Introduction Agreed with Mike Green to have 800 mm gap in Stage III. I.e. the distance between the two spectrometers, measured from the boundaries of the match coils, is 800 mm. i) Larger gap = smaller forces. ii) Smaller gap = less beam scraping. This configuration can accommodate a ~10 cm thick solid absorber between the two spectrometers.

3. 3 Optic Solutions Developed new software for beam matching.   calculated by EVOLUTION, not Monte Carlo! Stage III optics is the first time these new routines are being used. Goals: 1)fix currents in solenoids and end coils, fix momentum in upstream spectrometer, fix 800 mm gap; 2)tune currents in match coils to achieve desired   and d   /dz = 0 in downstream spectrometer; 3)run both flip and non-flip configurations, p = 140, 170, 200 & 240 MeV/c.

4. 4 Coils and Currents test Coils and Currents COILS CURRENTS - FLIP CURRENTS – NO FLIP

5. 5 Worst case forces Peak B-fields on the coil surfaces and forces Worst case p = 240 MeV/c Courtesy of H. Witte

6. 6 B-field Top: COILS and Spectrometers in Stage III Bottom: B z field p = 200 MeV/c Red = flip mode Blue = no-flip mode z (m) B z (T) r (m) 800 mm

7. 7 Beta functions p = 200 MeV/c ON-MOMENTUM   functions Red = flip mode Blue = no-flip mode z (m) r (m)   (m)

8. 8 Matching the p = 200 MeV/c beam Figure of merit: i)Measure   at 100 points in 1 m of uniform B-field region in downstream spectrometer ii)Take rms of these measurements Red = flip mode Blue = no-flip mode rms (cm) J (A mm -2 ) match coil #1 J (A mm -2 ) match coil #2

9. 9 Off momentum   z (m)   (m) r (m) FLIP MODENO-FLIP MODE p = 180 MeV/c p = 200 MeV/c p = 220 MeV/c

10. 10 Icool   - functions Actual Icool beam p = 200 MeV/c No more   evolution No more paraxial beams Input emittance:   = 6  mm rad Red = flip mode Blue = no-flip mode z (m)   (m) r (m)

11. 11 Icool transmission and emittance z (m) r (m) Loss (%)   (  mm rad) Loss < 0.2 % Emittance ~ constant Flip mode p = 200 MeV/c No-flip mode

12. 12 Conclusions We came up with a realistic layout for MICE Stage III. Optic solutions for all operating modes and all momenta for this layout have been determined. Worst case forces have been checked. In addition, a perfect software package is now available to deal with beam optics in MICE. It would be straightforward to do the matching one more time, should we decide to change the layout of Stage III.