1. Optical matching in MICE

Ulisse Bravar University of Oxford

2 June 2004 • Constraints• Software• MICE proposal mismatch• MICE Note 49 (September 2004, Bob Palmer)• New Coils from Mike Green • MICE Stages IV and V • Current issues

2. Constraints

• Baseline configuration: flip modep = 200 MeV/c

= 42 cm in LH

• Goals:

achieve minimum as stated: FC & CCuniform B-field inside spectrometer (to 1%): EC

uniform inside spectrometer: MC

3. Software

• Matching code from Bob Palmer: ICOOL + minimization routine ‘empty’ MICE channelparaxial tracks

• Numerical evolution of , by John Cobb: ‘empty’ MICE channel

from G. Penn, MuCool note 71:

2 ’’ – (’)2 + 4 2 2 – 4 = 0

4. MICE proposal

• MICE proposal to RAL:• coil configuration from

tab. 4.1 • currents from tab. 4.2,

case 1a

• p = 220 MeV/c• p = 200 MeV/c• p = 180 MeV/c

• MISMATCH for p = 200 MeV/c !!!

5. MICE Note 49

• Currents from Bob Palmer’s note, Sept. 2003Tab. 4 & 5 SFOFO = 43 cm

• 200 MeV/c looks OK:

= minimum in LH

= uniform in solenoid

• Mismatches at 180 and 220 MeV/c

6. New Coils

• Coil configuration from Mike Green and INFN-GE after CERN 2004 meeting (room temperature).

• Currents determined with Bob Palmer’s minimization routine.

• Again at p = 200 MeV/c looks OK.

• Note: big increase in match coil region.

7. MICE stages IV and V

8. Present issues

• Visibly, BP ‘better’ than MG.

How good is good?

Issues: • achromaticity

• beam scraping, large in MC, stay-clear area

• peak B-field in FC varies, i.e. B = 0 away from centre of LH

9. ICOOL simulations (1)

• Actual beam • ‘Empty’ channel

from paraxial beam consistent with from G. Penn eqn.

from beam with = 6 mm rad is mismatched

10. ICOOL simulations (2)

• ‘Empty’ channel + paraxial beam

• ‘Empty’ channel + actual beam

• ‘Full’ channel (i.e. LH + RF) + actual beam (i.e. = 6 mm rad)

• Problem: matching for p = 200 MeV/c, but p is NOT constant along ‘full’ channel.

11. Cooling

• MICE proposal• MICE Note 49• New coils

= 6 mm rad,

cooling = • 13.5% (MICE proposal)• 15.2% (MICE Note 49)• 14.6% (New coils)

12. Conclusions

• We have a realistic set of coils and currents with an appropriate optic solution

• Solution is OK for Stages V & VI (and IV)

• Need to determine optic solutions for all MICE momenta, various -values and flip, no-flip & semi-flip modes

• A lot of fine-tuning is necessary to achieve optimum performance

13. Appendix

Position of the MICE Coils at Room Temperature

Magnet Coil Coil Left Z

(mm) Coil Inner R

(mm) Coil Length

(mm) Coil Thickness

(mm) Current density J

(A mm-2)

Focus #1 100 263 210 84 -113.95 Coupling 1250 725 250 116 -96.21 Focus #2 2440 263 210 84 -113.95 Focus #3 2850 263 210 84 113.95

Matching #1 3660 255 202 100 65.06

Matching #2 4101 255 202 50 41.46

End #1 4541 255 120 138 65.22

Center 4721 255 1260 50 64.44

End #2 6041 255 120 149 67.11

Present coil configuration, MICE Stage VI. Coils and currents from CERN 2004 meeting. Flip mode, p = 200 MeV/c, = 42 cm in LH.