m.apollonio MICE UK- RAL- 2/5/2007 1

MICE beam diffuserM. Apollonio ,P. Lau, W. Lau, J. Tacon, S. Yang – Univ. Oxford

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0. Z=-6010 mm for the upstream face of the diffuser. This is a figure established long time ago (CR, CM14 Osaka - 2006)

1. radial size R as big as possible

2. thickness limited number of discs to fulfil MICE configurations

3. mechanics & control design still evolving a) new carousel wheel (to cope with high moment of Inertia) b) motors c) ideas for control (logic)

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LEADING IDEA

trying to exploit all the radial space (15 cm) within the tin can envelope

being compatible with mechanical contraints

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7mm 15.5cm

Emi inflation in single layer lead diffuser: 2.8 6.1 mm rad

7mm

emi(after diff)=6 mm rad

Muons selected on the overall channelideal disc

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7mm

7mm

5cm 15.5cm

Emi inflation with a single layerof lead (small radius): 2.8 5.3 mm rad

7mm

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7mm

7mm

5cm 15.5cm

Emi inflation in a staggered lead diffuser: 2.8 6.1 mm rad

7mm 7mm

a more realistic diffuser

fixed annulusmovable disc + support

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emi(

R)/

emi(

R=

30

cm)

R_diffEmittance bias as a function of R_diff (partial inflation)

Pz=209 MeV/c, emi=10mm rad, B=4 T

Pz=148 MeV/c, emi=10mm rad, B=2.9 T

Pz=267 MeV/c, emi=10mm rad, B=4 T

single disc

staggered discs

m.apollonio MICE UK- RAL- 2/5/2007 810 mm

Proposal to accommodate many configurations STAGGERED/TAPERED with a fixed external annulus …just a sketch (see Peter/Joseph drawings)

24 t

o 2

7 c

m

30 c

m

trackerdiffuser

envelope

Supports (outer can/disc support): Al

Pb diffuser disc and outer annulus

1.5 to 15.5 mm

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J. Tacon

… th

e re

al th

ing

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= 1.4 mm radun-normalized

How many configurations we need? want? …

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… maybe 5 discs are enough (at least to begin with)

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New design for the main carousel:location of air-motors

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0.61 T

0.32 T

0.53 T

B>= 4T

B (T)

Z (m)

R (

m)

air-motors in the magnetic field can they work ?

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Diffuser Control Flow Chart:main cycle

Command: set disc-f for run mode

Start: go to Nf

TH empty (S off)?

Which discis in? Nd

Move C to position Nd

Extract disc

Go to empty station

Move C to position Nf

Insert disc

Go to empty station

Go to empty station

STOP

NB: need to know WHICH disc is in !

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SUMMARY

• diffuser plates will be staggered/tapered discs of 12.5 cm diameter + outer annulus

• thicknesses nearly finalized

• some re-design of the mechanics needed

• controls in progress:• optical sensors + switch• encoding/markers (for wheel position)• air-motors + gear-boxes: possible SHOW STOPPERs !!!