M.apollonioCM17 -CERN- (22/2-25/2/2007)1 M. Apollonio – University of Oxford sizes for PID &...

m.apollonio CM17 -CERN- (22/2-25/2/2007) 1

M. Apollonio – University of Oxford

sizes for PID & shields


Consider different optics for MICE

Consider the maximum radius a particle can reach in the tracker (TK) = 15 cm the absorber (ABS) = 15 cm the RF windows (RF) = 21.3 cm

It can be shown that ~ <R2>

Propagate the radius throughout MICE according to

These curves represent the ENVELOPE of the beam whichjust touches the TK, the ABS, the RF and the diffuser == muons with a given amplitude ==

MIN size of diffuserMIN radii in the downstream region

00

XX RR


CAVEAT: Z_diff=-6.010 m (corrected w.r.t. the original presentation given at a previous an.meeting)


current diffuser position

ideal minimum RD

RD-TRK= 15.1 cmRD-ABS= 13.5 cmRD-RF= 11.9 cm


Wang-200-42

Z-downstream: shield-in shield-out SW

TOF KL


current diffuser position

inside TKs inside ABS inside RF

ideal minumum RD

Every in the TKs will traverse both ABS and RF

RD must be as large as possible10 cm is definitely too small !!!



Wang 207-200-193 (with energy loss)

R grows linearly far fromthe solenoid (beta ~ z2)


Wang-240-42



Wang-240-42


NF-200-42RD-TRK= 15.2 cmRD-ABS= 13.5 cmRD-RF= 10.5 cm


NF-200-42


SFOFO-170-15



SFOFO-170-15


SFOFO-140-7

RD-TRK= 14.6RD-ABS= 30.9RD-RF= 11.5


SFOFO-140-7


Summary of min R – DIFFUSER (cm)

optics min RD (TK) min RD (ABS) min RD (abs)wang 207-200-193-42 15.2 13.8 12wang 200-42 15.1 13.5 11.9wang 240-42 15.1 14.8 13NF (TRD) 200-42 15.2 13.5 10.5SFOFO 170-15 15.3 22.1 10.8SFOFO 140-7 14.6 30.9 11.5


6399.5 6499.5 6574.5 6649.5 6729.5 7429.5 6524.5 6599.5 6689.5

250

250

100 100 50

50

40

40700

Definition of MIN Radius for PIDs and SHIELD holes!!! NOT IN SCALE (but figures should be correct)

TOF

KL SW

750

sole

no

id e

nd

p

late

max radius

650


optics R input hole R output hole R-TOF R-KL R-SWwang 207-200-193-42 246.5 295.5 272.1 324 587wang 200-42 246.5 296.6 272.1 323 587wang 240-42 223.2 262.5 243.3 284.5 507.3NF (TRD) 200-42 240.2 288 271 314.7 576.5SFOFO 170-15 243.3 291.2 268.9 317.9 576.5SFOFO 140-7 247.6 294.5 271 320 567

According to the defs given in previous slides these are the min radii(a) for the shield (to let every pass) and (b) for the PIDs (to accept every )

Within tolerances

1000x1000 mm2

600x600 700x700 mm2

Slightly out ? tolerances

Is it a problem?

iron shield


Wang-200-42

Z-downstream: shield-in shield-out SW

TOF KL

like having a 20 cmshorter SW calorimeter

But only for the outermuons


conclusions

the maximum radii for particles traversing MICE are propagated (from the max R in3 different places) through the apparatus (TKs, ABS, RF)

Considering several optics: min Radius (at fixed position z=-6010 mm) for the diffuser is defined: in order to have particles in the TKs it turns out Rd should be as large as possible

(compatible with mechanical contraints)

In any case RD=10 cm seems to be small !

min radii for downstream shield holes are computed upon the requirement of accepting every from trackers

min radii for PIDs are computed upon the requirement of having the maximalacceptance within the detector: this condition can be probably relaxed

Real B field in the “shield area” should take into account real map. This is just anapproximation whose purpose is giving some initial figures


radial size for the diffuserM. Apollonio – University of Oxford


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

I focussed on the radial size of it

• propagate muons back from centre tracker to the diffuser

• record x,y position and check whether they fall within the diffuser

• generate beams upstream with proper ALPHA/BETA and go through the diffuser• compute emittances check bias due to r_cut

• would like to convince you that R=10 cm is a bit tight and propose some solution


ICOOL sim, Pz=200 MeV/c

diffuser

Z=-6.010 -5.2 m


r=10 cm

r=15 cm


n

(mm rad)

R0(0.1%)

(cm)

R0(0.5%)

(cm)

R0(1%)

(cm)

1 4.8 4 3.7

3 9 7.5 7

6 12.5 10.8 10

10 15.8 13.8 12.8

Beam fraction within radius R0


try to see it another way … generate (gaussian) beams BEFORE DIFFuser:

1- thickness of 7 mm inflation: 2.7 6.5 mm rad (BETA=76 cm / ALPHA=.20 )

2- thickness of 12.7 mm inflation: 2.7 10 mm rad (BETA=127cm / ALPHA=.37 )

3- thickness of 8 mm inflation: 1.9 10 mm rad (BETA=189 cm / ALPHA=1.14 )

4- thickness of 14.2 mm inflation: 3.4 10 mm rad (BETA=128 / ALPHA=.4)

calculate emi before/after diffuser for several radii (compare with a large radius case)

Pz=209 MeV/c +/- 10%

Pz=148 MeV/c +/- 10%

Pz=267 MeV/c +/- 10%


ICOOL sim

diffuser

Z=-6.010


A tentative scheme for the diffuser

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

being compatible with mechanical contraints


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


7mm

7mm

5cm 15.5cm

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

7mm 7mm

realistic diffuser

fixed annulusmovable disc + support


7mm

7mm

5cm 15.5cm

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

7mm

m.apollonio CM17 -CERN- (22/2-25/2/2007) 3212.7 mm

8 mm

7 to 14.2 mm

Proposal to accommodate many configurations6, 10 mm rad @ Pz=200 MeV/c 10 mm rad @ Pz=140 MeV/c 10 mm rad @ Pz=240 MeV/c …just a sketch (see Stephanie/Wing drawings)

24 t

o 2

7 c

m

30 c

mtrackerdiffuser

envelope

Supports (outer can/disc support): Al

Pb diffuser disc and outer annulus



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


SUMMARY

• a diffuser with R=10 cm is too small. We should try to use all the space available

• the choice of R_diff can be inspired by the emi_bias plot, in which case you can choose between 12 and 13.5 cm

• the “staggered” solution provide uniform inflation (till R~15 cm) and is equivalent to the ideal full disc case. Important for high emittances and low momenta

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M.apollonioCM17 -CERN- (22/2-25/2/2007)1 M. Apollonio – University of Oxford sizes for PID &...

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