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m.apollonio CM17 -CERN- (22/2-25/2/2007) 1
M. Apollonio – University of Oxford
sizes for PID & shields
m.apollonio CM17 -CERN- (22/2-25/2/2007) 2
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
m.apollonio CM17 -CERN- (22/2-25/2/2007) 3
CAVEAT: Z_diff=-6.010 m (corrected w.r.t. the original presentation given at a previous an.meeting)
m.apollonio CM17 -CERN- (22/2-25/2/2007) 4
current diffuser position
ideal minimum RD
RD-TRK= 15.1 cmRD-ABS= 13.5 cmRD-RF= 11.9 cm
m.apollonio CM17 -CERN- (22/2-25/2/2007) 5
Wang-200-42
Z-downstream: shield-in shield-out SW
TOF KL
m.apollonio CM17 -CERN- (22/2-25/2/2007) 6
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 !!!
RD-TRK= 15.2 cmRD-ABS= 13.8 cmRD-RF= 11.9 cm
m.apollonio CM17 -CERN- (22/2-25/2/2007) 7
Wang 207-200-193 (with energy loss)
R grows linearly far fromthe solenoid (beta ~ z2)
m.apollonio CM17 -CERN- (22/2-25/2/2007) 8
Wang-240-42
RD-TRK= 15.1 cmRD-ABS= 14.8 cmRD-RF= 13.0 cm
m.apollonio CM17 -CERN- (22/2-25/2/2007) 9
Wang-240-42
m.apollonio CM17 -CERN- (22/2-25/2/2007) 10
NF-200-42RD-TRK= 15.2 cmRD-ABS= 13.5 cmRD-RF= 10.5 cm
m.apollonio CM17 -CERN- (22/2-25/2/2007) 11
NF-200-42
m.apollonio CM17 -CERN- (22/2-25/2/2007) 12
SFOFO-170-15
RD-TRK= 15.3 cmRD-ABS= 22.1 cmRD-RF= 10.8 cm
m.apollonio CM17 -CERN- (22/2-25/2/2007) 13
SFOFO-170-15
m.apollonio CM17 -CERN- (22/2-25/2/2007) 14
SFOFO-140-7
RD-TRK= 14.6RD-ABS= 30.9RD-RF= 11.5
m.apollonio CM17 -CERN- (22/2-25/2/2007) 15
SFOFO-140-7
m.apollonio CM17 -CERN- (22/2-25/2/2007) 16
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
m.apollonio CM17 -CERN- (22/2-25/2/2007) 17
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
m.apollonio CM17 -CERN- (22/2-25/2/2007) 18
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
m.apollonio CM17 -CERN- (22/2-25/2/2007) 19
Wang-200-42
Z-downstream: shield-in shield-out SW
TOF KL
like having a 20 cmshorter SW calorimeter
But only for the outermuons
m.apollonio CM17 -CERN- (22/2-25/2/2007) 20
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
m.apollonio CM17 -CERN- (22/2-25/2/2007) 21
radial size for the diffuserM. Apollonio – University of Oxford
m.apollonio CM17 -CERN- (22/2-25/2/2007) 22
• 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
m.apollonio CM17 -CERN- (22/2-25/2/2007) 23
ICOOL sim, Pz=200 MeV/c
diffuser
Z=-6.010 -5.2 m
m.apollonio CM17 -CERN- (22/2-25/2/2007) 24
r=10 cm
r=15 cm
m.apollonio CM17 -CERN- (22/2-25/2/2007) 25
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
m.apollonio CM17 -CERN- (22/2-25/2/2007) 26
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%
m.apollonio CM17 -CERN- (22/2-25/2/2007) 27
ICOOL sim
diffuser
Z=-6.010
m.apollonio CM17 -CERN- (22/2-25/2/2007) 28
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
m.apollonio CM17 -CERN- (22/2-25/2/2007) 29
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
m.apollonio CM17 -CERN- (22/2-25/2/2007) 30
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
m.apollonio CM17 -CERN- (22/2-25/2/2007) 31
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
m.apollonio CM17 -CERN- (22/2-25/2/2007) 33
m.apollonio CM17 -CERN- (22/2-25/2/2007) 34
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 CM17 -CERN- (22/2-25/2/2007) 35
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
Recommended