me0 stack options – preview of a gmm talk
DESCRIPTION
ME0 stack options – preview of a GMM talk. In Shashlik and CFCAL HE designs, space of D z~30 cm exists behind 10 lambda for muons 30 cm typically allows 2 overlapping chambers, each of thickness 10 cm plus 4+4 cm on each side for borated polyethylene and Pb shielding for neutrons - PowerPoint PPT PresentationTRANSCRIPT
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In Shashlik and CFCAL HE designs, space of Dz~30 cm exists behind 10 lambda for muons
30 cm typically allows 2 overlapping chambers, each of thickness 10 cm plus 4+4 cm on each side for borated polyethylene and Pb shielding
for neutrons
On the other hand, in HGCAL, a tail catcher of hadron showers is currently implemented as potentially dual purpose with ME0 muon detection In fact this design is not being used for muon reconstruction yet
Some thoughts following conversations with Valeri Andreev, Roger R, Marcello M, Archana, Karl Gill, Alain Herve, Pawel…
ME0 stack options – preview of a GMM talk 1
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Proposed at ECFA workshop
High Rapidity Muon (HRM) layout
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Support of HE mechanical load and moment:Nose engineering drawing
Bolts at outer radius
Sliding joint to strong back at inner radius
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Version A) Shashlik and CFCAL sims: 1x6 layer chambers, HE support from sliding joint to fixed-r conn. to strong back: requires ME0 inner, outer sections
Current ME0 “stack” cartoons Version B) HGCAL sim: 4x1 layer
chambers, 0.47 l and 5.1 X0 between measurements
~36
cm
~4 cm
~8 cm
muon
HE strong back - stainless ~10 cm
~8 cm
~4 cm
6-layer chambers
6-layer chambers
2.5 borated polyethylene1.2 Pb for n shielding
0.90 cm3.45 cm0.90 cm
…
34.8
cm
Brass absorberBrass spacer
3.45 cm
Brass absorberBrass spacer
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From VirdeeEuroschool 2003… tail catching
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A (6-layer chambers): Pros
“Traditional” muon chamber design like CSC, DT
6 muon layers versus 4 layers
Internal alignment is precise Cost savings Lots of space to bring ME0
services, cables Cons
Likely not a good HE calorimeter tail catcher
Mechanical support is more complicated
Comments on versions A and B
B (single layer chambers)
Pros Good HE calorimeter tail
catcher Simple mechanical
support Cons 4 muon layers versus 6
layers Alignment concerns Increased cost Almost no space for ME0
services except at outer periphery, extremely thin packages required
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Version C) 3x2 layer chambers, 0.54 l and 6.0 X0 between chamber measurements
Other possibilities Version D) 2x 3 layer
chambers, 0.77 l and 8.6 X0 between chamber measurements
2.3 cm
3.4 cm
2.3 cm …
34 c
m
3.4 cmBrass absorber
Brass spacer
Brass absorber
Brass spacer
2-layer m
2-layer m
4.0 cm
4.5 cm
4.0 cm
…
4.5 cm
34.2
cm
3-layer m Brass spacer
Brass absorber
3-layer m Brass spacer
Brass absorber
3-layer m Brass spacer
Brass absorber
3-layer m Brass spacer
Brass absorber
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C (3 x 2layer chambers) Pros Familiarity with 2-layer
packages from GE1/1 etc Pretty good HE tail
catcher Cons Thicker brass spacers –
is it a mechanical problem?
Comments on Versions C and D
D (2 x 3layer chambers) Pros Muon radiation isolation
between successive chambers (more X0 in brass, is it enough?)
Fair HE tail catcher Cons Unfamiliar package Even thicker brass
spacers – is it a mechanical problem?
8
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2-layer m
Version E) 2-layer units increases lever arm/pointing by a factor 2
2-layer units also convenient for construction (similar to GE1/1)
Variant of ME0 stack that staggers 2-layer units In Shashlik and CFCAL sims: 1x6 layer
chambers
HE strong back - stainless
~4 cm
~10 cm
2-3.2 cm
~4 cm
2-layer m
2-layer m
2-layer m
2-layer m
2-layer m ~7 cm
~36
cm
~4 cm
~8 cm
HE strong back - stainless ~10 cm
~8 cm
~4 cm
6-layer chambers
6-layer chambers
2.5 borated polyethylene1.2 Pb for n shielding
~36
cm
2.5 borated polyethylene1.2 Pb for n shielding
~17 cm
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ME0 is used for muons to link to inner Tracker tracks
Especially at highest eta, Tracker uses endcap pixel disks Error ellipse is therefore likely to be rather round
Pads, therefore, are better for matching than narrow strips This also favors use as a tail catcher in a projective
calorimeter But ignores the possibility of modest rejection
of low-Pt muon candidates Skinny radial strips best for this Studies are needed to identify the dominant effect?
Finally, ME0 segmentation
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Verify the numbers, at least approximately
Try to install version A stack in HGCAL sim for now HE: tail catcher capability doesn’t see to be high
priority for studies, HGCAL group has expressed their flexibility
“Give” or at least “lend” the 34.8 cm space in z (and the cost) to the muon community for optimization Z= 5193 – 5541 mm in present HGCAL (V.Andreev xml
layout)
Later on, versions C (3 x 2layer HE-like) and E (staggered 3 x 2-layer muon units) look to be attractive alternatives for all HE choices
Conclusions - suggestions
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Backup slides
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From the TDR of the HCAL
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Brass density 8.4-8.73 (casting, rolling variations) Composition 63% Cu and 37% Zn by weight At 8.4, density of Cu=5.292 g/cm3, density of Zn
3.108 g/cm3 At 8.73, reduce interaction and rad lengths by
3.93%
Interaction lengths, radiation lengths Cu l=137.3 g/cm2, X0=12.86 g/cm2 Zn l=138.5 g/cm2, X0=12.43 g/cm2
Interactions add up weighted average of the r/l and r/X0
For 63/37 brass, calculate l=16.4 cm, X0=1.511 cm
Behind the calculations
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Valeri 1.0 l for EE 0.3 l for EE stainless
back 4.0 l for Si-brass 4.15 l for Scint-brass
9.45 l in front of GEM 1.85 l for GEM-brass
Valeri vs. my l calculationsMe: 1.0 l for EE (take as a
given) 0.3 l for EE stainless
back 3.9-4.07 l for Si-brass 4.28-4.45 l for Scint-
brass
9.48-9.82 l in front of GEM (or 0.03-0.37l higher)
1.90-1.98 l for GEM-brass
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(0, 5, 10, … cm)Stack cartoon ruler