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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 talk1

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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

~3

6 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 cm

3.45 cm0.90 cm

…

34.

8 c

m

Brass absorber

Brass spacer

3.45 cm

Brass absorber

Brass 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

cm

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 c

m

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

~3

6 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

~3

6 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