13-Feb-2014 Phase 2 upgrade “ME0 stack options” J. Hauser, UCLA  In Shashlik and CFCAL HE designs, space of  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  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… 1

13-Feb-2014 Phase 2 upgrade “ME0 stack options” J. Hauser, UCLA  Proposed at ECFA workshop

13-Feb-2014 Phase 2 upgrade “ME0 stack options” J. Hauser, UCLA  Support of HE mechanical load and moment: Bolts at outer radius Sliding joint to strong back at inner radius

13-Feb-2014 Phase 2 upgrade “ME0 stack options” J. Hauser, UCLA  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  Version B) HGCAL sim: 4x1 layer chambers, 0.47 and 5.1 X 0 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 polyethylene 1.2 Pb for n shielding 0.90 cm 3.45 cm 0.90 cm … 34.8 cm Brass absorber Brass spacer 3.45 cm Brass absorber Brass spacer

13-Feb-2014 Phase 2 upgrade “ME0 stack options” J. Hauser, UCLA From Virdee Euroschool 2003… tail catching

13-Feb-2014 Phase 2 upgrade “ME0 stack options” J. Hauser, UCLA 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 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

13-Feb-2014 Phase 2 upgrade “ME0 stack options” J. Hauser, UCLA  Version C) 3x2 layer chambers, 0.54 and 6.0 X 0 between chamber measurements  Version D) 2x 3 layer chambers, 0.77 and 8.6 X 0 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  4.0 cm 4.5 cm 4.0 cm … 4.5 cm 34.2 cm 3-layer  Brass spacer Brass absorber 3-layer  Brass spacer Brass absorber 3-layer  Brass spacer Brass absorber 3-layer  Brass spacer Brass absorber

13-Feb-2014 Phase 2 upgrade “ME0 stack options” J. Hauser, UCLA 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? D (2 x 3layer chambers)  Pros  Muon radiation isolation between successive chambers (more X 0 in brass, is it enough?)  Fair HE tail catcher   Cons  Unfamiliar package  Even thicker brass spacers – is it a mechanical problem? 8

13-Feb-2014 Phase 2 upgrade “ME0 stack options” J. Hauser, UCLA 2-layer   Version E) 2-layer units increases lever arm/pointing by a factor 2  2-layer units also convenient for construction (similar to GE1/1)  In Shashlik and CFCAL sims: 1x6 layer chambers HE strong back - stainless ~4 cm ~10 cm cm ~4 cm 2-layer  ~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 polyethylene 1.2 Pb for n shielding ~36 cm 2.5 borated polyethylene 1.2 Pb for n shielding ~17 cm

13-Feb-2014 Phase 2 upgrade “ME0 stack options” J. Hauser, UCLA  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?

13-Feb-2014 Phase 2 upgrade “ME0 stack options” J. Hauser, UCLA  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

13-Feb-2014 Phase 2 upgrade “ME0 stack options” J. Hauser, UCLA

 Brass density (casting, rolling variations)  Composition 63% Cu and 37% Zn by weight  At 8.4, density of Cu=5.292 g/cm 3, density of Zn g/cm 3  At 8.73, reduce interaction and rad lengths by 3.93%  Interaction lengths, radiation lengths  Cu =137.3 g/cm 2, X 0 =12.86 g/cm 2  Zn =138.5 g/cm 2, X 0 =12.43 g/cm 2  Interactions add up weighted average of the  / and  /X 0  For 63/37 brass, calculate  =16.4 cm, X 0 =1.511 cm

13-Feb-2014 Phase 2 upgrade “ME0 stack options” J. Hauser, UCLA Valeri  1.0 for EE  0.3 for EE stainless back  4.0 for Si-brass  4.15 for Scint-brass  9.45 in front of GEM  1.85 for GEM-brass Me:  1.0  for EE (take as a given)  0.3 for EE stainless back  for Si-brass  for Scint-brass   in front of GEM (or higher)  for GEM-brass

13-Feb-2014 Phase 2 upgrade “ME0 stack options” J. Hauser, UCLA

 (0, 5, 10, … cm)