Spaghetti calorimeter

1
Spaghetti calorimeter
A reminder of the calorimeter design from L.T.s
presentation at CERN on 29/03/03
Readout square (or rectangular) cells connected
to PMT photocatode by light guides shaped as
Winston cones
2
Muon vs electron identification

• We have carried out simulation studies in G4MICE
  to optimize the m/e separation capabilities by
  varying
• sampling fraction, i.e. lead layer thickness
  0.5-0.2 mm
• readout segmentation, i.e. cell size
• 3.75x3.75 cm2, 3.25x3.25 cm2, 2.5x2.5 cm2,
  2.5x4.0 cm2

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Momentum
muons
electrons
at production
at calorimeter
at calorimeter (20 lost) (0.5 lt130 MeV/c)
Muons P(MeV/C)
Datacards used ltEkingt120.5 MeV , DE/E0.1
4
Lead absorber
Eff. for signalgtthreshold in 3rd or 4th layer
vsmomentum (useful mainly for trigger
purposes) For different absorber thickness and
readout cell sizes
Eff. In Layer 3
Eff. In Layer 4
Eff. In Layer 3
Efficiency on muons improves when less material
is traversed (thinner layers, smaller cells), but
electron contamination increases accordingly
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A much lighter absorber pure polystirene

• The option of a fully active detector
  (scintillator) has been suggested
• We have considered the option with no absorber
  only polystirene fibers
• Efficiencies are very optimistic !!!!
• Readout with 3.75cm cells a huge number of PMTs

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e/m separation algorithmsBaricenter coordinate
cells 3.75 cm
electrons
muons
ZB (a.u.)
ZB (a.u.)
cells 2.50 cm
ZB (a.u.)
ZB (a.u.)
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Summary

• Some checks to be done on beam distributions
  obtained with G4MICE
• Optimization
• 1) for fast signal (threshold cut)
• Better efficiency on muons with thinner lead
  layers
• No significant gain on low energy muons with
  fully active detectors, but much larger
  contamination from electrons
• 2) e/m identification
• Baricenter coordinate seems to be a very good
  separation criterium
• Improving with thicker absorber and smaller
  redout cells, but to be checked as a function of
  muon momentum
• Fully active detector provides very poor
  identification capabilities