1. MAMUD Magnetized hadronic calorimeter and muon veto for the K +   +  experiment L. DiLella, March 29, 2005 Purpose:  Provide pion – muon separation (muon veto)  Bend the beam away from the small angle photon veto located at the end of the hall

2. Criteria for the design of the hadronic calorimeter and muon veto  Integration with LKr calorimeter  Distinguish hadronic showers from electromagnetic showers  need longitudinal and lateral segmentation  Sensitivity to minimum ionizing particles (MIP)  Bending power ~  T x m  p T kick  .  GeV/c deflects  GeV/c beam by  mr (  cm lateral displacement at  m) An important background from K +   +   decay: “catastrophic” muon energy losses  muon bremsstrahlung  e + e  pair production  high Q 2  + e  scattering  muon decay in flight  deep inelastic muon – nucleon scattering  + + N   + + hadrons electromagnetic shower In all processes (except muon decay) the outgoing  +  has generally enough residual energy to be detected

3. Proposed structure   Iron plates  cm thick   cm gap between plates  Total length  m  Front face at z =  m (0.6 m behind LKr cryostat) ~ 8 m between calorimeter end and beam dump at the end of the hall Proposed longitudinal segmentation:  independent sections of  gaps each One section : ~  x 0, ~  int a reasonable matching to LKr ( ~  x 0, ~  int ) “Optimal configuration”: instrument all gaps with active detectors “Minimal configuration”: instrument only first three and last section with active detectors (Choice depends on available budget)

4. Active detector material : Extruded polystyrene scintillator strips  cm long,  cm high,  cm thick read out by a single  mm diameter wave-length shifting fibre (as in the MINOS and OPERA experiments) Orthogonal strips in adjacent gaps (x, y) Scintillator is extruded with TiO  white cladding and groove where fibre is glued The fibres from strips at the same x (y) coordinate in one section go to a single  cm diam. PMT to form a calorimeter “cell” In total (minimal configuration):  strips per instrumented gap  strips per section  x  cells,  y-cells  PMT’s per section  fully instrumented sections Performance of MINOS strip 8 m long, 4 cm high, 1 cm thick Observe two fibre light attenuation lengths: 1  0.7 m, 2  3.9 m For our case expect  photoelectrons per strip from a minimum ionizing particle 4 cm

5. Cost estimate OPERA Proposal (CERN/SPSC 2000-028):   x  m  scintillator planes (  m  in total)  Each plane:  m long strips read out INDIVIDUALLY from both sides using  -channel multi-anode PMTs  Total number of strips  channel multi anode PMTs  Estimated cost (including fibres and PMTs): kCHF  Extrapolation to MAMUD (minimal configuration):   x  m  scintillator planes (  m  in total)  Each plane:   m long strips  Total number of strips  read out in groups of  by  cm diam. PMTs  Total number of  cm diam. PMTs =  Estimated cost  0.15 x OPERA  cost of iron and coils (not including 1040 channels of read-out electronics) “Optimal configuration”: two times more strips and PMT’s