V. Korbel, DESY1 Progress Report on the TESLA Tile HCAL Option To be filled soon

V. Korbel, DESY2 The HCAL Calorimeter for the TESLA Detector at DESY A Tool for Energy Flow Measurement: The calorimeter is used: to separate clusters from charged and neutral particles to measure energy and position (> angle) of neutrals to track minimum ionising particles This requires: rather good energy resolution, very fine granularity of cells compared to existing hadronic calorimeters. At TESLA 2 HCAL options under study: sandwich scintillator/absorber calorimeter with tile structure digital sandwich calorimeter with very fine granularity.

V. Korbel, DESY3 TESLA Detector, cross section Energy Flow Measurement: additional information from: vertex detector intermediate trackers TPC >> vertex of event momentum of charged tracks particle identification particle impact point at ECAL

V. Korbel, DESY4 TESLA Detector, cross section, more details Barrel HCAL Endcap HCAL Endcap Yoke HCAL Small angle calorimeters Full hermeticity down to < xx mrad

V. Korbel, DESY5 Cut across the barrel calorimeter 16 tapered modules 8 x symmetry Sandwich layers, 38 (53) max: 5 mm scintillator 1.5 mm gap for fibre RO, reflector foil 20mm Fe absorber 1 s/w layer =1.15 X 0, 0.12

V. Korbel, DESY6 The layer structure of the HCAL Sandwich layers; 38 in barrel,45 in end caps with scintillator tiles: sizes: ~5x ~16x16 cm 2 ~ tiles Cells: cells are non projective 9 (10) cell layers in barrel (end cap), grouped from 3,3,3,4,4,4,5,5,7 (3,3,3,4,4,4,5,5,7,7) s/w layers cell volumes: (0.22 ) 2 x0.36  (0.71 ) 2 x0.84  (1.6 R Moliere ) 2 x 3.5 X 0...(5 R Moliere ) 2 x 8 X 0 ~ cells Optimal HCAL granularity for E-Flow reconstruction of jet energies, ~angles and jet-jet masses.

V. Korbel, DESY7 The calorimeter modules: 10 cell layers additional front side ring surrounding end cap ECAL One of 32 Barrel HCAL modules Some free space left 1 quadrant assembled to wheel End cap HCAL 9 cell layers

V. Korbel, DESY8 The complete calorimeter Containment: barrel: =5.6 endcaps =11.9 Beam hole is closed by the mask calorimeter (Lumi-measurement) tungsten (electromagnetic shield) graphite (neutron shield)

V. Korbel, DESY9 original fibre RO concept as described in the TESLA-TDR. Original concept of tile plate read out 1. layer Problematic are the small scintillator tile sizes (~ 5x5 cm 2 ) to be read out Study other possibilities

V. Korbel, DESY10 R&D studies on the tile-WLS fibre system Green WLS fibre: attenuation length Scintillator light yield Tile uniformity Reflector foil: mirror or diffraction, light yield Reflector foil: LY uniformity WLS fibre: bending in small radius WLS fibre: ageing, rad. hardness WLS fibre: fibre end polishing and mirroring Tile-WLS system: coupling, light yield, uniformity >>>> 5x5 cm 2, than: 7x x16cm 2 tiles Tile-WLS system: coupling, light yield, uniformity >>>> 5x5 cm 2, than: 7x x16cm 2 tiles Scintillator : ~6600 m 2, costs! R&D Y-11, Kuraray BC-91, Bicron BC-408, BC-416, SC-306, Protvino Tyvek, 3M Super-reflector Al-vapour, various reflector paintings,polished optimally

V. Korbel, DESY11 Details of TFS optimisation studies Centre/straight fibreDiagonal/bent fibre Double looped fibre No stress on fibre, L= cm fibre refl. =tile reflector more stress on fibre, L= cm fibre refl. =tile reflector most stress on fibre, probably ageing L= cm fibre refl.inside tile > special reflective coating needed WLS-clear fibre connection easy to implement here clear RO fibre to couple: max. attenuation length

V. Korbel, DESY12 R&D studies Yield of channel in recalibration >> design of detector construction features some R&D results the minical the HCAL prototype performance, preliminary

V. Korbel, DESY13 WLS fibre end polishing Enlarged view, 20  m Polished with 3  m and 0.3  m sand-micro-polishing paper

V. Korbel, DESY14 Yield of different TF configurations: Some results:

V. Korbel, DESY15 Light yield and uniformity for tiles 4.0 – – – 6.0Uniformity (%) 15 x x 10 5 x 5Tile (cm 2 ) LY / photo e - (nA) Photo e Relative LY LY (nA) 15 x 1510 x 10 5 x 5Tile a x a (cm 2 ) improve LY for large tiles with WLS loops signal of large cells will be increased by more sampling layers actual established LY is ~20 pe/cell/MIP uniformity is ok, needs confirmation by simulation studies. light yield uniformity

V. Korbel, DESY16 Achievements of the TFS studies: 1. Scintillator: Bicron BC-408, Russian scint. SC301, 65% yield 2. 3M Super-reflector 3. Kuraray Y Open WLS-end only polished (~0.3  m) 4. WLS-fibres glued to tile 5. Diagonal bent fibre insertion 6. Light yield adjustment with reflector dimmer strip ( +/- 4-5%) More: --ageing studies --uniformity trimming

V. Korbel, DESY17 Assembled from up to 27 scintillator layers: 165 tiles of: 5x5 cm 2 >> 45 cells 10x10 cm 2 >> 8 cells 20x20 cm 2 >> 2 cells read out by WLS fibres (without clear RO fibres) to photodetectors --3x16 MA-PM’s,(H8711), --1x32 APD array,(H-s8550) --Si-PM’s. Tile and sandwich structure Track cambers? A pre-prototype : the „minical“-array For cosmics and e-beam tests Cell structure

V. Korbel, DESY18 The need of a HCAL prototype Study with pions, electrons and muons: ---stand alone runs: cluster development and separation angular resolution longitudinal and lateral containment threshold stability and cross-talk software compensation calibration with muons stability of LED monitoring noise contribution energy resolution measure the constant term ---together with an ECAL prototype: Energy Flow properties, Electron-Pion separation ---compare with digital HCAL version (same HCAL iron stack structure) To tune the simulation programs and optimise the reconstruction !

V. Korbel, DESY19 HCAL prototype Required volume ~ 1 m3 ~ calorimeter cells Fe-structure is same for analogue and digital HCAL 10 GeV pions 100 GeV pions 100 cm Leakage detector needed!

V. Korbel, DESY20 Best coupling shape for WLS fibres? Loops ph.e./tile ph./cell unbent fibres: along edge, no groove: along groove in centre diagonal fibre, groove: diagonal, minimal bend: Other criteria to use unbent fibres: easy to insert, less risk of damage no bending stress, > less ageing

V. Korbel, DESY21 The HCAL Calorimeter for the TESLA Detector at DESY A Tool for Energy flow measurement: The calorimeter is used: to separate clusters from charged and neutral particles to measure energy and position (>angle) of neutrals to track minimum ionising particles This requires rather good energy resolution, very fine granularity of cells compared to existing HCALs. At TESLA 2 HCAL options under study: sandwich scintillator/absorber calorimeter with tile structure digital sandwich calorimeter with very fine granularity.

V. Korbel, DESY22 Summary List of talks: How to continue:

V. Korbel, DESY23 Last transparency List of talks: How to continue: