Felix Sefkow DESY LDC at Vienna November 17, 2005 LDC HCAL Felix Sefkow DESY LDC at Vienna November 17, 2005

HCAL detector outline Basic configuration Open design issues Optimization Felix Sefkow LDC at Vienna, 17.11.2005 LDC HCAL

Configuration The HCAL is inside the coil. No substantiated objections raised. Felix Sefkow LDC at Vienna, 17.11.2005 LDC HCAL

Technology The conceptual choice between scintillator and gas as active medium should be based on testbeam results. If a classification by Baseline / Alternative had to be done at this (inappropriate) time, my matrix would look like this Fe B B’ A Pb A W A A A where baseline means: can proceed to technical design and costing now C.c.: The conceptual choice between scintillator and gas as active medium should be based on testbeam results. Felix Sefkow LDC at Vienna, 17.11.2005 LDC HCAL

Alternative options W has less than half the hadronic interaction length of Fe Gain depth or reduce magnet volume Pb (with scintillator) offers “hardware compensation” Both W and Pb would allow to build HCAL and ECAL with the same absorber - this opens new degrees of freedom to optimize the ECAL – HCAL transition The study of these options requires (at least) A full-fledged engineering design (only Fe is self-supporting) To evaluate the amount of dead zones for support Re-optimization of the granularity due to different Moliere radii Testbeam – since the role of neutrons is quite different Felix Sefkow LDC at Vienna, 17.11.2005 LDC HCAL

Dimensions Barrel Endcap Mass 500t + 2 * 200t Depth 4.4 (5.3)  180 < R < 280 cm -220 < z < 220 cm Endcap 30 < R < 270 cm 250 < |z| < 380 cm Mass 500t + 2 * 200t Depth 4.4 (5.3)  Active area ~ 5000 m2 (for 38 (50) layers) Felix Sefkow LDC at Vienna, 17.11.2005 LDC HCAL

Important details Barrel endcap transition Endcap FCAL transition Endcap ring and a smallest possible gap are probably needed for inside-out clustering / pattern recognition Endcap FCAL transition Cut-out most likely degrades forward jets Apparently has already disappeared – new picture would be nice! Felix Sefkow LDC at Vienna, 17.11.2005 LDC HCAL

Depth This HCAL is a bit skinny. PFLOW reduces the problem (for charged particles) To what extent – at high E? Shower shape “extrapolation” unreliable Cannot use last HCAL layer as leakage veto! How much does the tail catcher recover? 1st layer active! Felix Sefkow LDC at Vienna, 17.11.2005 LDC HCAL

Sampling TDR: Steel thickness follows from X0 20mm Fe, 5mm Scint, 1.5mm r/o Steel thickness follows from X0 Scintillator should be thin but give enough light from MIPs for calibration Thinner scintillator might become possible with more efficient photo-sensors Compensation possible with steel But check sampling statistics At least gain interaction depth Or € from coil volume Volume ratio (Wigmans) Felix Sefkow LDC at Vienna, 17.11.2005 LDC HCAL

Granularity Scintillators: trade granularity against amplitude resolution 3cm tile size optimized for shower separation – and semi-digital readout Variation with depth not fully explored Felix Sefkow LDC at Vienna, 17.11.2005 LDC HCAL

Clock+Config+Control Readout architecture The mechanical structure of the TESLA TDR HCAL was based on readout with clear fibres to photodetectors to be placed near the front end electronics With SiPMs other configurations become possible – one example: following the ECAL architecture With highly integrated electronics and early data reduction Slab FE FPGA PHY VFE ASIC Data Clock+Config+Control Conf/ Clock Felix Sefkow LDC at Vienna, 17.11.2005 LDC HCAL

Calibration and electronics We assume that we need at least a simple light injection system for debugging and timing checks Radioactive sources have an interesting potential Requires auto-triggering electronics The final electronics design depends on calibration procedure Eg power pulsing may exclude cosmics Benefits of time resolution for clustering should be further evaluated NB: Also for RPCs, operational stability and monitoring issues are still to be addressed (testbeam) – with possible consequences on readout architecture Felix Sefkow LDC at Vienna, 17.11.2005 LDC HCAL

Mechanical structure The mounting scheme for the ECAL – hanging with rails on the HCAL might need to undergo revision, too. Felix Sefkow LDC at Vienna, 17.11.2005 LDC HCAL

Summary The HCAL readout architecture and mechanical structure should be revised. Most important issues for optimization are Depth Cracks Sampling Granularity Calibration Timing And don’t forget background Felix Sefkow LDC at Vienna, 17.11.2005 LDC HCAL

Backup slides Felix Sefkow LDC at Vienna, 17.11.2005 LDC HCAL

PFLOW performance By far not the final word, but state of the art A. Raspereza Felix Sefkow LDC at Vienna, 17.11.2005 LDC HCAL

Use the weights which optimize hadron energy resolution Imaging quality Shower in scintillator appears* wider than in gas Large model dependence of shower width * unweighted Use the weights which optimize hadron energy resolution Felix Sefkow LDC at Vienna, 17.11.2005 LDC HCAL

Making decisions Henry Ford I Felix Sefkow LDC at Vienna, 17.11.2005 LDC HCAL