Paul Colas, CEA Saclay, Akira Sugiyama, Saga U. TPC Paul Colas, CEA Saclay, Akira Sugiyama, Saga U. R&D Optimization Priorities Interfaces

Charge to the ILD TPC technical group Main goal: getting organized to be able to build the best TPC (i.e. adapted to Physics issues) in time to take data at the ILC. Define R&D and design needs (together with LCTPC collaboration) Optimization (with other ILD subdetectors) dimensions, resolution Internal optimization : pad size, material budget, consumption Costing Define criteria for technology choice For all subjects, check the interfaces with other detectors Reinforce funding by more collaborative work : 16 institutes contribute 04/06/2016 ILD TPC

Outcome of the Santander LCTPC meeting Gating studies (Large aperture GEM) Saga-KEK-Saclay tests en of 2016 at DESY Continue work on GridPix option Decision to get various ion velocities measured in T2K gas within RD51 Further studies of distortions : systematics on sagitta 04/06/2016 ILD TPC

t0 = Ground Breaking 2033? After Y. Sugimotos The yoke and the solenoid have to be assembled on surface site very early (start Y3): task force The remaining of the tracker is for end of Y8 04/06/2016 ILD TPC

TPC endplate possible layouts One can have 8 ‘wheels’ of module with the size of the Large Prototype, or less wheels with larger modules Four wheels, 84 modules x2 Three wheels, 55 modules x2 Advantage of large modules : fewer different kinds of modules to be produced, easier alignment, less cracks. However size is limited by HV stability and replacement possibility. 04/06/2016 ILD TPC

TPC mechanics New ‘lightweight’ endplate for the Large Prototype (Cornel) to be tested Mechanical calculations to be re-started: - hanging model - Deformations under weight and pressure Deflexion O(150 µm) @ 3 mbar 04/06/2016 ILD TPC

Anti-DID task force Magnet : essential piece of the tracking system, one of the most costly parts of ILD, to be lowered in the pit among the first parts (year 3.5) , not even entirely designed, linked to crossing angle and homogeneity required for TPC, long to build (6-8 years Saclay estimate, 9-12 years Toshiba estimate) -> MOST CRITICAL PART OF ILD 04/06/2016 ILD TPC

D. Arai and K. Fujii 4. Ion Disk Effect Evaluation of track distortions due to space charge effects of positive ions : design and implementation of a program to do analytic evaluation using Green’s function 4. Ion Disk Effect Green’s function can be series-expanded in terms of modified Bessel functions!

Multiform information in space and time - Different information depending on the subdetector part : coordinates on different varieties for Si, 3D (modulo t0) for TPC - A few 10 µs typical reading time in VTX (cumulate typic. 100 BX, that is 105 g + few e-) - Continuous reading of the TPC during a train: sliding projection - Matching between Si and TPC requires best possible resolution of TPC (200 µm) and good time resolution for ext. Si (O(3 ns)). 04/06/2016 ILD TPC

Geometry Versatile Kalman filter : various measurement surfaces Turbine blade shape meas. surface（Fwd. Si） Planar 2-dim. meas surface（VTX pixel） Planar 1-dim. meas. surface（Si Strip） Conical surface （Beam Pipe） Cylindrical meas surface（TPC） KalTest Versatile Kalman filter : various measurement surfaces Segment-wise helical track model :for non-uniform B-field (Bo Li, K. Fujii) 04/06/2016 ILD TPC

Track to Bunch crossing assignment Distance between extrapolated vertices from the TPC from 2 consecutive BXs: 300ns x 70 µm/ns : ~2 cm : need to get rid of tracks from other beam crossings, while keeping efficiency for delayed decays. TPC to Si matching Whenever a track has parts in both detectors, one needs to match them to associate them: distortions must be allowed for in a first step, and then corrected.

GridPix progress Wafer-based post-processing to add a protection layer and a mesh on pillars on top of the chips (107 chips at a time) March 2015, there was a successful test with 3 modules (96 chip each) partially equipped : 160 chips! This shows that this technique is applicable to large areas This opens the way for ultimate dE/dx resolution 04/06/2016 ILD TPC

Summary and conclusions The magnet is a critical issue. There is no rush to finalize electronics and cooling, the design can benefit from more R&D. The technology choice must be prepared, but is not urgent. Despite limited (or fragmented) funding and uncertainties on the future, engineered R&D continues, to be ready for a TDR when necessary. Still many questions are open, and there is a strong need for simulation. A train-based reconstruction should be started. 04/06/2016 ILD TPC