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

2. 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

3. 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

4. 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

5. 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

6. 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 3 mbar
04/06/2016
ILD TPC

7. 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

8. 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!

9. 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

10. 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

11. 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.

12. 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

13. 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