TPC Paul Colas Technical meeting, Lyon

Technologies under study 25/04/2017 Paul Colas - TPC Technologies under study MPGDs suffer less from ExB effects than MWPCs. They require less heavy mechanics. Panels with each technology have been made and tested. European GEMs Micromegas Standard kapton triple GEM with ceramic spacers Mesh on top of a charge-dispersing resistive anode GridPix Integrated grid on 55 µ digital pixels Asian GEMs

Eu GEM modules : flatness improved 25/04/2017 Paul Colas - TPC Eu GEM modules : flatness improved Quality control: foil flatness GEM stack of 2 modules measured flat by almost a factor of two GEM stacks: 6.1% → 4.2% PREVIOUS CURRENT

25/04/2017 Paul Colas - TPC For the Eu GEMs, it has been checked that minimizing the ion backflow does not worsen the resolution. (January 2017)

Gridpix : ‘digital TPC’ 25/04/2017 Paul Colas - TPC Gridpix : ‘digital TPC’ Reconstruct every ionization electron with a high efficiency. Measure dE/dx by cluster counting Recently progress has been done with Timepix 3 and chip protection against sparks has been improved.

25/04/2017 Paul Colas - TPC Distortions Module frames at ground while the top GEM or Micromesh is at HV induces distortions at the level of O(1mm). New design should suppress this effect. Eu GEM Micromegas

25/04/2017 Paul Colas - TPC Need for gating In TPCs, ions are produced and migrate very slowly (1 m/s) . They produce a charge density which can be one or two orders of magnitude above the primary ionization (IBF*Gain). The resulting electric field can be the origin of distortions. At the ILC, the bunch trains last about 1ms every 200 ms, giving rise to ion disks slowly drifting to the cathode

25/04/2017 Paul Colas - TPC Need for gating In TPCs, ions are produced and migrate very slowly (1 m/s) . They produce a charge density which can be one or two orders of magnitude above the primary ionization (IBF*Gain). The resulting electric field can be the origin of distortions. At the ILC, the bunch trains last about 1ms every 200 ms, giving rise to ion disks slowly drifting to the cathode After 2 disks, the electrons receive a kick of up to 60 µm, too much wrt the systematics

25/04/2017 Paul Colas - TPC Gating options The ions must be stopped before penetrating too much the drift region. The device to stop them must be transparent to electrons. Here is the example of a highly transparent wire mesh used to create a counter field near the amplification device

25/04/2017 Paul Colas - TPC Gating options The ions must be stopped before penetrating too much the drift region. The device to stop them must be transparent to electrons. Here is the example of a GEM with a Delta V polarization.

GEM gating – Large aperture GEM transparency 25/04/2017 Paul Colas - TPC GEM gating – Large aperture GEM transparency

25/04/2017 Paul Colas - TPC

Measurement in Japan with GEMs Measurement at CERN with Micromegas 25/04/2017 Paul Colas - TPC Measurement in Japan with GEMs Measurement at CERN with Micromegas Simulation studies in progress D V (Volts)

Test beam results with a gating GEM 25/04/2017 Paul Colas - TPC Test beam results with a gating GEM A module with a gating GEM has also been tested in beam in November 2016. The results are consistent with no more degradation than expected (~10%) The analysis is still in progress, but GEM gating seems to be a possible solution for the gating at ILC

25/04/2017 Paul Colas - TPC

25/04/2017 Paul Colas - TPC

Magboltz simulation : CD ~94 µm/sqrt(cm) 25/04/2017 Paul Colas - TPC Magboltz simulation : CD ~94 µm/sqrt(cm)

GEM resolution w and w/o gating 25/04/2017 Paul Colas - TPC GEM resolution w and w/o gating Consistent with a transparency of 86 %

25/04/2017 Paul Colas - TPC CO2 cooling CO2 cooling has been demonstrated (with Micromegas so far). Requires 1mm diameter serpentine Cables Each module requires: A low-voltage cable to supply the electronics (2mm²) One or several HV cable for the amplification device A double-fibre for the signals A cooling tube Fully integrated design : 0.25 X0

The ILD TPC A 8-wheel design A 4-wheel option 2 x 2.3 m length 25/04/2017 Paul Colas - TPC The ILD TPC 2 x 2.3 m length Covering radii from 0.35 to 1.7 m A 8-wheel design 240 modules with about the size of present LP modules. A 4-wheel option 80 modules each side. For each module (6800 channels) : 1 HV cable 1 double optical fibre 1 low-voltage 32A cable 160 W to remove (becomes negligeable is power pulsing can be fully implemented.

25/04/2017 Paul Colas - TPC

Endplate panels Panel height 336 mm Panel width : from 278 to 454 25/04/2017 Paul Colas - TPC Endplate panels Panel height 336 mm Panel width : from 278 to 454 About 6800 pads per panel

25/04/2017 Paul Colas - TPC Summary Despite very difficult conditions, the R&D is still in progress : gating tests are promising, flatness of the EU GEM chambers is improved, pixel readout is getting mature Realist implementation plans are about to start. This is also a preparation for the technology choice.