TPC for 4-th concept S.Popescu IFIN-HH, Bucharest

A bit of history Our 4 th concept detector is quite young First proposal was at SNOWMASS 2005 Our main concept is based on the good results of the dual readout calorimeter DREAM (see the talk of A.Penzo) 4-th concept web page – But we need a good tracker  so first choice is a gaseous tracker  1 atm TPC

4 th concept TPC requirements -1 We need a good track finding  goal of tracking efficiency is 99% We need a good dE/dx  our goal is < 10% Momentum resolution   (p)/p 2 ~ GeV -1 Crossing time of the ILC is 337 ns > LHC 25 ns TPC is under study by LC TPC R&D groups No new idea is introduced, just an overview on our possible solutions

4 th concept TPC requirements -2 Using the R.L. Gluckstern method (NIM 24, 1963, 381) we calculate an optimized geometry for obtaining a good momentum resolution –Low magnetic field ~ 2T –Using Si pixel layers and Si strips –Using a fixed TPC size Ri=0.2m Ro= 1.4m

to10 Si pixel layers 3cm apart 1.4 TPC volume Ri = 0.2 m Ro = 1.4 m m 3 Si strip layers DREAM calorimeter Beam pipe

200 TPC pads 2T, 80  m (r  ) pad resolution coordinates 5  m resolution/ pixel layer 7  m resolution/strip layer

200 TPC pads 2T, 5  m resolution/ pixel layer 7  m resolution/strip layer

200 TPC pads 2T, 80  m (r  ) pad coordinates 5  m resolution/ pixel layer 7  m resolution/strip layer Conclusion: nr of Si strip layers doesn’t influence too much !!! We will use 8-10 Si Pixel layer 80  m spatial resolution 3 Si strip layer

GEM and PAD readout solution Looking into solution proposed by D.Karlen group arXiv:physics/ paper Results are encouraging after their tests in the magnetic field As main characteristics the TPC is: –30 cm drift length –2 GEM foils used 2.5 mm apart, 5mm away from Readout pads –Electric field in the drift volume V/cm –Operated at 4 T magnetic field –200 pads row  100  m pad spatial resolution –For a momentum resolution goal of  (1/pt) =2x10 -4 GeV/c A good method of defocusing the drifting electrons charge cloud after amplification is required !!!

GEM solution

MiCROMEGAS TPC readout solution What is a micromegas? –MICRO Mesh GASeous detector (I.Giomataris et al NIM A376(1996)29) –A very thin (3 to 5  m) metallic Ni (or Cu) mesh, with  m pitch, at  m away from anode plane –A strong field kV/cm  avalanche multiplication of e coming from drift volume Advantages of the MICROMEGAS –No ExB effect : good for 2 track separation –High gain ex: ArCH 4, 100  m pitch 10 3 – 10 5 for V mesh :400 – 480 or , He/isobutan V mesh :500 over 50  m –fast electron signal on the anode plane –Small ion feedback in the drift volume

Medipix2 and Micromegas Readout solution Developments of the NIKHEF/ Saclay /Twente/CERN First developments was using GEM foils and Medipix2 CMOS pixel sensor Good proof of principle : first events recorded March 2003 A nice combination of MediPix2 and Micro Mesh GASeous detector immediately came out

Medipix2 and Micromegas Readout solution Good results obtained with the new Medipix2 CMOS pixel sensor –256x256 pixel, 55  m x 55  m pixel pitch, area of 14x14mm2 New micromegas was used (holds >500V over 50  m) He/isobutan 80/20 (gas gain ) Preamp threshold 3000 e - quite high Required gain On average 1.8 e - /mm; 0.5 cl/mm per track reconstruction Single e - efficiency 0.9  detection of single (drifting) e - is possible Results published in NIM A540 (2005) 295

Medipix2 and Micromegas Readout solution We are looking forward for the future TimePixGrid which will consist in: –A CMOS pixel matrix TimePIX covered by Micromegas  integration onto wafer  InGrid J.Timmermans talk, Berkeley

Other Readout developments bulk Micromegas Berkeley/Orsay/Saclay group What is a bulk micromegas –Use of woven wire –Exist in rolls of 4x4 commonly produced –More robust for stretching and handling –Could be an interesting new technology… studies on going

Cooking bulks

Hybrid tracker - a good compromise We would like to combine a good momenta determination from three arbitrarily precise r/phi points With a robust pattern recognition in the gaseous tracking system Our option are Si/TPC/Si or the Club-sandwich (Si-TPC-Si-TPC-Si) “club sandwich” Our choice will be most probably the Si/TPC/Si formula

all gas TESLA club sandwich all Si (8 layers) SiD (8 layers) sandwich Higgs Dilpetons SUSY SPS1A 500 GeV SUSY SPS1A 1 TeV Schumman slide 4 th concept

Summary and outlook 4-th concept TPC detector optimization study has been launched Our first analysis on the momentum resolution optimization, make us think we will use: – 8,9 or 10 Si pixel layers, 3 Si strip layer, TPC size of Ri=0.2 m, Ro=1.4 m, and a magnetic field around 2T Comparison between GEM, Micromegas, Bulk micromegas Readout solution has been done We will probably choose the Medipix2+Micromegas solution We are looking forward for the InGrid solution (see J.Timmermans’s talk)

Summary and outlook Towards the detector optimization, there are still many issues to be attacked like –Gas optimization detailed studies –Electronic Readout system more detailed studies – Geant 4 analysis and very much more….