European gaseous tracking hardware History GEM and Micromegas

European gaseous tracking hardware • History • GEM and Micromegas • Ongoing R&Ds • Preliminary studies – drift velocities – aging – ion feedback, extraction – tests in magnetic fields P. Colas, DAPNIA Saclay - electronics for tests 12/12/2021 P. Colas - European R&D for gaseous trackers 1

HISTORY A DECADE OF TRACKING STUDIES 1992: First discussions on detectors in Garmisch. Partenkirschen (LC 92). Silicon? Gas? 1996 -1997: TESLA Conceptual Design Report. Large TPC, 1. 5 Mchan. 2000: TESLA Technical Design Report. Micropattern (GEM, Micromegas) as a baseline 5/2001: Kick-off of the R&Ds 11/2001: DESY PRC for the TPC (includes north-American teams) DRAFT – Recommendations of the 52 nd Meeting of the PRC DESY 25 -26 th October 2001 PRC R&D-01/03: LC TPC R&D The PRC recommends the approval of the proposed R&D programme. It encourages the collaboration to perform in high magnetic fields tests of the different end-plate geometries (GEM, MICROMEGAS and standard wire chambers) and to use the performance of the ALEPH TPC as bench mark for a TESLA detector. It asks for a status report in one year. 5/2003: interim report planned 12/12/2021 P. Colas - European R&D for gaseous trackers 2

Challenging requirements: High two-track separation in jets both in Z and in Rf (O(8 mm)) High background from photons and neutrons (600 n/BX) High granularity, small diffusion High granularity Low ion feedback or efficient gating Low H-content of the gas Low material budget of the endplate (thin frame) Particle identification Good d. E/dx resolution chamber Excellent jet resolution (E-flow) => Micropattern detectors electrons ions 12/12/2021 ions P. Colas - European R&D for gaseous trackers 3

GEM and Micromegas GEM: Two copper perforated foils separated by an insulator The multiplication takes place in the holes. Usually used in 3 stages, even 4 Micromegas : a micromesh sustained by 50 -100 mm - high insulating pillars. The multiplication takes place between the anode and the mesh One stage 200 mm 12/12/2021 P. Colas - European R&D for gaseous trackers 4

GEM and Micromegas S 1/S 2 ~ Eamplif / Edrift S 1 S 2 12/12/2021 P. Colas - European R&D for gaseous trackers 5

GOALS OF THE STUDY Assess the new technologies Choose a gas Understand the electron transparency, extraction efficiency, ion feedback Check that micropattern detectors keep their good properties in a magnetic field Study d. E/dx resolution Obtain optimal position resolution wt >20 -> potential transverse diffusion less than 200 mm at 1 m Get in touch with industry for detector manufacturing (thinner frames, grids) Or improve the wire chamber technology Orsay: Small-gap, Asymmetric wire chamber Munich 12/12/2021 P. Colas - European R&D for gaseous trackers 6

Due to the high value of wt and the low grid transparency, does it work in a magnetic field? -> TESTS 12/12/2021 P. Colas - European R&D for gaseous trackers 7

Aachen : small GEM device for current measurements 2 T magnet in Julich 5 T magnet in DESY (Orsay-Saclay : 1 cm and 15 cm micromegas TPCs for current measurements 2 T magnet in Saclay TPC studies in the Saclay magnet (june 2002, Feb 2003) 2 Tesla, 53 cm bore diameter 12/12/2021 P. Colas - European R&D for gaseous trackers 8

DESY Hamburg Large prototype 12/12/2021 P. Colas - European R&D for gaseous trackers 9

CERN-Karlsruhe: designed to fit in the DESY Magnet Berkeley-Orsay-Saclay to fit in the Saclay magnet Both will make use of the STAR electronics 12/12/2021 P. Colas - European R&D for gaseous trackers 10

Berkeley-Orsay-Saclay TPC 1024 pads Under construction Pad layout Field cage Readout 12/12/2021 Detector P. Colas - European R&D for gaseous trackers 11

Ar CF 4 Drift properties: attachment is negligible below 400 V/cm and above 15 k. V/cm (supported by our measurements) 12/12/2021 P. Colas - European R&D for gaseous trackers 12

Novosibirsk: Russian GEM manufacturing company in Nijni Novgorod (80 mm holes at a 140 mm pitch) Possibility of gating the 1 st GEM by pulsing the HV on it. 12/12/2021 P. Colas - European R&D for gaseous trackers 13

12/12/2021 P. Colas - European R&D for gaseous trackers 14

Orsay-Saclay: no change observed in the iron 55 peak position beween 0 and 2 T 12/12/2021 P. Colas - European R&D for gaseous trackers 15

No deterioration of the ion feedback (rather a small improvement for GEMs) The ion feedback is well understood for micromegas 12/12/2021 P. Colas - European R&D for gaseous trackers 16

DESY-Hamburg 12/12/2021 P. Colas - European R&D for gaseous trackers 17

Aachen-DESY-Hamburg-Rostock Amsterdam Nikhef Silicon pixels for a digital readout. See individual electrons to reconstruct cluster by cluster. First need a GEM or a Micromegas to multiply each electron by 104 Medipix chip under study in Nikhef (Harry Van der Graaf, Jan Timmermans) Orsay-Saclay First results very soon? • Tests have been performed in a magnetic field • Cosmic setup under construction with Berkeley MAY BE THE FUTURE • Collaboration began with Canada for resolution improvement studies 12/12/2021 P. Colas - European R&D for gaseous trackers 18

STAR READOUT ELECTRONICS TEST BENCH VME processor Pulse generator Optical link Mother board Front end cards 12/12/2021 P. Colas - European R&D for gaseous trackers 19

Work on the STAR Electronics (J. Kaminski, S. Kappler, M Ronan) 12/12/2021 P. Colas - European R&D for gaseous trackers 20

CONCLUSION • The R&D is being carried out in several places at the same time. There are two 2 T and one 5 T magnets in operation in Julich, Saclay and DESY. • Lots of cross-collaborations, even through Atlantic. • Intense simulation effort. • In parallel, tests of various aspects of the micropattern detectors. Micromegas and GEM TPCs are currently operating in magnetic fields. Ion feedback, aging, transparency, gain, drift velocities are being studied for several gases. 12/12/2021 P. Colas - European R&D for gaseous trackers 21