GEM based TPC readout

Transcription

1 FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 1/28 GEM based TPC Lea Hallermann DESY Hamburg FLC meeting 27th August 2007

2 FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 2/28 content 1 new setup system challenges 2 introduction framing profile 3 motivation chamber measurement plans 4

3 FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 3/28 reminder

4 FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 4/28 new setup system challenges GEM based TPC - a story about the MediTPC DAQ

5 new setup for MediTPC new setup system challenges = therefore running DAQ needed 18 rows à 48 pads pitch 1.27 x 7mm 2 (old:2.2 x 6.2 mm 2 ) segmented outer region against crosstalk cutout for laser setup non staggered FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 5/28

6 new setup for MediTPC new setup system challenges 18 rows à 48 pads pitch 1.27 x 7mm 2 (old:2.2 x 6.2 mm 2 ) segmented outer region against crosstalk cutout for laser setup non staggered = therefore running DAQ needed FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 5/28

7 important elements new setup system challenges modified ALEPH DAQ from charge signal to lcio file: anode preamp TPD FIC PC support systems: clock, trigger, voltage supply FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 6/28

8 FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 7/28 DAQ new setup system challenges

9 FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 8/28 appearance new setup system challenges VME crate with FIC pulse generator as clock NIM crate with trigger and clock logic Fastbus crate with TPDs and data cables power supply

10 problems and solutions new setup system challenges connection to Fastbus Nabil s aura helped no voltage on preamps new fuses soldered on TPDs low clock signal changed serial to parallel clock not enough channels in one Fastbus crate removed SMTPD module 8 instead of 7 TPDs available (8 64 = 512 channels) external clock and voltage supply needed noise better grounding (especially of clock) new clock module FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 9/28

11 current status and outlook new setup system challenges Medi TPC is back at the magnet DAQ is connected and works reliable at the moment just noise visible data taking with new setup at different magnetic fields two track measurements with laser setup FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 10/28

12 FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 11/28 introduction framing profile GEM based TPC - something about

13 FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 12/28 GEM principle introduction framing profile 200 E d = 1 kv/cm 70 µm 140 µm z - Position / µm U=250 V -100 standard CERN GEM: cm 2 framed and unframed ones available x - Position / µm E i = 6 kv/cm 200

14 framing - why and how introduction framing profile 3 needed for UNIMOCS, unframed ones were stored in lab framing procedure developed expertise: Klaus - GDD group, Adrian - TPC group Aachen, notes from Canada and CERN tools: framer, frames, epoxy glue, oven FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 13/28

15 framing in pictures introduction framing profile FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 14/28

16 FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 15/28 procedure introduction framing profile stretch GEM on framer 30 min stretching at 40 C glue first frame 3 h curing at 40 C glue second frame 15 h curing at room temperature extract GEM from framer

17 FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 16/28 testing introduction framing profile good results (about 580 V) built in UNIMOCS chamber

18 profile measuring setup introduction framing profile every 20 th hole in x and y is measured 814 points FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 17/28

19 FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 18/28 profile introduction framing profile z 374µm with fit to the frame: deviation reduced to z 320µm

20 FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 19/28 consequences introduction framing profile bended GEM yields deviating distances and therefore varying field strenghts local variation of collection/extraction efficiencies effective gain G Eff = C G X deviates shield GEM 3 transferfield field 2 ( 2 mm) GEM 2 transferfield field 1 ( 2 mm) GEM 1 PCB 1 SMD connectors induction field ( 3 mm) pads PCB 2 connectors to the endplate

21 FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 20/28 gain studies introduction framing profile TDR gas ( : Ar CH 4 CO 2 ) at 0 T E Drift = 250 V/cm, U GEM =350 V, E Trans,Ind = 1000 V/cm

22 FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 20/28 gain studies introduction framing profile TDR gas ( : Ar CH 4 CO 2 ) at 0 T E Drift = 250 V/cm, U GEM =350 V, E Trans,Ind = 1000 V/cm

23 FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 20/28 gain studies introduction framing profile TDR gas ( : Ar CH 4 CO 2 ) at 0 T E Drift = 250 V/cm, U GEM =350 V, E Trans,Ind = 1000 V/cm G eff : +0.8% 0.0% G eff : +0.7% 0.0% G eff : +4.7% 6.4%

24 introduction framing profile framing works well automatization of profile measurement more systematic studies with generated GEM stacks to estimate impact of bended GEM on gain GEM I GEM II GEM III vary field strenghts and distances possibility to minimize the effect? experimental check of simulations, if possible FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 21/28

25 FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 22/28 motivation chamber measurement plans GEM based TPC - assembly of a small TPC

26 FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 23/28 motivation motivation chamber measurement plans open questions for large prototype bigger GEM structures needed is GRP frame needed? can be glued on top of each other with just small spacer in between? what s the minimal possible distance between two? at which size of GEM foil capacitance becomes a problem? GEM performance studies

27 FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 24/28 history motivation chamber measurement plans assembled by B.Voigt diameter: 21 cm, height: 20 cm studies of charge transfer processes and ion feedback were performed via current measurements therefore a Fe 55 source was used

28 FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 25/28 assembly motivation chamber measurement plans source mounted inside chamber due to reach of Fe 55 rings for better homogeneity of field

29 FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 26/28 gas tightness motivation chamber measurement plans chamber not gas tight homemade o-rings will be exchanged by professional ones problem: groove to deep for standard o-ring workshop

30 FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 26/28 gas tightness motivation chamber measurement plans chamber not gas tight homemade o-rings will be exchanged by professional ones problem: groove to deep for standard o-ring workshop chamber went off the milling machine cut out a piece of groove

31 measurement plans motivation chamber measurement plans tracks from Fe 55 source and cosmic muons Fe 55 spectrum effective gain by current measurements (impact of non-planar ) study of variations caused by changed distances and different mountings of FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 27/28

32 summary and future plans FLC meeting 8/27/2007 GEM based TPC Lea Hallermann 28/28 MediTPC DAQ works again perform set of measurements with cosmics gain simulations got program from Sven Lotze, first simulations done systematic studies and experimental check drift tower is set up, wait for chamber finish assembly and study GEM performance