Presentation is loading. Please wait.

Presentation is loading. Please wait.

MICROMEGAS per lupgrade delle Muon Chambers di ATLAS per SLHC Arizona, Athens (U, NTU, Demokritos), Brookhaven, CERN, Harvard, Istanbul (Bogaziçi, Doğuş),

Similar presentations

Presentation on theme: "MICROMEGAS per lupgrade delle Muon Chambers di ATLAS per SLHC Arizona, Athens (U, NTU, Demokritos), Brookhaven, CERN, Harvard, Istanbul (Bogaziçi, Doğuş),"— Presentation transcript:

1 MICROMEGAS per lupgrade delle Muon Chambers di ATLAS per SLHC Arizona, Athens (U, NTU, Demokritos), Brookhaven, CERN, Harvard, Istanbul (Bogaziçi, Doğuş), Naples, Seattle, USTC Hefei, South Carolina, St. Petersburg, Shandong, Thessaloniki M.Alviggi, GR1-Napoli, 16 dicembre 2008 Thanks to P.Iengo per la maggior parte dei plot

2 2

3 Micromegas as candidate technology Combine triggering and tracking functions Matches required performances: – Spatial resolution ~ 100 m ( track < 45°) – Good double track resolution – Time resolution ~ few ns – Efficiency > 98% – Rate capability > 5 kHz/cm 2 Potential for going to large areas ~1m x 2m with industrial processes 3

4 Prototype P1 Standard bulk micromegas fabricated at CERN-TS/DEM Homogeneous stainless steel mesh 325 line/inch = 78 m pitch Wire diameter ~25 m Amplification gap = 128 m 450mm x 350mm active area Different strip patterns (250, 500, 1000, 2000 µm pitch; 450mm and 225 mm long) Drift gap: 2-5 mm 4

5 Test beam set up P1 CERN H6 beam line in November 2007 & June to August GeV pion beam Scintillator trigger External tracking with three Si detector modules (Bonn Univ.); independent DAQ Three non-flammable gas mixtures with small isobutane admixture used in 2008: Ar:CO 2 :iC 4 H 10 (88:10:2), Ar:CF 4 :iC 4 H 10 (88:10:2), Ar:CF 4 :iC 4 H 10 (95:3:2) Data acquired for 4 different strip patterns and 5 impact angles (0 to 40 degrees) Test beam set up2008 Test beam set up

6 Readout channels DAQ based on ALTRO CHIP Micro Megas trigger Two inverted diodes for spark protection Zero channels died FEC 32 channels 200 ns integration time 64 charge samples/ch 100 ns/sample 15 pre-samples 1 ADC count ~ 1000 e - DAQ PC (ALICE DATE) Typical ADC spectra Noise subtraction (from 12 pre-samples) Cluster position from center of gravity

7 Cluster charge (ADC counts) Cluster charge distribution Gas mixture: Ar:CF 4 :iC 4 H 10 (88:10:2) Drift gap 5 mm; drift field = 200 V/cm Strip pitch = 250 µ m Horizontal axes: ADC count ADC count = 1000 electrons 7 HV mesh = 460 V Gain measurement from HV mesh scan Exponential gain increase Stable operation (small spark rate) for gain of 3–5 · 10 3

8 8

9 Spatial resolution Si tracker σ extr 50 µm MM cluster position Convoluted 9 Strip pitch: 250 µm Gas: Ar:CF 4 :iC 4 H 10 (88:10:2) Track impact angle: 90° Convoluted resolution of Si tracker + extrapolation σ(Si+MM) = 63 µm MM intrinsic resolution σ(MM) 40 µm

10 Spatial resolution … more 10 x-raying the micromegas Look for areas where micromegas is inefficient, i.e. tracks in Si tracker with no hits in the micromegas pattern of pillars Equipped micromegas area (8 mm) 2.54 mm Pillar distance Si tracks

11 Micromegas as a TPC…. Track inclination: 40° Ar:CF 4 :iC 4 H 10 (95:3:2) Drift field: 360V/cm 11 Even with non-optimal r/o electr. measuring the arrival time on each strip it is possible to measure the drift velocity or, with known drift velocity, the drift distance Rob Veenhof Drift path (mm) Drift time (ns) v d = 8.4 cm/us 8 cm/µm Cluster First strip Last strip

12 …Micromegas as a TPC A time resolution of a nanosecond results in space points with a resolution along the drift direction of 100 µm Each micromegas gap delivers a set of space points, the more the track is inclined the more space points are available Solves the problem of spatial resolution for large track inclination 12

13 Therefore… Robust detector Works with non-flammable gases Spatial resolution is excellent with small strip pitch MM as TPC will give track segments & excellent space resolution; needs time measurement (ns) Electronics should measure time, may relax on charge Trigger capability to be proven with faster electronics 13

14 What next ? Test beam stopped ; setting up cosmics test stand in and in few other labs (Naples,Demokritos) optimize gas mixtures wrt drift velocity, diffusion, primary ionization, sparks, ageing… Analysis of test beam data taken in 2008 with goals: Definition of readout segmentation Definition of requirements for r/o electronics Construction and test of 1300 x 400 mm 2 prototype (Rui de Oliveira) 14

15 The 50% prototype Active area: 1.3 x 0.4 Segmented mesh (cut) to reduce mesh capacity 250 and 400 µm strip pitches Long and short strips Construction has started in CERN/TS-DEM Expect MM board to be ready by early 2009 Chamber to be completed spring 2009 Test beam in May The stretched micromegas mesh on its frame

16 Backup Richieste CSN1 RD51 16

17 17 ns*100 σ = 30 ns σ m 1.2 ns

18 Inclined tracks 18 Impact angle: 50° Cluster First strip Last strip

19 Micromegas as TPC (II) 19 Track under 50° with relative time info

20 Software tool Software tool* for quasi online and off- line reconstruction (based on ROOT) Permits alignment of Si tracker modules with MM chamber Combines data from Si tracker and MM online resolution Also: simple event display 20 *) Thanks to Woo Chun Park (U. South Carolina)

21 Simple event display 21 Si module6 Si module1 Si module3 Micromegas

22 Spatial resolution – online Residuals of MM cluster position and extrapolated track from Si Convolution of: – Intrinsic MM resolution – Tracker resolution (extrapolation) – Multiple scattering 22 Si tracker Micromegas Beam Gas: Ar:CF 4 :iC 4 H 10 (88:10:2) Drift field: 200 V/cm Strip pitch: 250 um Strip width: 150 um Strip pitch: 500 um Strip width: 400 um Strip pitch: 1000 um Strip width: 900 um mm : 85 um MM : 60 um : 212 um MM : 203 um : 102 um MM : 82 um ~60 µm

Download ppt "MICROMEGAS per lupgrade delle Muon Chambers di ATLAS per SLHC Arizona, Athens (U, NTU, Demokritos), Brookhaven, CERN, Harvard, Istanbul (Bogaziçi, Doğuş),"

Similar presentations

Ads by Google