GEM Studies pro les and grids - Deutschlands größtes ...hallerma/talks/grouptalk809.pdf · FLC...

profile studiesgrid development and data analysis

summary and outlook

GEM Studiesprofiles and grids

Lea Hallermann

DESY HamburgUniversity of Hamburg

FLC meeting3rd August 2009

FLC meeting 2009-08-03 GEM studies - profiles and grids Lea Hallermann 1/ 32


summary and outlook

outline

1 profile studiesmeasurement and reconstructiongain simulationimpact on dE/dx, reconstruction and resolution

2 grid development and data analysisstructure evolutionMediTPC setuphit efficiency

3 summary and outlook



summary and outlook

measurement and reconstructiongain simulationimpact on dE/dx, reconstruction and resolution

laser measurement

0,01 µm

9 b is 11 mm

L K - G 10/15

H ö c h s te P r ä z is io n

laser device

triangulation principleprecision 1 µmfrequency 1 Hz

meander movement of x-ytable

→ list with measurement dataz value in mm

⇒ pattern recognition formatching of z value withx-y coordinates needed



summary and outlook


pattern recognition is tricky

1 find points on frame (6-8)

large slope followed byflatnesssymmetry around theassumed reversal pointdon’t take holes

2 get reversal point

3 build difference to nextreversal point

4 match x-y coordinates viaknown path length ofmeander

4000 4200 4400 4600 4800 50000

0.5

1

1.5

2



summary and outlook


profile reconstruction

-0.6

-0.4

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0.6

0 10 20 30 40 50 60 70 80 90 100 110 0 20

40 60

80 100

120

-0.6-0.4-0.2

0 0.2 0.4 0.6

z[mm]

gem_pitch_ceramic

x[mm]

y[mm]

z[mm]

CERN GEM with GRP frame

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0

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0 20 40 60 80 100 120 0

20 40

60 80

100 120

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0 0.2 0.4 0.6

z[mm]

gem_jap_gfk

x[mm]

y[mm]

z[mm]

SciEnergy GEM with GRP frame



summary and outlook


x [mm]

10 20 30 40 50 60 70 80 90 100

y [m

m]

0

20

40

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100

z [m

m]

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x [mm]

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m]

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z [m

m]

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Figure: GEM 7 (∆z: 355 µm) - GEM 17 (∆z: 509 µm) - GRP frames

x [mm]

10 20 30 40 50 60 70 80 90 100

y [m

m]

0

20

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z [m

m]

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m]

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Figure: GEM 18 (∆z: 733 µm) - GEM 26 (∆z: 922 µm) - GRP frames



summary and outlook


x [mm]

10 20 30 40 50 60 70 80 90 100

y [m

m]

0

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60

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100

z [m

m]

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m]

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m]

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Figure: GEM 27 (∆z: 434 µm) - SciEnergy GEM (∆z: 871 µm) - GRP frames

x [mm]

10 20 30 40 50 60 70 80 90 100

y [m

m]

0

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m]

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m]

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Figure: ceramic frames: (∆z: 690 µm) - pitch: 225 µm (∆z: 465 µm)



summary and outlook


data set

Medi TPC settings:

triple GEM, 325 V per GEMP5 gas, 4TED =90V/cm, ET =1500V/cm,EI =3000V/cm

each GEM rotated twice → 24 GEMs⇒ 24x23x22 = 12144 combinations

x [mm]

10 20 30 40 50 60 70 80 90 100

y [m

m]

0

20

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z [m

m]

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m]

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m]

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x [mm]

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y [m

m]

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z [m

m]

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-0.1

0

0.1

0.2



summary and outlook


gain calculation via parametrization

GEM III

GEM II

GEM I

anode

cathode

induction field

transfer field

transfer field

drift field 90 V/cm

1.5 kV/cm

1.5 kV/cm

3 kV/cmGEM III

GEM II

GEM I

anode

cathode

induction field

transfer field

transfer field

drift field

1.8 kV/cm1.6 kV/cm

88 V/cm

1.3 kV/cm1.5 kV/cm

3.1 kV/cm2.8 kV/cm

92 V/cm

gain is parametrized with the help of field settings

changing distances yield changing fields

gain calculated, normalized to 1 for every bin (1 x 1mm2)⇒ filled in one histogram⇒ 2D map of gain



summary and outlook


results of simulation

binning like pad layout: (1 x 6mm2)

normalized effective gain0.8 0.85 0.9 0.95 1 1.05 1.1 1.15 1.2

entri

es

0

200

400

600

800

1000

1200

1400310×

Entries 2.06448e+07

Mean 1.002

RMS 0.03006

Underflow 0

Overflow 0

norm

aliz

ed e

ffect

ive

gain

0.98

0.99

1

1.01

1.02

x [mm]10 20 30 40 50 60 70 80 90 100

y [m

m]

0

20

40

60

80

100

Figure: Deviations - at 4 Tesla - normalized to the nominal effective gain.Mean 1.002, RMS 3%



summary and outlook


motivation for studies of impact on dE/dx

not width of gain distribution but stability of mean interesting

width can be taken into account with calibration

analyses with cuts on dE/dx need stability of gain for differenttracks

example: discrimination of pions and Kaons over dE/dx verysensitive

gain mean variation at most 0.05 to 0.1 sigma(LEP experience)→ 0.25% - 0.5% for ILD with 5% dE/dx resolution

⇒ studies of stability for different regions



summary and outlook


stability of mean value

norm

aliz

ed e

ffect

ive

gain

0.98

0.99

1

1.01

1.02

x [mm]10 20 30 40 50 60 70 80 90 100

y [m

m]

0

20

40

60

80

100tracks: every pad of first row connected with

every pad of last row

track width: 3 pads per row



summary and outlook


stability of mean value

mean gain values of tracks0.98 0.99 1 1.01 1.02

entri

es

0

500

1000

1500

2000

2500

Entries 9604Mean 1.004RMS 0.002723


mean gain values of tracks0.98 0.99 1 1.01 1.02

entri

es

10

210

310


norm

aliz

ed e

ffect

ive

gain

0.98

0.99

1

1.01

1.02

x [mm]10 20 30 40 50 60 70 80 90 100

y [m

m]

0

20

40

60

80

100tracks: every pad of first row connected with

every pad of last row

track width: 3 pads per row



gain mean values of tracks0.98 0.985 0.99 0.995 1 1.005 1.01 1.015 1.02

entri

es

020406080

100120140160180200220240


10 20 30 40 50 60 70 80 90 1000

20

40

60

80

100



entri

es

0

50

100

150

200

250

300


10 20 30 40 50 60 70 80 90 1000

20

40

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Entries 1024Mean 1.007

RMS 0.0005195


entri

es

0

100

200

300

400

500

600


RMS 0.0005195

10 20 30 40 50 60 70 80 90 1000

20

40

60

80

100



entri

es

0

50

100

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200

250

300


10 20 30 40 50 60 70 80 90 1000

20

40

60

80

100


RMS 0.0005727


entri

es

0

100

200

300

400

500

600


RMS 0.0005727

10 20 30 40 50 60 70 80 90 1000

20

40

60

80

100



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es

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300


10 20 30 40 50 60 70 80 90 1000

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es

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es

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10 20 30 40 50 60 70 80 90 1000

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Entries 1024Mean 1RMS 0.003025


entri

es

0

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40

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Entries 1024Mean 1RMS 0.003025

10 20 30 40 50 60 70 80 90 1000

20

40

60

80

100


summary and outlook


stability over regions

region mean value RMSleft-left 1.001 0.36 %left-mid 1.005 0.12 %left-right 1.007 0.05 %mid-left 1.005 0.10 %mid-mid 1.006 0.06 %mid-right 1.006 0.12 %right-left 1.006 0.07 %right-mid 1.004 0.14 %right-right 1.000 0.30 %

Table: Mean values and root mean squares of averaged track gains indifferent regions. The RMS represents the fluctuation of the effectivegain corresponding to tracks within one region.



summary and outlook


open questions

variations are in critical region for dE/dx measurements

do longer tracks - over more GEMs - see smaller variations?

is bending stable over time?⇒ measurements with applied voltage

influence of grid and upright position?⇒ additional measurements

calibration strategies?

impact on track reconstruction and point resolution?



summary and outlook


track reconstruction and point resolution

idea for check of impact

simulate cosmics with ’perfect’ GEMs

→ MarlinTPC Simulation ⇒ lcio files

reconstruct the files with MultiFit

without calibrationwith gain variations as calibrationcomparison



summary and outlook

structure evolutionMediTPC setuphit efficiency

support structure development

TPC prototypes mainly use framed 10 × 10 cm2 GEMs

towards ILD larger coverage is needed

new support structure requires

small dead regionsmechanical stability and flatnessleast possible radiation length

first tests with nylon thread and rapid prototyping grids

nylon threadABS polymers polyamid (PA 12)



summary and outlook


ceramics seem to work best

Aluminum Oxide Al2O3

radiation length X0 = 7.1 cm(GRP X0 = 13.3 cm)

harder

higher contour accuracy

minimum width: 1 mm

thickness: 1 mm,height: 2 mm



summary and outlook


grid GEM - that’s it!

standard CERN GEMs gluedto both sides of grid

glue only on outer bars

dispensing robot used

procedure worked well

one GEM burned

replacing works well



summary and outlook


proof of principle

voltage test for electricalstability in air

GEMs stand > 600Vsame values as beforegluing

grid GEM tested in smallprototype

Iron 55 spectra measuredsimilar values,somewhat lower

ADC counts0 1000 2000

entri

es

0

5000

10000

370 V over both GEMs

Voltage per GEM [V]370 372 374 376 378 380 382 384 386

effe

ctiv

e do

uble

GEM

gai

n

0

1000

2000

3000

4000

grid mountingframe mounting

-1 = 1 kVcmT/I

, E-1 = 250 VcmD

TDR gas, 0 T, E

preliminary

Voltage per GEM [V]370 372 374 376 378 380 382 384 386

effe

ctiv

e do

uble

GEM

gai

n

0

1000

2000

3000

4000



summary and outlook


data taking with MediTPC

triple grid GEM

sensitive volume10 × 10 × 66 cm3

pad size: 1, 27 × 7 mm2

12 rows, 48 pads

cosmics

95% Argon, 5% CH4

magnetic field up to 4 T



summary and outlook


first glimpse - pulses per pad

0 5 10 15 20 25

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summary and outlook


grid is visible

0 5 10 15 20 25 30 35 40 45

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025003000350040004500

2500

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4500

Number of Pulses per Pad Entries 3907384Number of Pulses per Pad



summary and outlook


measurements and goals

parameters

triple grid GEM, voltages around 325 V

drift: 90 V/cm, transfer: 1.5 kV/cm, induction: 3 kV/cm

P5 gas, staggered pad plane

data points at 4 T, 3.5 T, 3T, 2T, 1T

goals of the studies

quantize impact of grid on

hit efficiencytrack efficiencyresolution

design of 2nd generation grid



summary and outlook


data reconstruction

X0 5 10 15 20 25 30 35 40 45

Y

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X0 5 10 15 20 25 30 35 40 45

Y

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X0 5 10 15 20 25 30 35 40 45

Y

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tracks with exact 9 hits required→ sample 9/9



summary and outlook


data reconstruction

X0 5 10 15 20 25 30 35 40 45

Y

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X0 5 10 15 20 25 30 35 40 45

Y

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X0 5 10 15 20 25 30 35 40 45

Y

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tracks with exact 9 hits required→ sample 9/9

X0 5 10 15 20 25 30 35 40 45

Y-10

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X0 5 10 15 20 25 30 35 40 45

Y-10

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X0 5 10 15 20 25 30 35 40 45

Y-10

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9 or 10 hits per track required→ sample 9/10



summary and outlook


hit efficiency - principle

if track reconstructed with 9 hits (9/9), a tenth hit should bereconstructed in sample 9/10 in row 3



summary and outlook




to be assured: same event (trigger), same track (slope andintercept)

x position of track fit in row 3 is used for efficiencydetermination



summary and outlook




to be assured: same event (trigger), same track (slope andintercept)

x position of track fit in row 3 is used for efficiencydetermination

histo 1: all reconstructed tracks in sample 9/9

histo 2: subset of histo 1 for all tracks of sample 9/10, whichhave a hit at the right position in row 3distance hit - fit < 200 µm (residuals over whole drift distanceof MediTPC)



summary and outlook


hit efficiency - determination

entry for each trackof sample 9/9

x of track fit [mm]0 10 20 30 40 50 60

hits

0

100

200

300

400

500

600

700X Position of Fit in Row 4 - Reco 9/9

Entries 46981X Position of Fit in Row 4 - Reco 9/9



summary and outlook


hit efficiency - determination

entry for each trackof sample 9/9

entry if same trackand hit in sample9/10 around fitposition

x of track fit [mm]0 10 20 30 40 50 60

hits

0

100

200

300

400

500

600

700X Position of Fit in Row 4 - Reco 9/9

Entries 46981X Position of Fit in Row 4 - Reco 9/9

x of track fit [mm]0 10 20 30 40 50 60

hits

0

100

200

300

400

500

600

X Position of Fit in Row 4 - Reco 9/9 - if Hit in 9/10 occursEntries 40331

X Position of Fit in Row 4 - Reco 9/9 - if Hit in 9/10 occurs



summary and outlook


hit efficiency

x [mm]0 10 20 30 40 50 60

effic

ienc

y

0

0.2

0.4

0.6

0.8

1

1.2

single hit efficiency in a grid covered row / ndf 2χ 129.9 / 46Prob 6.161e-10p0 0.001981± 0.8724

/ ndf 2χ 129.9 / 46Prob 6.161e-10p0 0.001981± 0.8724

single hit efficiency in a grid covered row



summary and outlook


hit efficiency - cross check

same study for a row, which is not covered by a horizontal grid bar

x [mm]0 10 20 30 40 50 60

effic

ienc

y

0

0.2

0.4

0.6

0.8

1

1.2

single hit efficiency in a NOT covered row / ndf 2χ 85.59 / 46Prob 0.0003541p0 0.001119± 0.9617

/ ndf 2χ 85.59 / 46Prob 0.0003541p0 0.001119± 0.9617

single hit efficiency in a NOT covered row

96 % instead of 87 % in a covered row, vertical bars visible as well



summary and outlook


further studies

investigation of fluctuations in hit efficiency

charge per Hit is lower in covered row

number of pulses per hit lower as well

0 500 1000 1500 2000 2500 3000 3500 4000 4500 50000

0.02

0.04

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0.08

0.1

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0.14

charge per hit

normal row - 2

covered row - 4

charge per hit

0 1 2 3 4 5 6 7 8 9 100

0.1

0.2

0.3

0.4

0.5

# pulses per hit

normal row - 2

covered row - 4

# pulses per hit



summary and outlook


track efficiency and resolution

with the help of a 9/10 and a 10/10 reconstruction a trackefficiency will be determined

single point resolution has to be checked row wise

driftlength Z [mm]0 100 200 300 400 500 600

reso

lutio

n X

[mm

]

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

PRELIMINARY

ChiSquared-WithPRCGlobalMethod-SigmaFixed

grid frame

2Gas: P5 (Ar:CH4/95:5) Pad Pitch: 1.27x7.0mm



summary and outlook

summary and outlook

bending of GEMs influences dE/dx measurement

stability of reconstruction and resolution will be tested viasimulation

additional experimental test interesting - not in scope of thisthesis

time dependence - voltageupright positionimprovement through grid

grid has a small, tolerable influence

hit efficiency above 85%

more sophisticated studies will follow

impact on track efficiency and resolution will be checked

design of new large prototype module with grid GEMs


GEM Studies pro les and grids - Deutschlands größtes ...hallerma/talks/grouptalk809.pdf · FLC...

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