Two-Dimensional Floating Strip Micromegas Detectors

Two-Dimensional Floating Strip Micromegas Detectors

Felix Klitznera, Jona Bortfeldtb,a

a.) Ludwig-Maximilians-Universitat Munchenb.) CERN

RD51 Collaboration MeetingMunchen

20.06.2018

F. Klitzner (LMU) 2d-FSMM Detectors 20/06/2018 1 / 15

Outline

1 IntroductionFloating Strip Micromegas with One-Dimensional Readout

2 Two-Dimensional Floating Strip MicromegasFirst Measurements: Heidelberg Ion Therapy CenterSignal Simulation with ANSYS and Garfield++Three Different Optimized Anode DesignsMeasurement Results: 20 MeV Protons and 150 GeV Muons/Pions

3 Summary


Floating Strip Micromegas with 1d Readout

MICROMEsh GASeous detectorsdrift regionÑ collecting ionization chargeamplification regionÑ electron avalanchefast signals O(100 ns)Ñ high-rate capabilitychallenge: dischargesÑ non-destructive but dead timeÑ efficiency drop @ high particlerates or high rate backgroundsolution: ’floating’ copper stripsanode strips individually connectedto HV via high ohmic resistorssignals decoupled capacitively

Ñ discharge confined to few stripsÑ fast recovery after discharge

+500V

-200Vcathode

mesh

copperanode strips

pillars 150μm

6mmNe:CF4

500μm 300μm

0.3kV/cm

33kV/cm

recharge R

copper readout strips

drift region

amplification region(Ar:CO2)

charged particle

signal decoupling: congruent readout stripsÑ excellent spatial resolution (100 µm) andefficiency (ą98%) at 7 MHz/cm2

question: two-dimensional strip readout?


First Measurements with a 2d Readout @ HITKapton flex PCB: 64x64 mm2 active area

copper anode strips, pitch 500 µm, width300 µm, connected to HV via screen printedresistorsparallel readout strips, width 80 µmperpendicular readout strips, width 400 µm

Ion Range Radiographyions (Einitial known) traverse patientÑ measure residual energy Ñ contrastÑ measure location Ñ spatial info

Prototype @ HITCarbon ions up to 2 MHz18 layer scintillator stack

1

1

1

1

1

1

1

1

18 1

PM-TSA

attenuator

APV0

APV2

APV4

APV6

APV10

APV11

APV12

APV13

z

xy

data

beam

phantom

APV8ADC + FEC

SRT


Ñ it works!Ñ 2d hit position

measurableÑ image recon-

structable

Signal Simulation: Fields, Drift & AmplificationANSYS: 3d model of anodeÑ calculate electrical/weighting fields ofall electrodes

Garfield++: import field configurationÑ simulate charge carrier drift andamplification

charge q at velocity #�v ptq:Ñ induces current Iind(t) on electrodes(Shockley-Ramo-theorem):

Iindptq “ ´rq{Vws ¨#�E r #�x ptqs ‚ #�v ptq

with weighting potential Vw andweighting field #�E r #�x ptqs

Garfield++: simulation of readoutelectronics response (APV25 chips)

weighting field yANSYS

equipotential surface map

x-strip

floating strip

y-strip


Signal Simulation: Induced Currentstwo electrons placed top of theamplification gap centered above bothfloating stripsfast electron signal (ď2 ns):negative current on floating strips andpositive current on y-stripsion movement towards the micro-meshÑ slow component of the signalbipolar current (ions) on the y-strips dueto weighting field line configuration

time [ns]0 50 100 150 200 250 300 350

sign

al [f

C /

ns]

0.0012−

0.001−

0.0008−

0.0006−

0.0004−

0.0002−

0

fast electronsignal

continuousion drift

floating strip

x (cm)0.05− 0.04− 0.03− 0.02− 0.01− 0 0.01 0.02 0.03 0.04 0.05

z (c

m)

0.03−

0.025−

0.02−

0.015−

0.01−

0.005−

0

0.005

0.01

avalanche centerof gravity

weighting field lines

Garfield++

floating strip

y-strip

x-strip

time [ns]0 50 100 150 200 250 300 350

sign

al [f

C /

ns]

0.04−

0.02−

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

3−10×

ion drift closer to the anode

ion drift closer to the mesh

y-strip


Signal Simulation: Electronics ResponseAPV25 chips:charge integrating amplifier with CR-RCshaping (time constant τ “ 50 ns)

convolution of induced current Ii ptq onelectrode i with transfer functionhptq « t

τe´t{τ yields approximation of

APV25 response

0 100 200 300 400 500 600 700 800 900 1000time [ns]

0.5−

0.4−

0.3−

0.2−

0.1−

0

sign

al a

mpl

itude

[a.u

.]

full signal

electron signal

ion signal

simulated APV25 response floating strip / x-strip

0 100 200 300 400 500 600 700 800 900 1000time [ns]

0

0.05

0.1

0.15

0.2

0.25

sign

al a

mpl

itude

[a.u

.]

full signal

electron signal

ion signal

simulated APV25 response y-strip


Different Anode Designs: Strip ResponseDesign-4

x-stripsy-strips

floating strips

150 µm

150

µm

100 µm 40

0 µm

0 5 10 15 20 25time [25ns]

1200−

1000−

800−

600−

400−

200−

0200400600800

char

ge [a

dc c

hann

els]

x-stripsy-strips

strip with maximum charge

Test Beam Data

Eamp = 37.5 kV/cm

Edrift = 0.33 kV/cm

Ne:CF4 80:20 vol.%

average from 30k protons

Design-5

x-stripsy-strips

floating strips

150 µm

2x 80 µm

400

µm 15

0 µm

0 5 10 15 20 25time [25ns]

1200−

1000−

800−

600−

400−

200−

0200400600800

char

ge [a

dc c

hann

els]

x-stripsy-strips


Eamp = 37.5 kV/cm

Edrift = 0.33 kV/cm

Ne:CF4 80:20 vol.%


Test Beam Data

Eamp = 37.5 kV/cm

Edrift = 0.33 kV/cm

Ne:CF4 80:20 vol.%

Design-6

x-stripsy-strips

floating strips

150 µm

80 µm

400

µm 15

0 µm

0 5 10 15 20 25time [25ns]

1200−

1000−

800−

600−

400−

200−

0200400600800

char

ge [a

dc c

hann

els]

x-stripsy-strips


Eamp = 37.5 kV/cm

Edrift = 0.33 kV/cm

Ne:CF4 80:20 vol.%


Test Beam Data

Eamp = 37.5 kV/cm

Edrift = 0.33 kV/cm

Ne:CF4 80:20 vol.%

all anode designs show raw strip signals with:x-strips: unipolar negative strip pulse on they-strips: positive, bipolar signal with negative undershoot

ÝÑ signal amplitude on x-strips depending on overlapping area with floating stripsÝÑ signal amplitude on y-strips independent of y-strip pattern


Measurement Results - 20 MeV Protons (1)

20 MeV proton beam

AP

V2 5

floating strip Micromegas,two-dimensional readout,128 strips

scintillator + photomultiplier

ADC + FEC

data

scaler

trigger

discriminator

zy

x

AP

V2 5

thin triple GEM,two-dimensional readout250 strips

36 37 38 39 40 41[kV/cm]ampE

0

0.2

0.4

0.6

0.8

1

strip

pul

se m

axim

um ra

tio y

/x

design-4design-5design-6

Test Beam Data

20 MeV protons

Ne:CF4 80:20 vol.%

Edrift = 0.33 kV/cm

electronics channel

saturation

trigger: thin triple GEM in front ofMicromegas

amplitudey /amplitudex „ 1 possible

pulse height ratio dependency driven bysaturation of readout electronics onx-strips

hit efficiency (20 mm w.r.t. GEM) around95% for all designs and strip layers

0 0.2 0.4 0.6 0.8 1 1.2 1.4[kV/cm]driftE

0.6

0.65

0.7

0.75

0.8

0.85

0.9

0.95

1

effic

ienc

y

, micom 0drift

hit efficiency vs. E

design-4, x-layerdesign-4, y-layerdesign-5, x-layerdesign-5, y-layerdesign-6, x-layerdesign-6, y-layer

Test Beam Data

20 MeV protons

Ne:CF4 80:20 vol.%

Eamp = 40.6 kV/cm



protons

AP

V2

5

AP

V2

5z

y

x APV2

5 APV2

5

θ

x-inclination angle

x

detectors tilted w.r.t. beam axis in x- andy-direction

µTPC angle reconstruction worksindependently for both strip layers

angular resolution depending on drift- andamplification field

angular resolution „ 2˝ for optimizeddrift and amplification field for both layers

t

t

inclinedparticle track

z = vdrift·t

ionizationelectrons

x-stripsy-strips

Test Beam Data

20 MeV protons

Eamp = 42.19 kV/cm

Edrift = 0.33 kV/cm

Ne:CF4 80:20 vol.%

Design-5

x-layer @ 40 1°

y-layer @ 30 1°

+-

+-


Measurement Results - 20 MeV Protons (3)DC beam intensities between 2 kHz and900 kHz („0.74 kHz/cm2 to325 kHz/cm2)

pulse height „ constant for all beamintensities for both strip layers

particle reconstruction efficiency staysalmost constant over the intensity rangefor both strip layers

0 500 1000 1500 2000 2500 3000 3500 4000cluster charge [adc channels]

0

200

400

600

800

1000

1200

entri

es /

[40

adc

chan

nels

]

2 kHz25 kHz717 kHz903 kHz

Test Beam Data

20 MeV protons

Ne:CF4 80:20 vol.%

Eamp = 39 kV/cm

Edrift = 0.33 kV/cm

Design-5 y-layer

100102

104106

108110

112114

116118

strip number0

5

10

15

20

25

time [25 ns]

200−

0

200

400

600

800

1000

1200

1400

puls

e he

ight

[AD

C c

ount

s]

Design-5

y-layer @ 900 kHz

event display

0 100 200 300 400 500 600 700 800 900beam intensity [kHz]

0.86

0.88

0.9

0.92

0.94

0.96

0.98

1

effic

ienc

y

x-layery-layer

Test Beam Data

20 MeV Protons

Ne:CF4 80:20 vol.%

Eamp = 39 kV/cm

Edrift = 0.33 kV/cm

Design-5

asymmetric

beam profile

beam focused

between pillars


Measurement Results - 20 to 150 GeV Muons (1)setup at CERN SPS with 4 TMMchambers as track reference at particlerates of O(kHz)[muons] toO(MHz)[pions]

extrapolate track into floating stripMicromegas and check for hit within500 µm to track prediction

Ñ excellent efficiencies around 95% forall designs and both readout strip layers

42 43 44 45 46 47 48 49[kV/cm]ampE

0.6

0.65

0.7

0.75

0.8

0.85

0.9

0.95

1

hit e

ffici

ency

with

in 0

.5 m

m

design 4, x-layerdesign 4, y-layerdesign 5, x-layerdesign 5, y-layerdesign 6, x-layerdesign 6, y-layer

Test Beam Data

20 to 150 GeV muons

Ne:CF4 80:20 vol.%

Edrift = 0.17 kV/cm

TMM1 TMM2 TMM3 TMM4FSM3 FSM4FSM2FSM1

design 4 (100µm)(100-30) Mesh

design 4 (100µm) (60-25) Meshdesign 5 (2x80µm)

(63-25) Meshdesign 6 (80µm) (63-25) Mesh

39 mm179 mm201 mm42 mm 85 mm39.5 mm 55 mm

pions,muons 150GeV

9x10cm trigger scintillators2

0 0.2 0.4 0.6 0.8 1 1.2 1.4[kV/cm]driftE

0.6

0.65

0.7

0.75

0.8

0.85

0.9

0.95

1

hit e

ffici

ency

with

in 0

.5 m

m


Test Beam Data

20 to 150 GeV muons

Ne:CF4 80:20 vol.%

Eamp = 46.8 kV/cm


Measurement Results - 20 to 150 GeV Muons (2)fit residual distributions with doublegaussian, take narrow sigma and correctfor track uncertaintycorrect for systematic mis-reconstructiondue to charge discretization on stripsx-layer spatial resolution stronglydepending on transverse diffusion ofelectrons in drift regionoptimum spatial resolution around 50 µmfor y-layer and 65 µm for x-layer

42 43 44 45 46 47 48 49[kV/cm]ampE

0.04

0.05

0.06

0.07

0.08

0.09

0.1

0.11

0.12

0.13

0.14

spat

ial r

esol

utio

n [m

m]


Test Beam Data

20 to 150 GeV muons

Ne:CF4 80:20 vol.%

Edrift = 0.17 kV/cm

0 0.2 0.4 0.6 0.8 1 1.2 1.4[kV/cm]driftE

0.015

0.02

0.025

0.03

0.035

0.04

0.045

0.05

elec

tron

trans

vers

al d

iffus

ion

[cm

/cm

]

Ne-CF4-80-20

Ar-CO2-93-7

MAGBOLTZ

Simulation

0 0.2 0.4 0.6 0.8 1 1.2 1.4[kV/cm]driftE

0.04

0.05

0.06

0.07

0.08

0.09

0.1

0.11

0.12

0.13

0.14

spat

ial r

esol

utio

n [m

m]


Test Beam Data

20 to 150 GeV muons

Ne:CF4 80:20 vol.%

Eamp = 46.8 kV/cm


Measurement Results - 150 GeV Pions

particle fluxes up to 5 MHz/cm2

smaller amplification voltages applied fordesigns 5 and 6 for stable operation(most probably due to cleanliness issuesor anode PCB defects)

10% decrease of pulse height visiblebetween lowest and highest rate

particle reconstruction possible with over95% efficiency at 50 µm spatial resolutionat 5 MHz/cm2

0 1 2 3 4 5]2beam flux [MHz/cm

0.045

0.05

0.055

0.06

0.065

0.07

0.075

0.08

0.085

spat

ial r

esol

utio

n [m

m]

design 4, y-layerdesign 5, y-layerdesign 6, y-layer

Test Beam Data

150 GeV pions

Ne:CF4 80:20 vol.%

Edrift = 0.33 kV/cm

different gas gain

0 1 2 3 4 5]2beam flux [MHz/cm

0.6

0.65

0.7

0.75

0.8

0.85

0.9

0.95

1

hit e

ffici

ency

with

in 0

.5 m

m

design 4, x-layerdesign 4, y-layer design 5, x-layer design 5, y-layer design 6, x-layer design 6, y-layer

Test Beam Data

150 GeV pions

Ne:CF4 80:20 vol.%

Edrift = 0.33 kV/cm

different gas gain


Summary

different two-dimensional floating strip Micromegas designs have been presented

readout strip layers: different signal polarities, duration and amplitude

simulations explain signal formation and readout electronics responseÑ detector understood

similar pulse height on both readout strip layers can be reached

measurements with 20 MeV protons and 150 GeV muons/pions:Ñ hit efficiencies around 95% for all designs and strip layers

µTPC angle reconstruction possible on both strip layers independently:Ñ angular resolution around 2˝ for optimized drift- and amplification field

excellent spatial resolution:Ñ 65 µm on x-layer and 50 µm on y-layer at up to 5 MHz/cm2 beam flux

THANK YOUF. Klitzner (LMU) 2d-FSMM Detectors 20/06/2018 15 / 15

BACKUP


Signal Reconstruction - Methodscluster reconstruction

reconstructed position

cathode

micro-mesh

anode stripscluster of 3 strips

pillare-

charged particle

charge spread

search for strips with a depositedcharge ą 3 x σstrip, no further cutscharge spreads over stripsÝÑ Gaussian distributed charge signaltypically more than 2 strips hitÝÑ forming cluster of strips

xcen “

ř

clusterxstrip¨qstrip

ř

clusterqstrip

µTPC reconstruction

charged particle

cathode

micro-meshpillar

anode strips

e-

inclination angle

Δ strips

Δ ttmax

(strip,time) data points

θ

measure arrival time of electrons:

ÝÑ Θ “ arctan´

psa¨vd¨25 ns

¯

ps = strip pitchslope a = ∆t

∆stripsvd = electron drift velocity

slope from linear fit to(strip,time) data pointsvd simulated or measured



detectors tilted w.r.t. beam axis in x- andy-directionµTPC angle reconstruction worksindependently for both strip layersangular resolution depending on drift- andamplification fieldangular resolution for optimized drift andamplification field around

´

`2.3˝

´1.8˝

¯

protons

AP

V2

5

AP

V2

5

zy

x APV2

5 APV2

5

θ

x-inclination angle

x

Test Beam Data

20 MeV protons

Eamp = 42.19 kV/cm

Edrift = 0.33 kV/cm

Ne:CF4 80:20 vol.%

Design-5

x-layer @ 40 1°

y-layer @ 30 1°

+-

+-

]°re

cons

truct

ed a

ngle

[

38

39

40

41

42

[kV/cm]ampE37 38 39 40 41 42

]°an

gula

r res

olut

ion

[

2−1−01234

Design-4

x-layer @ 40 1°+-

Edrift = 0.33 kV/cm

Ne:CF4 80:20 vol.%

]°re

cons

truct

ed a

ngle

[272829303132

[kV/cm]driftE0 0.2 0.4 0.6 0.8 1 1.2 1.4

]°an

gula

r res

olut

ion

[

3−2−1−01234

Design-4

y-layer @ 30 1°+-

Eamp = 40.6 kV/cm

Ne:CF4 80:20 vol.%


Spatial Resolution Determination

extrapolate track into the detector undertest (detector excluded in track fit)

determine residual∆x = xpredicted - xmeasured

fit residual distribution with a doublegaussian function within ˘3σ

extract sigma of core gaussian and correctit for the track accuracy at the position ofthe detector under test

the spatial resolution of the detector isthen given by:σSR =

b

σ2excluded ´ σ2

track

/ ndf = 38.56 / 282χp0 9.4± 425.9

p1 0.001016± 0.007476

p2 0.00098± 0.05288

p3 63.5± 81.6

p5 0.00247± 0.09383

0.4− 0.2− 0 0.2 0.4hit predicted - hit measured [mm]

0

100

200

300

400

500

entr

ies

/ 0.0

13m

m

/ ndf = 38.56 / 282χp0 9.4± 425.9

p1 0.001016± 0.007476

p2 0.00098± 0.05288

p3 63.5± 81.6

p5 0.00247± 0.09383

600− 500− 400− 300− 200− 100− 0z position [mm]

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0.045

0.05

0.055

0.06

trac

k ac

cura

cy [m

m]

TM

M1

TM

M2

FS

M1

FS

M2

FS

M3

FS

M4

TM

M3

TM

M4


Charge Discretization Correction

0.5− 0.4− 0.3− 0.2− 0.1− 0 0.1 0.2 0.3 0.4 0.5[strip pitch]η

0.4−

0.3−

0.2−

0.1−

0

0.1

0.2

0.3

0.4re

sidu

al [m

m]

Entries 206550

1−10

1

10

Entries 206550y-layer

two strips incluster

calculate difference betweenreconstructed hit position and the centerof the nearest strip η as a function of thestrips in a clusterresidual distribution depending on η dueto systematic mis-reconstruction of thehit position due to discretization ofcharge on the readout stripscorrecting the hit position in a seconditeration yields a visible improvement ofthe spatial resolution

0.5− 0.4− 0.3− 0.2− 0.1− 0 0.1 0.2 0.3 0.4 0.5[strip pitch]η

0.4−

0.3−

0.2−

0.1−

0

0.1

0.2

0.3

0.4

resi

dual

[mm

]

Entries 97428

1−10

1

10

Entries 97428

two strips in cluster

x-layer

0.4− 0.3− 0.2− 0.1− 0 0.1 0.2 0.3 0.4residual [mm]

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

entri

es /

0.00

8mm

before correction

after correction

x-layer

2 strips in cluster


A Comparison: 2-Dimensional Resistive Strip Micromegas

’Resistive-strips micromegas detectorswith two-dimensional readout’[doi:10.1088/1748-0221/7/02/C02060]

’Signal Characteristics of a Resistive-StripMicromegas Detector with an IntegratedTwo-Dimensional Readout’[arXiv:1406.6871]same (negative) signal polarity observedon x- and y-stripssignal spreads in time over adjacenty-stripsÝÑ charge spreads along resistive strips


Signal Simulation with ANSYS and Garfield++10k electrons homogeneously distributedat beginning of amplification gap

negative contribution of y-signalnegligible between floating strips

strongest signal on y-strips if chargecreated between floating strips

negative signal on x-strips due tocapacitively coupled floating strip signal

time [ns]0 50 100 150 200 250 300 350 400

ind

uce

d c

har

ge

[arb

. un

its]

100−

80−

60−

40−

20−

0

20

310×

floating stripy-stripx-strip

x-position [cm]0.05− 0.04− 0.03− 0.02− 0.01− 0 0.01 0.02 0.03 0.04 0.05

y-po

sitio

n [c

m]

0.05−

0.04−

0.03−

0.02−

0.01−

0

0.01

0.02

0.03

0.04

0.05

0

5

10

15

20

25

30

35

40

45

50

ratio between positive and negative component of y-strip signal



measurements at four different beamintensities between 2 kHz and 0.9 MHz

pulse height independent of beamintensity for both strip layers

hit efficiency 20 mm w.r.t. GEMartificially increases due to multipleclusters in the detector in a single event

use leading cluster of GEM and require ahit in the Micromegas within 100 ns

if no good cluster was found: fragmentclusters which have been falsely mergedinto a single cluster and find closestcluster (position- and timewise)

after cluster recovery hit efficiency staysalmost constant over the whole intensityrange for both strip layers

100102

104106

108110

112114

116118

strip number0

5

10

15

20

25

time [25 ns]

200−

0

200

400

600

800

1000

1200

1400

puls

e he

ight

[AD

C c

ount

s]

Design-5

y-layer @ 900 kHz

event display

beam intensity [kHz]0 100 200 300 400 500 600 700 800 900

effic

ienc

y

0.86

0.88

0.9

0.92

0.94

0.96

0.98

1

x-layer, hit within 20mmy-layer, hit within 20mm

x-layer, hit within 20mm and 100nsy-layer, hit within 20mm and 100nsx-layer, hit within 20mm and 100ns (fragmented)y-layer, hit within 20mm and 100ns (fragmented)

Eamp = 39 kV/cm

Edrift = 0.33 kV/cm

Design-5


Three Different Two-Dimensional Thin Anode Designs

floating strip pitch/width: 0.5 mm/0.3mmreadout strips orientation parallel to floating strips denoted as ’x-strips’readout strips orientation perpendicular to floating strips denoted as ’y-strips’

Design-1

active area:64x64 mm2

128 strips80 µm x-strips (middle)400 µm y-strips (bottom)

x-stripsy-strips

floating strips

400

µm

300 µm

80 µm

Design-2


384 strips300 µm x-strips (middle)400 µm y-strips (bottom)

x-stripsy-strips40

0 µm

300 µm

floating strips

Design-3


384 strips400 µm y-strips (middle)400 µm x-strips (bottom)

x-stripsy-strips

floating strips

400 µm

400

µm

300 µm

35 µm thick copper strips insulated by two 25 µm thick Kapton layers

ÝÑ overall thickness of anode: 155 µmF. Klitzner (LMU) 2d-FSMM Detectors 20/06/2018 15 / 15

Typical Signal on Strip with Maximum Chargeall anode designs show raw strip signals with:

a negative strip pulse on the x-strips (expected)a positive, shorter strip pulse on the y-strips with a negative undershoot (unexpected)

Design-1

x-stripsy-strips

floating strips

400

µm300 µm

80 µm

time [25ns]0 2 4 6 8 10 12 14 16

char

ge [a

dc c

hann

els]

2000−

1500−

1000−

500−

0

500

1000

x-stripsy-strips

readout saturated signalon x-strips

Design-2

x-stripsy-strips

400

µm

300 µm

floating strips

time [25ns]0 2 4 6 8 10 12 14 16

char

ge [a

dc c

hann

els]

-2000

-1500

-1000

-500

0

500

1000x-stripsy-strips

highly readout saturatedsignal on x-strips

Design-3

x-stripsy-strips

floating strips

400 µm

400

µm

300 µm

time [25ns]0 2 4 6 8 10 12 14 16

char

ge [a

dc c

hann

els]

600−

400−

200−

0

200

400

600

800x-stripsy-strips

y-strips signal higherthan x-strips signal


Measurement Results - Cluster Reconstructionpulse height ratio phy{phx

[kV/cm]ampE30 32 34 36 38 40 42 44

puls

e he

ight

ratio

0

0.2

0.4

0.6

0.8

1

1.2

1.4

anode layout 1anode layout 2anode layout 3

20 MeV protons

Ne:CF 80:20 vol.%4

@ E = 0.083kV/cmdrift

signals with similar height observed foranode design-3, converging to a factor ofphy{phx «1.4 for Eamp ě34 kV/cm

phx on anode design-2 shows a fullysaturated signal on the APV25

anode design-1 also shows a saturation ofthe signal on the x-strips

Ñ best simultaneous signal reconstructionobserved for anode design-3

y position [mm]20 25 30 35 40 45 50 55 60 65 70 75 80

x po

sitio

n [m

m]

10

20

30

40

50

60

70

0

500

1000

1500

2000

2500

3000

3500

4000mean pulse height vs position, plane 1

Fe-55 sourcemean]

mean pulse heightmean]

y-layer [adc channels]mean]

Ne:CF 80:20 vol.%mean]

4

@E = 40.6kV/cm,mean]

amp

man] E = 0.083kV/cmmean]

drift

mean]

pulse height [adc channels]0 500 1000 1500 2000 2500 3000

entri

es

0

500

1000

1500

2000

2500

3000

x - la y e ry - la y e r

cosmic muons

Ne:CF 80:20 vol.%4

@E = 43.6kV/cm,amp

E = 0.083kV/cmdrift


Documents

Two-Dimensional Floating Strip Micromegas Detectors