THGEM report

Second part: starting since Mai;first part includes the period between January 2008 - April 2008.

1Elena Rocco

Induction and Drift scans summary for THGEM without rim

The fields conditions are the same for all measurements*: Einduction=3 KV/cm, Edrift=1.5KV/cm and e collimated X-Ray source (diam=1mm) has been used

with a rate about 1.7 KHz/mm2.

*for the treated THGEM the Edrift was 2 KV/cm .2

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

Gai

n

Drift Field (KV/ cm)

THGEM 0 mm rim THGEM electro chem. polished Kapton THGEM

DRIFT SCAN

∆V=1.45 KV

∆V=1.475 KV

∆V=1.35 KV

1.0 1.5 2.0 2.5 3.0 3.5 4.0

200

400

600

800

1000

1200

1400

1600

1800

Gain

Induction Field (KV/ cm)

THGEM 0 mm rim THGEM electro chem. polished Kapton THGEM

INDUCTION SCAN

∆V=1.475 KV

∆V=1.45 KV

∆V=1.35 KV

Gain overview

33

1.3 1.4 1.5 1.6 1.7 1.8100

1000

Einduction

=3.5 KV/cm, Edrift

=1.5 KV/cm

Gain

Delta V (KV)

THGEM electro chem. polished THGEM 0 mm rim THGEM with 0.1 mm of rim THGEM made of kapton

∆V=1.35 KV, G~300

∆V=1.325 KV, G~205

∆V=1.3 KV, G~145

∆V=1.675 KV, G~860

∆V=1.725 KV, G~1880

∆V=1.7 KV, G~1350

∆V=1.75 KV, G~2800

∆V=1.775 KV, G~4170

∆V=1.8 KV, G~5580

∆V=1.375 KV, G~220

∆V=1.475 KV, G~1550

∆V=1.5 KV, G~2500

∆V=1.49 KV, G~2060

∆V=1.475 KV, G~1510

∆V=1.4 KV, G~390

∆V=1.45 KV, G~940

∆V=1.44 KV, G~790∆V=1.425 KV, G~600

∆V=1.415 KV, G~490

∆V=1.465 KV, G~1250

The gain of the electro-chem. polished THGEM is overlapped by the gain of the kapton THGEM

(Except for the THGEM with the asymm. rim)

Time stability measurements

4

0 2 4 6 8 10 12 14 16 18

0

2000

4000

6000

Gain

Time (hours)

THGEM 0 mm rim THGEM with 0.1 mm of rim THGEM with asymm. rim; rim (0.1 mm) face to the anode THGEM electro chem. polished

∆V=1.49 KV

∆V=1.775 KV

∆V=1.45 KV∆V=1.35 KV

Same working conditions: Einduction=3.5 KV/cm Edrift=1.5KV/cm; rate ~0.7-0.8 KHz collimated source

Remarks: the drift field is not optimized for these meas.

More about the THGEM in Kapton

Material structure;

Drift scan measuring the currents on all the electrodes.

5

Description of the structure of the THGEM made of Kapton

LF 110, Dupont 50 μm

LF 110, Dupont 50 μm

Copper

Polyimide: Apical, AV, Kareka

Kapton H, Dupont

Sheldhall G2300 17/50*

Sheldhall G2500 17/50*

LF 111, Dupont

*17/50 means 17 μm of copper and 50 μm of kapton

Epoxy acrylic

6

Section 1 Section 4

Directions of the cross sections

Drift scan measuring the currents on the THGEM made of Kapton

0.0 0.5 1.0 1.5 2.0 2.5 3.0

-30

-25

-20

-15

-10

-5

0

5

10

15

20

25

30

THGEm in Kapton; Einduction

=3.5 KV/ cm,Delta V=1.45 KV. High rate (> 100 KHz) collimator of 3mm of diameter.

Cu

rren

t (n

A)

Drift Field (KV/ cm)

Current on the Anode Current on the Bottom Current on the Top Current on the Drift

0.0 0.5 1.0 1.5 2.0 2.5 3.0

-30

-25

-20

-15

-10

-5

0

5

10

15

20

25

30

THGEm in Kapton; Einduction

=3.5 KV/ cm,Delta V=1.45 KV. High rate (> 100 KHz) collimator of 3mm of diameter.

Cu

rren

t (n

A)

Drift Field (KV/ cm)

Electrons Current Ions Current Currents Sum

THGEM

DRIFT

ANODE

6.5 mm

5mm Bottom side

Top side

Configuration inside the chamber

7

Currents measured on all the electrodes (anode, bottom THGEM, top THGEM, drift). The sensitivity for each devices used to read out the current is ± 1nA.

New systematic studies

8

1 2 3

4 5 6

7 8 9

d=0.5mm

d=0.5mm

d=0.5mm

d=0.4mm

d=0.4mm

d=0.4mm

d=0.3mm

d=0.3mm

d=0.3mm

p=0.9mm

p=0.8mm

p=0.7mm

p=0.6mm

p=0.7mm

p=0.8mm

p=0.6mm

p=0.7mm

p=0.5mm

Fixed diameter,Varying the difference pitch&diameter

Fig.2 .THGEMs labelling. Fig.3 .THGEMs geometry for fixed thickness and cleaning.In the increasing diameter direction there’s a

correspondent increasing of the breakdown voltage

The THGEM scheme on the “plaque”

9

Some pictures for looking in details the hole edges

G10_1_sideA

G10_1_sideB

G10_G_sideA

G10_G_sideB

10

Measurements planned and characterization procedure

Characterisation procedure:

1. Kept in the oven for 24h;2. Measurements of the maximum

voltage applied to the THGEM in Ar/CO2 (70/30);

3. Switching on voltage and setup of the electronics setting irradiating the chamber;

4. Time stability measurement for a night (~12 h);

5. Quick characterisation: induction & drift scans, voltage scans, currents measurements (for gain estimation too).

1 2 3

4 5 6

7 8 9

directions of THGEMs characterization

Rim constant: d=0.3 mm

Pitc

h co

nsta

nt: p

=0.7

mm

Voltage conditions: the idea is to keep the same voltage for all THGEMs.

11

G10 – sample #2

12

THGEM

DRIFT

ANODE

Thickness

6.5 mm

5mm

PARAMETERS:• Diameter = 0.3 mm• Pitch= 0.6 mm• Thickness = 0.6 mm• Rim = 0 mm• Gas: Ar/CO2 – 70/30

GEOMETRICAL CONFIGURATION

Side A Side B

Induction Scan

13

0 2 4500

600

700

800

900

1000

1100

1200

Peak Position Energy Resolution

Induction Field (KV/ Cm)

Peak

Pos

itio

n (

AD

C c

h.-

Ped.

Su

btr.

)

20

22

24

26

28

30

En

ergy Resolu

tion (%

)

∆V=1.77 KV collimated source rate~1.6 KHz/mm2

1 2 3 4500

600

700

800

900

1000

1100

1200

Pulse Height Current Measured

Induction Field (KV/ cm)Pe

ak P

osit

ion

(A

DC

ch

. -

Ped.

Su

btr.

)

12

14

16

18

20

22

24

26

28

30

Cu

rrent (n

A)

Comparison between the pulse height measurement and the current measurement*

*For current measurement I used different rate

Same curve

Drift field not optimized ED=1.5 KV/cm Drift field optimized ED=1.5 KV/cm

Drift scans

14

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5400

500

600

700

800

900

1000

1100

1200

1300

1400

Pea

k P

osit

ion

(A

DC

ch

.- P

ed.

Su

btr

.)

Drift Field (KV/ cm)

Einduction

=3 KV/ cm E

induction=3.5 KV/ cm

Einduction

=4 KV/ cm

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

20

25

30

35

40

45

50

En

ergy

Res

olu

tion

(%

)

Drift Field (KV/ cm)

Einduction

=3 KV/ cm E

induction=3.5 KV/ cm

Einduction

=4 KV/ cm

∆V=1.77 KV collimated source rate~1.6 KHz/mm2

0 1 2 3400

500

600

700

800

900

1000

1100

1200

Pulse Height Current measured

Drift Field (KV/ cm)

Pea

k P

osit

ion

(A

DC

ch

.- P

ed S

ubtr

.)

18

20

22

24

26

Cu

rrent (n

A)Comparison between

the pulse height measurement and the current measurement*

Same curve

*For current measurement I used different rate

∆V=1.77 KV collimated source rate~1.6 KHz/mm2

Gain estimation from current measurement

15

REMARKS: @ the same voltage there’s almost the same gain but different geometry!!!

1.3 1.4 1.5 1.6 1.7 1.8100

1000

Gain

Delta V (KV)

THGEM electro-chem. polished without rim THGEM without rim THGEM with rim=0.1mm THGEM made of kapton THGEM with different geometry

1.66 1.68 1.70 1.72 1.74 1.76 1.78

1000

Collimated source 1 mm of diameter,E

induction=3.5 KV/ cm and E

drift=1 KV/ cm (optimized).

Gain

Delta V (KV)

Gain

∆V=1.675 KV G~620

∆V=1.77 KV G~3420

Currents behaviour

16

0.0 0.5 1.0 1.5 2.0 2.5 3.0

-30

-20

-10

0

10

20

30

40

Cu

rren

t (n

A)

Drift Field (KV/ cm)

Anode Current Bottom THGEM Current Top THGEM Current Drift Current

Drift Scan

1.0 1.5 2.0 2.5 3.0 3.5 4.0-40

-30

-20

-10

0

10

20

30

40

Cu

rren

t (n

A)

Induction Filed (KV/ cm)

Anode Current Bottom THGEM Current Top THGEM Current Drift Current

Induction Scan

Time Stability Measurement

17

0 2 4 6 8 10 12 14 16 18 20 22 24

1200

1500

1800

2100

2400

2700

3000

3300

3600

3900

4200

4500

4800

Gain

Time (hours)

Energy Spectrum

V=1.77KV, Einduction=3.5 KV/cm, Edrift=1.5 KV/cm (not optimized), rate=0.8 KHz, collimated source

Problems with the fit due to the low statistics for the first quick acquisition

0 500 1000 1500 2000-10

0

10

20

30

40

50

60

70Data: RUN1200_BModel: Gauss Chi^2/DoF = 7.64017R^2 = 0.89543 y0 0 ±0xc1 42.06558 ±2.35413w1 32.76208 ±4.74061A1 207.53534 ±25.88851xc2 670.33861 ±7.23481w2 215.11112 ±15.54975A2 1263.27492 ±76.27703xc3 1052.18048 ±1.05339w3 203.21437 ±2.24038A3 7994.77666 ±74.42436

Cou

nts

ADC channels

Energy Spectrum

Good statistics

0 500 1000 1500 2000

0

2

4

6

8

10

12Data: RUN0900_BModel: Gauss Chi^2/DoF = 0.52652R^2 = 0.53932 y0 0 ±0xc 1080.10429 ±2.71053w 222.14204 ±5.42106A 834.39498 ±17.6342

Cou

nts

ADC channels

B Gauss fit of RUN0900_B

Bad statistics