What we did up to now:Summary of the measurements performed up to now with the gas setup built for the

THGEMs coated with the CsI.

• Photocurrent measurements (Leszek’s chamber) with several gas mixtures (Ne, Ar, CH4, NeCH4 X/100-X, ArCH4 X/100-X, ArCO2 70/30) at different pressures (i.e. atm pressure, 0.2 bar, 30 mbar) for a dummy THGEM coated with CsI and with a dummy THGEM as a drift (see Jarda’s presentation GDD 32 meeting);

• Quick characterization (drift and voltage scans) for a double structure THGEM (C7 type: d=0.4 mm, p=0.8 mm, t=0.4 mm, rim=0.01 mm) used as a single structure with 55Fe source flushing the gas at atmospheric pressure and with several gas mixtures (NeCH4 90/10, CF4, ArCH4 X/100-X, ArCO2 70/30);

• Optimization of the voltage on the double THGEM structure for few gas mixtures at atmospheric pressure with 55Fe source;

• Drift scan with the UV light (Oriel Lamp) on the double THGEM used as a single and as a double structure just with the Ar/CO2 gas mixture (70/30);

• Single Photon spectrum acquisition and estimation of the rate of the photons from the current measured onto the anode.

Same setup, several & different purposes

Gas mixer

Avantes – UV lamp

picoammeters

55Fe

Double Double THGEM THGEM C7C7

Leszek’s Leszek’s chamber chamber Dummy/dummyDummy/dummy

Quartz window of the double THGEM chamber (type C7)

Oriel Lamp

Three positions of the shutter: 1.completly open, 2.closed (some internal reflections),3.Open + filter 3.0 OD

N2 inlet

Hidden N2 exhaust

Setup for photocurrent measurements and optimization of performance for the double

THGEM structure with the iron source

Setu

p f

or

UV

lig

ht

meas.

wit

h

the d

ou

ble

TH

GE

M s

tru

ctu

re

Filter 0.5 Filter 0.5 ODOD

Narrow Filter

Filter 3.0 Filter 3.0 ODOD

Some examples about performed meas.

THGEM: C7d=0.4 mmpitch =0.8 mmt=0.4 mmrim=0.01 mm

drift = wires

THGEM 2THGEM 1

anode

d=4.5 mmd=1.6 mmd=1.6 mm

200 400 600 800 1000 1200 1400 1600

0

1000

2000

3000Data: CK122_BModel: Exp2PMod1 Chi^2/DoF = 1461.68412R^2 = 0.99289 a 2793.52937 ±9.03815b -0.00231 ±6.9399E-6

Cou

nts

ADC channels

Energy Spectrum

-0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8

-680

-660

-640

-620

-600

-580

-560

-540

-520

-500

-480

V=1 kV, atm pressure Ar/ CO2 70/ 30;

Oriel + 0.5 OD+ narrow filter

Cu

rren

t (p

A)

Drift Field (kV/ cm)

V=1 kV V=0.9 kV

Single Photon spectrum

Collection efficiency of electron from CsI

-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0-350

-300

-250

-200

-150

-100

-50

0

50

100

150

200

250

V1=1.36 kV, V

2=1.36 kV, E

induction=3 kV/ cm, E

drift=0.67 kV/ cm;

Atm pressure Ar/ CO2 70/ 30; source 55Fe big collimator.

Cu

rren

t (p

A)

Transfer Field (kV/ cm)

Anode Current Bottom 2 Current Top 2 Current Bottom 1 Current Drift Current Top 1 projection Current

Transfer scan of the double THGEM with Iron source