Progress in THGEM Progress in THGEM technology at PNPItechnology at PNPI

Leonid Kudin, Elena Chernishova, Boris Komkov, PNPI,Leonid Kudin, Elena Chernishova, Boris Komkov, PNPI,CBM meeting, Dubna, 13-18 octoberCBM meeting, Dubna, 13-18 october

The situation and main problems of TGEM The situation and main problems of TGEM production at PNPIproduction at PNPI

Design-engineering problem (done,OK);Design-engineering problem (done,OK);

Technological problem (done for TGEM, partly done for Technological problem (done for TGEM, partly done for RETGEM);RETGEM);

Problems of making (done at a stretch for prototypes, but Problems of making (done at a stretch for prototypes, but limited by old equipment for mass production);limited by old equipment for mass production);

Problems of testing (to the moment partly done, but need Problems of testing (to the moment partly done, but need new more precision electronics and new gas-mixing facility new more precision electronics and new gas-mixing facility for quality results receiving);for quality results receiving);

Need aging tests especially for RETGEMsNeed aging tests especially for RETGEMs

Last period main efforts of our group were applied in two directions:

• Quality improvement of TGEMs;

•Formation and perfection of the technology of RETGEMs productions;

After the big struggle at PNPI for the efficiency of our outmoded facilities we produced 100 (approx.) TGEMs with sensitive area 40x40 sq.mm with different holes diameters, pitch, and rims.

Part of them were tested and some results are presented below.

For the moment we can announce with confident, that we can do THGEMs

with following parameters:

Holes diameters - 0.3mm and larger;

Min. pitch -0.5mm;

Max. area 200x200 sq.mm (limited by equipment);

Max. rate of holes drilling 1.5/sec. (limited by equipment);

Our activities and progressOur activities and progress

Our activities and progressOur activities and progressFor today we can provide the following parameters of precision and uniformity:

•Holes positions - +/- 10microns (limited by equipment);

•Hole-rim eccentricity no more, than 5 micron ;Hole-rim eccentricity no more, than 5 micron ;

•Desired rim size forming from 10 to 100micron is controlled during the process.

•Rim’s forming as non standard process is under patenting now and cannotRim’s forming as non standard process is under patenting now and cannot

be discussed now –be discussed now –sorrysorry....

Some results of TGEM studySome results of TGEM study

•Fe55 RA source (5.9 keV X-rays);

•70%Ar+30%CO2 mixture;

•90%Ar+10%CO2 mixtureg1

g2

Uc

Ua

2.87mm

1.37mm

Fig.1

THGEM geometry

TGEMUcg1= (0.2-0.7)kV,

E drift=(0.6-2.4) kV/cm;

Uag2=(0.2-0.5)kV,

E induction=(1.4-3.6) kV/cm;

Ug1g2 depends from TGEM thickness

Self-triggering mode of data acquisition

8mm

40 mm

AMP

Fe55 X-ray sourceGas mixture: Ar=90%;CO2= 10%

The main results of TGEMs testing

Fig.2bFig.2a

THGEM1 geometry: Th=1mm;d=0.4mm;R=0.02mm, Cu plated

5.9 keV

Max Gas gain 1.2*104

Gas mixture: Ar=70%;CO2= 30%

RA source Fe55

THGEM2 (Th=0.5mm;d=0.5mm:R=0.1mm)

Region of sparks

5.9 keV

Max Gas gain 1.25*103

Fig.4a Fig.4b

Electronic calibrationElectronic calibration

Fig.3a Fig.3b

60fQ90fQ

30fQ

Charge injected to the input spectrometric electronic through capacitor =1 pF;

1mV amplitude on the input corresponds 1fQ of the injected charge

RETGEM. Technology production and results.RETGEM. Technology production and results.

The main steps of RETGEM technology:

Base plate preparation (FR4 etching);

Base plate cleaning, plus dielectric undercutting (1-3 microns);

Surface activation and chemical Cu deposition;

Cu oxidation;

RETGEM plate drilling

Desirable resistance can be reach by variation of the thickness CuO coating from 106 to 1011 Ohm*cm

Some problems of technology

1. What need to provide a good uniformity and strength of resistive coating:

• A good base plate surface preparation before Cu deposition (to provide a good adhesive properties (solvable);

• Equal thickness of coating on the large area. Very difficult to reach with chemical Cu deposition. In farther we ‘ll try to use Cu sputtering.

Moreover to provide effective control of the thickness of coating the process of sputtering is more convenient.

2. More often drill bit replacement (1bit /1000 holes approx.)

We hope to improve a quality of RETGEMs essentially.

Defects from insufficient base plate surface preparation.

Glue residue on the surface is presents . As result sharpness of the edge of holes.

RETGEM1 RETGEM1 Th=0.4mm; d=0.3mm; R=108 Ohm*cm

Gas mixture: Ar=70%;CO2= 30%; Fe55 source;CuO plated

11

3

2

4

1

2

3 4

5.9 keV

RETGEM2 RETGEM2 Th=0.5mm;d=0.5mm; R=1010 Ohm*cm

Gas mixture: Ar=70%;CO2= 30%; RA source Fe55

ConclusionsConclusions It is significant, that technology of single TGEMs It is significant, that technology of single TGEMs

at PNPI are in progress.at PNPI are in progress. We received some experience in RETGEMsWe received some experience in RETGEMs technology and understanding problems and ways technology and understanding problems and ways

of its solutions.of its solutions. Nearest plans:Nearest plans: Perfection of the technology of resistive coating Perfection of the technology of resistive coating

for RETGEMS;for RETGEMS; Prototype for test beam on the base of THGEMs Prototype for test beam on the base of THGEMs

preparation.preparation.