1. Progress in THGEM technology at PNPI Progress in THGEM technology at PNPI Leonid Kudin, Elena Chernishova, Boris Komkov, PNPI, CBM meeting, Dubna, 13-18 october

2. The situation and main problems of TGEM production at PNPI  Design-engineering problem (done,OK);  Technological problem (done for TGEM, partly done for RETGEM);  Problems of making (done at a stretch for prototypes, but limited by old equipment for mass production);  Problems of testing (to the moment partly done, but need new more precision electronics and new gas-mixing facility for quality results receiving);  Need aging tests especially for RETGEMs

3. 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 progress

4. For 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 – sorry..

5. Some results of TGEM study Fe 55 RA source (5.9 keV X-rays); 70%Ar+30%CO2 mixture; 90%Ar+10%CO2 mixture g1 g2 Uc Ua 2.87mm 1.37mm Fig.1 THGEM geometry TGEM Ucg1= (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

6. Fe55 X-ray source Gas 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*10 4

7. 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*10 3 Fig.4aFig.4b

8. Electronic calibration Fig.3a Fig.3b 60fQ 90fQ 30fQ Charge injected to the input spectrometric electronic through capacitor =1 pF; 1mV amplitude on the input corresponds 1fQ of the injected charge

9. 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 10 6 to 10 11 Ohm*cm

10. 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.

11. RETGEM1 RETGEM1 Th=0.4mm; d=0.3mm; R=10 8 Ohm*cm Gas mixture: Ar=70%;CO2= 30%; Fe55 source; CuO plated 1 1 3 2 4 1 2 3 4 5.9 keV

12. RETGEM2 RETGEM2 Th=0.5mm;d=0.5mm; R=10 10 Ohm*cm Gas mixture: Ar=70%;CO2= 30%; RA source Fe55

13. Conclusions  It is significant, that technology of single TGEMs at PNPI are in progress.  We received some experience in RETGEMs technology and understanding problems and ways of its solutions. technology and understanding problems and ways of its solutions. Nearest plans:  Perfection of the technology of resistive coating for RETGEMS;  Prototype for test beam on the base of THGEMs preparation.