1 Fulvio TESSAROTTO CERN, 13/11/ COMPASS THGEM meeting Construction of the large size Hybrid Prototype The bulk Micromegas technology Examples of large area Bulk MM Our 300 mm x 300 mm What we did so far The structure of the final detector Conclusions Fulvio Tessarotto ( I.N.F.N. – Trieste )

2 Production of 300x300mm2 Micromegas We have seen that with the small hybrid prototype we achieve good results. To build large size prototypes we need large Micromegas. Several technologies are available, with advantages and disadvantages: - standard technology: mesh (free or glued) touching pillars on anode mechanical construction delicate and tolerances too strict for 600x600 - bulk technology: mesh sandwiched between photoresist layers simpler and “standard” at CERN - MAMMA technology: mesh tensioned and “floating” very nice and promising for large surface but not completely mature yet Fulvio TESSAROTTO CERN, 13/11/ COMPASS THGEM meeting

3 Bulk Micromegas technology Fulvio TESSAROTTO NIMA 560 (2006) 405 CERN, 13/11/ COMPASS THGEM meeting

4 Signal characteristics (from Wikipedia) Fulvio TESSAROTTO CERN, 13/11/ COMPASS THGEM meeting

5 Read-out board Laminated Photoimageable coverlay Frame Stretched mesh on frame Laminated Photoimageable coverlay Exposure Development + cure BULK Micromegas production steps CERN, 13/11/ COMPASS THGEM meeting

6 Bulk Micromegas examples (Rui de Oliveira) Largest size produced: 1.5m x 0.6m Limited by equipment Limiting size at CERN is now 2.2mx 1.2m In a single piece BULK Technology DUPONT PC 1025 coverlay BOPP Meshes SERITEC stretching T2K ILC DHCAL CERN, 13/11/ COMPASS THGEM meeting

7 Following the serial production for the TPC chambers of T2K we could take advantage of: - a set of frames with pre-tensioned mesh already available - easy production of new set of frames with pre-tensioned mesh - all elements (materials, procedures, etc…) are available The price is affordable: ~ Euro / piece for production We have now two 300x300 Micromegas Fulvio TESSAROTTO CERN, 13/11/ COMPASS THGEM meeting Production of 300x300mm2 Micromegas

8 What we did so far Production of Micromega 300x300 - anodic PCB: requirements (TS+CERN) mechanical design CAD (Inventor) chamber frame and PCB G. Menon pcb design (Altium) and gerber production M. Gregori modification to pcb design (CERN) O. Pizzirusso discussion with ELTOS and TVR Company for PCB quality S. Levorato order and production of anodic PCB (4 ordered, 2 received) - Micromegas: shipping PCB to CERN for Micromegas production (2 pieces) production of “COMPASS RICH” Micromegas (CERN) O. Pizzirusso electrical test and correction of problems (CERN) O. Pizzirusso shipping to Trieste - Test chamber gluing the Micromegas to the chamber frame G. Menon the drift wire plane is ready M. Gregori the THGEM is ready to be tested S. Dasgupta Fulvio TESSAROTTO CERN, 13/11/ COMPASS THGEM meeting

9 Dedicated anonde PCB CERN, 13/11/ COMPASS THGEM meeting

10 The bulk Micromegas grown onto the anode; CERN, 13/11/ COMPASS THGEM meeting A protection layer is seen

11 Rear side of the Micromegas PCB CERN, 13/11/ COMPASS THGEM meeting Standard connectors mounted

12 The Micromegas being glued CERN, 13/11/ COMPASS THGEM meeting

13 The chamber for the hybrid 300x300 Fulvio TESSAROTTO CERN, 13/11/ COMPASS THGEM meeting

14 THGEM for the hybrid prototype Fulvio TESSAROTTO Typical 55 Fe spectrum CERN, 13/11/ COMPASS THGEM meeting

15 Resistive anode with r/o pads and strips similar to ATLAS MAMA project obtained using lithographic mask at CERN (first prototype with useful surface of 100 x 100 mm 2 ) Mesh streched and screwed on the anode frame Alternative technology for our Micromegas Fulvio TESSAROTTO CERN, 13/11/ COMPASS THGEM meeting

16 RESISTIVE ANODE  Why ? (RECALL)  Reduce the discharge energy  Protect the detector and the FE (no need of FE on board protections !)  Reduce the dead-time associated to discharges  + HV applied to the anode, mesh grounded  larger signal amplitude  Introduced in Micromegas within the MAMMA-ATLAS project  Resistive anodes by  Photolithography  Screen printing  Sputtering  A technology not yet mature  Within our R&D  First attempt (MAMMA like)  signal reduction: ~ 20% only  Try a Resistive anode via consolidated technology  PLEASE NOTE: not an essential ingredient, but definitively a big advantage CERN, 13/11/ COMPASS THGEM meeting

17 A RESISTIVE ANODE FOR US  Scheme (not to scale)  Only 1 single pad shown  Principle  Blue pad at HV via internal connection  Resistive by a SMD resistor at the PCB rear surface  Red pad: signal induced by RC coupling  Status: small size anode received Silvia DALLA TORRE PCB 0.1 mm fiberglass Metallic pads CERN, 13/11/ COMPASS THGEM meeting

18 New PD’s Fulvio TESSAROTTO CERN, 13/11/ COMPASS THGEM meeting

19 The THGEM+Micromegas version Fulvio TESSAROTTO CERN, 13/11/ COMPASS THGEM meeting

20 The THGEM+Micromegas version Fulvio TESSAROTTO CERN, 13/11/ COMPASS THGEM meeting

21 The THGEM+Micromegas version Fulvio TESSAROTTO CERN, 13/11/ COMPASS THGEM meeting

22 The THGEM+Micromegas version Fulvio TESSAROTTO CERN, 13/11/ COMPASS THGEM meeting

23 The THGEM+Micromegas version Fulvio TESSAROTTO CERN, 13/11/ COMPASS THGEM meeting

24 The THGEM+Micromegas version Fulvio TESSAROTTO CERN, 13/11/ COMPASS THGEM meeting

25 The THGEM+Micromegas version Fulvio TESSAROTTO CERN, 13/11/ COMPASS THGEM meeting

26 The THGEM+Micromegas version Fulvio TESSAROTTO CERN, 13/11/ COMPASS THGEM meeting

27 The THGEM+Micromegas version Fulvio TESSAROTTO CERN, 13/11/ COMPASS THGEM meeting

28 CONCLUSIONS   Bulk Micromegas of large size have been produced and used   Two 300x300 mm 2 active area Micromegas produced for us   All components of the 300x300 hybrid PD are available   The large size prototype will be tested soon   Preliminary work on the drawings of the final detector has started Fulvio TESSAROTTO Seoul, 28/10/ Institute of Electrical and Electronics Engineers IEEE NSS / MIC / RTSD