Large THGEM sampling elements for DHCAL status report S. Bressler, L. Arazi, A. Broisman, A. Breskin, L. Moleri, M. Pitt, C. D. R. Azevedo, J. F. C. A. Veloso, F. D. Amaro, J. M. F. dos Santos Weizmann Institute of Science, Israel Aveiro University, Portugal Coimbra University, Portugal Calice Week 15-17 September 2014, CIEMAT-Madrid

Thick Gas Electron Multiplier (THGEM) The THGEM is an expanded version of the GEM, made from a G10/FR4 substrate: G10 board is covered with copper on both sides Small holes are mechanically drilled. Cheap and easy to produce over large areas (standard PCB technology) Self sustainable (no need to be attached/glued to a frame) Very Robust, resistant to damage (discharges, mechanical stress) High gains can be achieved in several gas mixtures Typical values: thickness= 0.4/0.8 mm a= 1 mm d= 0.5 mm h= 0.1/ no rim Calice Week 15-17 September 2014, CIEMAT-Madrid

THGEM Structures: Double and Single sided 300×300 mm2 individual elements Two type of structures were made: Double and Single sided with and without rim Segmented (6 strips 300 x ~48 mm2) Gap ~ 2 mm 300×300 mm2 individual elements Small defects may occur A single defect in one of the holes can ruin an entire board Calice Week 15-17 September 2014, CIEMAT-Madrid

Calice Week 15-17 September 2014, CIEMAT-Madrid 300300 mm2 elements 2 Chambers were constructed and are operating at the Weizmann Institute (Israel) and Aveiro University (Portugal) Working in parallel at both labs. Test several configurations and find the most stable for test beam Calice Week 15-17 September 2014, CIEMAT-Madrid

THGEM Structures: Double and Single sided Standard (Double Sided) Copper clad on both sides of the THGEM Usual configuration with a few mm drift and Induction gap charge multiplication in the induction gap is possible. Single Sided – WELL type Copper covered only in one of the sides No Induction gap: electrode is attached to readout Multiplication at the bottom of the well. Large gains achieved due to electric field confinement No induction gap; thinner detector. Calice Week 15-17 September 2014, CIEMAT-Madrid

Single Sided – WELL type configurations Resistive layer quenches the energy of occasional discharges Resistive layer + Cu electrodes Cu electrodes (thin wires) allow the rapid clearance of the charge, preventing its spreading across the resistive layer Less inductive signals in the neighboring pads Lower multiplicity 300×300 mm2 elements Resistive Plate Small prototypes Calice Week 15-17 September 2014, CIEMAT-Madrid

Single Sided – WELL type Resistive Plate Plastic Material with high bulk resistivity 0.3-0.6 mm thick Connected to readout using conductive ink / glue Small prototypes have been tested: detector becomes more stable; with less discharges at higher gains. A. Rubin “First studies with the Resistive-Plate WELL gaseous multiplier” 2013 JINST 8 P11004 Calice Week 15-17 September 2014, CIEMAT-Madrid

Single Sided – WELL type Resistive Plate Recent tests with thinner plates have been very successful in reproducing the results obtained with thicker plates. Larger area resistive plates are now being produced (10x10 and 30x30 cm2) New gluing/painting techniques are required and are being tested. Calice Week 15-17 September 2014, CIEMAT-Madrid

Calice Week 15-17 September 2014, CIEMAT-Madrid 300300 mm2 elements SRS/APV READOUT Fe55 Spectra Calice Week 15-17 September 2014, CIEMAT-Madrid

Detection of low rate MIP with cosmic rays 300300 mm2 elements Detection of low rate MIP with cosmic rays Calice Week 15-17 September 2014, CIEMAT-Madrid

Trigger from top THGEM electrode MICROROC Trigger from top THGEM electrode Efficiency 97% Multiplicity 1.16 Study the detector response to MIPs (not x-rays) using cosmic muons Study discharge probability With an injector Assemble large prototype Design is in progress Test beam Fe55 Calice Week 15-17 September 2014, CIEMAT-Madrid

300300 mm2 elements Long term measurement – WELL configuration Single WELL THGEM setup. Several days monitoring and recording: gain atmospheric pressure room temperature HV trips Ne/CH4 (95/5) Calice Week 15-17 September 2014, CIEMAT-Madrid

Calice Week 15-17 September 2014, CIEMAT-Madrid 300300 mm2 elements Long term measurement – WELL configuration Calice Week 15-17 September 2014, CIEMAT-Madrid

Calice Week 15-17 September 2014, CIEMAT-Madrid 300300 mm2 elements Long term measurement – WELL configuration After a few days of stable operation gas flow was increased (10 mL/h to 20 mL/h). Gain increased but a power failure in the building prevented further measurements. After Power was restored, power up the detector at same voltage but higher gas flow 50 mL/h. Initial gain decrease is not explained by P&T variations. Compatible with charging up. Calice Week 15-17 September 2014, CIEMAT-Madrid

Calice Week 15-17 September 2014, CIEMAT-Madrid 300300 mm2 elements Long term measurement – WELL configuration After several days at 50 mL/h the gas flow was decreased to 20 mL/h. Immediate decrease in charge gain (gas purity?). After stabilization the source was removed for several hours. Discharge rate is independent on the source. Once irradiated again the charge gain dropped due to charging up. Discharge probability continuously dropping. Calice Week 15-17 September 2014, CIEMAT-Madrid

Calice Week 15-17 September 2014, CIEMAT-Madrid 300300 mm2 elements Long term measurement – WELL configuration Voltage at the WELL was increased. As expected gain increased and so did the discharge probability Calice Week 15-17 September 2014, CIEMAT-Madrid

Calice Week 15-17 September 2014, CIEMAT-Madrid 300300 mm2 elements Long term measurement – WELL configuration Gain change upon controlled change of operation conditions The gain is constant for constant conditions Discharge rate proportional to the gain. Overall the 300x300 mm2 THGEM is now stable for more than one month (since 25/07 and still running ), even surviving a major power failure. Calice Week 15-17 September 2014, CIEMAT-Madrid

Improvements: Uniform Gas Flow inside the chamber Snake like structure inside the chamber: gas flows uniformly trough the chamber provides support for THGEM Calice Week 15-17 September 2014, CIEMAT-Madrid

Calice Week 15-17 September 2014, CIEMAT-Madrid Future developments Smaller is better? Combining several small high quality elements makes it easier to produce a larger picture. Calice Week 15-17 September 2014, CIEMAT-Madrid

Calice Week 15-17 September 2014, CIEMAT-Madrid Future developments Same principle can be applied to THGEM: large area coverage can be achieved by stacking smaller elements/tiles. Mechanical support will be given by the snake like structure inside the chamber. Assembly Stage: quality control on smaller elements Choose only good quality elements Defective elements can be easily discarded Production is easier (post treatment is currently done to the larger electrodes) Trieste Group developed brushing technique to improve the quality Very easy to assemble Final result will be cheaper/better quality It will be developed with Industry (Weizmann is advising) Calice Week 15-17 September 2014, CIEMAT-Madrid

Calice Week 15-17 September 2014, CIEMAT-Madrid Future developments Technology transfer to industry …… Calice Week 15-17 September 2014, CIEMAT-Madrid

Calice Week 15-17 September 2014, CIEMAT-Madrid Future developments Technology transfer to industry …… …… and back (?) Calice Week 15-17 September 2014, CIEMAT-Madrid

Future developments Technology transfer to industry …… …… and back (?) Israeli company (Lingacom Ltd‏) is commissioning a large ( 20/30 m2 ) THGEM detector for cargo screening applications. Electrodes are already produced, prototype phase will take place during the next couple of months. strip readout high efficiency large area coverage First time a MPGD detector is developed in the industry The Weizman Institute and Lingacom Ltd‏ have applied for a common grant: possible synergies: production and testing facilities from Lingacom Ltd will be available to the scientific community. Calice Week 15-17 September 2014, CIEMAT-Madrid

Large THGEM sampling elements for DHCAL Two prototypes operating at Weizmann and Aveiro Cosmic rays detection Microroc and SRS readout 300x300 mm2 THGEM continuously operating for almost 2 months Gain is stable for controlled conditions Next Test beam (Dec. 2014) We plan to test two 300x300 mm2 chambers and 100x100 mm2 RPWELL Connection with industry: tile detector, with several elements stacked side by side. Snake like structure inside the detector will ensure a proper gas flow in the chamber Sharing the production and testing facilities developed in Industry will make the THGEM more affordable and available to the scientific community. The progress made so far show that we are on the good track. THGEM potential is huge and exciting times lay ahead of us. Calice Week 15-17 September 2014, CIEMAT-Madrid