RES MPGDs Bari 12052019 CERN MPT workshop Rui

RES MPGDs Bari 12/05/2019 CERN MPT workshop Rui De Oliveira 1

Existing Resistive MPGD structures • GEM Family • GEM • Resistive GEM (single or double sided) • Micro Wells • Micro resistive Wells • Single resistive layer • Double resistive layer • Micromegas Family • BULK • Resistive BULK Micromegas • Single resistive layer • Double resistive layer • Micro BULK • Micro resistive BULK • Resistive Floating mesh • Single resistive layer • Double resistive layer • Floating mesh • THGEM Family • THGEM • Resistive THGEM • Resistive THwell • ML THGEM • MM THGEM • THwell 2

Resistive layers • Spark protection • Spark energy ½ CV 2 600 u. J in a GEM (10 x 10) , 30 u. J in a classical MM , 10 n. J u. Rwell • Below 10 M we have observed damages, we start to have enough energy to vaporize materials ( no existing study on energy versus material vaporization) • Charge sharing • Rate capability is affected • Depends a lot on the currents evacuation structure (single , double layers , exotics) • Resistive layers tested at CERN • • • Polymer paste 10 Kohms to 100 K/Square too low values Ru. O Thick film paste 10 K to 100 M/square nice but too many limitations Resistive Kapton only a few values available Dissipative films 1 G/square and above too high values DLC 100 K to 1 T/square perfect range and possibilities 3

2016 DLC coated Polyimide • DLC/Polyimide DLC 0. 1 to 1 um 100 K to 1 G/square Polyimide 50 um APICAL NP Kapton HN • DLC/Polyimide/Cu Copper 0. 2 Vac + 5 um Cr 10 nm Polyimide 50 um APICAL NP DLC 0. 1 to 1 um 4

u. Rwell structure Pick up pads/lines PCB support 5

u. Rwell structure Cr + Copper 5 um Polyimide 50 um DLC 0. 1 um typ Pick up pads/lines 75 um dielectric composed of : 50 um PREG 25 um Kapton 5 um Epoxy Glue 6

u. Rwell structure Cr + Copper 5 um Polyimide 50 um DLC 0. 1 um typ Pick up pads/lines Why? 75 um dielectric composed of : 50 um PREG 25 um Kapton 5 um Epoxy Glue 7

u. Rwell structure Patterned Copper Etched Polyimide DLC Pick up pads/lines + 1 gluing + 1 patterning + 1 etching Probably the simplest MPGD Flexible detectors can be produced Low mass detectors mass production compatible Top electrode fully supported Lateral current evacuation Rate limitation 10 to 100 K depending on size Only 50 um amplification gap (today) 8

Single resistive Micro. Megas structure Pick up pads/lines PCB support 9

Single resistive layer Micro. Megas structure DLC 0. 1 um Polyimide 50 um Pick up pads/lines Glue 25 um Epoxy without glass 10

Single resistive layer Micro. Megas structure DLC 0. 1 um Polyimide 50 um Pick up pads/lines Why? Glue 25 um Epoxy without glass 11

Single resistive Layer Micro. Megas structure SS Mesh 400 to 700 LPI DLC 0. 1 um Polyimide 50 um Pick up pads/lines + Only 1 gluing + 1 Bulking Single piece different gaps possible different meshes possible Lateral current evacuation Rate limitation 10 to 100 K depending on size Flexible detectors are complex to produce BULK steps are still manually performed 12

IBF GEM 180 LPI 5% With 400 LPI 1% With 700 LPI ? Single resistive Layer Micro. Megas structure SS Mesh 400 to 700 LPI DLC 0. 1 um Polyimide 50 um Pick up pads/lines + Only 1 gluing + 1 Bulking Single piece different gaps possible different meshes possible Lateral current evacuation Rate limitation 10 to 100 K depending on size Flexible detectors are complex to produce BULK steps are still manually performed 13

2018 Copper coated DLC on one side • Cu/DLC/Polyimide Copper 5 um DLC 0. 1 um typ 100 K to 1 G/square • Cu/Polyimide/DLC/Cu Polyimide 50 um APICAL NP Kapton HN Copper 5 um Polyimide 50 um APICAL NP DLC 0. 1 um typ Copper 5 um 14

First application 15

High rate u. Rwell with 2 DLC layers ! Base PCB 16

High rate u. Rwell with 2 DLC layers ! Cu/PI/DLC/Cu bot Cu patterning + gluing 17

High rate u. Rwell with 2 DLC layers ! Microvia drilling + plating + top Cu patterning 18

High rate u. Rwell with 2 DLC layers SBU New CU/PI/DLC/Cu gluing + microvia drilling + Cu Plating 19

High rate u. Rwell with 2 DLC layers ! Process called ‘SBU’ Sequential Build Up 20

High rate MM with 2 DLC layers Base PCB 21

High rate MM with 2 DLC layers PI/DLC/Cu foil gluing 22

High rate MM with 2 DLC layers Micro via drilling + Cu plating + top Cu patterning 23

High rate MM with 2 DLC layers New PI/DLC/Cu gluing + microvia drilling + Cu Plating + Cu Patterning 24

High rate MM with 2 DLC layers Bulk creation on top of the structure 25

May 2019 Cu and DLC both sides: • Cu/Cr/DLC/Polyimide/DLC/Cr/Cu • Base material currently in production 16/04/2019 26

Low mass detector, medium rate version RES GEM Low mass detector high rate version + high rate capabilities Simple production Low material budget Single piece, could be flex Only PCB processes Compatible with mass production • Single sided resistive GEM have already been produced TBF (To Be Found) 16/04/2019 27

PROBLEMS • Need to increase signal amplitude • Vacuum Copper adhesion problem • DLC adhesion problem • Full resistive scheme problem 28

Increase signal amplitude STD detector Resistive detector The amplifier is only fighting with C 2//C 3 to get charges The amplifier is still fighting with C 2//C 3 to get charges We have to reduce C 3 and C 2 But the only coming charges depends on C 5/C 6 ratio 29

C 5/C 6 sharing? E means dielectric constant C 5 and C 6 are sharing a common part of the resistive electrode in blue , but the exact area have not yet been calculated precisely C 5= Eo x Er 2 x S/h 2 C 6= Eo x Er 1 x S/h 1 C 5/C 6= Er 2 x h 1 / Er 1 x h 2 = 8 The ratio do not depends on the Area S In the above case , at least 20% of the charges will be lost in this node through C 6 whatever the frequency and Area S. In u. Rwells the ratio is close to 1 , we should reduce a lot the thickness of C 5 to increase this ratio 30

75 um diel 20 um diel or less 31

CU adhesion problem • We have checked chemically the thickness and we found 3 um instead of 8 • After investigation the difference comes from the hermiticity of the layer due probably to the amorphous structure. • After Galvanic coating the layer keeps well its adhesion. • We will may be ask for smaller CU layers in future DLC adhesion problem • We have faced large DLC delamination during Polyimide etching • After sandblast treatment no more large delamination, but there is still microscopic cracks around the holes • Could we investigate a way to improve DLC adhesion ? • Increase energy deposition at the beginning of the deposition? • Only deposit diamond structure at the beginning of the deposition? 32

Full resistive rising problem The induced currents versus irradiation seems to show an activity (Yi measurements on TH-Rwells) No signal seen by FE in FTM -The induced charges are may be delayed in time? -Increase integrating time? -Increase the resistive value to reduce signal time development and spreading like RPCs? -The charges are may be also distributed in too many lines, too large spreading? Spice simulation needed? -Could we spice simulate the signal transmission for FTM before next productions? 33

New possibilities 34

Low channel count, high granularity detectors possible with u. Rwell Conventional Multiplexing -Top Mesh is divided in pads -Reading these pads gives the sector position X -Fine position given by the strips within the sector -With 0. 8 mm pitch (X and Y) a 50 cm x 50 cm detector can be red with 256 E-channels , a space resolution in the range of 50 um could be achieved in theory. Y

Fine DLC patterning • DLC can be patterned down to 0. 2 mm line and space with conventional PCB photolithography with horizontal sandblasting machines. • Pumice 0. 1 mm grain size max • Al 2 O 3 powder • We have not found any chemistry etching nicely DLC • Potassium permanganate seems to be the closest • Lift-off patterning works fine but cuts the possibility of doing roll to roll base material mass production. 36

Some productions : 20 cm x 20 cm Micro BULK detector 10 cm x 10 cm µRwell detector “study kit” Large µRwell detector Like CMS GE 21 module M 4 120 cm x 55 cm 16/04/2019 37

Conclusion • Single DLC layer detectors are now quite easy to produce • Still work to be done on large size • Signal pick up improvement • Production of double DLC prototypes are on going • In the coming weeks first deliveries of SBU • Still improvement to do on: • Copper and DLC adhesion • Signal transfer understanding in full resistive structures 38

Thank you 39