16062021 J A Merlin GEM group On behalf

16/06/2021 J. A. Merlin GEM group On behalf of the CMS 1

General Production, QC and delivery schedule was built in agreement with KCMS and Mecaro, taking into account the production capacity of the factory, the manpower situation and the requirements of the project. Pre-production 10 foils of each type (M 2, M 3, M 6 and M 7). Additional time between production batches for the in-depth validation of the technology + validation of the QC and logistics (“mass production” mode) Mass production 114 foils of each type (M 2, M 3, M 6 and M 7). 1 week contingency after 2 production batches Note It is agreed to alternate the production of the different modules in order to provide regularly foils of each type and anticipate possible issues with a particular design. 30 foils of each type per cycle Start of the pre-production = T 0 16/06/2021 J. A. Merlin GEM group On behalf of the CMS 2

Ø 10 foils M 7 (pilote run): • Two weeks for production • Two weeks for QC • One week for shipping • Two weeks for validation at CERN (geometry, cleanliness, HV stability) Ø 10 foils of M 6, M 3 and M 2 • Production rate: 5 foils per week • QC rate : 5 foils per week • Shipment: 3 weeks, all three batches together after the last foil is tested Overall time for pre-production: 3 months from T 0 Validation of the pre-production = T 1 16/06/2021 J. A. Merlin GEM group On behalf of the CMS 3

Ø Production cycle: • Four batches (30 M 7 + 30 M 6 + 30 M 3 + 30 M 2) • Production rate: 10 foils per week • QC rate: 10 foils per week • Two weeks for contingency • Shipment: 3 weeks after M 7+M 6 and after M 3+M 2 • Total time per cycle: 3 months (excluding shipping time) Ø Four cycles to cover the entire production Validation of the first cycle= T 2 Validation of the second cycle= T 3 Validation of the third cycle= T 4 Validation of the fourth cycle= T 5 Ø Overall production time for mass production: 12 months 16/06/2021 J. A. Merlin GEM group On behalf of the CMS 4

Ø Current schedule: (GE 21 Dashboard) https: //docs. google. com/spreadsheets/d/1 d. Hp. Lsa. R 2 Dov 14 e. SK 10 f. Hv. YS 2 NG 5 P 048 Wzd. QCf. Hr. XAX 8/edit#gid=475885852 Mitigation Ø In the current schedule, T 0 is set to Jan 25 th 2020 not valid anymore considering new developments related to foil performance Ø So-called “double-polarity signal issue” (cross-talk effect recently observed with double-segmented foil design) Ø Additional R&D is needed Ø T 0 needs to be shifted by about 8 weeks 16/06/2021 J. A. Merlin GEM group On behalf of the CMS 5

Ø Reducing the size of the sectors on the bottom of GEM 3 increases the cross-talk effect (reflected signal inducing signal on non-irradiated strips facing the HV partition) 16/06/2021 J. A. Merlin GEM group On behalf of the CMS 6

Ø For large amplitude signals (typically HIPs), the cross talks induces a negative undershoot that can trigger the electronics fake signals with large occupancy More details: https: //docs. google. com/presentation/d/1 Exn. I 1 x. DV 9 SQz. A 8 Sv. Hi. MBg 7 n. R 4 i. Ka. QOh 0 c. Vv. Zamz. Ll. QQ/edit? usp=sharing 16/06/2021 J. A. Merlin GEM group On behalf of the CMS 7

Evaluation of the performance with cross-talk Ø Evaluated the expected rate of HIPs interacting with the chamber (Fluka, GEANT 4, Garfield): first round of simulation completed, data is under review (1 -2 weeks) Ø Evaluate the portion of the detector that needs to be masked to prevent SBIT overflow: currently estimated to two eta partitions (half of a module) Ø Evaluate the impact on the trigger performance taking into account HIP rate and masking size (3 -4 weeks) New GEM design proposal Ø Determine the range of HV segment size to test using 10 x 10 and 30 x 30 chambers: on-going (1 week) Ø Design a new foil with several sizes of HV segments (1 week) Ø Produce prototype foils for two chambers (3 -4 weeks) Ø Measure cross-talk effect vs. HV segment size (2 weeks) Ø Measure impact on discharge propagation behaviour (1 week) + measure impact on rate capability (1 week) Additional work Ø Estimate (precisely) the primary charge released by Alphas and scan different alpha energy to determine the cross-talk activation threshold (two weeks) Ø Evaluate the options to reduce the masking size using OH discrimination (or changing SBIT mapping logic) Minimum 8 weeks of delay on the production schedule 16/06/2021 J. A. Merlin GEM group On behalf of the CMS 8

Thank you 16/06/2021 J. A. Merlin GEM group On behalf of the CMS 9