Module Assembly Using Robotized Gantry for the CMS Endcap Timing Layer*

The High Luminosity LHC (HL-LHC) will deliver an instantaneous luminosity of 5×10^34 cm^-2s^-1, with an expected total integrated luminosity of 3000 fb^-1 by the end of the decade. To fully exploit these new conditions, the CMS detector will need a completely new timing detector featuring higher radiation tolerance and timing capabilities. With this new timing detector, which will be installed during the CMS Phase II upgrade, the CMS will have the ability to measure the production time of a minimum ionizing particle (MIP) precisely. This will help resolving the pileup of nearly simultaneous 200 collisions per bunch crossing. The timing detector will consist of two sub-detectors, the Barrel Timing Layer and the Endcap Timing Layer (ETL). The ETL will be the first generation, fully silicon based, subsystem covering the high eta region. It utilizes Ultra-Fast Silicon Detectors (UFSDs) based on the Low Gain Avalanche Diode (LGAD) technology [1]. A robotized gantry will be used at Fermilab during the assembly of the ETL modules that house the sensor and the first stage of data acquisition. With a relative precision on the order of 10 μm for the placement of the components, the robotized gantry will be critical in achieving the quality needed for the roughly 7000 modules that are planned for the assembly. Once the critical components are placed in the module, each module will then be mechanically examined before being transferred to the wire bonder, which proves the electrical connections within the module. After wire bonding, the gantry is used again to affix a ceramic cover plate to the sensor side of each module. The cover plate results in sturdy individual modules that can be carried around and handled without concern of damaging the most critical components, as well as providing a thermal pathway for the modules. I will present the work I have done to prepare the robotized gantry. This work includes programming and troubleshooting issues as well as optimizing the module assembly procedure. So far, we have assembled dummy modules to measure and improve the performance of the gantry which paves the way for prototype module assembly. [1] CMS Collaboration, "A MIP Timing Detector for the CMS Phase-2 Upgrade", CERN-LHCC-2019-003; CMS-TDR-020