Speaker
Description
The CMS Collaboration is preparing to replace its current endcap calorimeters for the HL-LHC era with a high-granularity calorimeter (HGCAL), featuring a previously unrealized transverse and longitudinal segmentation, for both the electromagnetic and hadronic compartments, with 5D information (space-time-energy) read out. The proposed design uses silicon sensors for the electromagnetic section and high-irradiation regions of the hadronic section, while in the low-irradiation regions of the hadronic section, plastic scintillator tiles equipped with on-tile silicon photomultipliers (SiPMs) are used. The full HGCAL will have approximately 6 million silicon sensor channels, in around 30,000 detector modules. Each of these modules will be readout by a front-end board (hexaboard) using among other components a dedicated readout chip called the HGCROC. Either 3 or 6 HGCROCs, for 198 channel or 444 channel data readout respectively, are housed on each hexaboard depending on whether it is for the outer region of the HGCAL or the inner region of the HGCAL in the high radiation environment.
The HGCROC chips are available in a BGA-376 package. Before the Hexaboards can be approved for use in the HGCAL, it is very essential to know whether all the pins (balls) of the HGCROCs are properly soldered to the pads on the Hexaboard and make a good electrical contact to the board. It is also essential to make this decision very quickly because of the very large number of boards that will be required. A charge injection (CI) system is being designed and built in order to qualify the hexaboards at the factory level. The CI system will incorporate capacitive signal injection into the hexaboards so that no electrical/mechanical contact need be made to the board so that it remains in pristine state before silicon sensor can be wire-bonded to it. The CI system incorporates a programmable switch matrix so that the test signal can be injected into any desired combination of inputs of the hexaboard at a time. The hexaboard inputs are injected with charge and the corresponding data is readout by a hexa-controller and analysed to evaluate the electrical connection between the hexaboard and the HGCROC chips. This paper will discuss the design and performance of the CI system for the quality control of assembled hexaboards of the CMS HGCAL.
| Field of contribution | Experiment |
|---|
