Speaker
Description
The Light Dark Matter eXperiment (LDMX) aims to discover dark matter particle candidates produced with electron collisions on a thin, fixed target. To observe such cases via a missing momentum search, the detector consists of tracker modules before and after the target, an electromagnetic calorimeter (ECal), and a hadronic calorimeter (HCal). The HCal consists of alternating layers of absorber and scintillator bars, where signal photons in the scintillator bars are collected by counter-motherboards (CMBs) and sent onwards to the main readout electronics boards. Lund is responsible for producing all the HCal's readout boards, featuring the H2GCROC chip developed by the CMS collaboration as the front end. Over the past year, the Lund team characterised 10 prototype boards mounted with H2GCROCs by the CERN Electronics Workshop. The Lund team developed a standardised testing procedure using internal charge injections, focusing on checking the pedestal alignment and pulse sampling by the analogue-to-digital converter (ADC), as well as time-over-threshold (TOT) and time-of-arrival (TOA) measurements. An "outlier"-scan was developed to identify and characterise samples deviating from the expected pulse structure. In the future, a study will be conducted on the interplay between the HGCROC-board, CMB, and scintillator bars by flashing LEDs into these bars to produce a controlled external signal.