A New LED Pulser Board For The ATLAS Reaction Plane Detector in LHC Run 4*

The CERN LHC is projected to complete the High-Luminosity (HL) upgrade by 2029, marking the start of Run 4. Several detector sub-systems will be upgraded to meet the challenges resulting from the unprecedented particle collision rate achieved by the accelerator. One such system is the Zero Degree Calorimeter (ZDC) for both the ATLAS and CMS experiments. 

The HL-ZDC will be installed inside the TAXN absorber, 126 meters downstream of the interaction point, for heavy ion related data taking. The extreme radiation environment that the detector will be exposed to requires a LED calibration system, that allows for monitoring the HL-ZDC Photo-Multiplier Tubes (PMTs) performance during data taking. 

The University of Illinois at Urbana Champaign (UIUC), in collaboration with Kansas University (KU), is developing a new LED pulser board to be deployed in the HL-ZDC. When provided external triggers, this board will drive LEDs of different colors to pulse the HL-ZDC PMTs, monitoring their response at different wavelengths. This contribution will present the design of the new board and the evaluation of its performance. Next steps towards the final design of the pulser will be discussed, together with plans for radiation hardness tests at irradiation facilities at CERN.