Form 8

Research Result Report
ICRR Inter-University Research Program 2023
Research Subject:
Hyper-Kamiokande OD PMTs QA
Principal Investigator:
Stephane ZSOLDOS, King’s College London / Kavli IPMU
Participating Researchers:
Stephane ZSOLDOS, King’s College London / Kavli IPMUFrancesca di Lodovico, King’s College London

Summary of Research Result：
The Hyper-Kamkiokande OD PMTs QA station has been designed to process several PMTs at atime, and the footprint of the system allows it to be deployed on a tabletop and operated by asingle person. The PMTs will be powered up and readout by VME64 modules, which allow foreasy deployment at different sites and repurposing at the end of the project.
To streamline cable management, splitters will be installed inside the boxes, allowing for direct
loading and unloading of cables. Ensuring continuity, cables from the outside feedthrough panels
to the readout electronics and power supply will remain connected to prevent potential issues. Asample feedthrough has already been installed on the box. Additionally, there are plans to design
a high voltage lock to prevent opening the box when PMTs are operational.
For production ef ciency, a 3D printer has been procured at KCL and con gured to produce 30mounts. Extensive testing has been conducted with CAD prototypes to ensure durability andmaterial optimization. Modular designs with separate mount and legs have been chosen foradaptability. To accommodate potential light measurement needs, a pocket has been integrated on
top of the photocathode for inserting caps which hold optical bers mount at several locations.
The design footprint is 20x20cm², and leg length will be adjusted based on the type of PMTs
procured. NNVT PMTs require shorter potting for cables and do not necessitate long legs, while
Hamamatsu PMTs require an average of 30cm legs. The modular design allows for easy
adjustment of leg length during printing.
All necessary components for instrumenting and testing one box have been procured. This
includes a 405nm LED butt-coupled to an SMA optic ber with a width of 400 microns and 0.22
NA. Testing has con rmed that the system produces suf cient light to be coupled into a 1-7 ber
bundle. A 3mm nylon gland is utilized for feedthrough in the dark box, with black mastic/tapes
ensuring light-tightness. Operators will not need to remove cables inside. As part of the setup,
light output will be mounted with aspherical lenses diffuser at strategic points within the box. Asample has been procured and is ready for testing. The objective is to illuminate the box at
various points, with PMTs being internally triggered.
Samples of MCX cables and BNC to MCX adapters have been obtained for testing readout froma waveform generator, also sourced from KCL. These components will be instrumental in future
calibration of the QA system. Additionally, the DAQ board has been ashed to waveform dump
rmware to facilitate of ine analysis. Plans are underway to develop custom software forwaveform processing. This will involve setting an internal trigger in the PMTs noise at -10mV,
determining the constant fraction discriminator time to set the integration window for charge
calculation (with an 80ns width), and displaying the charge histogram directly through front-end
software. Subsequent analysis will involve tting photo-electron peaks and measuring gain
automatically.

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Form 8