Development and production of an intelligent PMT readout system for OSIRIS

Wysotzki, Christian; Stahl, Achim (Thesis advisor); Wiebusch, Christopher (Thesis advisor)

Aachen : RWTH Aachen University (2023)
Dissertation / PhD Thesis

Dissertation, RWTH Aachen University, 2023


The Jiangmen Underground Neutrino Observatory (JUNO) is a neutrino detector currently under construction in South China. The experiment is built to contribute substantially to central unsolved neutrino physics questions. Examples are the determination of the neutrino mass ordering and precision measurements of neutrino mixing angles. An inalienable prerequisite for precise measurements is a high radiopurity of the detector, especially of the liquid scintillator. In order to investigate the radioactivity of the liquid scintillator, the dedicated Online Scintillator Internal Radioactivity Investigation System (OSIRIS) is built. It uses photomultiplier tubes (PMTs) for the detection of light caused by radioactive decays. A new system is developed for OSIRIS which attaches the PMT readout electronics directly at its back. This system directly processes the digitized PMT signals and is therefore denoted as intelligent PMT (iPMT).The design of the iPMT system with a focus on the electronics is described in detail. As part of this thesis, an FPGA design for the PMT readout and the control of the iPMT is implemented and tested. Furthermore, an FPGA design for the synchronization of the iPMTs with each other and with calibration systems in OSIRIS isdeveloped.Characterizing measurements with a focus on central capabilities of the system are presented. This includes properties of the readout chain and an evaluation of the timing and synchronization system. An exemplary evaluation of the performance with a PMT is presented. Concluding, the electronics assembly of the iPMTs for OSIRIS is described. Prior shipment to China, the iPMTs undergo functional verification tests, and the corresponding results are presented. In total, 75 iPMTs are successfully tested for the use in OSIRIS.


  • Department of Physics [130000]
  • Chair of Experimental Physics III B [133510]