TA-WKS-2018-047

PANDA is a hadron physics experiment at the FAIR facility at GSI which will employ a high intensity antiproton beam of up to 15 GeV/c to do high precision studies of, among others, objectives like charmonium spectroscopy and search for gluonic excitations. The measurements require a robust and compact PID system placed inside a magnetic field of $>$1 Tesla with the main components being two DIRC detectors for pion/kaon separation.

Due to the boundary conditions in the focal plane vicinity of the PANDA DIRC detectors microchannel-plate (MCP) PMTs were identified as the only suitable photon sensors. As the long-standing lifetime problem of these devices was overcome recently by employing an atomic layer deposition (ALD) technique to coat the MCP pores, we have investigated further improved and lifetime-enhanced 2-inch MCP-PMTs from PHOTONIS and Hamamatsu. The currently best performing tube is a PHOTONIS XP85112 with two ALD-layers which meanwhile has accumulated close to 20 C/cm$^{2}$ intergrated anode charge (IAC) without any sign of aging. The best of the new Hamamatsu 2-inch MCP-PMT prototypes has reached $>$5 C/cm$^{2}$ without aging.

In addition to the current status of our ongoing lifetime measurements in this talk we will present performance results of the latest hiQE MCP-PMTs with high collection efficiency from PHOTONIS and a new Hamamatsu ALD-coated MCP-PMT without protection film. These are the most advanced commercial MCP-PMTs to date.

We will also present first measurement results obtained with a new quality assurance setup for mass production MCP-PMTs which shall be used to screen all tubes before being installed in the PANDA DIRCs. This setup consists of a 3D-stepper with a PiLas laser and a high performance PADIWA/TRB data aquisition system to measure the response of all anode pixels simultaneously. Among other things this system will allow us to study otherwise difficult to measure background parameters like position dependent dark count rates and ion afterpulsing. Also temporal and spacial distributions of recoil electrons as well as electronic and charge-sharing crosstalk among the anode pixels can be investigated.