1. Detectors and Cross Talk Presented below are cross talk measurements carried out on 2 Burle and 1 Hamamatsu MCP PMTs and 1 Hamamatsu MultiAnode PMT (MAPMT). Cross Talk MCP PMTsH9500 MAPMT Conclusions Cross Talk in Position Sensitive Photon Detectors Rachel Montgomery* on behalf of the PANDA Cherenkov group Burle 85011Burle PrototypeHamamatsu SL10 Pore size (µm)2510 Number of pixels8 x 8 4 x 1 Active area (mm 2 )51 x 51 22 x 22 Total area (mm 2 )71 x 7169.5 x 69.527.5 x 27.5 Geometrical efficiency0.440.470.61 Peak quantum efficiencyAt 400nm At 300nm Table 1: Properties of the MCPs which were tested. Hamamatsu H9500 Pixel size (mm)2.8 x 2.8 Number of pixels16 x 16 Active area (mm 2 )49 x 49 Total area (mm 2 )52 x 52 Geometrical efficiency0.89 Peak quantum efficiencyAt 350nm Table 2: Properties of the H9500 MAPMT. Figure 6: Hamamatsu H9500 PMT. The H9500 dynodes are arranged horizontally across the PMT face – does this make a difference? Figure 7: Close up of the H9500 face, indicating dynode orientations. One Pixel Horizontal Vertical >1 dynode chains Acknowledgements and thanks to Albert Lehmann, Universitaet Erlangen-Nuernberg, for his MCP cross talk studies. One pixel is illuminated with light, false signals are obtained from non- illuminated pixels Timing resolution may be degraded and position information compromised Results Only vertical laser scans exhibited symmetry in cross talk patterns. RESULTS: Rather homogenous response and significant cross talk. Burle 85011 Burle Prototype Figure 4: Cross talk results for Burle 85011 and Burle prototype MCP’s. Less homogenous response and even more cross talk. Figure 5: Surface scan cross talk results for Hamamatsu SL10 MCP. SL10 MCP Very homogenous response from individual channels. Significant cross talk between channels. Laser scans show dynodes affect cross talk pattern shapes and symmetry during horizontal scans. Non-optical cross talk was observed. Cross Talk: H9500 PMT Surface scans indicated smaller pore sizes yield more cross talk. The Hamamatsu SL10 displayed the most homogenous response. Cross Talk: MCP PMTs Inherent property of position sensitive photon detectors. Studied in 3 MCP PMTs and 1 MAPMT. Cross Talk Single photon sensitivity in 2T magnetic fields Sufficient position resolution Excellent timing resolution (<50ps single photons) High photon rate stability (MHz) Photon Detector Requirements for PANDA Disc DIRC Candidates include: microchannel plate (MCP) photomultiplier tubes (PMTs) and MultiAnode PMTs. Resulting applications include medical imaging. MCP PMTs: MAPMT: Horizontal and vertical laser scans highlighted different cross talk patterns caused by arrangement of dynodes. Horizontal Figure 7 Figure 8 Vertical Figure 8: Typical cross talk patterns obtained from horizontal and vertical scans. Figure 9: Cross talk pattern symmetry observed during vertical scans. Figure 9Figure 10 Above scanned pixel Below scanned pixel * E-mail: r.montgomery@physics.gla.ac.uk Figure 3: Hamamatsu SL10. Figure 1: Burle 85011. Figure 2: Burle Prototype. RESULTS: Figure 10: Oscilloscope trace showing non-optical cross talk in 2 illuminated pixels. Oscilloscope measurements allowed observation of non- optical cross talk in the form of a secondary peak with constant timing.