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 PMTs H9500 MAPMT Conclusions Cross Talk in Position Sensitive Photon Detectors Rachel Montgomery* on behalf of the PANDA Cherenkov group Burle 85011 Burle Prototype Hamamatsu SL10 Pore size (µm) 25 10 10 Number of pixels 8 x 8 8 x 8 4 x 1 Active area (mm 2 ) 51 x 51 51 x 51 22 x 22 Total area (mm 2 ) 71 x 71 69.5 x 69.5 27.5 x 27.5 Geometrical efficiency 0.44 0.47 0.61 Peak quantum efficiency At 400nm At 400nm At 300nm Table 1: Properties of the MCPs which were tested. Hamamatsu H9500 Pixel size (mm) 2.8 x 2.8 Number of pixels 16 x 16 Active area (mm 2 ) 49 x 49 Total area (mm 2 ) 52 x 52 Geometrical efficiency 0.89 Peak quantum efficiency At 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. RESULT S: Rather homogenou s response and significa nt cross talk. Burle 85011 Burle Prototype Figure 4: Cross talk results for Burle 85011 and Burle prototype MCP’s. Less homogenou s response and even more cross talk. Figure 5: Surface scan cross talk results for Hamamatsu SL10 MCP. SL10 MCP Very homogenou s response from individua l channels. Significa nt 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 9 Figure 10 Above scanned pixel Below scanne d pixel * E-mail: [email protected] Figure 3: Hamamatsu SL10. Figure 1: Burle 85011. Figure 2: Burle Prototype. RESULT S: 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.