LAPPD Figures for Papers and Talks

Compare intermcp 500 200 100

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Average pulse shape for 500 V (thick line), 200 V (thin), and 100 V (dashed) across the inter-MCP gap, with 400 V across the anode and photocathode.

Twodemountables fit

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The TTS for the two configurations. The high gap-voltage configuration is the shaded black histogram, with $\sigma$=78 picoseconds for the fitted Gaussian (dashed line). The TTS for configuration with low gap voltages is shown by the blue solid line, with a fitted $\sigma$ of 128 psec.

Twodemountable templates

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Average pulse shape for 2 different configurations of the demountable $\LAPPD$: one with low voltages ($<$100 V) across all of the gaps (blue solid line), and one with higher gap voltages (dashed black).

Tres spatialuniformity final

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The fitted sigma of the TTS was measured at 30 points over a 7mm by 7mm square. This plot shows the locations and values of each measurement, relative to the stripline pattern. The color scale represents the range of measured time resolutions.

Pore schematic

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A schematic of photoelectrons entering the pore of an MCP. Both the dashed red and dotted blue trajectories reach height $z_1$ at the same time, but arrive at $z_2$ at different times due to different velocities and path lengths.

Final gapvoltages

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Transit-time spread of MCPs in the 8" chamber, plotted as a function of the key operational voltages: across the gap between the photocathode and top of the first MCP (green circles), between the two MCPs (red triangles), and between the bottom of the second MCP and anode (blue squares). Timing for all gap voltages is preferred to be above 200 V, and performance is most sensitive to the photocathode and inter-MCP gaps.

Demountable assy

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A picture of the assembled demountable LAPPD before placing and sealing the top window.

Phd new

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Distribution of signal amplitudes from the demountable $\LAPPD$ operating at 2700 V, including pedestal events (zero bin).

Gaindist

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The reconstructed MCP gain distribution for good pulses, with peak at around 3 x 10^7.

June22 v11 rev102 tfit final

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he single-PE transit-time spread measured for the $\LAPPD$ stack inside the 8" chamber, derived using the template fit method. The RMS of the distribution is 58 psec; The sigma of the fitted gaussian is 50 psec. Numerically integrating the distribution, one finds that 68$\%$ of all events fall within $\pm$47 psec.