Notes:

• Run 72 noise sigma are with standard unbalanced PTOF0
• Run 72 detector bias in these plots derived from apparent Luke gain, which is much less than calculations based on applied bias, leakage, drift, and gap.

• The plot above shows calculated and Luke-gain-derived detector bias as a function of applied (drifted) HV.
• Calculated includes effects of 1) leakage current measured at test resistor 2) counter-bias buildup during rampup & prebias 3) loss across the gap
• For the calculation the gap is assumed to be 1 mm. The gap was measured to be smaller than that so the calculated bias is an underestimated
• For positive bias the Luke-derived bias is 41±3% of the calculated bias.
  • It's a somewhat higher fraction at lower biases. The trend appears linear, approaching 47% at the 0V limit
• For the negative HV point checked the Luke-derived bias is 16.5% of the calculated bias.

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