As a quick-look at the affect of the change in the MCP HV step I have plotted the mean PHA and observed rate for selected events from the diffracted X-rays from HZ43 and its zeroth order. Points are plotted for each ObsID. The vertical dashed line separates historical data (Nov 1999 and Mar 2011) from those of the test. For the diffracted X-rays I selected the CRSV = 10-20 region, the area of the lowest gain.

Median PHA of
diffracted X-rays in CRSV = 10-20 Rate of
diffracted X-rays in CRSV = 10-20

Median PHA of
X-rays in zeroth order Rate of
X-rays in zeroth order

As expected the median PHA increases as the MCP HV step values increase. The rate in the CRSV 10-20 range increases as the step values are raised, indicating that we have recovered some "QE". The evidence for an increase in the zeroth order is weaker but we did not expect to recover any significant QE due to gain recovery in the zeroth order.

Last modified: Thu Jan 26 14:33:38 EST 2012