Testing CTI Correction Calibration

Dick Edgar has produced calibration products for the CTI correction algorithm in acis_process_events. These consist of a 1024x1024 image of the energy-independent trap density and two numbers; the power law index of the charge loss energy dependence and the fraction of the charge lost that is trailed into the followin pixel. His methods for producing these are loosely based on what Leisa and I did originally many years ago, so the results should be similar but not exactly the same.

The original dataset is a sum of all cold standard calibration source measurements from Jan 2000 - Jan 2001. This is approximately the same dataset that Dick used to create his trapmaps, so CTI evolution should not be a factor. The CTI correction software is my own, but has been shown to duplicate the results from acis_process_events. To keep this simple, only G02346 events from Node 3 are considered. Because of the pulseheight droop in the center of the FI CCDs, nodes 1 and 2 would have worse spectral resolution before correction and would yield and larger improvement after correction.

The results are very good. For I3, where two CTI correction calibrations exist, the new calibration produces slightly better FWHM results (< 2.5%). The spectral shapes appear very similar as well. For S0, S4 and S5 there is no current CTI correction calibration, however the results of the new calibration seem consistent with other devices.

One set of results are for I3 during epoch 11-14, November 2002 through October 2003. This data was CTI corrected using the above trapmap, calibrated for an earlier epoch, and a new trapmap calibrated for the same epoch as the data.

A complete set of results are also shown for epoch 18-21, May 2004 through April 2005.

Go to:

Epoch 1-4: I3, S0, S4, S5,

Epoch 11-14: I3,

Epoch 18-21: I0, I1, I2, I3, S0, S2, S4, S5,

Epoch 0 (-110C): I0, I1, I2, I3, S0, S2, S4, S5

Summary Table

I3

S0

S4

S5

I3, Epoch 11-14

S2, Epoch 18-21

I0, Epoch18-21

I1, Epoch18-21

I2, Epoch18-21

I3, Epoch18-21

S0, Epoch18-21

S4, Epoch18-21

S5, Epoch18-21

I0, -110C

I1, -110C

I2, -110C

I3, -110C

S0, -110C

S2, -110C

S4, -110C

S5, -110C