The ACIS gain and spectral resolution depend on both the date of an observation and the focal plane temperature at the time of an observation. Due to continuous radiation damage, and the subsequent increase in charge transfer inefficiency (CTI), a time-dependent gain correction must be applied to ACIS data. In addition, the ACIS gain and spectral resolution depend on the focal plane temperature. Automated pipeline processing corrects the ACIS gain on a photon by photon basis given the date and focal plane temperature at the time each photon is detected. The plots below summarize the present calibration status of the ACIS gain and spectral resolution (FWHM) for a FI chip (I3) and a BI chip (S3).
| Line Energy | -120.19 : -119.19 C | -116.19 : -115.19 C | -112.19 : -111.19 C |
|---|---|---|---|
| Al-Ka (1.49 keV) |
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| Mn-Ka (5.9 keV) |
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Gain-corrected photon energies for the ECS Al-Ka and Mn-Ka emission lines at three different focal plan temperatures. Each curve shows the gain-corrected photon energy for a given chipx (row) along the full range of chipy (column). The horizontal dotted lines correspond to the lab measured line energies and +-0.3% limits about the line energy.
| Line Energy | -120.19 : -119.19 C | -116.19 : -115.19 C | -112.19 : -111.19 C |
|---|---|---|---|
| Al-Ka (1.49 keV) |
 |
 |
 |
| Mn-Ka (5.9 keV) |
 |
 |
 |
Gain-corrected photon energies for the ECS Al-Ka and Mn-Ka emission lines at three different focal plan temperatures. Each curve shows the gain-corrected photon energy for a given chipx (row) along the full range of chipy (column). The horizontal dotted lines correspond to the lab measured line energies and +-0.3% limits about the line energy.
| Al-Ka (1.49 keV) | Mn-Ka (5.9 keV) |
|---|---|
 |
 |
Measured FWHM from gaussian fits to the ECS data for the Al-Ka (left) and Mn-Ka (right) emission lines. Results are shown for the S3 (red) and I3 (black) CCDs as a function of chipy at focal plane temperatures of T=-120 C (solid line) and T=-116 C (dashed line).
Last updated July 9, 2020
