ACIS Instrument Support - Monthly Progress Report for August 2003

1. ACIS Characterization

1.1 Characterize and model radiation damage in ACIS CCDs

  ...  Continued running charge injection tests on I3.  Two tests 
to explore the energy/voltage relation.

 [...] Solved the mystery anomaly in charge injection test taken in
June (ObsID 60674).  Significantly less charge was produced
than expected due to a mistiming between the start of sequencing
and the reset to nominal DACs.  This can only occur if the preceeding
science run uses a mode that is implemented using a patch, in
this case CC3x3.  An additional delay will be added to ensure
this does not occur again.

 [...] Finished writing a paper describing results of cold irradiation
experiment performed last fall at GSFC. 


1.2 Monitor scientific on-orbit performance of ACIS

 [...] Participated in Chandra quarterly review.  Presented ACIS status 
report.

  ...  Continued analysis of ExtCalSrc data to study efficiency 
decrease at low energies.  Verifying spatial non-uniformity
of contaminant distribution.

  ...  Continued monitoring of ACIS CTI.  No significant changes beyond 
the long term slow increase.  (http://space.mit.edu/~cgrant/cti/)

  ...  Continued monitoring of ACIS gain.  All CCDs stable with a slow 
decline in gain slope (ADU/eV) except for I2 which continues to vary.
(http://space.mit.edu/~cgrant/gain/).

 [...  Updating CTI/gain monitoring software to be more automated.

 [...  Submitted abstract to Chandra symposium on ACIS performance
monitoring.  Beginning to compiled necessary data.

1.4 Update and improve CCD simulation

  ...  Continued work on improving FI and BI CCD models with a more 
physical representation of the electron traps that cause CTI.

  ...  Performed experiments to measure charge-vs-volume relationship 
for very small charge packets. This relationship is an important 
component of the CTI simulator.


2. Engineering

2.1 Instrument hardware engineering performance

  ...  Continue to monitor long term ACIS instrument performance.  A
review of the past 60 days of engineering data shows no anomalies or
trends.

2.2 Instrument science performance

  ...  Continued daily quick-look processing of ACIS telemetry and
maintained Web interface to ACIS real-time data.

  ...  Continued to publish the "annotated DOT" timeline reports.

 [...] Participated in ACIS telecon.

  ...  Continued to support charge injection operations by reviewing 
loads and comparing flight data to ground data to select new settings.


3. CXC Support

3.1 Provide user support

  ...  Updated ACIS memo listing calibration ObsIDs and observation
characteristics (ACIS Memo #165).

3.2 Provide data analysis support

 [...] Participated in CXC Cal/Ops RMF discussion group.

  ...  Continued to maintain ACIS calibration database of ground and 
flight data products


4. OCC Support

4.1 Use of MIT/ACIS EGSE at OCC

  ...  Continued support and maintenance of ACIS EGSE software and 
hardware at the OCC.


all recent memos available at http://space.mit.edu/ACIS/iacis.html