ACIS Instrument Support - Monthly Progress Report for August 2004

1. ACIS Characterization

1.1 Characterize and model radiation damage in ACIS CCDs

  ...  Continuing test of our CTI/background relation by running a series 
of alternating exposure mode observations with a grid of exposure times.  
In August there were two runs with frametimes of 1.5s and 2.5s, alternating
with a standard frametime of 3.2s.  This begins a second set which will
increase statistics.

  ...  Made simulations of oxygen concentration in silicon.  Did a literature
search on carbon-related multi-state defects in silicon.  Completed paper on
the mechanism of CTI change after annealing.  Resubmitted to IEEE Trans. on
Nucl. Devices.

1.2 Monitor scientific on-orbit performance of ACIS

  ...  Continued monitoring of ACIS CTI, gain, trailing pixel pulseheight
and detector efficiency.  Updated monitoring web pages.
(linked from http://space.mit.edu/~cgrant/acis.html)

  ...  Numerous discussions about new contamination analysis of HETG data.
The dither pattern can be used to track thickness variations on small
scales (<10 pixels).  Technique seems promising.

1.3 Update and improve CCD simulation

  ...  Continued work on improving FI and BI CCD models and CTI simulation 
code.  Did more analysis of laboratory charge injection data at different
temperatures.  This will be used to further understand the energy
dependence of CTI.

  ...  Made simulations of oxygen concentration in silicon.  Did a literature
search on carbon-related multi-state defects in silicon.  Completed paper on
the mechanism of CTI change after annealing.  Resubmitted to IEEE Trans. on
Nucl. Devices.

  ...  Presented ACIS status for Chandra Quarterly Review

2. Engineering

2.1 Instrument hardware engineering performance

  ...  Continue to monitor long term ACIS instrument performance.  ACIS 
engineering data continues to be stable.

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 telecons on the possible ACIS bakeout.  
Discussion of a -50C focal plane mini-bakeout.  ACIS team engineering
assessment is that the impact would be minimal to non-existent.

3. CXC Support

3.1 Provide user support

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

  ...  Helped resolve apparent anomaly in ObsID 4944.  Observation had
a slightly elevated background which increased an already understood
phenomenon.

3.2 Provide data analysis support

  ...  Working with CXC Cal on CTI correction calibration.  Current
calibration products were provided by MIT, but future updates will
need to be created by CXC.  After some debugging and limited testing,
CXC results are as good or better than the current calibration.

  ...  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

  ...  After UPS failure on August 2, restarted ACIS TST machines and
monitoring software.

  ...  Provided real-time support for CAP 932, a long CTI measurement.
Because of the earlier UPS failure, the usual remote monitoring of the 
commands by ACIS SOT was not possible.

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

  ...  Continued work on improving configuration management of the ACIS
workstations in the TST area of the Chandra OCC.

Outreach:

None


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