ACIS Instrument Support - Monthly Progress Report for May 2002

1. ACIS Characterization

1.1 Characterize and model radiation damage in ACIS CCDs

  ...  Continued analysis of no-squeegee cuckoo data.  Work continues on defining filters and correction factors that would improve over-all performance.  Preparing results for presentation at SPIE conference in August.

  ...  Continued running of charge injection tests on S0 from the command load.  Three more voltage levels tested which injected charge at energies similar to the External Cal Source lines.

 [...] Worked with PSU to implement time-dependent CTI information into their CTI corrector.

1.2 Design and characterize alternative CCD readout modes

  ...  Supported charge injection tests on-board with lab verification and testing.
 
1.3 Monitor scientific on-orbit performance of ACIS

  ...  Continued analysis of ExtCalSrc data to search for putative QE decrease at low energies.  Discussed results and analysis techniques with CXC Cal group members.

 [...] Reworked lab test structures for a compact leak free test setup suitable for travel that will meet stringent vacuum requirements.  May be used to test possible bakeout scenarios on radiation damaged CCDs.

  ...  Continued monitoring of ACIS CTI.  No significant changes beyond the longterm slow increase.  Updated web page (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.  Updated web page (http://space.mit.edu/~cgrant/gain/).

1.4 Update and improve CCD simulation

  ...  Continued work on detailed physical model of FI CCD including CTI and sacrificial charge.  Worked on a version of the simulator that can be incorporated into MARX.

  ...] Reanalyzing HIREFS calibration data of S3 to compare to CCD simulator output and to better understand gain function at very low energies.  Wrote ACIS Memo #201 "Comparison of BI simulator to s3 HIREFS Data at -120C".


2. Engineering

2.1 Instrument hardware engineering performance

  ...  Continue to monitor long term ACIS instrument performance.  Everything looks nominal.

2.2 Instrument science performance

 [...] Published memo on anomalies found in all FI CCD continuous-clocking mode bias maps.  Anomalies are caused by cosmic rays and can be reduced by implementation of changed bias parameters (http://acis.mit.edu/acis/ccmode/ccmode.html).

  ...  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.

  ...  Continued to develop flight s/w algorithms to implement "Squeegee" clocking mode and to report precursor charge from ACIS CCDs.

  ...  Participated in ACIS telecons


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

 [...] Investigated origin of spurious low energy peak found in simulated X-ray data by CXC Cal.  Determined that it was caused by a bug in CXC processing software.

  ...  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.


New ACIS Memo:

201 - Comparison of BI simulator to s3 HIREFS Data at -120C

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


Outreach:

none