ACIS Instrument Support - Monthly Progress Report for August 2002

1. ACIS Characterization

1.1 Characterize and model radiation damage in ACIS CCDs

  ...  Continued analysis of no-squeegee cuckoo data.  Presented
results at SPIE meeting in August.  Spectral resolution is improved
10% and 13% at 1.5 and 5.9 keV over the standard CTI correction.
Sacrificial charge correction is sensitive to CTI model parameters.

  ...  Continued running charge injection tests on I0 from the command 
load.  Tests will determine the correspondence between voltage settings and 
amount of injected charge.  Fives tests spanning energies from about
600 eV to more than 6 keV.  Updated memo on charge injection 
analysis (ACIS memo #199N).

  ...  Continued preparations for September irradiation/bakeout test at GSFC's 
particle irradiation facility.  Analyzed flight data to explore CCD-to-CCD differences in CTI change from bakeout.

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.  Investigating apparent differences between 
external calibration source time dependence and gratings measurements.

  ...  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.

 [...  Discussed origin of N-K edge data in FI CCD QE model with HETG Cal after report of possible calibration problem.  Provided QE simulator data with and without the edge.

  ...  Presentation at SPIE conference describing BI CCD simulator.

2. Engineering

2.1 Instrument hardware engineering performance

  ...  Continue to monitor long term ACIS instrument performance.

 [...] Supported Knowledge Capture activities by generating list of the seven most probably, serious failures to worry about in the context of a long-life mission, and delivering a preliminary submission to the data base of 667 documents.

2.2 Flight software maintainence

 [...  ACIS flight software patches review conducted on August 6 (Rev C).  All reviewed patches are optional and include algorithms for reporting precursor charge and rejected grades and to fix the T-plane latchup bug.

2.3 Instrument science performance

  ...  Continued analysis of new CC mode bias parameters.

  ...  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

  ...  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

 [...] Co-author on CXC ACIS calibration presentation at SPIE conference.  Provided data on ACIS QE change.

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:

199N - Charge Injection Test on ACIS (updated)

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


Outreach:

Presentations at SPIE conference "X-ray and Gamma-ray Telescopes and Instruments for Astronomy", August 2002

 * Grant, et al., "Sacrificial charge and the spectral resolution performance of the Chandra Advanced CCD Imaging Spectrometer"
 * Prigozhin, et al., "Model of the backside illuminated Chandra CCD
 * Plucinsky, et al., "The Flight Spectral Response of the ACIS Instrument"