ACIS Instrument Support - Monthly Progress Report for January 2000


1. ACIS Characterization

1.1 Characterize and model radiation damage in ACIS CCDs

  ...] Finished a series of raw frame mode measurements on S2 with the ext. cal. source to study the effects of CTI.  Two sets of data taken at a focal plane temperature of -118 C.

  ... Continued analysis of raw mode data
     ...] Determined time constants for two short traps from charge re-emitted into pixels trailing behind an X-ray event (ACIS Memo #179)
    [... Examined feasibility of better determining time constant for the millisecond trap from charge re-emitted into pixels trailing behind large cosmic ray events.

 [...] Conducted cold irradiation with soft protons and reverse annealing at room temperature test of a ccdid-7 with Penn State at Goddard.  

 [...] Conducted warm irradiation with soft protons of a ccdid-17 at Goddard.  New test design allows the irradiated area to cover all rows and half the columns of a single output node, more like the flight CCD irradiation.  Previous tests had much smaller irradiated areas.

  ... Characterized CCDs before and after January tests.

1.2 Monitor scientific on-orbit performance of ACIS

  ... Continued monitoring of ACIS CTI.  No additional radiation damage detected in either FI or BI CCDs.

  ...] Supported discussion of optimal focal plane temperature with data analysis of CTI and FWHM of calibration lines. (ACIS Memo #181)

  ...] Investigated temporal structure in FI CCD CTI measurements due to changing particle background rates (ACIS Memo #180)

 [... Began a collaboration between the radiation damage modelers and the flight software experts in developing algorithms to telemeter additional data with each X-ray event that would ameliorate the effects of CTI.


2. Engineering

2.1 Instrument hardware engineering performance

  ...] Performed and evaluated test of ACIS focal plane cooling on 15 January 2000.  Coldest focal plane temperature reached was approximately -122 C.  Lower temperatures would require turning off the detector housing heater.

 [...] Focal plane temperature permanently lowered to -120 C on 29 January 2000

2.2 Flight software maintenance

 [...] Published first external release of ACIS Flight Software Users' Guide (http://www.acis.mit.edu/swuserA/)

 [...] Uploaded release B of standard patch set for the ACIS Flight Software

2.3 Instrument science performance

  ... Continued quick-look processing of all ACIS science runs, using EHS telemetry supplied by the GOT.  Additional users were instructed in same.

 [...] Improved Web interface between OCAT and the "annotated" DOT

 [... Monitored performance of new ACIS Flight Software patches including FEP bias parity error fix.  FEP bias parity errors never exceeded trigger value, otherwise patch functioned properly.


3. ASC Support

  ... Continued to assist the CXC MTA in automating ACIS CTI monitoring