This directory contains quantum efficiency vs energy tables for each ACIS
flight detector (one file per detector, with the detector focal plane position
indicated by the first two characters of the filename.)  

Each file contains an ascii header filed by an  ascii table. 
See the file header for details.  Header information is reproduced in this
file (README_qe_898.)
A listing of the QE data files follows:
-rw-rw-r--  1 mwb         23888 Sep 16 10:02 i0_w203c4r_eff_898_release.qdp
-rw-rw-r--  1 mwb         23897 Sep 16 10:02 i1_w193c2_eff_898_release.qdp
-rw-rw-r--  1 mwb         23877 Sep 16 10:02 i2_w158c4r_eff_898_release.qdp
-rw-rw-r--  1 mwb         23898 Sep 16 10:03 i3_w215c2r_eff_898_release.qdp
-rw-rw-r--  1 mwb         23881 Sep 16 10:03 s0_w168c4r_eff_898_release.qdp
-rw-rw-r--  1 mwb         23823 Sep 16 10:03 s1_w140c4r_eff_898_release.qdp
-rw-rw-r--  1 mwb         23881 Sep 16 10:03 s2_w182c4r_eff_898_release.qdp
-rw-rw-r--  1 mwb         23857 Sep 16 10:03 s3_w134c4r_eff_898_release.qdp
-rw-rw-r--  1 mwb         23917 Sep 16 10:03 s4_w457c4_eff_898_release.qdp
-rw-rw-r--  1 mwb         23899 Sep 16 10:03 s5_w201c3r_eff_898_release.qdp
!Release notes for ACIS CCD quantum efficiency curves, 15 September 1998
!M. Bautz mwb@space.mit.edu  for the ACIS SI Team.
!
!Filenames:
!	i0_w203c4r_eff_898_release.qdp
!	i1_w193c2_eff_898_release.qdp
!	i2_w158c4r_eff_898_release.qdp
!	i3_w215c2r_eff_898_release.qdp
!	s0_w168c4r_eff_898_release.qdp
!	s1_w140c4r_eff_898_release.qdp
!	s2_w182c4r_eff_898_release.qdp
!	s3_w134c4r_eff_898_release.qdp
!	s4_w457c4_eff_898_release.qdp
!	s5_w201c3r_eff_898_release.qdp
!
!where 
!	the first two characters indicate detector position in the focal plane;
!and
!	wxxxcyy indicates CCD serial number (e.g, w182c4r)
!
!Format:
!ASCII table suitable for use with qdp. The files contain this
!message, followed by a 9-line qdp header which identifies the device.
!Following the qdp header there are two columns:
!1) Energy (keV)
!2) Quantum Efficiency (for ASCA grades 0,2,3,4,6)
!
!Description:
!These files provides the best available quantum efficiency estimates
!for  ACIS detectors as of the release date.  Ten files, one for each
!focal plane detector, are released.
!The predictions are for ASCA grades 0,2,3,4,6, with
!the following event and split-event thresholds:
!Chip Type	Event Threshold			Split Threshold
!		(adu)	(electrons,		(adu)	(electrons,
!			approximate)			approximate)
!FI		38	40			13	14
!BI		20	26			13	15
!(adu = analog-to-digital converter unit converter units) 
!
!Detectors S1 and S3 are back-illuminated (BI); the other detectors are
!front-illuminated (FI).
!
!These estimates were derived from MIT CSR subassembly calibration 
!measurements,
!and reflect the spatially averaged detection efficiency of each device.
!Consult Chapter 4 of the September, 1998 release of the ACIS calibration 
!report for a full explanation of the assumptions, model, best-fit model
!parameters, probable errors, and  limitations inherent
!in these model predictions.
!
!
!Intended use:
!When combined with ancillary response functions (arf) representing the HRMA
!effective area and  ACIS optical blocking filter transmission as functions of 
!energy,and the normalized response function matrices previously
!released and available from  http://www.acis.mit.edu), viz:
!  w215c2r_norm.rmf  for FI devices; 
!  w134c4r_norm.rmf  for BI device S3;
!  w140c4r_norm.rmf  for BI device S1,
!these quantum efficiency
!curves may be used for estimating  counting rates and simulating
!spectra expected from proposed ACIS/AXAF observations. They are, per force,
!best available ACIS detection efficiency estimates for use in continuing
!analysis of AXAF ground calibration data.  
!
!Because the modelling of the BI detectors is expected to improve 
!significantly before the launch of AXAF, the BI quantum
!efficiency curves released herewith are specifically NOT intended for the 
!analysis of AXAF data on astronomical sources. 
!
!Notes/Bugs: 
!1. Please read the ACIS Calibration report, release of September, 1998,
!for a complete discussion of the limitations of these predictions.
!Systematic relative errors in the spectrally-averaged absolute efficiency 
!of the  FI detector models  may be of order 5% over the 0.4-6 keV. Errors 
!may be larger outside this band.
!Errors in the efficiency of one FI device relative to another should be
!considerably smaller than 5%, except possibly at energies above 6 keV. 
!Systematic Errors in the predicted absolute efficiency of the 
!BI devices may be as large as 25% below 1.5 keV.
!
!2. Typical estimated errors as a function of energy for FI devices
!are to be released separately in the file s2_w182c4r_effrange_898.qdp.
!
!3. The quantum efficiency is sampled on a fixed energy grid of 0.01 keV 
!spacing between 0.100 and 11.990 keV. This sampling may be  too coarse
!just above the characteristic edges of nitrogen, oxygen and silicon,
!where fine structure has been measured on scales of a few eV. A subsequent 
!release will provide finer sampling near these edges. 
!
!4.These predictions are intended to represent the spatially averaged
!quantum efficiency of each ACIS device. Generally,
!quantum efficiency of FI devices is uniform over the device 
!within +-5% at all energies below 6 keV. Spatial variations in 
!quantum efficiency in the BI chips 
!may be as large at 20%. See the September, 1998 release of the
!ACIS calibration report for details. 
!
!5. The BI quantum efficiency estimates are based on a single deadlayer model
!for both BI devices, but the two models have 
!different depletion layer thicknesses. Thus, below about 1 keV, the
!predicted efficiencies are identical for the two BI chips. The BI detector
!S3 is more efficient than the BI detector S1.
!
!6. The data in the FI files  are replica files in 
!/benz/h4/mwb/acis/cal/rsp/qe898/ as of 1998 Sep  4 16:17 (for FI chips)
!and
!/benz/h4/mwb/acis/cal/rsp/qe898/ as of 1998 Sep  15 15:16 (for BI chips).
!