Principal: alberto
Deputy: kgordon
Data Analyst(s): Dave Frayer and/or Stefani Wachter
Priority: Normal
Downlink Priority: Normal
Analysis Time: 8hrs
Last Updated: July 9, 2003

Objective

Objective: The behavior of the 70um and 160um arrays will be checked as a function of time since thermal anneal. The performance criteria will be read noise, dark current, stim repeatability, and responsivity. The main goal is to determine what frequency to anneal the Ga:Ge arrays. In addition, the behavior of read noise and dark current between anneals will be characterized.

Description

The goals of this task are to determine the thermal anneal frequency for the 70um and 160um arrays (major goal) and to characterize the behavior of the arrays between anneals (minor goal). The reason to anneal the Ga:Ge arrays is that the damage caused by cosmic rays accumulates and the achievable S/N decreases significantly. Thermal anneals have been shown to remove the affects of cosmic ray damage and "reset" the arrays. The default anneal frequency for both arrays is 3 hours. As it is not possible to accurately simulate the environment SIRTF will be in after launch, the actual desired anneal frequency is likely to be different from the default. The desired anneal frequency is also likely to be different between the 70um and 160um arrays. In order to determine the desired anneal frequencies, we will take data to evaluate the performance of both arrays for a period of 4hrs in here (Campaign K) and 6hrs in Campaign Q. At the start of this task, both arrays will be thermally annealed. For the next 4 hours, we will take data to evaluate the read noise, dark current, stim repeatability, and responsivity for both arrays. Taking other data with the 70um or 160um arrays is unlikely to be desirable during this task. Taking 24um data during this task is possible, but with the caveat that when the 160um stim is flashed, the 24um arrays sees this stim.

Data Collected

  • 8282 DCEs 
    

 A single IER contains now a mixture of the commands from
the IERs below. For Campaign K we use 5 sets.

70um and 160um Thermal Anneal Behavior   MIPS-160 --> (see below)
--------------------------------------------------- 
  mips_annl70um_heat.exp
  mips_annl160um_heat.exp 

 (then 5 (k)  and  7 (q) sets of these 4 IERS)
  mips_rn160um_10s50.exp
  mips_drk160um_3s226.exp
  mips_rn70umA_10s50.exp
  mips_drk70umA_3s226.exp
  
  mips_rn160um_10s50.exp
  mips_drk160um_3s226.exp
  mips_rn70umA_10s50.exp
  mips_drk70umA_3s226.exp 

  mips_rn160um_10s50.exp
  mips_drk160um_3s226.exp
  mips_rn70umA_10s50.exp
  mips_drk70umA_3s226.exp

  mips_rn160um_10s50.exp
  mips_drk160um_3s226.exp
  mips_rn70umA_10s50.exp
  mips_drk70umA_3s226.exp

  mips_rn160um_10s50.exp
  mips_drk160um_3s226.exp
  mips_rn70umA_10s50.exp
  mips_drk70umA_3s226.exp

where:

mips_rn160um_10s50.exp or mips_rn70umA_10s50.exp take 50 DCEs 10 secs with 160um or 70um at its dark position
without stims; andmips_drk160um_3s226.exp or mips_drk70umA_3s226.exp take "calibrated darks" (with stims),
226 DCEs 3sec each.

    Data Reformatting Requirements

    Array Data Desired:

    70 and 160 µm

    Data Reformatting Option:

    Special Instructions:
    none

    Task Dependencies

    Calibration Dependencies

    none, but refer to the laboratory values for comparison.

    Output and Deliverable Products

  • more tan 4200 DCES

    Data Analysis

    The goal is to evaluate the read noise, dark current, stim repeatability, and responsivity for both arrays. Run data through DAT and SSC pipeline. Using the data, compute the read noise, dark current, stim repeatability, and responsivity as a function of time since anneal. This data will be used to assess the variation of the achievable S/N as a function of time since anneal. The dark current dataset will be run through mips_sloper, mips_caler, and mips_enhancer with the appropriate switches. The script 'mips_makedark_ge' will be used to ensure that all the appropriate switches are set to these three programs. The dark calibration image will be created by mips_enhancer and will include uncertainties. The IDL program 'merge_dark70' will be used to merge the two dark positions into a single calibration image. The read noise dataset will be run through mips_sloper. The resulting output will be used as input to the IDL program 'get_rdnoise.pro'. This program will output the read noise calibration image as well as a suitably averaged read noise measurment (over the entire array). (see also MIPS-911 & 912 for further details).

    Software Requirements

    Actions Following Analysis

    The anneal frequency for each array will be chosen to keep the achievable S/N within a reasonable (specified?) range. The variation of the read noise and dark current with time since anneal will be used as input to the MIPS.

    Failure Modes and Responses

    If this test fails to execute or if it gives ambiguous answers, we will use the 3 hours as the nominal anneal frequency until other data can be taken/analyzed to give a better estimate of the anneal frequency.

    Additional Notes