CSR Charts

1
GLAST Large Area Telescope ISOC Peer Review
Section 7.1 Pre Launch Operations and
Calibrations Eduardo do Couto e Silva Manager
of the Science Verification Analysis and
Calibration Department of IT Subsystem
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Outline

• Connection between IT/SVAC and ISOC/SOG
• IT/SVAC Requirements
• Examples of IT/SVAC activities
• Lessons Learned from IT/SVAC
• Examples of preliminary data analysis
• Summary

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Connection between SVAC/IT and SOG/ISOC

• The Science Verification Analysis and
  Calibration (SVAC) Department of the IT
  subsystem will gradually transition into the
  Science Operations Group of the ISOC.
• The main responsibilities of the SVAC Department
  are
• Coordinate Data Analysis for Science Verification
  
• Perform final pre launch calibrations
• Perform first in-flight calibrations prior to
  hand off to ISOC/SOG (see talk in section 7.2)
• Deliver calibration products to ISOC/SOG

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IT Pre Launch Experience with EM

• The Science Operations Group (SOG) has been
  recently created and does not yet have all of its
  documentation in place
• In this talk we will present an overview of the
  IT/SVAC experience using the Engineering Model
  (EM) test as an example of the activities that
  will be performed by the SOG during mission
  operations
• The lessons learned on following items will be
  discussed
• Documentation
• Data Processing
• Operations
• Calibrations
• Data Analysis

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Science Verification, Analysis and Calibration
(SVAC) Plan
Science and Calibration requirements from
Subsystems Plans were captured in LAT-MD-00446
Science Requirement Document
443-SRD-00010
LAT Performance Specifications
LAT-SS-00010
Level II Levels III and IV Level III
LAT-SS-00016, LAT-SS-00017 LAT-SS-00018,
LAT-SS-00152, LAT-SS-00210
ACD, CAL, TKR Specifications
GLAST LAT SVAC Plan
LAT-MD-00446
Calibration
Data Analysis
Science Verification
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SVAC Plans and Technical Documents
LAT-MD-00446 LAT-MD-01587 LAT-MD-00613
LEVEL III
Co-owned with Systems Engineering
Contributed Manpower Plan
Co-owned with Project Scientist
LEVEL IV
Existing docs are shown in red boldface
Hardware Test Plan/Results Calibrations
Simulations Databases Interfaces
Engineering Model EM
LAT-MD-00573 LAT-TD-01588
LAT-TD-00582 LAT-TD-00578 LAT-TD-00571
LAT-TD-01593
LAT-TD-01340
LAT-MD-00575 LAT-TD-01590 SAS
responsibility LAT-TD-00580 LAT-TD-00573
LAT
LAT-MD-00576
LAT-MD-00577
LAT-MD-00581
Co owned with Instrument Operations Center
LAT-TD-01595
At this time we are reviewing the EM documents
and lessons learned to produce the necessary
documentation for the LAT Integration
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Level III Documents - Contents
Co owned with Systems Engineering
Co owned with Project Scientist

• LAT-MD-00446 - SVAC Plan
• Instrument Calibrations
• SVAC Compliance
• Pre Launch Test Matrix
• Post Launch Test Matrix

• LAT-MD-01587 SVAC Test Requirements Plan
• Hardware Required
• Flight Software Required
• Test Configuration
• EGSE Required
• MGSE Required
• Test Software
• Support Instrumentation
• Test Data Record
• Data Format
• Test Products
• Analysis Activities
• Environmental Conditions
• Test performance Procedures
• Facility Requirements
• Quality Program Performance Requirements
• System Assurance Requirements
• Test Equipment Calibration

Contributed Manpower Plan

• LAT-MD-00613 - SVAC Plan
• Engineering Model
• TKR,CAL,SAS
• Calibration Unit
• ACD,TKR,CAL,SAS,IOC
• LAT
• ACD,TKR,CAL,SAS,IOC

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Level IV Technical Documents Contents

• Test Plan/Results
• LAT-MD-00573 SVAC EM Plan
• Describes the hardware data taking
  configurations, infrastructure needed for
  calibrations, calibration types, data analysis
  requirements. Run time estimation using MC
  simulation
• LAT-MD-01593 SVAC Results from the Engineering
  Model Test
• Describes the results and how requirements were
  met
• Calibrations
• LAT-TD-01588 Calibration Algorithms for the
  Engineering Model
• Describes the calibration algorithms developed in
  conjunction with SAS and subsystems
• Simulations
• LAT-TD-00582 EM Geometry for the Monte Carlo
  Simulation
• Describes the geometry used in the simulation,
  includes table to translate nomenclature from
  software developers to engineers and also
  contains traceability
• Database
• LAT-TD-00578 SVAC Database for the Engineering
  Model
• Describes the table schema and how a web based
  engine will allow access to a subset of
  calibration data for the purpose of tracking
  changes in time.
• Interfaces
• LAT-TD-00571 SVAC/SAS Interface Control
  Document
• Describes the responsibilities between SAS and
  SVAC for data analysis (Statement of work)
• LAT-TD-01340 SAS Calibration Infrastructure
• Describes SAS calibration infrastructure that
  holds the primary calibration data

Using Engineering Model as an example
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Documentation Lessons Learned

• EM Lessons Learned
• Lots of documents and not enough time for people
  to read them (i.e., less than optimal feedback
  from subsystems)
• In some cases ideas were discussed in details but
  were not mature enough to be implemented (e.g. EM
  database)
• Difficult to keep up with update needs given the
  manpower limitations within IT
• For SOG
• Documentation shall be kept at a level that is
  adequate to guide planning while allowing for
  technical reviews
• Interfaces need more attention and shall be more
  detail oriented

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Data Analysis Chain
GENERAL USER
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Data Processing Lessons Learned

• EM Lessons Learned
• Data transfer was tedious and was partially
  automated
• Reprocessing of data occurred more often than
  expected
• The Information about datasets necessary for data
  analysis was not available through a user
  friendly interface (despite our planning!)
• For SOG
• Fix communication problems between interfaces and
  devise system tests to minimize needs to
  reprocess data
• Investigate with SAS how to automate Data
  Processing
• Create better requirements to implement database
  queries

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Calibrations Lessons Learned

• EM Lessons Learned
• In some cases procedures were developed on the
  fly (not a serious impact since we did not have
  to deal with many software versions)
• IT was not directly involved in all calibrations
• For SOG
• Implement better configuration control of data
  and procedures to produce data
• Develop sufficient expertise within SOG to handle
  all possible calibrations
• Understand better requirements for interfaces
  with FSW

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Operations Lessons Learned

• EM Lessons Learned
• In some cases it was difficult to determine the
  data taking configuration
• Not all information was available during data
  taking
• New configurations were added during the data
  taking period without adequate planning
• For SOG
• Implement better user guides and operator
  training
• Develop a process to critically review
  operational procedures and to address unscheduled
  configuration changes
• Understand interface with FSW

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EM Ground Calibration Set-up
Cosmic Background
Not a monochromatic beam!
Gammas66 17.6 MeV
34 14.6 MeV, FWHM 1.5 MeV
lots of electrons
Beam pipe
CAL
TKR
Electrons are produced by gamma conversions in
the iron shield in front of the accelerator
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CAL Energy Spectrum
Preliminary
Photon Source OFF
From Gary Godfrey
Photon Source ON
Mostly photons
Energy (MeV)
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Source Calibration
Preliminary
From Gary Godfrey
Expect two energy lines
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Flux Measurement
Preliminary
9 of the of photons produced by the source are
measured by the EM
Top TKR face
Extrapolation to Photon Source
From Gary Godfrey
10 error is dominated by the knowledge on the
BGO position
EM Rec Direction cosine In 0.02 bins
 
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Energy Measurement
IDs are described in LAT-MD-00446
Calibrations
Data Analysis
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EM Energy Spectrum (VDG DATA)
Preliminary
Event selection nTkrTracksgt1 zDir lt -0.9 (25
deg from vertical) maxCalgt4MeV
From Xin Chen
Expected g Spectrum Delta function (17.6
MeV) Breit-Wigner (mean 14.5, width1.5MeV)
Energy (MeV)
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Energy Spectrum (VDG MC)
Preliminary
Event selection nTkrTracksgt1 zDir lt -0.9 (25
deg from vertical) maxCalgt4MeV
From Xin Chen
Events converted in top layer of Tracker only
Expected g Spectrum Delta function (17.6
MeV) Breit-Wigner (mean 14.5, width1.5MeV)
Energy (MeV)
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Data Analysis Lessons Learned

• EM Lessons Learned
• Expected experimental backgrounds were not
  thoroughly studied prior to the test
• Some algorithms and pieces of the offline
  software were not validated prior to the data
  taking period
• Calibrations took longer than expected
• For SOG
• Develop with SAS, IT and LAT Collaboration tools
  for instrument and sky simulations to address
  needs of first-year operations
• Develop better communications across interfaces
  and sharpen calibration requirements

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Summary

• Lessons Learned
• The IT/SVAC group will revisit all EM technical
  issues to ensure a successful LAT integration.
  IT/SVAC will participate in the planning process
  to build the infrastructure required for the SOG
  during the IT integration
• Concerns
• More discussions and planning are needed to
  address how the operational procedures and
  calibrations exercised during Integration will be
  adapted to the Flight Software environment (not
  present during EM)