GLAST LAT Project
Gamma-ray Large
Area Space
Telescope
ISOC Peer Review - March 2, 2004
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 I&T Subsystem
Document: LAT-PR-03213-01
Section 7.1 Pre-launch Operation and Calibration
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
Outline
• Connection between I&T/SVAC and ISOC/SOG
• I&T/SVAC Requirements
• Examples of I&T/SVAC activities
– Lessons Learned from I&T/SVAC
– Examples of preliminary data analysis
• Summary
Document: LAT-PR-03213-01
Section 7.1 Pre-launch Operation and Calibration
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
Connection between
SVAC/I&T and SOG/ISOC
The Science Verification Analysis and Calibration (SVAC)
Department of the I&T 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
Document: LAT-PR-03213-01
Section 7.1 Pre-launch Operation and Calibration
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
I&T 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 I&T/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
Document: LAT-PR-03213-01
Section 7.1 Pre-launch Operation and Calibration
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
Science Verification, Analysis and Calibration (SVAC) Plan
Science and Calibration requirements from Subsystems Plans were captured in LAT-MD-00446
Level II
Science Requirement Document
443-SRD-00010
LAT Performance Specifications
LAT-SS-00010
Levels III and IV
ACD, CAL, TKR Specifications
Level III
GLAST LAT SVAC Plan
Calibration
Document: LAT-PR-03213-01
Data Analysis
LAT-SS-00016, LAT-SS-00017
LAT-SS-00018, LAT-SS-00152,
LAT-SS-00210
LAT-MD-00446
Science Verification
Section 7.1 Pre-launch Operation and Calibration
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
SVAC Plans and Technical Documents
LEVEL III
LAT-MD-00446
LAT-MD-01587
Co-owned with Project Scientist
Co-owned with Systems Engineering
LEVEL IV
Contributed Manpower Plan
Existing docs are shown in red boldface
Hardware Test
Plan/Results
LAT-MD-00573
Engineering Model
EM
Calibrations
LAT-TD-01588
Simulations
Databases
LAT-TD-00582
LAT-TD-00578
LAT-TD-01593
LAT-MD-00575
LAT
LAT-MD-00613
Interfaces
LAT-TD-00571
LAT-TD-01340
LAT-TD-01590
SAS responsibility
LAT-TD-00580
LAT-TD-00573
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
Document: LAT-PR-03213-01
Section 7.1 Pre-launch Operation and Calibration
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
Level III Documents - Contents
Co owned with Project Scientist
•
LAT-MD-00446 - SVAC Plan
–
–
–
–
Instrument Calibrations
SVAC Compliance
Pre Launch Test Matrix
Post Launch Test Matrix
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
Document: LAT-PR-03213-01
Co owned with Systems Engineering
•
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
Section 7.1 Pre-launch Operation and Calibration
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
Level IV Technical Documents – Contents
•
Test Plan/Results
– LAT-MD-00573 – SVAC EM Plan
•
Using Engineering Model as an example
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
•
•
Calibrations
– LAT-TD-01588 – Calibration Algorithms for the Engineering Model
•
•
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 calibration algorithms developed in conjunction with SAS and subsystems
Simulations
– LAT-TD-00582 – EM Geometry for the Monte Carlo Simulation
•
•
Describes the results and how requirements were met
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
Document: LAT-PR-03213-01
Section 7.1 Pre-launch Operation and Calibration
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
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 I&T
• 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
Document: LAT-PR-03213-01
Section 7.1 Pre-launch Operation and Calibration
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
Data Analysis Chain
In the future the FSW
Filter will go in here
SAS/ONLINE
EM
EBF
Online
Analysis tools
online
scripts
Converter
ROOT tree
Files
(digi)
SAS
Recon
Calibration
scripts
Calibration
Constants
ROOT tree
Files
(recon)
SAS
User Interface
“GENERAL”
USER
Document: LAT-PR-03213-01
ROOT ntuple
files
SAS
Converter
IDL
Structures
Section 7.1 Pre-launch Operation and Calibration
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
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
Document: LAT-PR-03213-01
Section 7.1 Pre-launch Operation and Calibration
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
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)
– I&T 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
Document: LAT-PR-03213-01
Section 7.1 Pre-launch Operation and Calibration
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
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
Document: LAT-PR-03213-01
Section 7.1 Pre-launch Operation and Calibration
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
EM Ground Calibration Set-up
Cosmic Background
Gammas:66% 17.6 MeV Not a monochromatic beam!
34% 14.6 MeV, FWHM = 1.5 MeV
+
CAL
TKR
lots of electrons
Beam pipe
Electrons are produced by gamma conversions in the iron shield in front of the accelerator
Document: LAT-PR-03213-01
Section 7.1 Pre-launch Operation and Calibration
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
CAL Energy Spectrum
400
Preliminary
Photon Source OFF
From
Gary Godfrey
300
200
100
0
1
10
100
1000
2500
Photon Source ON
2000
Mostly photons
1500
1000
500
0
1
Document: LAT-PR-03213-01
10
100
Energy (MeV)
1000
Section 7.1 Pre-launch Operation and Calibration
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
Source Calibration
Preliminary
From
Gary Godfrey
Expect two energy lines
Document: LAT-PR-03213-01
Section 7.1 Pre-launch Operation and Calibration
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
Flux Measurement
Preliminary
9% of the of photons produced by the source are measured by the EM
From
Gary Godfrey
Extrapolation to Photon Source
Top TKR face
10% error is dominated by
the knowledge on the
BGO position
EM
EM Rec Direction cosine
In 0.02 bins
1200
N
 EM  (0.02  2 ) sr  0.093  0.01
N BGO 1152 s 13.35Hz


(0.15) sr
 BGO


t
 7

pipe

Document: LAT-PR-03213-01
 
 9
 45  
cos
 

 180  

BGO
(6cm) 2  4  e

4  (21.84cm) 2
Section 7.1 Pre-launch Operation and Calibration
 0.15
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
Energy Measurement
Operational Settings
IDs are described in LAT-MD-00446
Perform C18,C19,C20,C22,C23,C24 to
establish baseline for data taking
Raw spectrum of individual crystals
ROOT tree
Files
(digi)
Perform Calibrations
C14,C15,C16,C18 on each crystal
Calibration
Constants
ROOT tree
Files
(recon)
ROOT ntuple
files
Produce Energy Calibrated
Spectrum using all crystals
Calibrations
Use Data Analysis Cuts and VDG
Flux Calibration to obtain final
spectrum
Data Analysis
Document: LAT-PR-03213-01
Section 7.1 Pre-launch Operation and Calibration
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
EM Energy Spectrum (VDG DATA)
Preliminary
Event selection: nTkrTracks>=1 && zDir < -0.9 (25 deg from vertical) && maxCal>4MeV
From
Xin Chen
Expected  Spectrum
Delta function (17.6 MeV)
Breit-Wigner (mean 14.5,
width=1.5MeV)
Energy (MeV)
Document: LAT-PR-03213-01
Section 7.1 Pre-launch Operation and Calibration
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
Energy Spectrum (VDG MC)
Preliminary
Event selection: nTkrTracks>=1 && zDir < -0.9 (25 deg from vertical) && maxCal>4MeV
From
Xin Chen
Events converted in top layer of
Tracker only
Expected  Spectrum
Delta function (17.6 MeV)
Breit-Wigner (mean 14.5,
width=1.5MeV)
Energy (MeV)
Document: LAT-PR-03213-01
Section 7.1 Pre-launch Operation and Calibration
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
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, I&T and LAT Collaboration tools for
instrument and sky simulations to address needs of firstyear operations
– Develop better communications across interfaces and
sharpen calibration requirements
Document: LAT-PR-03213-01
Section 7.1 Pre-launch Operation and Calibration
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GLAST LAT Project
ISOC Peer Review - March 2, 2004
Summary
• Lessons Learned
– The I&T/SVAC group will revisit all EM technical issues to
ensure a successful LAT integration. I&T/SVAC will
participate in the planning process to build the
infrastructure required for the SOG during the I&T
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)
Document: LAT-PR-03213-01
Section 7.1 Pre-launch Operation and Calibration
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