Transcript EMStatus.ppt

GLAST LAT Project
I&T Meeting – Jan 20,2004
GLAST Large Area Telescope:
Gamma-ray Large
Area Space
Telescope
EM1 Data Analysis and Calibration
Summary Report
Eduardo do Couto e Silva
SU-SLAC
SVAC I&T Manager
[email protected]
650-926-2698
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I&T Meeting – Jan 20,2004
GLAST LAT Project
SVAC EM Requirements
The Engineering Model (EM1) was used to develop the necessary
infrastructure for future hardware tests. Requirements and goals
were described in the (“SVAC EM Plan” LAT-TD-00573)
– SVAC EM requirements
R
R
Develop infrastructure for TKR and CAL calibrations
Measure the energy spectrum of van de Graaff photons
– SVAC EM goals
R Exercise flexibility of geometry input for the Monte Carlo
simulations.
R Validate a preliminary set of Monte Carlo distributions
R Prototype energy resolution algorithm
 Prototype alignment algorithm
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I&T Meeting – Jan 20,2004
GLAST LAT Project
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
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ROOT ntuple
files
SAS
Converter
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IDL
Structures
I&T Meeting – Jan 20,2004
GLAST LAT Project
EM Calibrations
Present status: 3 months after the end of the data taking period
• TKR
R Determine Operational Thresholds
R Measure Electronic Gain
R Identify noisy and dead strips
R Characterize TOT
– Slope and intercept with charge injection
– Mean and width of distributions
• CAL
R Determine Operational Thresholds (HI, LO and zero
suppression)
R Measure pedestal and gains
– Identify noisy and dead logs
R Determine muon peak position and width
R Measure light Asymmetry, Attenuation, Yield
R Measure position resolution without TKR tracks
R Measure position resolution with TKR tracks
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GLAST LAT Project
I&T Meeting – Jan 20,2004
Calibrations – To do List
Calibration List derived from Level III document – SVAC EM Plan – LAT-MD-00446
SVAC ID
Description
Comments
C10
TKR Noisy Channels
EGSE
SAS
recon
C11
TKR Dead Channels
EGSE
SAS
recon
C12
TKR ToT Signal
EGSE
C13
TKR ToT Distribution
C14
PID?
Seen variations on channel by channel. Maybe used for particle ID
SAS
PID?
Maybe used as a cross check of C12
CAL Light Asymmetry
SAS
recon
Would like to change this to Energy Scale (MeV/ADC count)
C15
CAL Light Attenuation
SAS
recon
Measure muon peaks (includes effects from optical and electronic gains).
Function of position in a log. Investigating light taper model
C16
CAL Light Yield
EGSE
CI
C18
CAL Pedestals
EGSE
CI
C19
CAL Electronic Gain
EGSE
CI
Need to get information from online
C20
CAL Integral non-linearity
EGSE
CI
Need to get information from online
C22
CAL Noisy Channels
EGSE
C23
CAL Dead Channels
EGSE
CI
C24
CAL LO Discriminator
EGSE
CI
I&T has no experience, done by CAL only. Need to capture information for
offline
C25
CAL HI Discriminator
EGSE
CI
I&T has no experience, done by CAL only. Need to capture information for
offline
C26
CAL Zero-Suppress
Threshold
EGSE
CI
I&T has no experience, done by CAL only. Need to capture information for
offline
C27
Deadtime
EGSE
C29
TKR GTFE Threshold Scan
EGSE
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CI
Need to define noise level
I&T has no experience, done by CAL only. Need to capture information for
offline
SAS
recon
Need to define width characterization (rms vs sigma)
SAS
From pedestal widths. None observed in EM. Need to develop infrastructure
SAS
From pedestal widths. None observed in EM. Need to develop infrastructure
Measure overall deadtime as part of the functional test plan
CI
Need to capture information for offline including GTFE split
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I&T Meeting – Jan 20,2004
GLAST LAT Project
Calibration Infrastructure
Tasks
Lessons learned
R Develop code to create constants from the digi files
•Redefined output format as we learned more about the instrument
 Develop code to read constants into recon
•Modified reconstruction to allow calibrations without zero
suppression in the CAL
•Modifying reconstruction to read in ToT constants on channel per
channel basis
•Developing a scheme to capture the instrument configurations
necessary for MC validation and for reference during calibrations
 Configuration control
•Created cvs repository to keep the calibration code
•Developing process to version control creation of constants and to
transfer information from online whenever needed
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I&T Meeting – Jan 20,2004
GLAST LAT Project
Energy Measurement
Operational Settings
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
IDL
Structures
Use Data Analysis Cuts and VDG
Flux Calibration to obtain final
spectrum
Data Analysis
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I&T Meeting – Jan 20,2004
GLAST LAT Project
CAL Energy Spectrum
400
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
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10
100
Energy (MeV)
1000
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I&T Meeting – Jan 20,2004
GLAST LAT Project
Source Calibration
From
Gary Godfrey
Expect two energy lines
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I&T Meeting – Jan 20,2004
GLAST LAT Project
Flux Measurement
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

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 
 9
 45  
cos
 

 180  

BGO
(6cm) 2  4  e

4  (21.84cm) 2
10
 0.15
I&T Meeting – Jan 20,2004
GLAST LAT Project
Experimental setup
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
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I&T Meeting – Jan 20,2004
GLAST LAT Project
EM Energy Spectrum (VDG DATA)
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)
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I&T Meeting – Jan 20,2004
GLAST LAT Project
Energy Spectrum (VDG MC)
Event selection: nTkrTracks>=1 && zDir < -0.9 (25 deg from vertical) && maxCal>4MeV
Events converted in top layer of
Tracker only
From
Xin Chen
Expected  Spectrum
Delta function (17.6 MeV)
Breit-Wigner (mean 14.5,
width=1.5MeV)
Energy (MeV)
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I&T Meeting – Jan 20,2004
GLAST LAT Project
Documentation for EM2
We are now updating the following documents
 SVAC EM Plan – LAT-MD-00573
•Defines the SVAC requirements
 Calibration algorithms for the EM – LAT-TD-01588
•Describes Algorithms
•Describes Output Formats for the calibration data
 LAT SAS EM Calibration Infrastructure – LAT-TD-01340
•Describes the SAS database and how calibrations are used by the
offline code
 SVAC Database for the EM – LAT-TD-00578
•Describes how calibration data is stored in ORACLE for trending
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I&T Meeting – Jan 20,2004
GLAST LAT Project
Summary
Current status 3 months after the end of the data taking period
•
Calibrations
– We have met all calibration requirements
– Lessons learned on the infrastructure are now being implemented
for EM2
•
Data Analysis
– We have met the requirements for the measurement of the energy
spectrum
– In addition we met most of the goals for the EM1 including the
development of an algorithm for energy resolution, which is now
being documented and will be presented in detail in the near
future by Xin Chen for a group review
•
Documentation
– We have started updating all documentation relevant to EM2
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