GLAST LAT Project
Gamma-ray Large Area
Space Telescope
S. Ritz
DOE Mini-review 12 October 2004
Introduction
S. Ritz
Technical and
Production Status
L. Klaisner
Instrument Science
Operations Center
Plans
R. Cameron
Project Status,
Cost and Schedule
L. Klaisner
1
GLAST LAT Project
DOE Mini-review 12 October 2004
Why study g’s?
Gamma rays carry a wealth of information:
– g rays do not interact much at their source: they offer a direct
view into Nature’s largest accelerators.
– similarly, the Universe is mainly transparent to g rays: can probe
cosmological volumes. Any opacity is energy-dependent.
– conversely, g rays readily interact
in detectors, with a clear signature.
Large Area
– g rays are neutral: no complications
Telescope
due to magnetic fields. Point
(LAT)
directly back to sources, etc.
Two GLAST instruments:
LAT: 20 MeV – >300 GeV
GBM: 10 keV – 25 MeV
Launch: February 2007
S. Ritz
GLAST Burst Monitor
(GBM)
2
GLAST LAT Project
DOE Mini-review 12 October 2004
GLAST Science
GLAST will have a very broad menu that includes:
•
•
•
•
•
•
•
Systems with supermassive black holes
Gamma-ray bursts (GRBs)
Pulsars
Solar physics
Origin of Cosmic Rays
Probing the era of galaxy formation
Discovery! Particle Dark Matter? Other relics from the Big Bang?
Testing Lorentz invariance. New source classes.
Huge increment in capabilities.
GLAST draws the interest of both the the High Energy Particle
Physics and High Energy Astrophysics communities.
GLAST is the highest-ranked initiative in its category in the
National Academy of Sciences 2000 Decadal Survey Report.
S. Ritz
3
GLAST LAT Project
DOE Mini-review 12 October 2004
GLAST LAT High Energy Capabilities
EGRET on GRO firmly established the field of high-energy gamma-ray
astrophysics and demonstrated the importance and potential of this energy
band.
GLAST is the next great step beyond EGRET, providing a huge leap in
capabilities:
• Very large FOV (~20% of sky), factor 4 greater than EGRET
• Broadband (4 decades in energy, including unexplored region E > 10 GeV)
• Unprecedented PSF for gamma rays (factor > 3 better than EGRET for
E>1 GeV)
• Large effective area (factor > 5 better than EGRET)
• Results in factor > 30-100 improvement in sensitivity
• Much smaller deadtime per event (25 microsec, factor >4,000 better than
EGRET)
S. Ritz
• No expendables
long mission without degradation
4
GLAST LAT Project
DOE Mini-review 12 October 2004
Sources
EGRET 3rd
Catalog: 271
sources
S. Ritz
5
GLAST LAT Project
DOE Mini-review 12 October 2004
Sources
LAT 1st Catalog:
>9000 sources
possible
S. Ritz
6
GLAST LAT Project
DOE Mini-review 12 October 2004
Anticenter Region
simulation: S. Digel
S. Ritz
7
GLAST LAT Project
DOE Mini-review 12 October 2004
Overview of LAT
g
• Precision Si-strip Tracker (TKR)
18
XY tracking planes. Single-sided silicon
strip detectors (228 mm pitch) Measure
the photon direction; gamma ID.
Tracker
• Hodoscopic CsI Calorimeter(CAL)
Array of 1536 CsI(Tl) crystals in 8 layers.
Measure the photon energy; image the
shower.
• Segmented Anticoincidence Detector
(ACD) 89 plastic scintillator tiles.
Reject background of charged cosmic
rays; segmentation removes self-veto
effects at high energy.
• Electronics System Includes flexible,
robust hardware trigger and software
filters.
ACD
[surrounds
4x4 array of
TKR towers]
e+
e–
Calorimeter
Systems work together to identify and measure the flux of cosmic gamma
rays with energy 20 MeV - >300 GeV.
S. Ritz
8
GLAST LAT Project
DOE Mini-review 12 October 2004
GLAST LAT Collaboration
United States
•
•
•
•
•
•
•
•
California State University at Sonoma
University of California at Santa Cruz - Santa Cruz Institute of Particle Physics
Goddard Space Flight Center – Laboratory for High Energy Astrophysics
Naval Research Laboratory
Ohio State University
Stanford University (SLAC and HEPL/Physics)
University of Washington
Washington University, St. Louis
France
PI: Peter Michelson (Stanford & SLAC)
•
~120 Members (including ~60 Affiliated
Scientists, plus 20 Postdocs, and 25
Graduate Students)
IN2P3, CEA/Saclay
Italy
•
INFN, ASI
Japanese GLAST Collaboration
•
•
Hiroshima University
ISAS, RIKEN
Swedish GLAST Collaboration
•
•
S. Ritz
Royal Institute of Technology (KTH)
Stockholm University
LAT Project is a partnership between
NASA and DOE, with international
contributions from France, Italy, Japan and
Sweden.
Managed at Stanford Linear Accelerator
Center (SLAC).
9
GLAST LAT Project
DOE Mini-review 12 October 2004
Highlights of Recent Activities
•
•
•
•
S. Ritz
Successful Mission CDR!
Collaboration meeting at SLAC 27-30 September
– Instrument test data analysis workshop
– Hardware and software status
– Science organization and planning
– Operations planning
– Cooperation with other experiments (multi-wavelength planning)
– GeV-TeV Symposium (joint with Mission Science Working Group)
Senior Scientist Advisory Committee
– year 1 data release plan proposal
– new members
– performance updating
– science planning policies
Data Challenges
– very successful DC1; planning/working now for DC2
10
GLAST LAT Project
DOE Mini-review 12 October 2004
Instrument Test Data Analysis
• A suite of detailed test data-taking runs is being defined for each
stage of the build. Using the data, there are two basic categories
of data analysis:
– (mostly) automated, basic go/no-go tests. These are done by
I&T, with ~instant result turn-around to support the schedule.
– this work: more detailed analyses using (mostly) the same
data. A key opportunity to look for more subtle, sophisticated,
and detailed effects:
» To uncover and quantify any instrumental effects early
that could have an impact on science data analysis &
feedback realism into the Monte Carlo
» Are there additions to the go/no-go test suite?
» To apply reconstruction algorithms to real data
» To start the work that will evolve in the Instrument
Science Operations Center (ISOC)
» To grow a group to participate in the beam tests analysis
effort (after instrument delivery)
– Relies on strong collaboration-wide support. First workshop in
June, second in September. Regular meetings via vrvs.
S. Ritz
11
GLAST LAT Project
DOE Mini-review 12 October 2004
Operations Phase LAT Organization Chart
 Dr. Rob Cameron appointed LAT
Instrument Science Operations Center
manager
– extensive operations experience at
SAO / Chandra X-ray Center
 LAT Collaboration Science Groups (LSGs)
responsible for collaboration’s analysis
and extraction of science results from LAT
data
– 11 Science Groups plus Multi-l
Coordination Working Group
– each science group to have 2 coleads; with one resident at Stanford
– day-to-day efforts coordinated by
Analysis Coordinator, also resident at
Stanford-SLAC
S. Ritz
12
GLAST LAT Project
DOE Mini-review 12 October 2004
Science Analysis Groups
 process started for updating the groups
 groups organized around expected collaboration publications, particularly
during the 1st year all-sky survey phase; each group should have responsibility
for 2-3 key (category 1) papers.
Science Analysis Groups
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Catalogs
Galactic Diffuse and Molecular Clouds
Extragalactic Diffuse
Blazars and Other AGNs
Other Galaxies (including clusters)
Pulsars, SNRs, and Plerions
Unidentified Sources and Population Studies
Dark Matter and Exotic Physics
Gamma-Ray Bursts
Solar System Sources
Calibration and Analysis Methods
LAT Multiwavelength Observation Coordination Group
S. Ritz
13
GLAST LAT Project
DOE Mini-review 12 October 2004
Space at SU – SLAC for ISOC and Analysis efforts
Fred Kavli Building at SLAC – KIPAC
(Kavli Institute of Particle Astrophysics and Cosmology)
Roger Blandford, Director
Steve Kahn, Deputy Director
S. Ritz
14
GLAST LAT Project
DOE Mini-review 12 October 2004
Space at SU – SLAC for ISOC and Analysis efforts
new building on campus
- replacement space for HEPL
- campus part of KIPAC
S. Ritz
15
GLAST LAT Project
DOE Mini-review 12 October 2004
GeV-TeV Symposium 30 September at SLAC
LAT Team and Mission
Science Working Group
have held ~annual joint
science symposia on a
wide variety of topics.
This year:
GeV-TeV Astrophysics in
the GLAST Era
+ Very useful workshop
discussion about
cooperation among
experiments!
S. Ritz
16
GLAST LAT Project
DOE Mini-review 12 October 2004
Data Challenges
• DC1 early alpha-testing. “End-to-end” testing of analysis software.
• Provide feedback on what works and what is missing from the data
formats and tools.
• Walk before running: design a progression of studies.
– DC1. Modest goals. Contains most essential features of a data
challenge.
• 1 simulated day all-sky survey simulation
• find the sources, including GRBs
• a few physics surprises
• exercise:
– exposure, orbit/attitude handling, data processing pipeline components,
analysis tools
– DC2 in 2005. More ambitious goals. ~One simulated month.
• toy one-month catalog.
• add source variability (AGN flares, pulsars). add GBM.
– DC3 in 2006. Support for flight science production.
S. Ritz
see http://www-glast.slac.stanford.edu/software/Workshops/Feb04DC1CloseOut/coverpage.htm
17
GLAST LAT Project
DOE Mini-review 12 October 2004
The DC1 Sky
One day all-sky survey. Generated E>20 MeV.
E>100 MeV
with some other cuts
for illustration
Lots to analyze!
A few surprises to find…
S. Ritz
18
GLAST LAT Project
DOE Mini-review 12 October 2004
Data Challenge 1 Sky
3C273
isotropic diffuse
3C279
Sources – 3EG and more, with a twist
S. Ritz
a number of physics
surprises in the DC1
data, including:
• 110 GeV gamma-ray
line source at the
galactic center
• new source populations
• all surprises were
detected at some level!
19
GLAST LAT Project
DOE Mini-review 12 October 2004
LAT Data Challenges: Updated Plan for DC2
DC2, based on lessons from DC1
S. Ritz
– 1 simulated month of all-sky survey gammas (backgrounds: see next
slide)
– key sky addition: source variability
• AGN variability, including bright flares, quiescent periods
• expand burst variety. Include GBM.
• pulsars, including Gemingas, w/ orbit position effects.
– more realistic all-sky attitude profile
– background rate varies with orbit position
– more physics surprises
– update geometry (including s/c); add nominal hardware problems (and
misalignments?); add deadtime effects and corrections
– Analysis Goals:
• produce toy 1-month catalog
• try out transient releases and quicklook analyses, monitor sources
• point source sensitivity and localization studies
• try first systematic pulsar searches (timing!)
• diffuse analyses
• recognize simple hardware problems (connect with ISOC)
• benchmark processing times, data volume, data transfers.
20
GLAST LAT Project
DOE Mini-review 12 October 2004
Summary
• Strong involvement of physicists at all levels of the project
– ready for earliest instrument test data analysis
– strategizing/prioritizing as issues arise
– getting ready early to do great science via data challenges
and updating organization of science groups
– increasing cooperation with other experiments, helping to
lead the way.
• Very strong support by SLAC of the international science
collaboration and the management of the fabrication.
• The hardware is coming! Great excitement in a team that
continues to grow even closer and stronger.
S. Ritz
21