Omar Tibolla. ISAPP. Belgirate (Italy) 30 June - 9 July 2005

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Omar Tibolla. ISAPP. Belgirate (Italy) 30 June -
9 July 2005
Gamma-ray Large Area Space Telescope -France
-Germany -Italy -Japan -Sweden -USA Energy
Range 10 keV-300 GeV. GLAST - An imaging
gamma-ray telescope (LAT) - A second instrument
for the study of Gamma Ray Bursts (GBM).
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Omar Tibolla. ISAPP. Belgirate (Italy) 30 June -
9 July 2005
The main instrument of GLAST is the Large Area
Telescope (LAT) a pair conversion telescope
Anticoincidence Shield (ACD) made of plastic
scintillator (Bicron-408) sensitive to charged
particles ACD is segmented to avoid self veto
from Calorimeter backsplash and also for
micrometeorites.
ACD contains 16 towers and each tower is divided
in two parts -the TRACKER (TKR) 18 layers in
each tower -Tungsten converters (1.08 ?0 78
prob) -2 orthogonal SSD planes of silicon
microstrip sensors for detecting the
electromagnetic shower -a CALORIMETER (CAL) of
CsI crystals dopped by Tl so the energy
deposited by the EM shower is converted in light
signal. CAL is characterized by fast decaying
fluorescent light (ns) and a long decaying
afterglow (ms).
TRACKER
CALORIMETER
ANTICOINCIDENCE SHIELD
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Omar Tibolla. ISAPP. Belgirate (Italy) 30 June -
9 July 2005
LAT Specifications and Performance Compared with
EGRET
Quantity EGRET LAT (Minimim Spec.)
Energy Range 20 MeV - 30 GeV 20 MeV - 300 GeV
Peak Effective Area (after background rejection) 1500 cm² gt 8000 cm²
Field of View 0.5 sr gt 2 sr
Angular Resolution 5.8 (100 MeV) lt 3.5 (100 MeV) lt 0.15 (gt10 GeV)
Energy Resolution 10 lt 10
Deadtime per Event 100 ms lt 100 µs
Source Location Determination 15' lt 0.5'
Point Source Sensitivity 10-7 cm-2 s-1 lt 6 x 10-9 cm-2 s-1
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Omar Tibolla. ISAPP. Belgirate (Italy) 30 June -
9 July 2005
The Glast Burst Monitor (GBM) will include two
sets of detectors -12 sodium iodide (NaI)
scintillators -2 cylindrical bismuth germanate
(BGO) scintillators The NaI detectors are
sensitive in the lower end of the energy range,
from a few keV to about 1 MeV and provide burst
triggers and locations. The BGO detectors cover
the energy range 150 keV to 30 MeV, providing
a good overlap with the NaI at the lower end and
with the LAT at the higher end.
Schematic layout of the 12 NaI and two BGO
detectors on the GLAST spacecraft
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Omar Tibolla. ISAPP. Belgirate (Italy) 30 June -
9 July 2005
GBM Specifications and Performance Compared with
BATSE
Quantity BATSE GBM (Minimum Spec.)
Energy Range 25 keV - 10 MeV lt 10 keV - gt 25 MeV
Field of View 4p sr all sky notocculted by the Earth
Energy Resolution lt 10 lt 10
Deadtime per Event lt 15 µs
Burst Sensitivity 0.2 cm-2 s-1 lt 0.5 cm-2 s-1
GRB Alert Location 25 lt 15
GRB Final Location 1.7 lt 1.5
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Omar Tibolla. ISAPP. Belgirate (Italy) 30 June -
9 July 2005
GAMMA-RAY BURSTS
PULSARS
EXTRAGALACTIC BACKGROUND LIGHT
Scientific purposes
And other extremely important features are the
COMPLEMENTARITY WITH GROUND-BASED GAMMA-RAY
TELESCOPES and that GLAST will study the Universe
in UNEXPLORED REGIONS OF EM SPECTRUM.
NEW PARTICLE PHYSICS
COSMIC RAYS AND INTERSTELLAR EMISSION
UNIDENTIFIED EGRET SOURCES
SOLAR FLARES
AGN/BLAZARS
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Omar Tibolla. ISAPP. Belgirate (Italy) 30 June -
9 July 2005
Background rejection with Classification Trees
using R .
-Signal file (ag-v3r3p7-merituple-prune20031218-fu
lltup.root)
722594 ? (power law, isotropic 4?)
-27 BKG files (ntuple_prune.root)
5551326 events
p, e- , e , albedo ?
A day of real data (part of Data Challenge 1).
Before bkg rejection with R CT was made in a
single step0?signal1?bkg
I tried to do it in 2 steps 1º separate
g from charged particles. 2º separate
with the same method signal g and albedo g
0? charged particle1? ? 2? ? sign
3? ? albedo
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Conclusions
Omar Tibolla. ISAPP. Belgirate (Italy) 30 June -
9 July 2005
-Big improvements using matrix of costs,
expecially in high energy bins.-Problems with
second steps.
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Conclusions (2)
Omar Tibolla. ISAPP. Belgirate (Italy) 30 June -
9 July 2005