Transcript SHOOT TO THE LECTURER IS STRICKLY FORBIDDEN!!!

Omar Tibolla. ISAPP.
Belgirate (Italy) 30 June - 9 July 2005
Large Area Telescope (LAT)
Gamma-ray Large Area Space
Telescope
-France
-Germany
-Italy
-Japan
-Sweden
-USA
Energy Range 10 keV-300 GeV.
GLAST :
GLAST Burst Monitor
(GBM)
- An imaging gamma-ray telescope
(LAT)
- A second instrument for the study
of Gamma Ray Bursts (GBM).
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:

TRACKER
-the TRACKER (TKR): 18 layers in each tower
-Tungsten converters (1.08 χ0 : 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
e+
(~ms).
ANTICOINCIDENCE
SHIELD
e–
CALORIMETER
Omar Tibolla. ISAPP.
Belgirate (Italy) 30 June - 9 July 2005
EGRETCompared LAT
LAT Quantity
Specifications and Performance
with(Minimim
EGRET Spec.)
Energy Range
20 MeV - 30 GeV
20 MeV - 300 GeV
Peak Effective Area
(after background rejection)
1500 cm²
> 8000 cm²
Field of View
0.5 sr
> 2 sr
Angular Resolution
5.8° (100 MeV)
< 3.5° (100 MeV)
< 0.15° (>10 GeV)
Energy Resolution
10%
< 10%
Deadtime per Event
100 ms
< 100 μs
Source Location Determination
15'
< 0.5'
Point Source Sensitivity
~ 10-7 cm-2 s-1
< 6 x 10-9 cm-2 s-1
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
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
< 10 keV - > 25 MeV
Field of View
4π sr
all sky not
occulted by the Earth
Energy Resolution
< 10%
< 10%
< 15 μs
Deadtime per Event
Burst Sensitivity
0.2 cm-2 s-1
< 0.5 cm-2 s-1
GRB Alert Location
~ 25°
< 15°
GRB Final Location
1.7°
< 1.5°
Omar Tibolla. ISAPP.
Belgirate (Italy) 30 June - 9 July 2005
GAMMA-RAY BURSTS
PULSARS
Scientific
purposes
EXTRAGALACTIC BACKGROUND LIGHT
And other extremely important features are the
COMPLEMENTARITY WITH GROUND-BASED GAMMARAY
TELESCOPES
and that
study the Universe
COSMIC
RAYS AND
NEWGLAST
PARTICLEwill
PHYSICS
INTERSTELLAR
EMISSION REGIONS OF EM SPECTRUM.
in UNEXPLORED
UNIDENTIFIED EGRET SOURCES
SOLAR FLARES
AGN/BLAZARS
Omar Tibolla. ISAPP.
Belgirate (Italy) 30 June - 9 July 2005
Background rejection with Classification Trees using R .
-Signal file (ag-v3r3p7-merituple-prune20031218-fulltup.root)
722594 γ (power law, isotropic 4)
-27 BKG files (ntuple_prune*.root)
5551326 events : p, e- , e + , albedo γ
A day of “real” data (part of Data Challenge 1).
Before bkg rejection with R CT was made in a single step:
0signal
I tried to do it in 2 steps:
1bkg
1º: separate  from charged particles.
2º: separate with the same method signal  and albedo 
0 charged particle
1 γ
2 γ sign
3 γ albedo
Omar Tibolla. ISAPP.
Belgirate (Italy) 30 June - 9 July 2005
Conclusions
-Big improvements using matrix of costs, expecially in high energy bins.
-Problems with second steps.
Omar Tibolla. ISAPP.
Belgirate (Italy) 30 June - 9 July 2005
Conclusions (2)