Transcript Document
Detection and
measurement of g rays
with the AMS02 detector
Simonetta Gentile
Università di Roma La Sapienza, INFN
on behalf of AMS Collaboration
Simonetta Gentile
XX ECRS ,Lisbon, 5th September, 2006
Outline
AMS detector
g detection performances:
• Energy resolution
• Angular resolution
Physics: Dark matter g
• Minimal Supersymmetric Standard Model
Conclusions
Simonetta Gentile
XX ECRS ,Lisbon, 5th September, 2006
The Alpha Magnetic Spectrometer
•Designed to take data on
International Space Station
for more than 3 years.
• Full assembled in 2008
•Study of charged
particles and nuclei with
rigidity 0.5 GV– few TV
• Direct search for
antimatter (antihelium)
Indirect search for
Total statistics expected above 10 10
events
Dark Matter .
Simonetta Gentile
XX ECRS ,Lisbon, 5th September, 2006
Dimensions 3m x 3mx3m,7 t
Large acceptance ~ 0.5m2sr.
• Transition Radiation
Detector
• Time of Flight
scintillator counters
• 8 layers of Si strips on
5 supporting planes in
superconducting
magnet
M.L. Arruda
• Rich Imaging Poster
Cerenkov detector
• Electromagnetic
calorimeter
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Simonetta Gentile
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Superconducting
Magnet
Flux Return Coils
B
B
Dipole
Coils
He Vessel
2500 Liters Superfluid He
BL2 = 0.9 Tm2
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Silicon Tracker
•Rigidity (DR/R < 2% up 20
GeV Protons) with Magnet
•Signed Charge (dE/dx)
•8 Layers in 5 planes, ~6.7m2
•Pitch (Bending): 110 mm
(coord. res. 10 mm )
•Pitch (Non-Bending): 208mm
(coord. res. 30 mm )
•Charge magnitude up Z ~ 26
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Electromagnetic Calorimeter
3D sampling calorimeter
p
e
•9 superlayers of 10 fiber/lead
planes each alternate in x and y
scintillating fibers viewed by PMT
• 16.4 X0 radiation length
• Measure energy (few %
resolution) and angle (1° - 0.5°
angular resolution) of g, e+,e10-3 p Rejection with 95% e Efficiency Via Shower Profile
1 GeV - 1 TeV
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Electromagnetic Calorimeter
ECAL
(E)/E ~ 3% @ 100 GeV e-
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Photons in AMS:
Two complementary modes
Conversion mode: g conversion
In upstream layers of the detector
Criteria:very small invariant mass, no TRD
Activity
Simonetta
Gentile in top layer, no particle activity
XX ECRS ,Lisbon,in
5ththe
September,
rest of2006
detector
Single photon mode: detection
In the electromagnetic calorimeter.
Criteria: “electromagnetic shape”
No activity in the rest of detector
Performances g-rays
detection
E/E~ 3% @100 GeV
g e+ + eg EM Shower
2 complementary
modes for
6%
photon detection
3%
Single Photon Mode
g EM Shower
θ ~ 0.02 o @100 GeV
1.0o
0.02o
g EM Shower
g e+ + e-
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Conversion Mode
g e+ + e-
Performances g-rays
detection
Effective Area of Tracker and ECAL
Tracker
Tracker
ECAL
ECAL
Cos(incident angle)
Acceptance ECAL (TRK) ~ 5 (3)·10-2 m2·sr from 10 GeV.
Proton rejection 105 ; e -Simonetta
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Test beam (conversion mode)
• Test beam with electrons (producing g up to 7 GeV).
• Dominant systematic multiple scattering of electrons
Simonetta Gentile
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g Origin
Energy range : 1-300 GeV
Sources in scope of AMS:
Galactic : pulsars, nebulas (VELA, CRAB,…)
Extra-Galactic : GRBs
Diffuse g emission : interaction of Charged
rays with galactic medium produce g (0)
Dark Matter
R. Pereira
Poster
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Cosmic Ray Fluxes
Cosmic Rays Composition :
AMS ~1/s
AMS ~1/hour
AMS ~1/day
Number of particles inside geometrical acceptance
( assuming 0.45 m2sr )2.8
p : 88 %
He nuclei : 9 %
e- : 2 %
g : < 1%
Standard CR spectra follows
a "power law"
E- with = 2-3
DM signal : exponential cutoff in the spectra
Simonetta Gentile
XX ECRS ,Lisbon, 5th September, 2006
g rays
EGRET map Eg>100 MeV
3C279
Cygnus
Region
Vela
Geming
a
Crab
Cosmic
Ray
Interaction
s
With ISM
PSR B170644
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LM
PKS 0208- C
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512
PKS
0528+134
AMS exposure to galactic g
Revolution : 90’
51º latitude
Calorimeter mode (geom. acc.= area x t obs)
Field of View : 23º
GC : ~ 15 days
Conversion mode (sel. acc.)
Larger Field of view: 43⁰
GC : ~ 40 days
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Astrophysical g sources
AMS expectations
Measurements and model
prediction for diffuse g rays
Simonetta Gentile
from central part of galaxy
g rays emission from Vela Pulsar
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Dark Matter
One of the most popular candidates for Dark matter is the
neutralino 0, the Lightest Supersymmetric Particle
(LSP), neutral, weak-interacting and stable in R-parity
conserving SUSY models.
NOT YET OBSERVED!
~
~
~0
~ 0 Mixture of superpartners of
~
0
1 a0Bb0W c0H1 d0H2
Higgs boson and W-boson and Z/g
bosons (B)
• Direct detection – elastic interaction on nucleus (CDMS,
DAMA, EDELWEISS)
Indirect detection
- Neutralino annihilation
0101 qq , W+W-, ZZ, ...
p ,D , gSimonetta
(continuum)
, e+
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Simonetta Gentile
XX ECRS ,Lisbon, 5th September, 2006
AMS
Gamma rays:
They are originated either from annihilation into a final
state containing Zγ or γγ (line signal) or from the decay of
other primary annihilation products (continuum signal).
Positrons:
Primarily from the decay of gauge bosons (e.g.,W+W-) as
primary annihilation products; or from heavy quark/lepton
decay
Antiprotons and antideuterons:
Production in WIMP annihilations by hadronization of
quark and gluon subproducts.
Balloons
Possible detectable products from: xx with
small physical backgrounds
g ray telescopes
and satellites
Indirect searches with AMS:
detection channels
Dark Matter - g ray case
Detection rate (source) :
g
• source
Ng v
m2
2 (r) dl() d
LoS
Astrophysics
SUSY
D M : g Galactic Centre (G. C.)…..
Nuclear recoils in
the dense center
g r0 a
r
Mass density
~(r) ~(r0 ) 0
r
r a Profile in our Galaxy
NFW : Navarro-Frenk-White (, , g) = (1, 2, 1)
Moore et al. : (, , g) = (1, 1.5, 1.5)
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Gamma sensitivity to different DM halo
profiles
B
B
Gamma rays
Many experiments will be covering the little known 1-300 GeV range in the next decade.
Case considered: Galactic center treated as point source. Favorable conditions to detect or
exclude AMSB scenarios; benchmark points of parameter space accesible in case of
cuspy profile as well as several KK candidates.
MSSM = Minimal SuperSymetric Model
mSUGRA = Minimal SUGRA model
A.Jacholkwska et al. Astro-ph/0508349,
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SUGRA
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2006= SuperGravity grand unified models
Phys. Rev D.74 vol 2
CONCLUSIONS
AMS02 is magnetic spectrometer on International Space
Station, ready in 2008:
• Large Acceptance
• Long term operation
AMS02 will provide:
Precise Cosmic Ray elemental and isotopic fluxes in a wide
energy range
Direct search for antimatter (antihelium)
Indirect search for Dark Matter (positrons, antiprotrons,
gamma).
Good g performance detection through conversion and and
calorimetric mode:
Angular resolution under ~3º (~0.1º) over 10 GeV.
Energy resolution ~3 % Simonetta
over 10Gentile
GeV
XX ECRS ,Lisbon, 5th September, 2006
CONCLUSIONS
Using Si-Tracker and EM Calorimeter, AMS-02 will
provide new g measurements in the range
1-300 GeV .
AMS-02 will study several galactic and extragalactic g
sources as Pulsars, GRBs…
(At least) constraints in various Cold Dark Models will be
provided.
Simonetta Gentile
XX ECRS ,Lisbon, 5th September, 2006
g-rays - AMS vs. GLAST
Similarities: Silicon for Tracker, Coverage
1-100 GeV
GLAST: quasi-independent detector
operation, charged particle vetoing,
conversion-optimized
Simonetta Gentile
XX ECRS ,Lisbon, 5th September, 2006