Transcript AMS-02 - Istituto Nazionale di Fisica Nucleare

AMS : A COSMIC RAY OBSERVATORY
Alpha
Magnetic
Spectrometer
ON THE INTERNATIONAL SPACE STATION
Carlo Bosio
INFN - Roma ‘La Sapienza’ University
Susy 2004 - 19 June 2004
AMS 02
TRD Gas
Cont.System
Outline:
• The Experimental Apparatus
• General Characteristics
• Detector Component
• AMS Physics Program:
• particles, N, g
• AntiMatter Search
• Dark Matter
Electronics
3 x 3 x 3 m3
7000 Kg
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AMS 02 Detector
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AMS 02: General characteristics:
Mechanical and geometrical characteristcs
• Minimum amount of matter (X0) before ECAL
• Acceptance 0.5 m2.Sr -> anti-He search
• Velocity measurement Db/b = 0.1 % to distinguish 9Be,10Be,
3He,4He isotopes.
• Rigidity R= pc/|Z|e (GV) proton resolution
20% at 0.5 TV and Helium resolution of 20% at 1 TV.
• Antihelium/Helium identification factor 1010.
Multiple and independent measurements to reach performances required :
• |Z| measured from Tracker, RICH, TOF.
• Sign of charge Z measured from tracker (8 points).
• Velocity b measured from TOF, RICH.
• Hadron/electron separation from TRD, ECAL.
Detector requirements :
• Suppress proton background 10 -6
• Tracking up to 1 TV
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AMS 02: General Characteristics
Experiment in International Space Station
(--> Constraints for launch and space):
- Environment (day/night: DT~100oC) ---> Thermal
- Launch: --->Vibration (6.8 G RMS) and G-Forces(17G)
- Limitation : Weight (14 809 lb) and Power (2000 W)
- Vacuum: < 10-10 Torr ---> Cooling..
- Reliable for more than 3 years ---> Redundancy
- Radiation: Ionizing Flux ~1000 cm-2s-1
- Orbital Debris and Micrometeorites
- Must operate without services and human intervention
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AMS 02: Detector
Transition Radiation Detector : p+/e+ < 10 -2 10-300 GeV
20 Layers Fleece +5248 6mm Straw Drift Tubes (Xe/CO2)
Time Of Flight Upper 1,2 :
scintillators, st =~120ps
Superconducting Magnet :
BL2 = 0.85 Tm2 V=0,6m3
trigger, b
Rigidity up to 1 TeV
charge separation, b
Tracker (8 layers) :
Charge separation
3double +2single sided silicon strips, 6m2
Time of Flight Lower 3,4
scintillators,Dt =~120ps
p+/e+ >3s <2 GeV
RICH :
b,Z2 He3,He4,B,C A<27,Z<28
Radiator (Aerogel,NAF )
3 s 1 - 12 GeV
Electromagnetic Calorimeter :e,g to 1 TeV, p+/e+ < 10 -4
Lead+scint. Fibers, 324 R7600 PMT’s (4 pixels)
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AMS 02 : Star Tracker
ASTC1
ASTC0
ASTC1
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ASTC0
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AMS: A TeV Magnetic Spectrometer
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AMS Physics program
•
Precision measurement on charged
particles and nuclei:
e±, g, p± , 3,4He, B, C, 9, 10Be,
elements Z<25. GeV – TeV range
•
High Energy Cosmic Gamma ray
astrophysics (GRB, SN,..)
•
Direct search for cosmic antimatter
(antihelium - sensitivity 10-9 )
•
Indirect search for non barionic Dark
Matter
•
Exotics (strangelets, mquasars,..)
•
Total statistic expected > 1010 events.
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AMS: Completeness of g, p, _e+
AMS will have the unique possibility to
measure in space, with the same detector
_
g, anti-p, e+ spectra
it will be the only experiment in space able to make an extensive test
of the neutralino based dark matter scenario.
No other detectors, planned or operating will be able to do this
measurements Cosmic Rays Fluxes
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Cosmic anti matter
The Primordial Antimatter content of the universe is unknown
(..if there is any at all…)
Cobe excludes < 20 Mpc
• Single anti-He or anti-C
nucleus in CR is a strong
evidence of anti matter
domains or anti stars
Presently, no antinucleus Z>2
has ever been found in CR
• Very Large statistics of
primary cosmic rays on a
large energy/rigidity range
• Particle Identification
including charge sign
reconstruction and
redundancy
A high energy physics detector in space for a long period is necessary
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_
AMS: Cosmic Antimatter
PRIMORDIAL ANTIMATTER
He anti-He
Comparison AMS-01 AMS-02
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He
PRIMORDIAL ANTIMATTER
Limit on antihelium
1 year data taking
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Indirect Dark Matter Search
• Universe Matter budget ~ 95 % is Dark  non baryonic
• SUSY provides an excellent WIMP candidate – neutralino : 01
mixture of the superpartners of the neutral Higgs and EW gauge bosons
Indirect
limits
from LEP:
M>40GeV
0101  qq- , W+W-, H+H-, ...  p, e, n, p-, anti-D, g, e+,
lost
(identifying particles)
• Completeness of AMS-02: (all the four possible complementary channels)
–
–
–
–
p- : Excess at High Energy ( > ~ 5GeV)
D- : Excess at E < 1 GeV
e + : Structure in Spectra above few GeV
g : Energy Spectra differ from “power laws”,
or g line detection 0101  gg, Zg (1st loop)
Measurements possible because background very well known
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Indirect  detection
  < sv > 2/m2  g(propagation)
SUSY Parameters dependence
< sv >
(st times relative neutralino’s velocity)
tanb=50
tanb=5
m~ 0.4 m1/2
Coupling and mass spectrum
 Lower sensitivity for heavier  masses
W. de Boer et al, hep-0309029

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Indirect  detection
  < sv > 2/m2  g(propagation)
Astrophysics/Cosmology dependence:
W. de Boer et al, hep-0309029
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Clumpiness

” Dark” halo profile (NWF,
CR&M,etc) 

Propagation parameters
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DM searches with positrons
e+
Sensitivity to exotic flux greater than 10-7 E2(cm.s.sr.GeV)-1
Precise measurement of the energy spectrum after 3
years
~1% stat error at 50 GeV.
~30% stat error at 300 GeV
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rejection e+/p > 105
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DM searches with positrons
e+
Heat Data : a bump in energy at 7 GeV, no standard astrophysical interpretation of
e+/e- energy distribution
 Precise data extended to higher energies will be provided by AMS
MSSM simulation for AMS-02 need high “boost factors”
m  130.3 GeV
m  336 GeV
Based on the work of E.A. Balts et al. 99 large boost factor needed
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DM searches with anti-protons
p
Prospects with AMS-02 after 3 years
Background rejection : p /p > 106 , e-/p 103-104
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Secondary anti protons flux
Up to 300 GeV
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p
DM searches with anti-protons
Background secondary p
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1)
M=964 GeV (4200)
2)
M=777 GeV (1200)
Sizable effects:
Primary p ,from  annihilations
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g
Dark Matter - g ray
Detection rate (source) :
g~
Ng sv
m2

SUSY
2 (r) dl() d
 los
Astrophysics
• diffuse D M : galactic as n , e+ , p-, D-, Direct Detection
extragalactic
• source D M : -
Galactic Centre (G. C.) of Milky Way
Nearby Spiral Galaxies : e. g. M31, M87, or clouds: LMC, SMC
Dwarf Spheroidals : e. g. DRACO
Globular Clusters :  - centauris, Palomar13
 Enhancement factors from cuspy halos, clumpiness or/and SBH
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AMS-02 g
g
Two complementary detection modes :
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g
AMS-02 g
108 cm2s
Field of View
One year sky coverage
*
*
ExtraGalactic g spectrum
ECAL + g stand-alone trigger
LMC
Exposure of the Galactic Center
*
*
AMS-02 3 Y measurements
Galactic diffuse g spectrum
TRD+Tracker
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g
AMS-02 g
Msugra results: Integrated flux from the Galactic Center in the
focus point, region for two NFW profile parametrizations
R0 = 8.0 kpc, r0 = 0.3 GeV/cm3, a = 20 kpc
R0 = 8.5 kpc, r0 = 0.4 GeV/cm3, a = 4 kpc
R0: distance earth - GC;
a: core radius
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r0: halo density at R0 :
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Susy DM: summary
g
AMS offers:
Precise measurements of all particle spectra
Measurements of Nuclei fluxes for propagation
model
Wide range of SUSY annihilation products.
Potential gain in sensitivity by combining them
Could provide benchmark data to validate models
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Conclusions
 AMS is a High Energy Physics detector in space foreseen to operate on the
ISS for 3 years
• Most of the sub-detectors will be ready by end 2004
• Detector integration in 2005
• Global Thermal-Vacuum test at ESA (Nordwijk, NL) end 2005 / beg. 2006
• Then AMS is ready for launch
 The cosmic rays, including gamma, will be measured with a high accuracy
from the GeV to the TeV range , to search for:
• Antimatter
• Dark Matter
• Cosmic Ray Fluxes and propagation
• High Energy g sources
 All the physics channels are measured in the same conditions and
simultaneously, which will give a strong constraint on models and increase the
potential of discovery. Unique opportunity to perform Dark Matter searches
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The End
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