The Alpha Magnetic Spectrometer on the International Space Station

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The Alpha Magnetic Spectrometer on the
International Space Station

• Carmen Palomares
• CIEMAT (Madrid)
• On behalf of the AMS Collaboration

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AMS is a magnetic spectrometer to be installed on
ISS (? 450 km) The aim of AMS is the direct
detection of primary cosmic rays below the knee
(NO UHECR) Determination of energy with high
resolution Large statistics Very good particle
identification
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AMS-02

• Large geometrical acceptance 0.45 m2 sr
• Long exposure 3 years
• Redundant measurements of the main
• parameters

• Operational conditions
• High vacuum
• High radiation levels
• Strong gradients of temperature
• -60C 40C
• Weight lt 7 Tm
• Acceleration 3g (6g) launch (landing)
• Power consumption lt 2 kW

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AMS Goals
Antimatter search ( ) with a sensitivity 103
better than current limits
Dark matter search. Non-baryonic DM WIMP
(LSP) Signatures e,

• High statistics study of
• the cosmic ray spectrum
• Isotope separation
• Antiparticle spectrum

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AMS detector
Set of sub detectors devoted to the measurement
of energy and particle identification Z, mass,
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AMS detector
Energy ( , )
Tracker
?(p)/p 1.5 for 10 GeV
Max. Dynamic Range 1 TeV/n
ECAL
?(E)/E 3 for 100 GeV electrons
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AMS detector
Particle Identification
Charge (Z) Tracker sign(Z), ToF and RICH Z ? 26
(small charge confusion)

• Electron/hadron separation
• TRD p/e rejection factor 102 - 103
• in the range 1.5 300 GeV
• ECAL Hadron rejection factor 104
• for Elt1TeV

• (Mass)

• ToF ?(?)/? 3.5 (for ?1)
• RICH ?(?)/? 0.1 for protons
• ?(m)/m 2

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Galactic Cosmic Rays
The high energy CR are produced, accelerated and
propagated in the Galaxy and provide information
about the sources and the matter content and
magneto- hydrodynamical properties of our Galaxy

• Current critical measurements that can be
  achieved by AMS are
• Very accuracy measurements of the spectrum of H
  He (R? 1 TV)
• Chemical abundances (from H to Fe)
• The ratio of spallation products such as Boron
  to the primary nuclei
• such as Carbon as a function of energy (E ? 1
  TeV)
• The energy dependence of the fraction of
  antiparticles (E?100GeV)
• Isotopic ratios of elements (E ? 10 GV)
• Measurements unreachable by AMS
• Chemical composition near and beyond the knee

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Energy Spectrum
Protons and Helium The most abundant elements
Spectral index Origin and acceleration,
differences between both species Used to
determine the expected fluxes of and e ,
atmospheric neutrinos, etc
protons
AMS-02 expectations
Helium
AMS-02 expectations
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Hadrons Zgt2
In addition to the information provided by
primary CR such as C, N and O, secondary CR
(produced by spallation) are used to estimate the
amount of matter traversed by the
CR (confinement volume and time)
AMS-02 expectations
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Radiactive Isotopes Provide information about
the confinement time of CR in the Galaxy
10Be is specially interesting because of its
half time (t1/2 1.51 106 years) is of the
same order than the confinement time of the CR
in the Galaxy
AMS-02 expectations

• After 3 years, AMS will collect 105 10Be
• ?(m)/m 2

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Antiparticles
Pure secondary CR from interactions with the ISM
Exotic origin A very good understanding of the
expected CR fluxes
Positrons
Antiprotons
Data consistent with secondary CR
No conclusive data
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Antiparticles
AMS will measure the flux up to 400
GeV After 3 years will collect ?106
AMS will collect ?106 e and ?107 e- These
fluxes will allow to find out dark matter
AMS-02 expectations
AMS-02 expectations
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Summary

• AMS will be the first large acceptance magnetic
  spectrometer
• to operate in space for a long period of time
• Precise experimental measurements provided by
  AMS would
• yield information about the galactic
  properties, constraining
• propagation models
• AMS will be able also to discover some evidence
  for new
• physics (dark matter) or new objects (e.g.
  stars made of
• antimatter)
• Currently, AMS-02 is in the construction phase.
• The detector must be ready for the launch by
  the end of 2007

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More Slides
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Light Isotopes
D and 3He are secondary particles coming from
nuclear interactions with the ISM and provide a
description of the propagation of p and He
AMS-02 expectations
AMS-02 expectations
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• Good understanding of GCR origin and propagation
  will be
• used to discover some evidence for new physics
  (dark matter)
• or new objects (e.g. stars made of antimatter)