Sin ttulo de diapositiva

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Circa 500 BC
circa 2000 AD
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Search for Dark MatterThe AMS Experiment

• Nacho Sevilla Noarbe.
• CIEMAT, Madrid.

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Outline

• What is the dark matterproblem?
• What is the AMS experiment?
• How can AMS help us with dark matter?

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Dark matter problem

• (tentavely) Dark matter undetected major
  constituent of the universe which does not seem
  to emit or absorb any EM radiation, though its
  gravitational effects are dominant.
• Observational proof.
• Candidates.

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Dark matter problem observations

• Galactic scale

• Rotation curves in spirals.

?m ? 0.1

• X-ray measurements of galactic gas in
  ellipticals.

• Lensing events from MACHOs.

Credit The CHANDRA Collaboration
Credit The MACHO Collaboration
Credit Corbell, Salucci (1999)
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Dark matter problem observations

• Cluster scale

• Cluster members motion.

?m ? 0.2-0.3

• X-ray intergalactic emission.

• Cluster lensing of background objects.

Credit The CHANDRA Collaboration
Credit HST
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Dark matter problem observations

• Cosmological scale

• Local Group velocity against CMB.

?0 ? 0.3

• Peculiar velocity measurements.

• Combining latest CMB and high-Z supernovae
  results.

Credit The Supernova Cosmology Project and
BOOMERANG
Credit COBE
Credit The Sc Project
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Dark matter problem observations (some!)
Cluster scale
Galactic scale
Galactic
Cluster
Cosmological

• Cosmological scale

Scale

• Rotation curves in spirals.

• Cluster lensing of background objects.

• Combining latest CMB and high-Z supernovae
  results.

?m ? 0.2-0.3
?m gt 0.1
?0 ? 1
Credit Corbell, Salucci (1999)
Credit HST
Credit The Supernova Cosmology Project and
BOOMERANG
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Dark matter problem observations
OMEGA
SCALE
?m ? 0.1
Galactic
Galaxy rotation curves Credit Corbell, Salucci
(1999)
Cluster
?m ? 0.2-0.3
Gravitational lensing Credit HST
Cosmological
?0 ? 1
CMB SNIa observations Credit BOOMERANG and
the SN Cosmology Project
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Dark matter problem
Theoretical arguments

• CMB characteristics are better explained in
  inflationary models. (Most of) these in turn
  predict ? 1.

• If ?lum ?mass it turns out that structure
  should have formed rapidly requiring unobserved
  high fluctuations in the CMB.

• If ? ? 1, as we know that ?0 1 now, at Planck
  time it should have been 1?10-60 (? varies
  quickly if not unity).

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Dark matter problem candidates

• Baryonic dwarfs, planets, collapsed objects
• limited by well-tested BBN
• observations from MACHO experiments cannot
  account for all galactic dark matter.
• Non-baryonic neutrinos, axions, WIMPs (e.g.
  supersymmetric particles)...

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Dark matter problem candidates
NEUTRINOS

• They are well-known particles.

• There is strong indication that they do have
  mass...

BUT...

• it probably wont be enough.

• DM models based on neutrinos (usually called
  Hot Dark Matter) are not compatible with
  observations.

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Dark matter problem candidates
NEUTRALINOS (best SUSY candidate)

• Supersymmetry predicts these particles.

• The properties of the neutralino are remarkably
  close to those needed by a hypothetical dark
  matter particle constituent.

• Neutralino dark matter models (Cold Dark Matter)
  work well in their predictions.

BUT...

• Neutralinos (or supersymmetry for that case) has
  not been observed experimentally yet.

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Dark matter problem candidates

• Indirect searches for neutralino signatures in
  cosmic rays can be done from space-borne and
  balloon experiments.
• AMS on the International Space Station will do
  so with unprecedented sensitivity.

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The AMS experiment

• AMS (Anti-Matter Spectrometer) is a particle
  physics experiment in space.
• It will detect and identify huge statistics of
  primary cosmic rays, up to Z26.
• Among its physics goals, are anti-matter and
  dark matter search, cosmic ray propagation
  studies.
• It is mostly built in Europe, in close
  collaboration with NASA.
• AMS-01 was tested successfully on shuttle flight
  STS91 for ten days in 1998. AMS-02 will be on the
  ISS for three years from 2005.

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The AMS experiment
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  a I. Physikalisches Institut, RWTH, D-52056
Aachen, Germany b III. Physikalisches Institut,
RWTH, D-52056 Aachen, Germany c Laboratoire
dAnnecy-le-Vieux de Physique des Particules,
LAPP, F-74941 Annecy-le-Vieux CEDEX, France e
Louisiana State University, Baton Rouge, LA
70803, USA d Johns Hopkins University, Baltimore,
MD 21218, USA Center of Space Science and
Application, Chinese Academy of Sciences, 100080
Beijing, China g Chinese Academy of Launching
Vehicle Technology, CALT, 100076 Beijing, China h
Institute of Electrical Engineering, IEE, Chinese
Academy of Sciences, 100080 Beijing, China i
Institute of High Energy Physics, IHEP, Chinese
Academy of Sciences, 100039 Beijing, China j
University of Bologna and INFN-Sezione di
Bologna, I-40126 Bologna, Italy k Institute of
Microtechnology, Politechnica University of
Bucharest and University of Bucharest, R-76900
Bucharest, Romania l Massachusetts Institute of
Technology, Cambridge, MA 02139, USA m National
Central University, Chung-Li, Taiwan 32054 n
Laboratorio de Instrumentacao e Fisica
Experimental de Particulas, LIP, P-3000 Coimbra,
Portugal o University of Maryland, College Park,
MD 20742, USA p INFN Sezione di Firenze, I-50125
Florence, Italy q MaxPlank Institut fur
Extraterrestrische Physik, D-85740 Garching,
Germany r University of Geneva, CH-1211 Geneva 4,
Switzerland s Institut des Sciences Nucleaires,
F-38026 Grenoble, France t Helsinki University of
Technology, FIN-02540 Kylmala, Finland u
Instituto Superior Tecnico, IST, P-1096 Lisboa,
Portugal v Laboratorio de Instrumentacao e Fisica
Experimental de Particulas, LIP, P-1000 Lisboa,
Portugal w ChungShan Institute of Science and
Technology, Lung-Tan, Tao Yuan 325, Taiwan
11529 x Centro de Investigaciones Energéticas,
Medioambientales y Tecnológicas, CIEMAT, E-28040
Madrid, Spain y INFN-Sezione di Milano, I-20133
Milan, Italy y INFN-Sezione di Pisa, I-50100
Pisa, Italy z Kurchatov Institute, Moscow, 123182
Russia aa Institute of Theoretical and
Experimental Physics, ITEP, Moscow, 117259
Russia ab INFN-Sezione di Perugia and Universita
degli Studi di Perugia, I-06100 Perugia, Italy
ac Academia Sinica, Taipei, Taiwan ad Kyungpook
National University, 702-701 Taegu, Korea ae
University of Turku, FIN-20014 Turku, Finland a
Eidgenossische Technische Hochschule, ETH Zurich,
CH-8093 Zurich, Switzerland
Europe US ASIA
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The AMS experiment

• Superconducting magnet

• Silicon Tracker

• Scintillator system (TOF)

2 m

• Transition Radiation Detector

• Ring Imaging Cherenkov Detector

• Electromagnetic Calorimeter

2 m
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The AMS experiment the superconducting magnet

• Its purpose is to bend the trajectories of
  charged particles.
• It will be the first superconducting magnet to
  operate in space.
• It is a system of 12 racetrack coils 2 dipole
  coils cooled to 1.85 K by 2.5 m3 of superfluid
  helium.
• BL2 0.86 Tm2

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The AMS experiment the Silicon Tracker

• It will measure the rigidity (momentum/charge)
  and charge.
• With over 6 m2 of active surface, it will be the
  largest ever built before the LHC.
• Based on 8 thin layers of double-sided silicon
  microstrips, a spatial resolution of 10 mm will
  be achieved.
• This means around 200k channels.

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The AMS experiment the Time Of Flight system

• This sub-detector will measure the velocity of
  the particle by recording time of passage and
  position in 4 different planes.
• Each plane has 8-10 scintillator paddles seen by
  2 PMTs on each side.
• It can measure velocities with 3.6 relative
  error (for ? 1 protons).

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The AMS experiment theTransition Radiation
Detector

• The TRD is based on the radiation emitted by a
  moving charged particle when it traverses two
  different media.
• It will perform hadron/lepton separation.
• There are 20 layers of foam separated by drift
  tubes.
• h/e rejection of 102 103 in the range 3 300
  GeV.

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The AMS experiment the RICH detector

• Makes use of the Cherenkov light emitted in the
  radiator by relativistic charged particles.
• We can obtain the velocity and absolute charge of
  incoming particles.
• 3 cm thick aerogel radiator 680 multianode
  photomultipliers.
• We can achieve velocity measurements with a 0.1
  relative error for protons.
• CIEMAT is a major partner in this effort.

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The AMS experiment the Electromagnetic
Calorimeter

• The ECAL registers electromagnetic showers
  initiated by the particles.
• Thus we can measure the energy of the primary.
• It consists of 9 superlayers of scintillator/lead
  connected to 324 multianode photomultipliers.
• Energy is measured with a 3 error at 100 GeV.

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The AMS experimentAMS/?

• AMS will also be able to operate as a gamma ray
  detector!
• TRD structure provide 0.25Xo for
  electron-positron conversion.
• Tracker and Calorimeter can measure the e-e
  pairs.
• The Calorimeter alone can register unconverted
  photons.

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The AMS experiment AMS-01 on STS-91
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The AMS experiment AMS-01 on STS-91

• AMS had a successful operation in space during a
  10-day flight in 1998.
• Precise physics results were obtained
• New limit for nuclear antimatter (NHe/He lt
  1.110-6).
• Charged CR spectra (p,e?,D,He).
• Measurement of geomagnetic effects on CR.

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The AMS experimentenergy ranges
p 0.1 up to several TeV p-
0.5-200 GeV e- 0.1 up to
O(TeV) e 0.1-200 GeV He,.C
1 up to several TeV anti HeC
1 up to O(TeV) Light Isotopes 1-10
GeV/nucleon g 1-1000 GeV
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Searching for neutralinos

• Direct detection via inelastic scattering (DAMA,
  CDMS, UKDMC).
• Indirect detection
• Coannihilation in Earth/Sun ? ?? ?
• Coannihilation in galactic halo ?
• ANOMALIES IN CR SPECTRA

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Searching for neutralinos
Possible detectable products from ???xx

• Gamma photons
• They are originated either from coannihilation
  into a final state containing a photon (line
  signal) or from the decay of other primary
  coannihilation products (continuum signal).
• Positrons
• They come from the decay of gauge bosons
  (e.g.,W) as primary coannihilation products.
• Antiprotons and antideuterons
• Direct production in WIMP annihilations.

? ray telescopes and satellites
AMS
Balloons
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Searching for neutralinos

• Gamma rays
• Many experiments will be covering the 1-300 GeV
  range in the next decade.
• Gamma ray output from neutralino annihilation is
  highly model-dependent.

Credit Battiston (2002)
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Searching for neutralinos

• Positrons
• The relative fluxes of electrons and positrons
  are very uncertain at energies above 10 GeV.
• An excess of positron fraction is claimed by the
  HEAT balloon experiment, maybe hinting to
  neutralinos?

Credit Battiston (2002)
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Searching for neutralinos

• Antiprotons
• They seem to follow expected spectrum from CR
  interaction with ISM.
• However there are large uncertainties above 10
  GeV and below 1 GeV.

Credit Battiston (2002)
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Summing up

• Recent research points to a non-baryonic
  component of dark matter. Neutralinos are one of
  the best candidates to date.
• AMS will be a multipurpose detector in space that
  will look for signatures of neutralino
  coannihilation in the galactic halo.
• It will make use of high statistics, outstanding
  particle identification capabilities and
  multichannel observations.

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