09/09/2002Nacho Sevilla Noarbe. AMS.1 Circa 500 BC circa 2000 AD.

09/09/2002 Nacho Sevilla Noarbe. AMS. 1

Circa 500 BC circa 2000 AD

Search for Dark MatterThe AMS Experiment

Nacho Sevilla Noarbe.

CIEMAT, Madrid.


Outline

• What is the ´dark matter´problem?

• What is the AMS experiment?

• How can AMS help us with dark matter?


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.


0 1

m 0.2-0.3

m 0.1Galactic

Cluster

Cosmological

+

Dark matter problem: observations

+

SCALE OMEGA

Galaxy rotation curvesCredit:

Corbell, Salucci (1999)

Gravitational lensing

Credit: HST

CMB + SNIa observationsCredit: BOOMERANG and the SN Cosmology Project


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)...



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.

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

BUT...

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



• 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.


The AMS experiment• AMS (Anti-Matter Spectrometer) is a particle physics AMS (Anti-Matter Spectrometer) is a particle physics experiment in space. experiment in space. • It will detect and identify huge statistics of primary It will detect and identify huge statistics of primary cosmic rays, up to Z=26.cosmic rays, up to Z=26.• Among its physics goals, are anti-matter and dark Among its physics goals, are anti-matter and dark matter search, cosmic ray propagation studies.matter search, cosmic ray propagation studies.• It is mostly built in Europe, in close collaboration with It is mostly built in Europe, in close collaboration with NASA.NASA.• AMS-01 was tested successfully on shuttle flight AMS-01 was tested successfully on shuttle flight STS91 for ten days in 1998. AMS-02 will be on the ISS STS91 for ten days in 1998. AMS-02 will be on the ISS for three years from 2005.for three years from 2005.


Acceptance: 0.45 m2sr

The AMS experiment

TOF

TOF

USS IIUSS II

Veto counter

Vacuumcase

• Superconducting magnet

• Silicon Tracker

• Scintillator system (TOF)

• Transition Radiation Detector

• Ring Imaging Cherenkov Detector• Electromagnetic Calorimeter

~2 m~2 m


The AMS experiment:AMS/

• 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.

TOF

TOF

USS IIUSS II

Veto counter

Vacuumcase


The AMS experiment: AMS-01 on STS-91

AMS


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 < 1.1·10-6).* Charged CR spectra (p,e,D,He).* Measurement of geomagnetic effects on CR.


The AMS experiment:energy ranges

p+ 0.1 up to several TeVp- 0.5-200 GeVe- 0.1 up to O(TeV)e+ 0.1-200 GeVHe,….C 1 up to several TeVanti – He…C 1 up to O(TeV)Light Isotopes 1-10 GeV/nucleon 1-1000 GeV


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


Searching for neutralinos

• 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.

Possible detectable products from: xx

Balloon

s

ray t

ele

scop

es

an

d s

ate

llit

es

AM

S


Searching for neutralinosGamma 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)


Searching for neutralinosPositrons• 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?



Searching for neutralinosAntiprotons• They seem to follow expected

spectrum from CR interaction with ISM.

• However there are large uncertainties above 10 GeV and below 1 GeV.



Summing up• Recent research points to a non-baryonic component of Recent research points to a non-baryonic component of

dark matter. Neutralinos are one of the best candidates to dark matter. Neutralinos are one of the best candidates to date.date.

• AMS will be a multipurpose detector in space that will AMS will be a multipurpose detector in space that will look for signatures of neutralino coannihilation in the look for signatures of neutralino coannihilation in the galactic halo.galactic halo.

• It will make use of high statistics, outstanding particle It will make use of high statistics, outstanding particle identification capabilities and multichannel observations. identification capabilities and multichannel observations.

09/09/2002Nacho Sevilla Noarbe. AMS.1 Circa 500 BC circa 2000 AD.

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