Cosmic Rays measured atthe ISS

Dorottya Szécsi

BUW WS 2011/12.

GETA Seminar, 19th January 2012.

Cosmic Rays measured at the ISS BUW WS 2011/12.

IntroductionI Space instruments, primordial

particles created in the earlyUniverse – background freeenvironment

I Cosmology: baryon asymmetry,mass density composition

I Understanding of Dark Matter,Antimatter, the origin of CR etc.

I Strong demand for precisionmeasurements of cosmic rays: largedeviation of the e+/(e+ + e−) ratiopredicted by our model (withordinary cosmic ray collisions)

I International Space Station (ISS) –AMS launched 16 May 2011

Cosmic Rays measured at the ISS BUW WS 2011/12.

ContentsI PART 1. Overview of the AMS

I Instruments on-boardI How they workI What they measure

I PART 2. AMS Physics PotencialI Anti-MatterI Dark MatterI and all the rest

Cosmic Rays measured at the ISS BUW WS 2011/12.

PART 1. Overview of the AMS

Cosmic Rays measured at the ISS BUW WS 2011/12.

PM – Permanent Magnet

Charged particles in magnetic field:Lorentz force

I made of matter: curve one wayI made of antimatter (opposite charge):

the opposite way

I B = 1.4 kG

Cosmic Rays measured at the ISS BUW WS 2011/12.

Silicon TrackerI detects the trajectory of the

incoming particlesI identifies:

I magnitudeI polarity

of particles’ electrical chargeI the higher the particle’s

momentum, the straighter thearc

I Accuracy: 10 µmI ∼ 200000 readout channelsI charge separation of nuclei

up to Z = 26I anticoincidence counter

Cosmic Rays measured at the ISS BUW WS 2011/12.

TOF – Time of Flight Counters

I distinguish between upwardand downward travelingparticles

I scintillator: flashes of lightwhen struck by particles orphotons

I measures the transit time ofparticles between two layers

Cosmic Rays measured at the ISS BUW WS 2011/12.

RICH – Ring Imaging Cherenkov detector

He Li C O Ca

I velocity of the charged cosmic particlesI by measuring vertex angle of the cone of

Cherenkov lightI particle passes through a tile of silica aerogel (n=1.05) or NaF (n=1.33)I photomultiplier tubes

Cosmic Rays measured at the ISS BUW WS 2011/12.

ECAL – Electromagnetic Calorimeter

I electromagnetic particleidentification:

I electrons, positrons, and gamma raysI up to 1 TeVI angular resolution around 1◦I e/p separation: ∼ 104 > 200 GeV

I 9 modules made of layers of lead andscintillating fibers

I function: completely stop particles→ measuring energy

I electromagnetic showersI lead scintillating fiber sandwichI reading out: 4 PMTs

Cosmic Rays measured at the ISS BUW WS 2011/12.

TRD – Transition Radiation DetectorI Transition radiation:

I soft X-rays emitted by chargedparticles traverse the boundarybetween two media with differentdielectric constants

I electrons and positrons: higherprobability of emitting TR photonsthan heavy particles

I used in conjunction with ECAL →distinguish between light and heavyparticles of equal charge and momentum(positron, proton)

I Xenon/CO2 gas mixture:I Xe captures the TRI leak rate: 6 µg/s → 24 ys in space

Cosmic Rays measured at the ISS BUW WS 2011/12.

Conclusion of Part 1.

I AMS can measuresimultaneously:

I photonI electronsI protonsI nucleiI + anti

Cosmic Rays measured at the ISS BUW WS 2011/12.

PART 2. AMS Physics Potencial – Anti-Matter I.I Experimental evidence: our galaxy is

made of matter. BUT:I more than 100 hundred million

galaxies in the universeI theories trying to explain

matter-antimatter asymmetry: notcompatible with measurements

I → fundamental question in modernastroparticle physics and cosmology

I just one antihelium nucleus!I AMS-02: sensitivity of 109

I 3 orders of magnitude better thanAMS-01 in 1998

I extending the volume of theUniverse tested for the existence ofprimordial antimatter

Cosmic Rays measured at the ISS BUW WS 2011/12.

Anti-Matter II.

Sensitivity of AMS withthe permanent magnet onISS for 18 yearscompared with the otherearlier measurements.

Cosmic Rays measured at the ISS BUW WS 2011/12.

Dark Matter I.

I neither emits nor scatters light or other electromagnetic radiation→ cannot be directly seen with telescopes

I postulated by Fritz Zwicky in 1933I observations of the rotational speeds of galaxiesI believed to be composed of a new type of subatomic particle

I AMS: spectra for nuclei in the energy range [0.5 GeV/nucl ; 2TeV/nucl]

I with 1% accuracyI it can prove or disprove our theories

Cosmic Rays measured at the ISS BUW WS 2011/12.

Dark Matter II.

I Candidate: neutralinoI generic ingredient of

SUSY modelsI supersymmetricI AMS: neutralino

annihilation based on finalstate particles

I Picture: Accuracy ofAMS-02 measurements

I p̄/p spectrumI 10 years on ISS with the

permanent magnet

Cosmic Rays measured at the ISS BUW WS 2011/12.

Dark Matter III.

I Dependence of the measured positron spectrum shape on theneutralino mass.

Cosmic Rays measured at the ISS BUW WS 2011/12.

Strangelets (?)

I fragmet of "strange matter":up, down, strange quarks

I dark matter candidateI higher size: more stableI "quark star" (strange nucleus

interacting with neutronstar)I early Universe or cosmic-ray

collisionsI heavy-ion colliders: we don’t

see them...

Cosmic Rays measured at the ISS BUW WS 2011/12.

Discussion

I Alpha Magnetic Spectrometer 02 (AMS-02) is a particle physicsdetector on board of the ISS

I We had overviewed the instrument and the measuring basics.I AMS-02 uses the unique environment of space to advance

knowledge of the universe and lead to the understanding of theuniverse’s origin by searching for antimatter, dark matter andmeasuring cosmic rays.

I "The most sophisticated particle detector ever sent into space."

Cosmic Rays measured at the ISS BUW WS 2011/12.

References

I A.Kounine, 2010, XVI International Symposium on Very HighEnergy Cosmic Ray Interactions ISVHECRI 2010

I Diego Casadei, 2004, Talk given at Lake Louise Winter InstituteI http://www.ams02.org/ams-and-iss/I WikipediaI http://events.eoportal.org/presentations/10001154/10002501.html

Cosmic Rays measured at the ISS BUW WS 2011/12.

Thank you for your attention!