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Antimateria

Antimateria. Lezioni di Fisica delle Astroparticelle Piergiorgio Picozza. Dirac Nobel Speech (1933).

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Antimateria

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  1. Antimateria Lezioni di Fisica delle Astroparticelle Piergiorgio Picozza

  2. Dirac Nobel Speech (1933) “We must regard it rather an accident that the Earth and presumably the whole Solar System contains a preponderance of negative electrons and positive protons. It is quite possible that for some of the stars it is the other way about” • Earliest example of the interplay of particles physics and cosmology

  3. Antimatter • What is the role of matter and antimatter in the early Universe? • Is the present Universe baryon-symmetric or baryon asymmetric?

  4. Outlines • The antimatter component of cosmic rays: a) Cosmological models b) Antimatter and dark matter c) Present experimental observations • Future developments and prospects

  5. Antimatter Chronology 1930:Dirac identified the holes in the energy sea ofelectrons as protons 1930: Weyl formulated the charge conjungationsymmetry C 1931:Dirac accepted the C symmetry as a first principle,and defined positrons”the holes, predictingthe existence of the first “antiparticle” 1932:Anderson and independently Blackett &Occhialinidiscovered thepositron

  6. Antimatter Chronology 1954: “antiproton induced” events in cosmic rays (Amaldi) Spring 1955:Pauli completed the proof of the CPT symmetry Oct. 1955:Chamberlain, Segré, Wiegland and Ypsilantis discovered theantiproton May 1956:Lee and Yang suggested the violation of P and C symmetries for weak interactions July 1956:Lederman et al. discovered the KL state Oct. 1956: Piccioni et al. discovered the antineutron Jan. 1957:Lee, Oheme and Yang proposed the possibility of CP and T violation; Wu et al. discovered C and P violation in  beta decay,while Garwin & Lederman and Friedman & Telegdi in pionand muon decays

  7. Antimatter Chronology 1960’s: Baryon Symmetric Cosmologies (Klein, Alfven…) 1964:Cronin and Fitch discovered the CP violation in KL decay 1965:Zichichi et al. discovered the antideuteron at CERN, Ting et al. at Brookhaven 1967: Sakharov conditions 1970’s: Baryon Symmetric Cosmologies (Steckher…) 1970’s: gamma ray “evidence” 1979: discovery of antiprotons in cosmic rays (Bogomolov,Golden) 1996:discovery of the first antiatom (antihydrogen) at CERN ???: antinuclei in cosmic rays ( Pamela?, AMS02?)

  8. Antimatter on a Cosmological Scale?

  9. Pre Big-Bang models • 1930’s - 1960’s: Universe baryonic symmetric as implied by the rigorous symmetry of the fundamental laws of the nature. • Problem of separating M and M on large scale. • 1965 : Discovery of the cosmic background radiation.

  10. Simple Big Bang Model • The early Universe was a hot expanding plasma with equal number of baryons, antibaryons and photons. • As the Universe expands, the density of particles and antiparticles falls, annihilation process ceases, effectively freezing the ratio: - baryon/photon ~ 10-18. - Annihilation catastrophe. The present real Universe • Baryon/photon ~ 10-9 . From microwave background.

  11. Simple Big Bang Model • No clear mechanism to separate matter and antimatter. • Statistical fluctuation in density to avoid the annihilation catastrophe and provide for regions of matter and antimatter gives: Mobject < 10-30 of the mass of the Galaxy. (Kolb and Turner) • The simple Big Bang model does not work. • 1964: CP Violation in Nature

  12. Sakharov’s Conditionsfor BaryogenesisJETP Lett., 5 (1967) 24 • Baryon Number is not conserved. • Charge Coniugation Symmetry is not exact. • CP is not an exact symmetry. • Baryogenesis could have occurred during a period when the Universe was not in thermal equilibrium.

  13. Asymmetric Universe? • The Sakarov conditions enable the existence of a baryon-asymmetric Universe, • If CP violation is built into the Lagrangian, the sign of violation would be universal . Only matter, as we are. • but also: • They offer a solution for the separation of matter and antimatter in a baryonic symmetric scenario.

  14. A Symmetric Universe • The sign of CP violation needs non have been universal if it arises from spontaneous symmetry breaking. • When the CP violation occurred in the early Universe, it is possible there may have occurred domains of space dominated by matter and other dominated by antimatter. (Brown, Stecker and Sato). • Inflation might lead to domains of astronomical dimension. (Sato)

  15. Some conclusions • The theory needed to support a Baryon Asymmetric Universe is not complete • Our present understanding does not forbid Baryon Symmetry The observed M - M Asymmetry M/M < 10-5 in 10-8 of the Universe could be a LOCAL phenomenon

  16. Observations • Indirect. • By measuring: • The distortion of the CBR spectrum • The spectrum of the Cosmic Diffuse Gamma (GDG) • Direct: • By searching for Antinuclei • By measuring p and e+ energy spectra

  17. Gamma Evidence for Cosmic Antimatter?Steigman 1976, De Rujula 1996 • Osservation in the 100 MeV gamma range • Assumptions: Matter and antimatter well mixed Leading process: p p 0+ ……. 

  18. Cosmic Diffuse Gamma Background P. Sreekumar et al, astroph/9709257

  19. Antimatter/Matter fraction limits Antimatter/Matter fraction limit: • In Galactic molecular clouds: f<10-15 • In Galactic Halo: f< 10-10 • In local clusters of galaxies: f<10-5 Antimatter must be separated from matter at scales at least as 20 Megaparsec

  20. New limits • Supercluster of Galaxies: f<10-3,10-4Wolfendale • Cohen, De Rujula and Glashow: the signal expected from annihilation near boundaries of regions of matter and antimatter exceeds observational limits, unless the matter domain we inhabit is virtually the entire visible universe.

  21. Cosmic Radiation? Observation of cosmic radiation hold out the possibility of directly observing a particle of antimatter which has escaped as a cosmic rayy from a distant antigalaxy, traversed intergalactic space filled by turbulent magnetic field, entered the Milky Way against the galactic wind and found its way to the Earth. High energy particle or antinuclei

  22. extragalactic antimatter Stecker & Wolfendale 85 mc =20 GeV Stecker et al.85 mc =15 GeV Balloon data : Antiproton/proton ratio before 1990 1979

  23. mc=20GeV Tilka 89 dinamic halo leaky box Balloon data : Positron fraction before 1990

  24. New Generation of Antimatter Researches in Cosmic Rays

  25. Balloon Flights Wizard Collaboration - MASS – 1,2 (89,91) -TrampSI (93) - CAPRICE (94, 97, 98) - Flight (2003) - BESS (93, 95, 97, 98, 2000) - Heat (94, 95, 2000) - IMAX (96) - BESS Long duration flights (2004)

  26. Space experimentsTechnology and Physics • SilEye-1 MIR 1995-1997 • SilEye-2 MIR 1997-2001 • AMS-01 Shuttle 1998 • NINA-1 Resurs1998 • NINA-2 MITA 2000 • SilEye-3 ISS 2002 (April 25) • PAMELA Resurs 2003 • AGILE MITA 2003 • AMS-02 ISS 2006 • GLAST Sat. 2006

  27. Charge sign and momentum Beta selection Z selection hadron – electron discrimination CapriceSubnuclear physics techniques in space experiments SUPER CONDUCTING MAGNET

  28. Antiprotons

  29. Positron

  30. BASIC STRUCTURE of BESS

  31. Particle identification(p selection) (Y.Asaoka and Y.Shikaze et al., astro-ph/0109007, PRL in press) ANTIPROTON IDENTIFICATION PLOTS

  32. HEAT

  33. AMS Alpha Magnetic Spectrometer STS91 Mission June 2-12, 1998 Italy(INFN), China, Germany, Finland, France, Switzerland, Taiwan, US

  34. Search for Heavy Antinuclei • Gamma ray observations place strong limitations on antimatter in our Galaxy and in the local cluster of galaxies within 20 Mpc and further. • High-energy Antinuclei from antimatter domains beyond the gamma limits. • Antihelium/Helium from cosmic ray collision =10-14 • AntiIron/Iron =10-56 Necessity of an excellent identification capability

  35. ANTIMATTER LIMITS

  36. ANTIPROTRON

  37. Antiprotonssources • Secondary production by inelastic scattering on ISM • Extragalactic sources • Primordial black holes produced very early in the hot Big-Bang • Annihilation or decaying of dark matter remnants in the halo of our Galaxy

  38. Distortion on the secondary antiproton flux induced by an Extragalactic Antimatter component Extragalactic Antimatter •Background from normal secondary production Black Hole evaporation •Mass91 data from XXVI ICRC, OG.1.1.21 , 1999 •Caprice94 data from ApJ , 487, 415, 1997 •Caprice98 data from ApJ Letters 534, L177, 2000

  39. BESS 00 Distortion on the secondary antiproton flux induced by an Extragalactic Antimatter component Extragalactic Antimatter Black Hole evaporation •Background from normal secondary production Antiproton/proton Ratio •Mass91 data from XXVI ICRC, OG.1.1.21 , 1999 •Caprice94 data from ApJ , 487, 415, 1997 •Caprice98 data from ApJ Letters 534, L177, 2000 Kinetic Energy (GeV)

  40. Solar Field Reversal Effect astro-ph/0109007

  41. Mission in Progress

  42. Positrons 50 MeV - 270 GeV • Antiprotons 80 MeV – 190 GeV • Limit on antinuclei ~10-8(He /He) • Electrons 50 MeV – 3TeV • Protons 80 MeV – 700 GeV • Nuclei < 200 GeV/n (Z < 6) • Electron and proton components up to 10 TeV • study of the solar modulation after the 23rd solar cycle maximum. PAMELA MISSION GF 20.5 cm2 sr Mass 470 Kg Dimensions 120 x 40x45 cm3 Power Budget 360W

  43. Resurs-DK1: • TsSKB-Progress Samara Russia • Mass: 6.7 tons • Orbit: Elliptic • Altitude: 300 - 600 Km • Inclination: 70.4° • Life Time: > 3 years • Launch foreseen in 2005 from Baikonur with Soyuz TM rocket • 2 downlink station: Moscow and Khanty-Mamsyisk (Siberia)

  44. TOP AC (CAT) SIDE AC (CAS) BOTTOM SCINTILLATOR (S4) Principle of Operation

  45. TRD • Threshold detector :signal from e±, no from p. • 9 radiator planes (carbon fiber) and straws tubes (4mm diameter) filled with Xe/CO2mixture. • 102 e/p separation (E > 1GeV/c). TOF Time-of-flight • Level 1 trigger • particle identification (up to 1GeV/c) • dE/dx • Plastic scintillator + PMT • Time Resolution ~70 ps TRD TRK Anticoincidence system • Defines trackeracceptance • Plastic scintillator + PMT ANTI Si Tracker + magnet • Permanent magnet B=0.4T • 6 planes double sided Si strips 300 m thick • Spatialrisolution ~3m • MDR = 740 GV/c Si-W Calorimeter • ImagingCalorimeter : reconstructs shower profile discriminating e/p • Energy Resolution for e±E/E = 15% / E1/2. • Si-X / W / Si-Y structure • 22 W planes • 16.3 X0 / 0.6 l0 CALO Neutron detector • Extends the energy range for primary protons and electrons up to 10 TeV • 36 3He counters in a polyetilen moderator ND PAMELA DETECTOR

  46. TOF TRD Tracker Calorimeter Magnet PAMELA Detector

  47. exotic contribution Energy (GeV) Distortion of the secondary positron fraction induced by a signal from a heavy neutralino. Distortion of the secondary antiproton flux induced by a signal from a heavy Higgsino-like neutralino. standard Energy (GeV) Expected data from Pamela for two years of operation are shown in red. P.Picozza and A.Morselli,astro-ph/0103117

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