UHECR and HADRONIC INTERACTIONS. Paolo Lipari Searching for the origin of Cosmic Rays Trondheim 18th June 2009

Transcription

1 UHECR and HADRONIC INTERACTIONS Paolo Lipari Searching for the origin of Cosmic Rays Trondheim 18th June 2009

2 ~60 years of UHECR Energy Hadronic interaction Modeling Mass A

3 Energy measurement problem solved. Fly's Eye

4 st 1 Fly's Eye

5 Observed Light Emitted Photons Geometry Atmospheric Absorption Shower Size Fluorescence Yields

6 Small Model dependence

7 Area Energy Shape depends on : Primary Identity Interaction Model

8 COMPOSITION of UHECR Very high astrophysical importance Controversial - inconsistent observations. Xmax Fluctuations of Xmax Other methods

9 AUGER ICRC 2007

10 Elongation rate corrected for detector acceptance and comparison with previous results

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12 The theory curve <Xmax(E)> is determined by the parameters that describe hadronic interactions. (and by their energy dependence). Interaction Lengths Multiplicity Inclusive Spectra...

13 Xmax and the Composition of Cosmic Rays Proton Showers Logarithmic growth of average Xmax with energy Mass dependence

14 Xmax and the Composition of Cosmic Rays Proton Showers Logarithmic growth of average Xmax with energy Mass dependence

15 Obtain the average mass and its variation with energy

16 The importance of CORNERS (when real)

17 METHODOLOGY

18 C.R. DATA Astrophysical Information Hadronic Interactions

19 From Accelerator Data + Theory Astrophysics C.R. DATA Astrophysical Information Hadronic Interactions

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21 Data Astrophysical Information Hadronic Interactions

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24 Naive 2-component model

25 Sibyll-Interpretation

26 Sibyll-Interpretation Composition is Mixed 50% p 50% Fe Composition become heavier with increasing Energy

27 QGSJet-Interpretation Composition is Mixed 60% p 40% Fe Composition: Indication (1.5 s) of moderate increase of A with Energy

28 How can we include systematic uncertainties in the modeling of hadronic interactions in the estimate of properties of Cosmic Rays? Spread of predictions for diferent model. Overestimate? Some models are lower quality. Underestimate? Perhaps we are missing something important.

29 Alternative Approach to the problem. C.R. DATA Hadronic Interactions

30 CONSISTENCY Diferent Methods to measure same physical quantity must agree Fluorescence Xmax... versus versus Muons Surface detection

31 From Cosmic Ray Data Hadronic Interactions C.R. DATA Astrophysical Information Astrophysical Composition Methods Hadronic Interactions

32 From Cosmic Ray Data Hadronic Interactions C.R. DATA Astrophysical Information Astrophysical Composition Methods Hadronic Interactions 1 < A < 56 (very likely)

33 Astrophysical Composition Methods Energy Spectrum imprints of Energy Loss Cosmic Magnetic Spectrometer

34 Features in the Cosmic Ray Energy Spectrum can in principle give information on the nature of the particle Interpreted as the efect of energy loss during propagation from their extragalactic sources. Known target: 2.7 K CMBR radiation feld Energy Thresholds for protons : GZK Pair Production

35 Berezinsky et al. Inject Smooth power law Spectrum. Let propagation leave its imprint on the shape of the spectrum. ANKLE --> DIP e+e- production

36 COSMIC MAGNETIC SPECTROMETER Constraint on : AUGER RESULT B, Z Correlations of the Highest-Energy Cosmic Rays with Nearby Extragalactic Objects (AGN) Protons are preferred [...?...]

37 Deviation in GALACTIC Magnetic Field Deviation in EXTRA-GLACTIC Magnetic Field

38 IF one accepts (at least for the sake of discussion) the astrophysical hints of a proton dominated composition...

39 IF one accepts (at least for the sake of discussion) the astrophysical hints of a proton dominated composition... Proton Line!! (?)

40 Electromagnetic Showers versus Hadronic Showers Toy model discussion.

41 Electromagnetic Showers Radiation Length (Energy independent) Vertices : theoretically understood (and scaling)

42 Electromagnetic Showers Logarithmic growth of the penetration. Energy Conservation 2 Elongation rate = 85 (g/cm )/decade

43 Heitler toy model for electromagnetic showerws Electron-photon particle Splitting length λ Critical energy ε

44 Shower development in Heitler toy model:

45 Proton Shower Vertices : theoretically not understood (and not exactly scaling)

46 Hadron Hadronic particle Interaction Length Hadronic Interaction Length 1 Inelasticity multiplicity Λ f m Hadronic vertex f/m 1-f Energy sharing 1 (1-f) + f/m + f/m + f/m + f/m +...

47 Hadronic shower

48 Hadronic parameters Λ, inelasticity, hardness

49 Hadronic shower in toy model.

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52 [integer] Hadronic interaction parameters

53 IF Λ, and the other hadronic interactions parameters are energy independent Elongation rate is equal to the radiation length

54 IF Λ, and the other hadronic interactions parameters are energy independent Elongation rate is equal to the radiation length Energy dependent parameters: Elongation rate changes

55 Scaling model : 85 (g/cm2)/decade Increasing cross sections Softer spectra Elongation Rate For protons

56 π p

57 Exactly Scaling Interactions λp, λπ=const. λπ=const.

58 Exactly scaling models Diferent elongation ra λp, λπ=const. λπ=const. Best ft

59 Introduce Energy dependent softening of the spectra

60 It is possible to reproduce A desired composition with (in this example) an appropriate gradual softening of secondary meson spectra. Possible also to introduce A faster rise of the cross section Ambiguities! May possibilities... How can we distinguish among them? Predictions for LHC!!?

61 It is possible to reproduce A desired composition with (in this example) an appropriate gradual softening of secondary meson spectra. Possible also to introduce A faster rise of the cross section Ambiguities! May possibilities... How can we distinguish among them? WARNING!! Perhaps : this approach is completely incorrect the mass composition is indeed mixed... We have to rely on [accelerator data + theory]

62 Fluctuations on Xmax Very Interesting an puzzling piece of information! Not confrmed by HIRES Potentially very important

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64 Comparison of data and p-qgsjet02 fuctuation widths Use 2-sigma truncated gaussian width to ft Xmax distr. Detector resolution is NOT deconvoluted! HIRES P.Sokolski

65 Overall comparison of Xmax data with QGSJET02 p and FE HIRES

66 Overall comparison of Xmax data with QGSJET02 p and FE HIRES AUGER People Keeping this distribution for themselves At the moment. Good work to you!

67 RMS [Xmax] decreasing with energy! Need robust confrmation. What does it imply? Composition getting heavier! Proton shower fuctuations becoming smaller. Much larger cross sections (shorter interaction length) Particle production properties. (seems unlikely to me...) [but...]

68 THEORY Construction of Hadronic Models

69 HADRONIC INTERACTIONS Leading nucleon 50% of energy π ο γγ Electromagnetic Shower Decay Inclusive spectra of secondary particles Interaction

70 Ebeam = 175 GeV pp FERMILAB SAS Brenner et al (1982)

71 Phenomenological Evidence for FEYNMAN SCALING

72 NUCLEAR efects: pp vs 12 p- C NA49

73 Hadronic Interactions Composite (complex) Objects Multiple interaction structure QCD

74 1st Slide from R.Feynman seminar in ISR high pt Pion production Deep Inelastic Scattering Develop quark fragmentation Model from e+ e- Scattering Data consistent with QCD From R.Field

75 HARD scattering Parton Distribution Functions

76 Field -Feynman : Quark - Fragmentation

77 Parton Distribution Function

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79 Where does the approximate Feynman scaling comes from? The (iterative) Fragmentation of one COLOR STRING produces a SCALING SPECTRUM of HADRONS

80 Diquark Quark Basic Structure of a NON difractive PP interactions is made of TWO STRINGS Color Structure hard/semihard interactions result in additional strings

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82 Pythia MC Most particles in Fragmentation Regions Described by the beam remnants strings

83 EXTRAPOLATION to HIGH ENERGY (Pythia pp)

84 EXTRAPOLATION to HIGH ENERGY (Pythia pp)

85 PROTON Spectra (elasticity spectra)

86 PYTHIA PROTON Spectra protons Antiprotons

87 PROTON Spectra (elasticity spectra)

88 MULTIPLE INTERACTIONS Estimate of the average number of Elementary interactions per pp scattering Spatial Distribution [proton spin] (Transverse coordinates) of the partonic constituents. Fluctuations of the parton confguration of an interactig hadron. Beyond PDF's Parton Distribution Functions

89 Hadrons crossing time short Snapshot of the Parton Confguration.

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92 Very Important potential of LHC TeV PP collider

93 Problems at the Beginning of Commissioning 19th september 2008

94 Jorg Wenninger : june 2008 Hadron Collider summer school

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97 LHC Physics in 2009/2010 First beams: very early physics - rediscover SM physics Detector synchronization, in-situ alignment and calibration 10 pb-1: Standard Model processes measure jet and lepton rates, observe W, Z bosons frst look at possible extraordinary signatures signatures 30 pb-1 Measure Standard Model Processes (at 10TeV need ~ 30pb-1): ~ 104 Z e+e- (golden Z s for detector studies (1%)) Background for new physics ~ 105 W eν Need to understand 3 ~ 10 ttbar (measure σ to 10%) very well Initial Higgs searches and searches for physics beyond the SM > 200 pb-1 Entering Higgs discovery era and explore large part of SUSY and new resonances at ~ few TeV FNAL June 4,

98 Event rate Level-1 On tape Higgs discovery golden channel

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102 Cross section Measurements Prediction for LHC at sqrt[s] = 14 TeV

103 CROSS SECTION MEASUREMENT Optical Theorem [Luminosity Determination]

104 PROBLEM of PHASE SPACE COVERING

105 LHCF Calorimeter for neutral particles in the very forward region Two non-identical Detectors

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107 We are studying at the same time Gigantic Astrophysical Beasts Millions of light years away Length scale cm Microscopic Partonic constituents of matter -13 Length scale 10 cm Exciting Difcult

108 + e Particle Physics Anderson discovery of positron π ± Occhialini, Powell Cosmic Ray Physics Κ ±

109 Galactic/Extragalactic Cosmic Rays