Properties of Elementary Particles Fluxes in Primary Cosmic Rays - - PowerPoint PPT Presentation

Properties of Elementary Particles Fluxes in Primary Cosmic Rays Measured with AMS

Zhi-Cheng Tang / IHEP , CAS

• n behalf of the AMS Collaboration

Sep 2019 TAUP , Toyama

TRD TOF Tracker TOF RICH ECAL

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Transition Radiation Detector (TRD) Silicon Tracker Electromagnetic Calorimeter (ECAL) Ring Imaging Cherenkov (RICH) Time of Flight Detector (TOF)

Z and P (or E) are measured independently by the Tracker, RICH, TOF and ECAL

Magnet

AMS is a space version of a precision detector used in accelerators

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AMS is a unique magnetic spectrometer in space

Matter Antimatter

AMS is able to pick out 1 positron from 1,000,000 protons unambiguously separate positrons from electrons, antiprotons from protons and accurately measure all cosmic rays to trillions of eV. In 8 years, the detectors have performed flawlessly, collected more than 140 billion cosmic rays.

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Silicon Tracker and Magnet

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1.4 kG single point resolution: 10micron, MDR: 2TV

Transition Radiation Detector (TRD)

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e- p

e± p,p

TRD estimator = -ln(Pe/(Pe+Pp)) Separation Power 103 - 104

TRD Estimator ∧TRD e± p,p

dE/dx

One of 20 layers

p,p e±

Electromagnetic Calorimeter (ECAL)

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!± and #, % # Separation in AMS

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• Separation power is 103 to

104 with TRD

• Separation power is above

104 with ECAL and tracker

• TRD and ECAL are separated

by magnet they have independent particles identification

Measurement - Prediction

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400 GeV/c T estBeam Data 400 GeV/c Simulation

Calibration at CERN

with different particles at different energies

AMS 27 km 7 km

LHC

CERN France Switzerland Italy the Alps

400 GeV/c T estBeam Data 400 GeV/c Simulation

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Unique properties of AMS

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The accuracy of the rigidity scale is found to be ±0.033 TV-1, constant with time, limited only by available positron statistics

Measurements above test beam energy Accuracy of the rigidity scale Calibrate the detector in space, beyond test beam energy

p

p+p ->p, p, π±....

p

• The 4 elementary particles: proton, antiproton, positron and electron have infinite live

time, they can travel through the galaxy. They carry information of the origin and propagation history of cosmic rays.

• Protons, Electrons are produced and accelerated in Supernovae Remnants (SNRs) together

with other cosmic rays primary components. These particles interact with the interstellar matter and produce secondary components, including anti-particle: positrons, antiprotons

• New sources like dark matter produce particles and antiparticles in equal amount.

AMS

A major tool to look for new physics in space is to measure and compare the properties of the fluxes of these particles

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AMS Measurement of the Proton Flux

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See V. Formato’s talk for details

Latest results – 1 billion protons The result shows progressively hardening above 200GV and in agreement with our previous publication

The Spectra of Antiprotons and Protons

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AMS observed for the first time that above 60 GeV, p and ! p have identical behavior

Preliminary data, refer to upcoming AMS publication

Antiproton-to-Proton Flux Ratio

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Show no rigidity dependence above 60GV

Preliminary data, refer to upcoming AMS publication

Fit to a power law in the range [60,525] GV shows that the difference between the power law index of proton and antiproton is 0.05±0.06, consistent with 0

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AMS-02

Flattening Rise Fall

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• wards Understanding of the Origin of Cosmic-Ray Positrons

1.9 million positrons

• Phys. Rev. Lett. 122 (2019) 041102. Editor's Suggestion

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(a) An excess a!"#$ %& = (). ( ± ,. - GeV (b) A sharp drop-off at %& = (-./0.

12, GeV

Fits of the data to

25.2 GeV 284 GeV

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Φ45 6 = 78%9, 6 ≤ 6<; 8%9 ⁄ 6 6< ?@, 6 > 6<.

The Origin of Positrons

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Positrons from Cosmic Ray Collisions

Low energy positrons mostly come from cosmic ray collisions AMS 1.9 million positrons

Model based on positrons from cosmic ray collisions.

Astrophysical Journal 729, 106 (2011)

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The positron flux is the sum of low-energy part from collisions plus a new source at high-energy with a cutoff energy ES !"# $ = $& $ '& ()($ ' $+ ⁄ ).) + (1 $ ' $& ⁄

.1234(− $

' $1 ⁄ )

1/Es = 0 or Es = ∞ excluded at >99.99%

Es = 810 GeV

Positrons from Cosmic Ray Collisions

New High-energy Source

• AMS positrons

Positrons, Antiprotons from Dark Matter

Dark Matter Dark Matter

Electrons, … Interstellar Medium Protons, Helium, …

Supernovae

Positrons, Antiprotons from Collisions

Positrons from Pulsars

New Astrophysical Sources: Pulsars, …

On the Origins of Cosmic Anti-particles

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Rotation axis

Positrons from Pulsars

• 1. Pulsars produce and accelerate positrons to high energies.
• 2. Pulsars do not produce antiprotons.
• 3. Pulsars cause higher anisotropy on the arrival directions of

energetic positrons.

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Energy [GeV]

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5 10 15 20 25 30 2 4 6 8 10 12 14 AMS-02 Antiproton AMS-02 Positron

The spectra of antiproton and positron

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Preliminary data

At high energy Antiprotons have very similar trends with Positron Antiprotons can not come from pulsar

Positron Anisotropy

Astrophysical point sources will imprint a higher anisotropy on the arrival direction of energetic positrons than a smooth dark matter halo

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See M. A. Velasco Frutos's talk for details

Dark Matter

Collision of Dark Matter produces positrons and antiprotons. Dark Matter particles have mass M and they move slowly. Before collision the total energy ≈ 2M. The conservation of energy and momentum requires that the positron or antiproton energy must be smaller than M. So, there is a sharp cutoff in the spectra at M. Dark Matter Dark Matter Electrons, Protons Positrons, Antiprotons

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Positrons and Dark Matter

(Mass = 1.2 TeV) cosmic ray collisions + cosmic ray collisions

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AMS positron

• J. Kopp, Phys. Rev. D

88 (2013) 076013

AMS 28.1 million electrons Electrons from cosmic ray collisions

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• wards Understanding of the Origin of Cosmic-Ray Electrons

The contribution from cosmic ray collisions is negligible

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• Phys. Rev. Lett. 122 (2019) 041102

42.1 GeV

A significant excess at !" = $%. '().%

*).$ GeV

Fit to the data

7σ effect

Φ,- . = /0!1, . ≤ .4; 0!1 ⁄ . .4

78, . > .4.

Δ1= 0.094±0.014

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The electron flux can be described by two power law functions

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!"# $ = &($) )* $ + $* ⁄

• * + )/ $

+ $/ ⁄

• /

b

Power law a Power law

Solar & low-energy

At high energy, the fluxes of proton, antiproton and positron have similar energy dependence, while electrons decrease faster than

• ther three species. Positrons have a sharp drop off at high energy.

Preliminary data, refer to upcoming AMS publication

Fluxes of Elementary Particles

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AMS is exploring fundamental physics in space with many different types of cosmic rays. Many new and exciting phenomena are observed. By collecting data through the lifetime of ISS, AMS will greatly improve the accuracy of these measurements and will reach higher energy.

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AMS-02 Data 2018 Projection 2028 Dark Matter Model

AMS Publications in PRL

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1. First Result from the AMS on the ISS: Precision Measurement of the Positron Fraction in Primary Cosmic Rays

• f 0.5–350 GeV (2013)

2. Electron and Positron Fluxes in Primary Cosmic Rays Measured with the AMS on the ISS (2014) 3. High Statistics Measurement of the Positron Fraction in Primary Cosmic Rays of 0.5–500 GeV with the AMS on the ISS (2014) 4. Precision Measurement of the e+ + e- Flux in Primary Cosmic Rays from 0.5 GeV to 1 TeV with the AMS on the ISS (2014) 5. Precision Measurement of the Proton Flux in Primary Cosmic Rays from Rigidity 1 GV to 1.8 TV with the AMS on the ISS (2015) 6. Precision Measurement of the He Flux in Primary Cosmic Rays of Rigidities 1.9 GV to 3 TV with the AMS on the ISS (2015) 7. Antiproton Flux, Antiproton-to-Proton Flux Ratio, and Properties of Elementary Particle Fluxes in Primary Cosmic Rays Measured with the AMS on the ISS (2016) 8. Precision Measurement of the B to C Flux Ratio in Cosmic Rays from 1.9 GV to 2.6 TV with the AMS on the ISS (2016) 9. Observation of the Identical Rigidity Dependence of He, C, and O Cosmic Rays at High Rigidities by the AMS on the ISS (2017)

• 10. Observation of New Properties of Secondary Cosmic Rays Lithium, Beryllium, and Boron by the AMS on the ISS (2018)
• 11. Observation of Fine Time Structures in the Cosmic Proton and Helium Fluxes with AMS on the ISS (2018)
• 12. Observation of complex time structures in the cosmic-ray electron and positron fluxes with the AMS on the ISS (2018)
• 13. Precision measurement of cosmic-ray nitrogen and its primary and secondary components with AMS on the ISS (2018)

14.Towards Understanding the Origin of Cosmic-Ray Positrons (2019) 15.Towards Understanding the Origin of Cosmic-Ray Electrons (2019)

… “Helium Isotopes in the Cosmos ” … “Rigidity Dependence of Ne, Mg, and Si Cosmic Rays”

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In yellow: editors' suggestion

AMS contributions to TAUP 2019

• Properties of Elementary Particle Fluxes in Primary Cosmic Rays Measured with

AMS Z. Tang

• Anisotropy of Elementary Particle Fluxes in Primary Cosmic Rays Measured with

AMS M. A. Velasco Frutos

• New Properties of Primary Cosmic Rays Measured by AMS on ISS V. Formato
• New properties of secondary cosmic rays measured by AMS M. Paniccia
• Cosmic Ray Isotopes measured by AMS F. Giovacchini
• Observation of Complex Time Structures in the Cosmic-Ray Electron and

Positron Fluxes by the AMS V. Vagelli

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