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 on behalf of the AMS Collaboration Sep 2019 TAUP , Toyama

AMS is a space version of a precision detector used in accelerators Transition Radiation Time of Flight Detector (TRD) Detector (TOF) 1 TRD Magnet TOF Silicon Tracker 2 3-4 5-6 Tracker 7-8 Ring Imaging Cherenkov TOF (RICH) RICH Electromagnetic 9 Calorimeter (ECAL) ECAL Z and P (or E ) are measured independently by the Tracker, RICH, TOF and ECAL 2

AMS is a unique magnetic spectrometer in space Antimatter Matter 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. 3

Silicon Tracker and Magnet 1.4 kG single point resolution: 10micron, MDR: 2TV 4

Transition Radiation Detector (TRD) One of 20 layers dE/dx p,p e ± TRD estimator = -ln( P e /( P e + P p )) Separation Power e ± 10 3 - 10 4 e - p,p e ± p p,p TRD Estimator ∧ TRD 5

Electromagnetic Calorimeter (ECAL) 6

! ± and #, % # Separation in AMS • Separation power is 10 3 to 10 4 with TRD • Separation power is above 10 4 with ECAL and tracker • TRD and ECAL are separated by magnet they have independent particles identification 7

Calibration at CERN with different particles at different energies 27 km Italy AMS the Alps 7 km France Switzerland LHC CERN 6 10 400 GeV/c T estBeam Data 400 GeV/c T estBeam Data 5 10 400 GeV/c Simulation 400 GeV/c Simulation 4 10 Events 3 10 2 10 8 Measurement - Prediction 10 -0.02 -0.01 0 0.01 0.02

Unique properties of AMS Calibrate the detector in space, beyond test beam energy Measurements above Accuracy of test beam energy the rigidity scale The accuracy of the rigidity scale is found to be ±0.033 TV -1 , constant with time, limited only by available positron statistics 9

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. p+p ->p, p, π ± .... p AMS p A major tool to look for new physics in space is to measure and compare the properties of the fluxes of these particles 10

AMS Measurement of the Proton Flux Latest results – 1 billion protons The result shows progressively hardening above 200GV and in agreement with our previous publication See V. Formato’s talk for details 11

The Spectra of Antiprotons and Protons AMS observed for the first time that above 60 GeV, p and ! p have identical behavior Preliminary data, refer to upcoming AMS publication 12

Antiproton-to-Proton Flux Ratio Show no rigidity dependence above 60GV 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 Preliminary data, refer to upcoming AMS publication 13

T owards Understanding of the Origin of Cosmic-Ray Positrons Phys. Rev. Lett. 122 (2019) 041102. Editor's Suggestion 25 AMS-02 ] -1 1.9 million s 20 positrons -1 sr -2 m 15 2 [GeV 10 Rise Fall Flattening + e Φ 3 E ~ 5 Energy [GeV] 0 1 10 100 1000 14

Φ 4 5 6 = 78% 9 , 6 ≤ 6 < ; Fits of the data to 8% 9 6 6 < ? @ , ⁄ 6 > 6 < . (a) An excess a !"#$ (b) A sharp drop-off at 12, GeV % & = (). ( ± ,. - GeV % & = (-. /0. 25.2 GeV 284 GeV 15

The Origin of Positrons 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) ? Positrons from Cosmic Ray Collisions 16

The positron flux is the sum of low-energy part from collisions plus a new source at high-energy with a cutoff energy E S ! " # $ = $ & . 1 234(− $ ' $ + ' $ & ' $ 1 ) . ) + ( 1 $ ⁄ ⁄ ⁄ ' & ( ) ($ ) $ • AMS positrons E s = 810 GeV 1/E s = 0 or E s = ∞ excluded at >99.99% New High-energy Source Positrons from Cosmic Ray Collisions 17

On the Origins of Cosmic Anti-particles New Astrophysical Sources: Pulsars, … Supernovae Positrons Protons, from Pulsars Helium, … Interstellar Medium Positrons, Antiprotons from Collisions Dark Matter Positrons, Antiprotons from Dark Matter Electrons, … Dark Matter 18

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. Rotation axis 19

The spectra of antiproton and positron At high energy Antiprotons have very similar trends with Positron Antiprotons can not come from pulsar 30 ] 2 GeV 14 AMS-02 Antiproton Preliminary data 25 12 -1 AMS-02 Positron s -1 20 10 sr -2 8 [m 15 � 6 3 10 E ~ 4 5 2 Energy [GeV] 2 3 10 10 1 10 20

Positron Anisotropy Astrophysical point sources will imprint a higher anisotropy on the arrival direction of energetic positrons than a smooth dark matter halo See M. A. Velasco Frutos's talk for details 21

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 ≈ 2 M. Electrons, Protons Dark Matter Dark Matter Positrons, Antiprotons 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 . 22

Positrons and Dark Matter AMS positron J. Kopp, Phys. Rev. D 88 (2013) 076013 (Mass = 1.2 TeV) + cosmic ray collisions cosmic ray collisions 23

T owards Understanding of the Origin of Cosmic-Ray Electrons The contribution from cosmic ray collisions is negligible Phys. Rev. Lett. 122 (2019) 041102 AMS 28.1 million electrons Electrons from cosmic ray collisions 24

Δ 1 = 0.094±0.014 7 σ effect Fit to the data Φ , - . = /0! 1 , . ≤ . 4 ; 7 8 , . > . 4 . 0! 1 ⁄ . . 4 A significant excess at *).$ GeV ! " = $%. ' ().% 42.1 GeV 25 25

The electron flux can be described by two power law functions - * + ) / $ - / + $ * + $ / ! " # $ = &($) ) * $ ⁄ ⁄ Solar & Power Power law a b low-energy law 26

Fluxes of Elementary Particles Preliminary data, refer to upcoming AMS publication At high energy, the fluxes of proton, antiproton and positron have similar energy dependence, while electrons decrease faster than other three species. Positrons have a sharp drop off at high energy. 27

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. 25 ] 2 GeV AMS-02 Data 2018 -1 20 sr Projection 2028 -1 s -2 Dark Matter Model [m 15 + e Φ 3 E 10 ~ 5 Energy [GeV] 0 500 1000 1500 2000 28

AMS Publications in PRL In yellow: editors' suggestion 1. First Result from the AMS on the ISS: Precision Measurement of the Positron Fraction in Primary Cosmic Rays of 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) 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) 4. 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 ” … 29