Monthly Proton Flux Veronica Bindi, AMS Collaboration Physics and - - PowerPoint PPT Presentation

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Monthly Proton Flux

Solar modulation, Forbush decreases and Solar Energetic Particles with AMS

Physics and Astronomy Department University of Hawaii at Manoa Honolulu, Hawaii, US

Veronica Bindi, AMS Collaboration

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AMS on the ISS

May 19, 2011 and for the duration of the ISS.

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Particle Identification with AMS

AMS is a general purpose detector which measures particles

in the GV-TV rigidity range

More details ICRC 2017 highlight talk: A. Kounine

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Particle identification with AMS

More details ICRC 2017 CR-D session: A. Oliva, Q. Yan.

In 6 years of operation, AMS has measured over 100 billion events.

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AMS Scientific Goals

• M. Aguilar (AMS collaboration) PRL110,141102 (2013)

Indirect Dark Matter search Galactic Cosmic Rays study

Interesting features have been measured at high energies and more has to come in the near future. New Goal: Study of the time variation of the low energy part of the spectrum.

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Solar modulation: Dark Matter search

Uncertainties at low energies due to the effects of Solar modulation, increase the errors on theoretical models used for Dark Matter interpretation of the excess in the antimatter channels and in evaluation of the secondary background. Charge sign effects affect the DM signatures expected at low energies (anti-deuteron).

More details ICRC 2017 CR-D session: Z. Li, W. Xu

• M. Aguilar (AMS collaboration) PRL110,141102 (2013)

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Solar Modulation: GCR in heliosphere

• to understand the

propagation of GCRs in the heliosphere.

• to test theories of particles

diffusion (charge and mass) and drift (charge-sign).

• to study the effect on cosmic

rays due to the reversal in the solar polarity. Precise measurements of the time-dependent GCRs spectra are important:

Daily sunspot number: http://www.sidc.be/silso/datafiles

Solar activity measured by AMS

The Sun goes through an 11-year activity cycle shown by sunspots number. At each solar maximum the Sun flips its magnetic field polarity (A>0, A<0) showing a periodicity of 22 years.

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NM

NM Counts/sec

SSN

Cycle 23 Cycle 24 Cycle 22

The flux of galactic cosmic rays is anti-correlated with the intensity of the solar activity.

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AMS Monthly Proton Flux five years of data

Flux Intensity

More details ICRC 2017 CR-D session: C. Consolandi

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Monthly Proton & Helium Fluxes

Minimum of the flux around Feb 2014 for most of rigidities

Monthly fluxes

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Monthly Proton & Helium Fluxes

2011 Apr 2012 Jan 2012 Sep 2013 Jun 2014 Feb 2014 Nov 2015 Jul 2016 Apr 2016 Dec

)

• 1

GV

• 1

s

• 1

sr

• 2

Proton Flux (m

200 220 240 260 280 300 320 340

)

• 1

GV

• 1

s

• 1

sr

• 2

Helium Flux (m

30 35 40 45 50

p

He

[3.29-3.64]GV AMS will study how solar modulation affects all different cosmic ray species.

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Electron & Positron Fluxes

Energy (GeV) 2 3 4 5 6 7 8 910

• 1

10 1 10

Electrons Positrons

Each color represents a 27 days integration flux.

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Monthly e+ and e- flux Time profile

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Change of Solar Polarity and Particle Drift

AMS will measure the drift of positive vs negative particles during a solar minimum with positive polarity A>0.

A <0 A >0

[1.0 -1.2]GV

[2.0 -2.3]GV

A <0 A >0

Polarity inversion period from: X. Sun et al., Astroph. J., 798, 114 (2015)

Electrons A <0 Electrons A >0

AMS e+/e- ratio clearly shows the charge-sign dependence of solar modulation. Repeat the study with pbar/p.

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Short term solar activity

Solar Events measured by AMS

Solar Energetic Particles

Forbush Decrease AMS daily Normalized Flux

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More details ICRC 2017 SH session: M. Palermo

March 7, 2012 Two Solar Flares of class X5.4 and X1.3 (XRT Flare catalog). Two Coronal Mass Ejections with linear speeds of 2684 km/s and 1825 km/s (SOHO LASCO CME catalog).

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Normalized daily proton flux

Daily fluxes

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Forbush Decreases Characteristics

FD with long duration (20 days) and maximum decrease at 2 GV of 40%

FD event List

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FD Characteristics for Selected Events

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SEP Observed as an Excess above the GCR Background

AMS Proton daily flux

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AMS Daily Proton Flux

May 17, 2012 May 16 , 2012 (quiet day)

May 17, 2012 - Ground Level Enhancement (GLE) Solar Flare of class M5.1 (XRT Flare catalog). Coronal Mass Ejection with linear speeds of 1582 km/s (SOHO LASCO CME catalog).

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SEP

Solar Energetic Particle Flux

May 17, 2012

SEP flux obtained subtracting the galactic cosmic ray background

AMS

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IGRF Geomagnetic Cutoff in the AMS field of view

SEPs can be observed in the part of the orbit close to geomagnetic poles

GV GV

27% of orbiting period

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AMS Multi-orbit Observations Time evolution

May 17, 2012

SEP Average integration time about 10 minutes

AMS data provide information at high rigidity with fine resolution.

SEP flux May 17, 2012

AMS GOES GOES SOHO

AMS data, combined with other instruments at lower energy, will provide a baseline for the modeling of SEP production.

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SEP events Observed by AMS

AMS observed 27 high energy SEP events at ~ 1 GV from May 2011 to May 2016. AMS SEP events are typically associated with M and X class flares and fast CMEs.

GLE Ground Level Enhancement (GLE)

AMS data taking till 2024 - Agenda

Comparing data collected before, during and after the solar maximum AMS can study in details the effects due to the solar polarity reversal. AMS will measure the drift of positive vs negative particles during the solar minimum with positive polarity A>0. AMS will compare solar maximum of cycles 25 (A>0) and 24 (A<0) and the solar polarity reversal. AMS is measuring the modulation of different nuclei during a solar cycle.

Polarity: A<0 Reversal A>0 A>0 A>0 Reversal Polarity: A<0 Reversal A>0 A>0 A>0 Reversal ascending phase solar maximum descending phase solar minimum ascending phase solar maximum

Years: 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024

DRIFT :

e-, e+ , p, pbar

DIFFUSION : All species

• f GCR

FD and SEP :

Measured 27 SEPs and identified so far 33 FDs. Not expected major events during minimum Lots of new SEPs and FDs.

Cycle 24 Cycle 25

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Summary & Conclusions

A new era in galactic cosmic rays understanding has started, not only at high energy, but also at low energy in the region affected by the solar modulation thanks to the precise and continuous observations from space by PAMELA in solar cycle 23 and now AMS-02 in solar cycle 24 and 25. New and precise measurements are increasing our knowledge of important effects such as diffusion and drift in the heliosphere, allowing the detailed study of propagation. These measurements will serve as a high-precision baseline for continued studies of GCR solar modulation, SEPs, space radiation hazards, magnetospheric effects, trapped particles and in many other fields. Near future forthcoming AMS publications on solar modulation: time evolution of proton and helium fluxes, electron and positron fluxes, and antiproton/proton ratio.

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AMS FD Relationship with Solar Wind Parameters

AMS