+ overview of the main pamela physics results oscar adriani university of florence & infn...

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+ Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th , 2015

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Page 1: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+

Overview of the main PAMELA physics results

Oscar AdrianiUniversity of Florence & INFN Firenze

17th Lomonosov ConferenceMoscow, August 26th, 2015

Page 2: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+PAMELA main physics tasks

1. Provide new high precision data about CR primary and secondary fluxes, to put constraints on the current acceleration and diffusion models of cosmic rays in the Galaxy.

2. Search for signatures of exotic processes connected to the Dark Matter problem;

3. Help solving the cosmological problem about the existence of the apparent asymmetry between matter and antimatter;

4. Investigate the heliosphere and Earth magnetosphere.

Page 3: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

Main requirements: - high-sensitivity antiparticle identification - precise momentum measurement

PAMELA detectors

GF: 21.5 cm2 sr Mass: 470 kgSize: 130x70x70 cm3

Power Budget: 360W

Spectrometer microstrip silicon tracking system + permanent magnetIt provides:

- Magnetic rigidity R = pc/Ze- Charge sign- Charge value from dE/dx

Time-Of-Flightplastic scintillators + PMT:- Trigger- Albedo rejection;- Mass identification up to 1 GeV;- Charge identification from dE/dX.

Electromagnetic calorimeterW/Si sampling (16.3 X0, 0.6 λI) - Discrimination e+ / p, anti-p / e- (shower topology)- Direct E measurement for e-

Neutron detector36 He3 counters :- High-energy e/h discrimination

+ -

Page 4: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+PAMELAPayload for Matter/antimatter Exploration and Light-nuclei Astrophysics

Launch from Baykonur

• PAMELA on board of Russian satellite Resurs DK1• Orbital parameters:

- inclination ~70o ( low energy)- altitude ~ 360-600 km (elliptical) – now 500 km

(circular)

Launched on 15th June 2006PAMELA in continuous data-taking mode since

then!Recently celebrated 9 years!

Page 5: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+PAMELA published results Antiproton flux + antiproton/proton ratio (100 MeV-300 GeV)

Positron flux + positron/electron ratio (100 MeV-300 GeV)

Electron flux (1 – 500 GeV)

Proton and helium flux (1 GeV – 1.2 TeV)

B/C ratio (500 MeV – 100 GeV)

H and He isotope flux

AntiHe/He ratio

Proton flux vs. time – solar modulation (electron flux vs. time submitted)

Trapped proton and antiproton flux, albedo protons

SEP data (13 December 2006 and 17 May 2012 event)

Positrons anisotropy (just submitted)

Search for strangelets (just submitted)

Page 6: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

e-

Page 7: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+Absolute fluxes of primary GCRsProtons, helium nuclei, electrons

Page 8: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+Proton and Helium Nuclei Spectra &

H/He ratio

Adriani et al., Science 332 (2011) 6025

First high-statistics and high-precision measurement

over three decades in energy Deviations from single power law (SPL):

• Spectra gradually soften in the range 30÷230GV• Spectral hardening @ R~235GV ~0.2÷0.3

SPL is rejected at 98% CL

• Origin of the hardening?• (e.g. see P. Blasi, arXiv:1312.1590)• - At the sources: multi-populations, etc.?• - Propagation effects?

Clear evidence of different H and He slopes above ~ 10 GV

Page 9: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+Global picture: PAMELA vs AMS-02 proton spectrum

Solar modulation

O. Adriani et al, Phys. Rep. (2014)

0.988

Page 10: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+Electron Spectrum

e+ + e-

e-

(ICRC 2013)

Solar modulation

Page 11: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+

Secondary cosmic raysSecondaries from homogeneously distributed interstellar matter (light nuclei)Antiparticles (antiprotons, positrons)

Page 12: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+ Boron and carbon fluxes and B/C

Adriani et al., ApJ 791 (2014), 93

Tuning of cosmic-ray propagation models with measurements of secondary/primary flux ratio

Modelization of cosmic-ray propagation in the Galaxy

Page 13: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

Lithium and beryllium fluxes

●No MC corrections●Not unfolded●Only statistical errors

Li Be

Preliminary

●Shaded red area: particle slow-down effects(still to be corrected)

●Shaded grey area: relevant MDR effects for Be (due to saturated clusters)(still to be corrected)

N. Mori & E. Vannuccini et al.: “Measurement of Lithium and Beryllium cosmic-ray abundances by the PAMELA experiment” - CR 08: 01/08/2015

Page 14: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

Li/Be Ratio

●No MC corrections●Not unfolded●Only statistical errors

Preliminary

●Shaded grey area: relevant MDR effects for Be (due to saturated clusters)(Still to be corrected)

N. Mori & E. Vannuccini et al.: “Measurement of Lithium and Beryllium cosmic-ray abundances by the PAMELA experiment” - CR 08: 01/08/2015

Page 15: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+

Isotopic separation with β (ToF) vs. Rigidity or multiple dE/dx (Calorimeter) vs. rigidity

Hydrogen and helium isotopes

W. Menn et al.: “Measurement of the isotopic composition of hydrogen and helium nuclei in cosmic rays with the PAMELA experiment” - Poster 1 CR: 30/7/2015

Page 16: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+Anti He/He and search for Strange Quark Matter

No antiHe detected in a sample of 6.330.000 events with |Z|>=2,from 0.6 to 600 GV.

Widest energy range ever reached

• No anomalous A/Z particle has been found (for Z <8 ) in the rigidity range

1 < R < 1.0 x 103 GV and mass range 4 < A < 1.2 x 105

• Upper limit as a function of Baryon Number (A) set

Accepted by PRL

Page 17: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+ PAMELA Antiparticle Results: Antiprotons

Secondary production calculations

O. Adriani et al,PRL 102 (2009) 051101; PRL 105 (2010) 121101;Phys. Rep. (2014).

Page 18: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+Positron fraction

M. Aguilar et al, PRL 110, 2013

Good agreement with FERMI and AMS data

Page 19: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+Positron flux

Adriani et al. , PRL 111 (2013) 081102

In the highest bin a lower limit has been estimated with 90% confidence level, due to a possible overestimation of the proton contamination.

Clear evidence

The positron fraction increase is due to an harder positron spectrum and not to a softer electron one.

Solar modulation

Page 20: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+Positron-excess interpretations

A primary positron source is certainly necessary!

Dark matter

- boost factor required

- lepton vs hadron yield must be consistent with p-bar observation

Astrophysical processes

• - known processes

• - large uncertainties on environmental parameters

e+ (and e-) produced as secondaries in the CR acceleration sites (e.g. SNR)

Contribution from diffuse mature & nearby young pulsars.

Contribution from DM annihilation.

Page 21: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+Search for anisotropy in the positron data

Significance maps for backtraced positrons in the 10 GV <R<200 GV, over the following angular scales: 10◦, 30◦, 60◦, 90◦.The significance has been computed using the protons measured as the isotropic reference sample

No evidence of positrons anisotropyin PAMELA data

Submitted to AP

Page 22: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+

Cosmic rays in the heliosphere

Page 23: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+

O. Adriani et al., ApJ 765 (2013), 91;M. S. Potgieter et al., Sol. Phys. (2014), 289

protons

electrons

increasingfluxes

Decreasing solar activity

PAMELA covers one solar cycle

Cycle23

PAMELACycle24

Neutron Monitor count (Data from http://cosmicrays.oulu.fi ) Effect of solar activity on CR fluxes

Page 24: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+Solar modulation: electron spectra

Adriani et al., submitted to ApJ

The ratios as a function of energy between the measured half-years (e−) fluxes from January 2007 till December 2009 and the measured fluxes for the period July-November 2006 overlaid with the corresponding computed spectra (solid lines).

The error bars are the quadratic sum of the statistical and systematic errors.

Page 25: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+SEP events (SEP from Dec. 13, 2006)

Ad

rian

i et a

l. - Ap

J 742 1

02,

2011

Page 26: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+Preliminary PAMELA SEP Spectra

100 MeV 1 GeV Proton Energy

Flux

E. Christian et al.: “Unseen GLEs (Ground Level Events)”- SH01: 30/07/2015

Completing the spectrum

PAMELA bridges the gap between low energy space-based and ground-‐based measurements to obtain a complete spectrum

Page 27: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+

Cosmic rays in the magnetosphere

Page 28: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+

Cosmic rays in the magnetosphereSorry, I

have no time!!!

!

Page 29: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

All particlesPAMELA results

PAMELA overall resultsResults span 4 decades in energy and 13 in fluxes

Page 30: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

Summary and conclusions (1)

PAMELA has been in orbit and studying cosmic rays for almost 9 years. Its operation time will continue until end 2015, possibly until end of current solar cycle.• Antiproton energy spectrum and ratio Measured up to ~300 GeV. No significant deviations from secondary production expectations. • High energy positron fraction (>10 GeV) Measured up to ~300 GeV. Increases significantly (and unexpectedly!) with energy. Primary source?• Positron flux -> Consistent with a new primary source. • Anisotropy studies: no evidence of anisotropy.• AntiHe/He ratio: broader energy range ever achieved.

Page 31: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

Summary and conclusions (2)

• H and He absolute fluxes Measured up to ~1.2 TV. Complex spectral

structures observed (spectral hardening at ~200 GV).

• H and He isotope fluxes and ratio -> most complete measurements so far.

• Electron (e-) absolute flux Measured up to ~600 GeV. Possible deviations

from standard scenario, not inconsistent with an additional electron

component.

• B/C ratio and absolute fluxes up to 100 GeV/n.

• Solar physics: measurement of modulated fluxes and solar-flare particle

spectra

• Physics of the magnetosphere: first measurement of trapped antiproton flux

and detailed measurement of trapped proton flux.

Other studies and forthcoming results: Primary and secondary-nuclei

abundance (up to Oxygen), Solar modulation (long-term flux variation and

charge-dependent effects), Solar events: several new events under study.

Page 32: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+

Backup slides

Page 33: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+PAMELA & AMS (and Fermi) Electron (e-) Spectrum

Solar modulation

R. Munini et al.: “Solar modulation of galactic cosmic rays electrons and positrons over the 23rd solar minimum with the PAMELA experiment”- SH 07: 04/08/2015

Page 34: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+Electron energy measurements

spectrometer

calorimeter

Adriani et al. , PRL 106 (2011) 201101

Electron identification:• Negative curvature in the spectrometer• EM-like interaction pattern in the

calorimeter

Two independent ways to determine electron energy:

1.Spectrometer • Most precise• Non-negligible energy losses (bremsstrahlung) above the spectrometer unfolding

2.Calorimeter• Gaussian resolution• No energy-loss correction required

• Strong containment requirements

Page 35: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+

Solar neutrons can be produced by any solar event.PAMELA Neutron Detector (ND) is sensitive to neutrons fluxes coming from Sun.

Search of ND counts increasing after SEP event in comparison with counts during 1 orbit before the event.Two events under study: June 7th 2011December 13rd 2006

Search for solar neutrons

Page 36: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+New article about trapped protons

Differential fluxes are reported as a function of the first adiabatic invariant M, for sample values of K and L∗ invariants (equatorial region).

While spectral shapes are in a good qualitative agreement, measured flux intensities result to be up to about an order of magnitude lower with respect to model predictions, depending on the phase-space region. O. Adriani et al. ApJ

799, 1, L4 (2015)

Page 37: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+Light Nuclei and Isotopes

Tuning of cosmic-ray propagation models with measurements of secondary/primary flux ratio

2H/1H and 3He/4He are complementary to B/C measurements in constraining propagation models (Coste et al., A&A 539 (2012) A88)

Page 38: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+ Boron and carbon fluxes and B/C

Adriani et al., ApJ 791 (2014), 93

Tracking performance: σx = 14 μm, σy =

19 μm MDR = 250 GV

Modelization of cosmic-ray propagation in the Galaxy

Page 39: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+South-Atlantic Anomaly (SAA)

SAA

Page 40: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+South-Atlantic Anomaly (SAA)

SAA

SAA morphology

Lati

tud

eA

ltit

ud

e Altitude

Longitude

Neutron rate

Page 41: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+Geomagnetically trapped antiprotons

First measurement of p-bar trapped in the inner belt

29 p-bars discovered in

SAA and traced back to mirror

points

p-bar flux exceeds GRC flux by 3

orders of magnitude, as

expected by models

O. Adriani et al., ApJL 737 (2011), L29

Page 42: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+The PAMELA collaboration

BariFlorenceFrascatiItaly:

TriesteNaples Rome CNR, Florence

Moscow St.

Petersburg

Russia:

Germany:Siegen

Sweden:KTH, Stockholm

Page 43: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+Global picture: PAMELA vs AMS-02 helium nuclei spectrum

Solar modulation

1.036

Page 44: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+Lithium and Beryllium Isotopesβ (ToF) vs. Rigidity or Multiple dE/dx (Calorimeter) vs. rigidity

Ratio 7Li / 6Li

Lithium Beryllium

7Be / (9Be + 10Be)

W. Menn et al. : “Lithium and Beryllium Isotopes in the PAMELA experiment” - CR08:01/08/2015

Page 45: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+Primary positron sourcesDark Matter

e+ yield depend on the dominant decay channel ® LSPs (SUSY) seem disfavored due to

suppression of e+e- final states ® low yield (relative to p-bar)® soft spectrum from cascade decays

Other hypotheses possible and under study (i.e. Minimal DM Model, decaying DM, new gauge bosons, …)

Astrophysical processes

Local pulsars are well-known sites of e+e- pair production: they can individually and/or coherently

contribute to the e+e- galactic flux and explain the PAMELA e+ excess (both spectral feature and intensity)

® No fine tuning required® if one or few nearby pulsars dominate,

anisotropy could be detected in the angular distribution

LKP -- M= 300 GeV (Hooper & Profumo 2009)

More than 150 articles claim DM is discovered !

Page 46: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+Searching for a positron excess in the direction of the sun

No evidence of positron excess in the direction of the sun

Submitted to AP

Page 47: + Overview of the main PAMELA physics results Oscar Adriani University of Florence & INFN Firenze 17 th Lomonosov Conference Moscow, August 26 th, 2015

+

2012 May 17th2012 March 7th

2012 January 27th2012 January 23rd

PAMELA bridges the gap below ACE, GOES and many others and above the Neutron Monitors to obtain a complete spectrum

Completing the spectrum