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Cosmic Ray panorama
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PAMELA (2012)
http::// Pamela.roma2.infn.it
Experimental challenges : • e+/p ~ 10-3 • e+/e- ~ 10-1
• Flux ∝ E –α • α≈ 2.7 / 3.3 • Statistical precision
Pamela : < 0.1 evt year/GeV
Origin of Electrons
Primary particles ejected from SN/SNR … : • Injection → E -γe
• Energy loss (IC,Sync) → ~E -γe-1
TeV electrons : • Local < 1kpc • Individual sources visible ?
• ATIC
• Energy cut-off
Requirements : • Statistics • Energy resolution
arXiv 1402.0321 M Di Mauro et al.
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ATIC BEPS
Fermi HESS-LE / HESS
Origin of positrons Predictions & Uncertainties
Secondary particles from e.g • p/He + ISM → p + n + π+ ,…
Injection (proton spectrum) : E –yp-δ ≈ E-2.7
• γp ~ 2 (Fermi mechanism) • δ = 0.3 - 0.8 (Diffusion : B/C, ….)
Energy loss (IC, Sync) : E –γp-δ-1
Uncertainties arise from
• Proton spectrum : extrapolation to higher energy
• Cross-Section : • Parameters of the propagation
(Halo, diffusion, winds …)
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Cross –sections
Parameterization of p flux :
A&A 501 821-833 (2009)
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Primary source of positrons : nature ?
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(2013)
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Secondary origin only :
𝜑𝑒+φ𝑒−+ φ𝑒+
~ E –δ
(γp γe ~⁄ 1,
δ = 0.3 − 0.8 )
PAMELA – 2006 – 2014
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Set of Time-Of-Flight (TOF) plastic scintillators + PMT: • Trigger • Albedo rejection • Mass identification up to 1 GeV • dE/dx
Spectrometer microstrip Si tracking system (TRK) + permanent magnet 0.43 T • Charge sign, momentum • dE/dx
Electromagnetic calorimeter W/Si sampling (16.3 X0, 0.6 λI) • Discrimination e+ / p, p-bar / e-
(shower topology) • Direct E measurement for e-/e+
Neutron Detector polyethylene + 3He counters: High-energy e/h discrimination
Acceptance limited to
~ 21 cm2.sr
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NEW : all leptons analysis using
Calorimeter + Neutron Detector
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19 Mai 2011
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e± p
TOF : Main trigger
Up/Down direction
TRACKER : 8 layers Si – 10 µm 0.14 T MDR ~ 2 TeV
ACC(p) : 0.5 m2.sr ACC(e) : 0.04 m2.sr
e+
e-
p
Corinne Goy - LAPP - Rencontres du Vietnam 2014 17/07/2014
e
p ECAL :
Imaging Calorimeter 17 x0 Lead/Sci - 2%
No magnet – 0.25 m2.sr
Imaging calorimeter 22.5 X0 BGO / 2%
Shower shape in atmosphere 15 %
Large collection area (80- 100 m2.sr)
No magnet – ~2 m2.sr : Imaging Calorimeter
10 X0 CsI / 5-10%
: Earth shadow e+/e-
e+/p
e+/p
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FERMI
ATIC
HESS
e+/p
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All electrons flux (1) : AMS 2014 – 1 TeV
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Preliminary ICHEP 2014 Event Sample : 10.5 million events
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All electrons flux (2) : PAMELA 2014 -1 TeV
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Preliminary ICHEP 2014
(ICRC 2013)
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All electrons flux – HESS – several TeV
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Evidence for an energy cut-off at about 1-2 TeV
Systematic : • Atmosphere modeling • Proton shower modeling (π0) • Energy scale
γ1 = 3.0 +/- 0.1 γ2 = 4.1 +/- 0.3
Energy Scale
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~ 2- 5 % for Satellite /Balloon ~ 15 % for HESS
• Lots of protons →homogeneity response , time stability
• Linearity : ions (dE/dx) , E/p • Absolute E scale
• No standard candles in space • Test beam • MC description ... • E/p (p …)
𝜑 ∝ 𝜑0 × 𝐸−3
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Positron fraction - AMS – 500 GeV
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AMS - 30 months • 72 positrons (last bin) • Stat : 18% • Syst (cc) : 12%
Submitted to PRL
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• Energy scale syst. cancels • Acc/Eff syst. cancels • Main issues :
• Protons rejection • Charge confusion
Flat behaviour at high energies 𝑅𝑒𝑒 ~
𝑁𝑒+𝑁𝑒− + 𝑁𝑒+
Electron flux up to 700 GeV
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Spectral index larger than 3
Preliminary ICHEP 2014
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Positron flux up to 500 GeV
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Spectral index smaller than 3 above 35 GeV
Preliminary ICHEP 2014
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Interpretations (1)
Astrophysics : Pulsar Wind Dark Matter :
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• Leptophilic : constraint from anti-proton • (or nearby clumps)
• Larger cross-sections than required by the relic density • Or Boost factors • Or Sommerfeld effect
Corinne Goy - LAPP - Rencontres du
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Interpretations (2) – examples
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LAPTH & LAPP prelim.
𝑅𝑇𝑇 = 𝜑𝑒+
𝜑𝐿𝑒𝐿𝐿𝐿𝐿𝐿
DM e(10%) µ (30%) τ (45%) b (15%)
Decrease of the signal is a discriminating parameter AMS – ICRC
2012
Secondary + Primary fluxes
PULSAR
Anisotropy (1)
• In arrival direction of electrons and positrons.
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• AMS : can distinguish between positrons and electrons.
• Fermi : large statistic – higher E range
• compatibility with isotropic distribution of arrival directions
Indication of an astrophysical source … but could be mimicked by a nearby clump …
AMS positrons
AMS – 26 months
Preliminary ICHEP 2014
FERMI – 1 year
Phys.Rev. D82(2010)
Anisotropy (2) – prospects
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arXiv:1304.1791
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Subject to modelling
Outlook
• ½ TeV – TeV range is being explored • But statistically limited • 𝑁𝐿𝑒𝐿𝐿𝐿𝐿𝐿 ∝ 𝐴𝐴𝐴 𝑚2. 𝑠𝑠 × 𝑇
• T comes for free ! But ….
• PAMELA ~ 8 to 9 years • → won’t improve significantly stat
• AMS : ~3 years • a factor 4 to expect in stat (10 years) → δStat /2
• Next step requires a significant increase in the geometrical acceptance : CALET : 0.12 m2.sr GAMMA 400 : ~2.5 m2.sr CTA
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All electrons
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AMS - ~ 10 years projection
e+/(
e-+e
+)
CALET - launch 2015 on ISS (see next talk)
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Z
Imaging Calorimeter (W / Fiber) 3 X0
Absorption Calorimeter (PWO) 27 X0 1.35 λ
1000 el > 1 TeV – 5y
ACC : 0.12 m2sr. (~ AMS X 3)
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Acc : 3.9 m2sr
GAMMA 400
BGO/Si Imaging Calorimeter : 10 X0
Convertor + Tracker : W/Si
BGO Calorimeter 14 X0 :
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Drift space
• Positrons of several TeV • 5 m2.sr (AMS X 100)
• Calorimeter • W : 15 tons
• Issue is the magnet • Large permanent
magnet : • Weight – B field limited
• Superconducting • Lighter (1 tons) – larger B
field – mitigate CC
• TeV e+/e- → SRD 24 Corinne Goy - LAPP - Rencontres du
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AMS – 03 ?
Conclusion
• Positrons : • Up to ½ TeV is being
explored • AMS :
• Pos fraction : sub PRL • All leptons + ind. Fluxes: end
of 2014 • 10 years :
• few hundred e+ above 500 GeV
• Leptons : • Promising result with CALET • CTA with a large collection
area will be able to observe change of slope
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ES = 0.76 +1.00 -0.28 TeV 2013 : 18 months
30 months
BACKUP SLIDES
Geomagnetic field
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Max Latitude : • AMS : 47 • Pamela : 70 Corinne Goy - LAPP - Rencontres du Vietnam 2014 17/07/2014
AMS-01
Solar Modulation &
Solar Flares
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Below 10 GeV, the comparison between measurements and
with predictions is not straightforward.
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For illustration only
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A&A 501 821-833 (2009)
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Fermi positron
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Self consistency
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AMS : Charge confusion
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Electron / Proton separation : method
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TRD
ECAL
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Gamma-400 Russian conceptual scheme of the apparatus Converter/Tracker (W+Si)
Imaging Calor. (CC1)
Homogeneous Calorimeter
(BGO) (CC2)
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/12
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Anisotropy – Sun
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PAMELA
Energy Scale
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~ 2- 5 % for Satellite /Balloon ~ 15 % for HESS
• Lots of protons →homogeneity response , time stability
• Linearity : ions (dE/dx) , E/p • Absolute E scale
• No standard candles in space • Test beam • MC description ... • E/p (p …)
𝜑 ∝ 𝜑0 × 𝐸−3 ∆𝜑 𝜑 = −2 ∆𝐸 𝐸⁄⁄
Corinne Goy - LAPP - Rencontres du Vietnam 2014 17/07/2014