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1912 1932

Cosmic Ray panorama

17/07/2014 Corinne Goy - LAPP - Rencontres du Vietnam 2014 2

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.

3 Corinne Goy - LAPP - Rencontres du Vietnam 2014 17/07/2014

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 …)

4

Cross –sections

Parameterization of p flux :

A&A 501 821-833 (2009)

Corinne Goy - LAPP - Rencontres du Vietnam 2014 17/07/2014

Primary source of positrons : nature ?

5

(2013)


Secondary origin only :

𝜑𝑒+φ𝑒−+ φ𝑒+

~ E –δ

(γp γe ~⁄ 1,

δ = 0.3 − 0.8 )

PAMELA – 2006 – 2014

6

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


NEW : all leptons analysis using

Calorimeter + Neutron Detector


19 Mai 2011

8

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


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


FERMI

ATIC

HESS

e+/p

9

All electrons flux (1) : AMS 2014 – 1 TeV


Preliminary ICHEP 2014 Event Sample : 10.5 million events

10

All electrons flux (2) : PAMELA 2014 -1 TeV

11

Preliminary ICHEP 2014

(ICRC 2013)


All electrons flux – HESS – several TeV


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

13

~ 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


Positron fraction - AMS – 500 GeV

14

AMS - 30 months • 72 positrons (last bin) • Stat : 18% • Syst (cc) : 12%

Submitted to PRL


• 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

15

Spectral index larger than 3



Positron flux up to 500 GeV

16

Spectral index smaller than 3 above 35 GeV



Interpretations (1)

Astrophysics : Pulsar Wind Dark Matter :

17

• 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

Vietnam 2014 17/07/2014

Interpretations (2) – examples


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.


• 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


FERMI – 1 year

Phys.Rev. D82(2010)

Anisotropy (2) – prospects

20

arXiv:1304.1791


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

21

All electrons


AMS - ~ 10 years projection

e+/(

e-+e

+)

CALET - launch 2015 on ISS (see next talk)

22

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)


23

Acc : 3.9 m2sr

GAMMA 400

BGO/Si Imaging Calorimeter : 10 X0

Convertor + Tracker : W/Si

BGO Calorimeter 14 X0 :


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

Vietnam 2014 17/07/2014

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


ES = 0.76 +1.00 -0.28 TeV 2013 : 18 months

30 months

BACKUP SLIDES

Geomagnetic field

27

Max Latitude : • AMS : 47 • Pamela : 70 Corinne Goy - LAPP - Rencontres du Vietnam 2014 17/07/2014

AMS-01

Solar Modulation &

Solar Flares

28

Below 10 GeV, the comparison between measurements and

with predictions is not straightforward.


For illustration only

29

A&A 501 821-833 (2009)


Fermi positron


Self consistency


AMS : Charge confusion


Electron / Proton separation : method


TRD

ECAL

Gamma-400 Russian conceptual scheme of the apparatus Converter/Tracker (W+Si)

Imaging Calor. (CC1)

Homogeneous Calorimeter

(BGO) (CC2)

Corinne Goy - LAPP - Rencontres du Vietnam 2014 36 17/07/2014


/12

Anisotropy – Sun


PAMELA

Energy Scale

40

~ 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⁄⁄


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