ICRR,
6/7/2011

Energy spectrum of proton andhelium measured by PAMELAand acceleration of cosmic raysin the galaxy
M. Casolino,RIKEN, ASI, JapanINFN & University of Roma Tor Vergata
on behalf of the PAMELA collaboration

M. Casolino, INFN & University

M. Casolino, INFN & University

JEM-EUSO

Pamela Physics objectives in the Hillas PlotCollider

M. Casolino, INFN & University

Directe+ / eγ

Jem-Euso

P / P-The PAMELA apparatus
Spatial Resolution• ≅ 2.8 μm bending view• ≅ 13.1 μm non-bending view
MDR from test beam data ≅ 1 TV

Calorimeter Performances:• p/e+ selection eff. ∼ 90%• p rejection factor ∼ 105• e- rejection factor > 104

ND p/e separation capabilities >10above 10 GeV/c, increasing with energy

M. Casolino, INFN & University

GF ~20.5 cm2sr
Mass: 470 kg
Size: 120x40x45 cm3Power Budget: 360 W

M. Casolino, INFN & University

PHYSICAL QUANTITIESMEASURED BY PAMELA
1. DEDX(scintillators, tracker, calo) Z of the particle
2. DEFLECTION = 1/Rigidity
 Impulse (4-6 planes)
3. Time of flight = 1/Beta(12 betas)
4.Shower (No, Hadronic,Electromagnetic)
 lepton/hadron
5. Number of neutrons

 lepton/hadron
5% to 10% precision

e+ 0.171 GV Bending view

M. Casolino, INFN & University

e- 0.169 GV Bending view

PAMELA event

Flight data: 14.4 GV
non-interacting proton

M. Casolino, INFN & University

From E. Mocchiutti

PAMELA event

Flight data: 36 GV
interacting proton

M. Casolino, INFN & University

Flight data 84 GeV/cinteracting antiproton

M. Casolino, INFN & University

Flight data: 2.8 GV electron

M. Casolino, INFN & University

Selection of galactic component according togeomagnetic cutoff

2RcutoffINFN=14.9GV/L
M. Casolino,& University

Selection criteria
Fitted, single track
High lever arm, Nx
Rigidity R>0
Beta>.2
No anti INFN & University
M. Casolino,

antiparticles

particles

albedoparticles

albedoantiparticles

Rigidity (from Tracker)

Energy loss from tracker•Montecarlo efficency forcuts•Trigger efficiency•Tracking efficiency•Multiple Scattering•Correction for energy lossin det•Back scattering…
•Systematics under close
investigation, currently
about 1-2% uncertainty onabs flux.

Beta = v/c (from TOF)Particle selection criteria

pdp

LiHeHeRigidity (from Tracker)

Pamela overall results

Highprecision
chargedcosmic ray
measurementin Low EarthOrbit

In press on ApJ
arXiv:0708.2587
2008AdSpR..41..168C
2008AdSpR..41.2037D
2008AdSpR..41.2043C

Science 2011arXiv:1103.4055
Prl 106, 2011arXiv:0810.4995,
Nature, Astrop. Phys

ApJ 457, L 103 1996
ApJ 532, 653, 2000
arXiv:0810.4994, PRL,NJP11,105023

M. Casolino, INFN & University

Dark Matter Searches•Cosmology
Detection, not identification•LHC Search

1E 0657-56 - Bullet ClusterSupersymmetry, not necessarily DM•Direct Detection
Local structure and nature
DAMA•Indirect Detection
Various galactic scales

M. Casolino, INFN & University

γ: Galactic centre

positrons:
Antiprotons:
Galactic average Local galactic 1kpc

Different approaches to search for Dark Matter
PAMELA
LHC

FERMI

M. Casolino, INFN & University

Adapted from P. Lipari

UNDERGROUND

Antiproton/proton ratio
Confirms charge dependent
solar modulation
Consistent with models(galprop, donato…) at
high energy
PRL. 105, 121101,
September 13,2010)
PRL 102:051101,2009

M. Casolino, INFN & University

Antiproton absolute flux
PRL. 105, 121101,September 13,2010)
PRL 102:051101,2009

M. Casolino, INFN & University

Pamela positron fraction

Nature 458, 607-609 (2 April 2009)
M. Casolino,
INFN & University

Secondary production

Dark Matter Decay

Astrophysical sources,
SNR…

M. Casolino, INFN & University

From Fermi Symposium

M. Casolino, INFN & University

PAMELA e- spectrum

M. Casolino, INFN & University

PRL, 106 201101

Solid line GALPROP
calculation for adiffusion reacceleration
model; thedotted line is a single
power-law fit to the data
above 30 GeV; thedashed-dotted line is a
GALPROP calculation
including a component
from additional cosmicray electron sources.
Bottom:the PAMELA positron
fraction [28] comparedwith the previous
GALPROP calculations
with no(solid line) and withadditional e− and e+components (dasheddotted line).

Electron spectrum

M. Casolino, INFN & University

e- only ee+ + e-+

e + e-

From E. Mocchiutti

M. Casolino, INFN & University

Debate on the origin of cosmic rays
is still open•

Experimental evidence of Supernova acceleration is mounting– HESS TeV emision from SNR RX J1713.7-3946  hadronic inter. Of cr.
E>10^14eV F. Aharonian, et al., Astron. Astrophys. 464, 235 (2007).
– X-ray measurements of the same SNR  evidence that protons and nuclei can be
accelerated E>10^15 eV in young SNR Uchiyama, et al., Nature 449, 576 (2007).
– AGILE: diffuse gamma-ray (100 MeV – 1 GeV) SNR IC 443 outer shock 
hadronic acceleration M. Tavani, et al., ApJL 710, L151 (2010).
– Fermi: Shell of SNR W44 have  decay of pi0 produced in the interaction ofhadrons accelerated in the shock region with the interstellar medium A. Abdo, etal., Science 327, 1103 (2010).
– Starburst galaxies (SG), where the SN rate in the galactic center is much higher thanin our own, the density of cosmic rays in TeV gamma-rays (H.E.S.S infers cosmicrays density in SG NGC 253 three orders of magnitude higher than in our galaxy F.
Acero, et al., Science 326, 1080 (2009).
– VERITAS: SG M82 cosmic rays density is reported to be 500 times higher than inthe Milky Way VERITAS Collaboration, et al., Nature 462, 770 (2009)

M. Casolino, INFN & University

However, supernova-only model has
been challenged many times•

Multiple origin of cosmic rays:–••SN explosions of various sizes in either theinterstellar medium or in a pre-existing stellar wind,
WR stars P. L. Biermann, Space Science Reviews 74,385 (1995); L. Biermann, Astron. Astrophys. 271,649 (1993)

Nova stars and explosions in superbubbles, V. I.
Zatsepin, N. V. Sokolskaya, Astron. Astrophys. 458,1 (2006))
Different acceleration processes such as nonlinear
shock acceleration–D. C. Ellison, International Cosmic RayConference (1993), vol. 2 of International Cosmic
Ray Conference, pp. 219– DSA, diffusive shock acceleration, V. I. Zatsepin, N.
V. Sokolskaya, Astron. Astrophys. 458, 1 (2006).
– M. Ahlers, P. Mertsch, S. Sarkar, Physical Review D
80, 123017 (2009).
Wolfendale et al, (ICRC 2009) one source cause of knee

M. Casolino, INFN & University

Pamela galactic p and he2006-2008

γ30- 1000GV, p = 2.820 +- 0.003 (stat) +- 0.005 (syst)
γ30- 1000GV, he = 2.732 +- 0.005 (stat)+ 0.008 -0.003 (syst)

M. Casolino, INFN & University

Comparison with previous experiments

Note thedifferent (lower)
values for the
spectral indexes
in kinetic energy:
γ30- 1000GeV, p = 2.782 +- 0.003 (stat)+- 0.004 (syst)
γ15-6 00GeV/n, he = 2.71 +- 0.01 (stat)+- 0.007 (syst)

M. Casolino, INFN & University

Fitting p and He spectra

M. Casolino, INFN & University

P/HE RATIO:KINETIC ENERGY/NUCLEON
Ratio has lower
systematic
Less dependent
from solar
modulation

M. Casolino, INFN & University

RATIO P/HE
TOTAL KINETIC ENERGY

M. Casolino, INFN & University

Ratio P/He: Rigidity
1.

-0.101+-0.002
2.

Solar modulation

M. Casolino, INFN & University3.

230-240GV

Acceleration
is a rigidity
dependent
effect
The ratio
decreasesMore He athigh energies

Acceleration
mechanisms
or sources aredifferent
Measurement
valid also
below the(low) solar
modulation

Fitting the p/he ratio

M. Casolino, INFN & University

Deviations from the power law: >230-240 GV

γ80- 232GV, p = 2.85 +- 0.015
γ>232GV;p = 2.67 +- 0.03

M. Casolino, INFN & University

γ80- 240GV, he = 2.77 +- 0.01
γ>240 GV;he = 2.48 +- 0.06

Deviations from the power law: a) 30-240 GV
1.
2.

γ30- 80GV, p = 2.800 +- 0.007
γ80- 232GV, p = 2.85 +- 0.01

M. Casolino, INFN & University

Additionalsource(s)above 240 GV
Fisher and T
student test
reject single
power law tobetter than
99.7 CLDeviations from the power law: b) 30-240 GV

protons

γ30- 232GV, p = 2.28 +- 0.01
α80- 232GV, p = (1.1 +- 0.3)*10-4

M. Casolino, INFN & University

heliumγ30- 232GV, he = 2.68 +- 0.02
α80- 232GV, he= (1.2 +- 0.5)*10-4•Thespectrum
softens at30-240
GV•Singlepowerlaw isalso
ruled outat lowerrigidities

Proton spectral indexes

M. Casolino, INFN & University

Helium spectral indexes

M. Casolino, INFN & University

Proton and helium comparison

M. Casolino, INFN & University

At higher energies:
CREAM balloon data

M. Casolino, INFN & University

ApJL 2010
200 GeV/n: Indirect p, He
Direct C-Fe

M. Casolino, INFN & University

Forbush decrease: comparison with ePreliminary

M. Casolino, INFN & University

Longer recovery time for eDeeper forbush decr for e-•PAMELA data challenge the mechanisms
and processes of acceleration andpropagation in the galaxy•Complex, structured features are present
also in the GV – TV range.
•They hint to additional sources/phenomena•

http://pamela.roma2.infn.it

M. Casolino, INFN & University

PAMELA has survived five
years up to now, underdiscussion a possible
extension
Most of the collaborationin Italy is part of the JEMEUSO experiment(Picozza, PI of Pamela isnow PI of JEM-EUSO)
Current work involvescalibration tests of JE
detector module in TA site
in Utah.

M. Casolino, INFN & University