Primary Cosmic Rays : what are we learning from AMS

Primary Cosmic Rays : what are we learning from AMS Roberto Battiston University and INFN-TIFPA of Trento HERD Workshop IHEP-Beijing December 2-3 2013 1

Agile Fermi PAMELA AMS Direct study of the HESS MAGIC ARGO cosmic Borexino ICARUS LVD AUGER TA radiation ICECube ANTARES KM3net

Space experiments reach outstanding accuracy using primary radiation 3

AMS today

AMS: A TeV precision, multipurpose spectrometer TRD Identify e +, e - Particles and nuclei are defined by their charge (Z) and energy (E ~ P) TOF Z, E Silicon Tracker Z, P 1 Magnet ±Z 2 3-4 5-6 7-8 Tracker ECAL E of e +, e -, γ 9 RICH Z, E Z, P are measured independently by the Tracker, RICH, TOF and ECAL

AMS-02 (6.8 million e +, e events) The positron fraction is steadily increasing from 10 to ~250 GeV From 20 to 250 GeV, the slope decreases by an order of magnitude No structure in the spectrum Positron fraction

Data from ISS Nuclei in the TeV range Z = 7 (N) P = 2.088 TeV/c Z = 10 (Ne) P = 0.576 TeV/c Z = 13 (Al) P = 9.148 TeV/c Z = 14 (Si) P = 0.951 TeV/c Z = 15 (P) P = 1.497 TeV/c Z = 16 (S) P = 1.645 TeV/c Z = 19 (K) P = 1.686 TeV/c Z = 20 (Ca) P = 2.382 TeV/c Z = 21 (Sc) P = 0.390 TeV/c Z = 22 (Ti) P = 1.288 TeV/c Z = 23 (V) P = 0.812 TeV/c Z = 26 (Fe) P = 0.795 TeV/c

front view Boron Rigidity=3.7 GV Z TRK_L1 =5.3 Rigidity 3 GV Carbon Rigidity=3.3 GV Run/Event 1333501084/ 42231 Run/Event 1327519853/ 487070 side view front view Z TRK_L1 =6.4 side view Z TRD =5.1 Z TOF_UP =5.1 Z TRD =5.9 Z TOF_UP =6.1 Z TRK_L2-L8 =4.9 Z TRK_L2-L8 =6.1 Z TOF_LOW =4.9 Z TOF_LOW =6.1 Z RICH =5.1 Z RICH =5.9 Z TRK_L9 =5.0 Z TRK_L9 =6.5

Boron Rigidity=24 GV Rigidity 20 GV Carbon Rigidity=24 GV Run/Event 1326201809/ 798775 Run/Event 1329490720/ 473181 front view Z TRK_L1 =4.7 side view front view Z TRK_L1 =6.0 side view Z TRD =4.9 Z TRD =5.9 Z TOF_UP =5.1 Z TOF_UP =6.0 Z TRK_L2-L8 =4.9 Z TRK_L2-L8 =5.9 Z TOF_LOW =5.0 Z TOF_LOW =6.0 Z RICH =4.8 Z RICH =6.2

Boron Rigidity=187 GV Rigidity 200 GV Carbon Rigidity=215 GV front view Run/Event 1329086299/ 747549 Run/Event 132643580/ 132197 Z TRK_L1 =4.9 Z TRD =4.5 side view front view Z TRK_L1 =6.1 Z TRD =5.9 side view Z TOF_UP =5.0 Z TOF_UP =5.9 Z TRK_L2-L8 =4.9 Z TRK_L2-L8 =5.8 Z TOF_LOW =5.1 Z TOF_LOW =5.8 Z RICH =5.2 Z RICH =6.1

Boron Rigidity=680 GV Rigidity 700 GV Carbon Rigidity=666 GV Run/Event 1319990213/ 235892 Run/Event 1327184805/ 266043 front view Z TRK_L1 =5. 2 side view front view Z TRK_L1 =5.8 side view Z TRD =5.2 Z TRD =6.0 Z TOF_UP =5.5 Z TOF_UP =6.1 Z TRK_L2-L8 =5.0 Z TRK_L2-L8 =6.0 Z TOF_LOW =5.4 Z TOF_LOW =6.5 Z RICH =4.8 Z RICH =6.1 Z TRK_L9 =5.1 Z TRK_L9 =6.1

Carbon Fragmentation to Boron in Upper TOF Rigidity 10.6 GV Z TRK_L1 =6.1 Z TRD =6.0 Z 0 =9.9 Z 1 =5.3 Z TRK_IN =4.8 Z TOF_LOW =5.2 Z RICH =5.1

Electron E=1.1 GeV Positron E=1.1 GeV Run/Event 1315150703/ 667540 Run/Event 1316182344/ 919896 front view side view front view side view

Electron E=10.1 GeV Positron E=9.5 GeV Run/Event 1314950197/ 296945 Run/Event 1316692684/ 283617 front view side view front view side view

front view Electron E=99 GeV Positron E=100 GeV Run/Event 1318944028/ 505503 Run/Event 1334274023/ 338433 side view front view side view

Electron E=982 GeV Positron E=636 GeV Run/Event 1329775818/ 60709 Run/Event 133119-743/ 56950 front view side view front view side view

8% of total Data to 2028 Positron fraction A new phenomena has occurred e ± energy [GeV]

Interpretation of the AMS e+ fraction: - DM - Pulsars - Something else 18

Physics Example: Comparing data with a minimal model. Positron fraction Φ e + = C e + Ε γ e+ + C s Ε γ s e -E/E s Φ e - = C e - Ε γ e- + C s Ε γ s e -E/E s Data Fit to Data with Model χ 2 /d.f. = 28.5/57 e ± energy [GeV] The agreement between the data and the model shows that the positron fraction spectrum is consistent with e ± fluxes each of which is the sum of its diffuse spectrum and a single common power law source.

A fit to the data in the energy range 1 to 350 GeV yields: γ e- γ e+ = 0.63 ± 0.03, i.e., the diffuse positron spectrum is less energetic than the diffuse electron spectrum; γ e- γ S = 0.66±0.05, i.e., the source spectrum is more energetic than the diffuse electron spectrum; C e+ /C e- = 0.091 ± 0.001, i.e., the weight of the diffuse positron flux amounts to 10% of that of the diffuse electron flux; C S /C e- = 0.0078 ± 0.0012, i.e., the weight of the common source constitutes only 1% of that of the diffuse electron flux; 1/Ε s = 0.0013 ± 0.0007 GeV 1, corresponding to a cutoff energy of 760 +1000 280 GeV.

Bergstrom,Bringmann,Cholis,Hooper,Weniger 2013 Also : Ibarra,Lamperstorfer,Silk 2013

Sensitivity of minimal model to cutoff E s E s (GeV) 480 600 760 1000 1760

Positron fraction Cutoff energy = DM Mass 700 GeV DM model Pulsar model Background in 10 years from now e ± energy [GeV] What will the Positron Fraction look like at high energy? 24

25 Comparison of p/p with Models in 10 more years Ref: Donato et al., PRL 102, 071301 (2009)

26

Selected events are grouped into 5 cumulative energy bins: 16-350, 25-350, 40-350, 65-350 and 100-350 GeV. Their arrival directions are used to build sky maps in galactic coordinates, (b,l), containing the number of observed positrons and electrons North Galactic Pole (90 lat.) Solar System South Galactic Pole (-90 lat.) North-South direction East-West direction Forward-Backward direction Galactic C

The relative fluctuations of the positron ratio, e + /e -, across the observed sky map show no evident pattern Significance ( )

The amplitudes of spherical harmonic contributions at fixed angular scale,, are fit to data for dipole ( =1), quadrupole ( =2) and octopole ( =3) The fit amplitudes,, are found to be consistent with the hypothesis of isotropy at all energies and angular scales

AMS upper limits on at the 95% CL <0.030 for 16<E<350GeV No seasonal excess is observed and same results are obtained using solar ecliptic coordinates

AMS Electron Spectrum

AMS Positron Spectrum

16% E pulsar E e+e- conversion efficiency Cholis,Hooper 2013

The Vela supernova remnant The Vela pulsar The Crab pulsar Sources of very high energy cosmic-ray electrons? 38

39

40

41

42

43

AMS Electron plus Positron Spectrum

(Electron plus Positron) Spectrum comparison with recent measurements

Open issues: the electron + positron spectrum above 100 GeV AMS O(1 TeV ) AMS (2013)

Cholis,Hooper 2013

Cholis,Hooper 2013

54

Beware changing energy scale AND detector technique?

Anti-matter & Exotic sources (DM?) The electron bump? No bump in Fermi, AMS, PAMELA No fresh source of anti-p up to 100 GeV Positron excess reaching maximum 56

A structure around 135 GeV? Fermi data on a possible gamma line 57

15 years of space astroparticle physics, leave us with a number of hot issues : Electron/positrons ratio vs spectra Gamma rays line? CR spectral change? B/C spectral change? Pbar at higher energy 58

Scientific Objectives of future e/γ missions in space High energy particle detection in space Search for Dark Matter signatures Study of cosmic ray spectrum and composition High energy gamma astronomy Follow-up mission to both Agile Fermi/LAT and Pamela AMS-02 Extend the energy reach to the TeV region, providing better resolution Overlap with CTA on gamma ray astronomy Run in parallel for some time 59

What Nature gives us What From L. Baldini, SpacePart 2012

Expected rates detection tools/limitations ELECTRON AND POSITRON PHYSICS @ 5 sqm sr yr 5 m2 sr 3,14E+07 s/y ACCESSIBLE EXCLUDED EXCLUDED ev 10^8 10^9 10^10 10^11 10^12 10^13 10^14 10^15 scale 100MeV GV TV PV Integral. 1/y.@ 0,1-1.@ 1-10.@ 10-100.@ 100-1000.@ 1.000 ->.@ 10.000 ->.@ 100.000 ->.@ 1.000.000 -> e- 4,99E+10 3,11E+09 1,56E+08 9,33E+05 7,78E+03 7,78E+01 7,78E-01 7,78E-03 e+ 2,50E+09 1,56E+08 1,56E+07 1,40E+05 1,17E+03 1,17E+01 1,17E-01 1,17E-03 Detectors tracker, TOF, TRD, ECAL tracker, TOF, TRD, ECAL Tracker, TRD, ECAL Tracker, TRD, ECAL Tracker,SRD,ECAL Tracker,SRD,ECAL Variables R, beta, gamma, energy R, beta, gamma, energy R, gamma, energy R, gamma, energy R,Energy, Syncrotron Radiation R, Energy, Synchroton Radiation Physics Van Allen, solar, subcutoff solar, geomagnetic, galactic DM, galactic, asymmetries DM, galactic, asymmetries DM, galactic DM, galactic, moon shadow, sun shadow DM, galactic DM, extragalactic, knee acceptance vs R, live time, efficiency, MC, inner tracker, alignement, TOF calibration, TRD acceptance vs R, live time, efficiency, MC, inner tracker, alignement, TOF calibration, TRD acceptance vs R, live time, efficiency, MC, inner tracker, alignement, TOF calibration, TRD acceptance vs R, live time, efficiency, MC, inner/outer tracker, TRD, alignement, acceptance vs R, live time, efficiency, MC, outer tracker, alignement, SRD calibration, ECAL acceptance vs R, live time, efficiency, MC, tracker, alignement, SRD calibration, ECAL calibration, backtracing calibration, backtracing calibration, backtracing backtracing (Earth- calibration, backtracing calibration, backtracing Tools (near Earth) (near Earth) (near Earth) Moon, Earth- Sun) Earth-Moon, Earth-Sun Earth-Moon, Earth-Sun Background e- - - - p p p p p Background e+ p p p p p p p p Limitations multiple, scattering, acceptance,ams02 magnetic field - SRD Acceptance, MDR Tracker, ECAL must be in accceptance 61 SRD acceptance, MDR Tracker, ECAL must be in accceptance no statistics no statistics

Expected rates and detection tools/limitations PROTON and HELIUM PHYSICS @ 5 sqm sr yr 5 m2 sr 3,14E+07 s/y ACCESSIBLE ACCESSIBLE ACCESSIBLE 10^8 10^9 10^10 10^11 10^12 10^13 10^14 10^15 100MeV GV TV PV Integral. 1/y.@ 0,1-1.@ 1-10.@ 10-100.@ 100-1000.@ 1.000 ->.@ 10.000 ->.@ 100.000 ->.@ 1.000.000 -> p 4,99E+10 9,96E+10 1,99E+10 3,97E+08 7,19E+06 1,44E+05 2,86E+03 5,71E+01 He 1,80E+09 1,79E+10 3,58E+09 7,14E+07 1,29E+06 2,58E+04 5,15E+02 1,03E+01 Detectors tracker, TOF, RICH Tracker, (RICH) Tracker Tracker Tracker Tracker+ HCAL Tracker+ HCAL Tracker+ HCAL Variables R, beta R R R R R, Energy Energy Energy Physics Van Allen, solar, subcutoff solar, geomagnetic, galactic galactic galactic galactic, moon shadow, sun shadow galactic, moon shadow, sun shadow galactic extragalactic, knee acceptance vs R, live time, efficiency, MC, inner tracker, alignement, TOF calibration, RICH acceptance vs R, live time, efficiency, MC, inner tracker, alignement,, RICH acceptance vs R, live time, efficiency, MC, inner tracker, alignement, TOF calibration, RICH acceptance vs R, live time, efficiency, MC, inner/outer tracker, acceptance vs R, live time, efficiency, MC, outer tracker, alignement,, ECAL acceptance vs R, live time, efficiency, MC, tracker, alignement, HCAL calibration, calibration, calibration, backtracing calibration, backtracing alignement, backtracing calibration, backtracing backtracing Earth- Tools backtracing(near Earth) (near Earth) near Earth) Earth-Moon, Earth- Sun) Earth-Moon, Earth-Sun Moon, Earth- Sun Background p - - - - Background He He3/He4 He3/He4 He3/He4 He3/He4 - - - acceptance vs R, live time, efficiency, MC, tracker, alignement, HCAL calibration, backtracing Earth-Moon, Earth- Sun HCAL calibration, backtracing Earth-Moon, Earth- Sun Limitations multiple, scattering, acceptance,ams02 magnetic field - - different tracker acceptances, alignement MDR MDR+ HCAL HCAL HCAL 62

Interesting spectra fall with E -3 Increasing one decade (e.g. 1-10 TeV) @ constant statistics would require O(100) time more collection power Cp = S * Ω * t O(100) times this explain AMS-02/Pamela 400 Fermi/ (Agile or EGRET) 20

while maintaining Particle Identification and Charge sign and Energy resolution

How to reach O(100) higher Cp? S from O(1) m 2 to O(10)m 2 10 Ω from 1 sr to 10 sr 10 t from 5 to 20 years 4 Cp = S * Ω * t 400 times all the parameters should be increased at the same time

Need for redundant, accurate measurement in space

Future e/hadron/γ experiments CALET ISS-CREAM DAMPE (INFN participation) GAMMA-400 (INFN participation) HERD (INFN interest and preliminary discussions) + JEM-EUSO (INFN participation to prepartory phase) + possible next generation large acceptance, precision magnetic spectrometer

Conclusions Direct measurements of Cosmic Radiation in the 100 GeVmulti TeV scale could reveal fundamental phenomena which cannot be accessed by ground based accelerator physics It is a challenging but rewarding field, requiring large, accurate, experiments, operating for long period in space Accurate measurement of charge and energy are needed INFN will continue to work in this field, exploiting the large investments which have been made, with the goal of maximizing the science return followoing a strategy which, in the medium to long term, could lead to second generation experiments which would be able to fully address CR physics at the multi TeV scale