Solar physics with the PAMELA and CSES/Limadou missions
ROBERTA SPARVOLI UNIVERSITY OF ROMA “TOR VERGATA” AND INFN PAMELA Payload for Matter/antimatter Exploration and Light-nuclei Astrophysics
• Direct detection of CRs in space • Main focus on antiparticles (antiprotons and positrons)
• PAMELA on board of Russian satellite Resurs DK1 • Orbital parameters: - inclination ~70o (low energy) - altitude ~ 360-600 km (elliptical) – now 500 km (circular)
Launch from Baykonur à Launched on 15th June 2006 à PAMELA in continuous data-taking mode since then! à Soon celebrates 10 years! Main requirements à high-sensitivity antiparticle identification and precise momentum measure + - Time-Of-Flight plastic scintillators + PMT: - Trigger - Albedo rejection; - Mass identification up to 1 GeV; - Charge identification from dE/dX.
Electromagnetic calorimeter W/Si sampling (16.3 X0, 0.6 λI) - Discrimination e+ / p, anti-p / e- (shower topology) - Direct E measurement for e-
Neutron detector plastic scintillators + PMT: 2 GF: 21.5 cm sr - High-energy e/h discrimination Mass: 470 kg Size: 130x70x70 cm3 Spectrometer Power Budget: 360W microstrip silicon tracking system + permanent magnet It provides: - Magnetic rigidity à R = pc/Ze MDR up to 1.2 TV - Charge sign - Charge value from dE/dx e- Propagation of cosmic rays
Diffusive shock acceleration
Propagation through Galaxy
Propagation through the Heliosphere �~�
� ~�
� variation < 30GeV 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/electron/positron ratio flux vs. time – solar modulation Trapped proton and antiproton flux, albedo protons SEP data (13 December 2006 and 17 May 2012 event) Anisotropy of positrons and electrons Adriani et al. - Science - 332 (2011) 6025
H & He absolute fluxes
• First high-statistics and high-precision measurement over three decades in energy
• Deviation from single power law @98% CL
• Spectral hardening ~0.2÷0.3 @R~235GV PAMELA dataà Jul 2006 ÷ Mar 2008 Adriani et al. - Science - 332 (2011) 6025
H & He absolute fluxes
• First high-statistics and high-precision measurement over three decades in energy
• Deviation• Spectral featuresfrom single@injection ? power• Different law @98%astrophysical CL objects? • Spectral• Propagation hardeningfeature not ~0.2constrained÷0.3 by S/N ratio @R~235GVdata? PAMELA dataà Jul 2006 ÷ Mar 2008 Adriani et al. - Science - 332 (2011) 6025
H & He absolute fluxes
• First evidence of different H and He slopes above 10 GV
αHe-αp = 0.078 ±0.008 • Spectral features @injection? • Different astrophysical objects? • Propagation feature not constrained by S/N ratio data? B/C ratio
B nuclei are of pure secondary origin Adriani C,N,O + ISM B + … et al. B/C provides the - strongest constraint to ApJ
propagation parameters - so far (2014) 93 791
PAMELA data consistent with previous GALPROP code tuned to PAMELA B&C data measurements and with • Plain diffusion model (Vladimirov et al. 2012) a standard scenario • Solar modulation: spherical model ( φ=400MV ) Adriani et al. -- Nature 458 (2009) 607; Positrons -- Astropart. Phys. 34 (2010) 1 – PRL – 111 (2013) 081102 – PR 544 (2014) 323 First measurement ö extending up to 200 GV positron excess ö
• Clear evidence for an hardening of positron ösolar modulationö spectra (charge-dependent) Adriani et al. -- Nature 458 (2009) 607; Positrons -- Astropart. Phys. 34 (2010) 1 – PRL – 111 (2013) 081102 – PR 544 (2014) 323 First measurement ö extending up to 200 GV positron excess ö
• Clear evidence for an hardening of positron ösolar modulationö spectra (charge-dependent)
Dark matter annihilation/decay • Lepton vs hadron yield must be consistent with p-bar observation Astrophysical processes • Pulsars, «tick» sources • Large uncertainties on environmental parameters • Must be consistent with otherCR components PAMELA Results
7
-1 10
106 s sr GeV/N) 2 105 Proton (SAA)
All 10Flux (m 4 Proton (Flare)
Proton particles 103 Helium
2 10 2 PAMELA H (rat.) 3He (rat.) 10 Antiproton (SAA) results Carbon Electron 1 Boron
10-1 Positron Results span 4 10-2 decades in Antiproton energy and 13 in 10-3 fluxes 10-4
10-5
10-6
10-7
10-1 1 10 102 103 E (GeV/N) CRs in the heliosphere
LONG- TERM CR- FLUX VARIATION SOLAR- PARTICLE EVENTS ( SEPS) Solar cycles & CR modulation
22-year cycle
11-year cycle
Cycle 20 Cycle 21 Cycle 22 Cycle 23 The solar wind
• Convection with solar-wind velocity V • Adiabatic energy changes (∝ � � ) Heliospheric magnetic field (HMF)
A>0 magnetic-field reversal A<0
22-year cycle to return to the same polarity Drift & diffusion
A>0 A<0 A<0
HP HP HP Strauss et al. al. (2012) et Strauss
HCS HCS
HCS
• Diffusion, driven by small-scale HMF irregularities • Drift caused by gradients and curvature in the global HMF Drift path
GCR qA > 0 qA < 0
GCR
• Drift path changes at each field reversal à 22-year cycle • Asimmetry between particle of opposite charge àcharge dependent solar modulation PAMELA observations during 23° solar cycle
expected recovery
A<0
PAMELA Cycle 23
Neutron Monitor counts Maximum inclination of HCS (N-S mean) Data from http://cosmicrays.oulu.fi/
Computed HCS tilt angle Data from http://wso.stanford.edu/ Long-term variation of GCR protons during (Potgieteret al. 2014) 23° solar • 3D model • Parker eq: convection, minimum drift, diffusion& adiabatic en.changes Evolution of the proton energy spectra
§from July 2006 to December 2009
à Minimum solar activity Adriani et al. -- ApJ - 765 (2013) 91 Potgieter et al. – Solar Phys. – 289 (2014) 391 Potgieteret al. – ApJ – 810 (2015) 141 Long-term Adriani et al. -- ApJ -- 810(2015) 142 variation of GCR electrons during 23° solar minimum
Evolution of the electron energy spectra
§from July 2006 to December 2009
§ à Minimum solar activity • 3D model • Parker eq: convection, drift, diffusion& adiabatic en.changes Measured down to 80 MeV Particle- dependent solar modulation
• Larger modulation effect for protons than electrons
• Proton modulation consistent with that of positrons (preliminary) PAMELA observations during 24° solar cycle
A<0 A>0
PAMELA
Cycle 23 Cycle 24
Neutron Monitor counts Maximum inclination of HCS (N-S mean) Data from http://cosmicrays.oulu.fi/
Computed HCS tilt angle Data from http://wso.stanford.edu/ Long-term variation of GCR protons towards 24° solar maximum
Evolution of the proton energy spectra from 2006 to present
à Modeling during solar maximum activity (not-stationary condition) O. Adriani et al., PRL, accepted 10 May 2016 – Highlighted !! Evolution of the electron charge ratio: sign- dependent solar modulation
à -> Analysis from July 2006 to December 2015, covering the period from the minimum of solar cycle 23 (2006-2009) till the middle of the maximum of solar cycle 24. Results provide the first clear and continuous observation à à polarity reversal of the heliospheric magnetic of how drift effects on solar modulation have unfolded field took place between with time from solar minimum to solar maximum and 2013 and 2014. their dependence on the particle rigidity and the cyclic polarity of the solar magnetic field. Solar energetic particles (SEPs)
Sun can accelerate particles up to relativistic energies • Magnetic reconnections • CME-driven shock SEPs can be observed in the interplanetary space
Often associated to other solar phenomena, eg: • X and gamma-ray flares • Coronal-mass ejections (CMEs) • ...
Magnetic fieldlines
SEP observation on Earth:
• Propagation of SEPs along IMF lines Earth must be magnetically connected • Anisotropic emission flux observed on Earth depends on geomagnetic location The acceleration of solar particles
• The site/mechanisms of acceleration could be studied by analyzing the differential spectra of protons à fit with specific functions that describe different mechanisms
• Try to disentangle from transport mechanisms
• Events «well connected» (in which the Parker spiral connects directly the Sun with the Earth) are perfect because the transport effects are less important The event of June 7 2011
Preliminary The event of March 7 2012
Preliminary The event of April 11 2013
Preliminary Multi-particle measurements
Helium and protons flux evolution vs. time and helium enhancement studies are possible for events that present traces of He Dec 13°-14° 2006 Adriani et al. - ApJ - 742 (2011) 102 SEP event First instrument to directly measure relativistic SEPs in near-Earth space. GLE
It bridges the gap between low-energy direct space- based observations (GOES) with high-energy indirect gound-based measurements (NM GLEs) PAMELA observationdone during passages over high-latitude regions May 17°, 2012 SEP event Asymptotic direction during first polar pass after the event onset • First observed GLE of 24° solar cycle
• Earth magnetically connected to the Sun
• Associated to M1.5-class X-ray flare
• Extended emission (>100MeV) seen by Fermi-LAT Unique possibility to measure pitch angle distribution over broad IMF direction energy range, to disentangle interplanetary Pitch angle transport process Adriani et al. - ApJL - 801 (2015) L3 Adriani et al. - ApJL - 801 (2015) L3
May 17°, 2012 SEP event
First evidence of two simultaneous particle populations:
§ High rigidity component consistent with NM where particles are field aligned à Beam width ~40-60o (not scattered)
§ Low rigidity component shows significant scattering for pitch angles ~90o
§ The time coincidence of the two components suggests that the scattering must take place locally à effect of the magnetosheath SEPs observed by PAMELA
SEP-analysis issues: • Source identification & classification • Association to flares, CMEs… • GLEs • different class of events? • Spectra evolution • Intensity, time profile , spectral signatures… • Composition • p/He, 3He content… • Magnetospheric effects CRs in the magnetosphere
TRAPPED AND RE- ENTRAND ALBEDO PARTICLES The PAMELA Particle count rate (S11*S12) orbital environment
PAMELA sweep through the magnetosphere along a near-Earth semipolar orbit Latitude
Altitude Altitude
SAA (South-Atlantic Anomaly) Longitude Trajectory analysis
Trajectories propagated back and forth the measurement location
Particles classified according to trajectory behaviour ¡ Reach magnetosphere boundary ÷ Interplanetary origin ¡ Intersect atmosphere boundary ÷ Albedo ¡ Do not intersect the boundaries ÷ Stabily trapped Trapped antiprotons Adriani First observation of
geomagnetically trapped et al. p-bar - ApJ Lett. Lett. Produced by CR - interaction with 737 (2011) L29 atmosfere and trapped by the magnetosphere
Most abundant p-bar source near the Earth! Trapped protons
Observation of trapped Adriani radiation performed down to Lshell 1.1RE and et al. up to 4 GeV - Apj Lett
Comparison with . – empirical model 799,(
Improvement in low- 2015
altitude radiation- ) environment description L4 Positrons & electrons stably-trapped stably-trapped
albedo albedo
galactic galactic CSES/LIMADOU mission CSES mission
The basic idea of missions as CSES is to study seismic precursors. CSES is the first Chinese satellite for monitoring earthquake-related electromagnetic emission from the ionosphere.
In recent years it has become increasingly marked the idea that space represents a privileged place for the statistical study of pre-seismic effects, because you can cover large areas simultaneously.
Based on the strong interest of the Chinese space agency for the development of technologies for monitoring disasters, and the interest of Italian researchers to collect data of cosmic rays at low energies, a new collaboration was established between Italy and China for the construction of a major new satellite (CSES) dedicated to the study of the electromagnetic environment of the Earth. Instruments onboard CSES
Measurements Instruments Search-Coil Magnetometer Measurement of the electrical and Fluxgate Magnetometer magnetic fields and their perturbations in ionosphere Electrical Field Detector (CHN/ITA)
Plasma analizer Measurement of the disturbance of Langmuir probe plasma in ionosphere
Measurement of the flux and energy High Energy Particle Detector spectrum of the particles in the radiation (ITA) belts Measurement of the profile of electronic GPS Occultation Receiver content Tri-frequency transmitter CSES satellite
The satellite is based on the Chinese CAST2000 platform. It is a 3-axis attitude stabilized satellite and will be placed in a 98 degrees inclination Sun-syncronous circular orbit, at an altitude of 500 km, for a launch scheduled in the middle of 2017. Expected lifetime is 5 years.
CSES hosts several instruments onboard: 2 magnetometers, an electrical field detector (EFD), a plasma analyzer, a Langmiur probe and a High Energy Particle Detector (HEPD).
The Italian groups are developing the Qualification Model of the Electric Field Detector (EFD) and the Electrical, Mechanical&Thermal, Qualification and Flight Model of the High Energy Particle Detector (HEPD). Scientific objectives of HEPD
The High Energy Particle Detector is an apparatus devoted to the study of cosmic rays of Solar and Galactic origin in the energy range 3-300 MeV at 1 AU. It is capable of separating electrons and protons and identify nuclei up to Iron, thus allowing the addressing of important space physics issue such as the composition and energy spectra of galactic and solar particles (including Solar Energetic Particle events), modeling also the radiation environment around the Earth.
Its scientific scope is to study the low energy component of cosmic ray nuclei. The high-inclination orbit of the satellite allows the telescope to detect particles of different nature during its revolution: galactic cosmic rays, solar energetic particles, particles trapped in the magnetosphere and anomalous cosmic rays.
CSES/Limadou will complement the cosmic ray measurements of PAMELA at low energy. The HEPD The detector consists of: the Silicon Detector [direction of the incident particle - two planes of double-side silicon microstrip detectors], the Trigger Detector [triggering the experiment - two layers of plastic scintillators], the Energy Detector [layers of plastic scintillators followed by a matrix of an inorganic scintillator LYSO] and the Veto ! Detector [plastic scintillators].
HEPD specifications:
Energy range electrons: 3 MeV~100 MeV
Energy range protons: 30 MeV~200 MeV Angular resolution <8° @ 5 MeV Energy resolution <10% @ 5 MeV
Particle Identification > 90 % Mass (including electronics) ≤ 43 kg !
Power consumption ≤ 43 W Total acceptance for e- e p e/p separation < 10-4 for 95% electron eff.
! Current status Beam tests of QM performed at BTF beam facility (April The Electrical Model 2016) with electron EM and the beams at different Structural and energies Thermal Model STM of the HEPD are in China and passed all tests.
Development of the Qualification QM and the Flight Model FM continues at great speed. Conclusions
PAMELA has recorded Cosmic Ray data for 10 years, with an important program of solar physics: ¡ Short-term (SEPs) effects ¡ Medium-term (Forbush) effects ¡ Long-term (Modulation) effects
Also magnetospheric physics has been carried out: ¡ Measurement of trapped and quasi-trapped particles ¡ Significant improvement in magnetosphere modeling (radiation- environment) Conclusions
PAMELA acquisition time is running out.
For the future, the new detector HEPD onboard CSES can continue the solar and magnetospheric physics of PAMELA, with better emphasys on low- energy particles.
Launch is foreseen in 2017.