pamela space mission · • astromag/wizard project (pamela precursor) on board of the space...

PAMELA Space Mission

F.S. Cafagna, INFN Barifor the PAMELA Collaboration

F.S. Cafagna, Neutrino Oscillation Workshop, 11 Sept. 2008 2

PAMELA PAMELA CollaborationCollaboration

Moscow St. Petersburg

Russia:

Sweden:KTH, Stockholm

Germany:Siegen

Italy:Bari Florence Frascati TriesteNaples Rome CNR, Florence


WiZard activities• Astromag/WiZard project (PAMELA precursor) on board of

the Space Station Freedom CANCELED• Balloon-borne experiments: MASS-89,91 TS-93 CAPRICE-

94,97,98 • Space experiments*: NINA-1,2 SILEYE-1,2,3 ALTEA

(*study of low energy nuclei and space radiation environment)

1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007- - - - XASTROMAG

C 94 C 97 C 98TS 93M 89 M 91

SILEYE-1 SILEYE-2 SILEYE-3 ALTEA

NINA-2NINA-1

PAMELAheritage


PAMELA SciencePAMELA as a Space Observatory @ 1AU


PAMELA Science

Preliminary


PAMELA SciencePreliminary

Preliminary


PAMELA Science


Why Anti(particle)matter matters?

Earth



Earth


PAMELA detectors

Main requirements high-sensitivity antiparticle identification and precise momentum measure

GF: 21.5 cm2 srMass: 470 kgSize: 130x70x70 cm3Power Budget: 360W


PAMELA detectorsMain requirements high-sensitivity antiparticle identification and precise momentum measure

Spectrometermicrostrip silicon tracking system + permanent magnet

•Magnetic rigidity (R = pc/Ze)•Charge sign•Charge value from dE/dx

+ -

GF: 21.5 cm2 srMass: 470 kgSize: 130x70x70 cm3Power Budget: 360W

Time-Of-Flightplastic scintillators + PMT-Trigger;-Albedo rejection;-Mass identification up to 1 GeV;-Charge identification from dE/dX.

Electromagnetic calorimeterW/Si sampling

(16.3 X0, 0.6λI)• Discrimination e+/ p, pbar/e-(shower topology)

• Direct E measurement for e-

Neutron detectorplastic scintillators + PMT:-High-energy e/h discrimination


• Antiprotons 80 MeV - 150 GeV

• Positrons 50 MeV – 270 GeV

• Electrons up to 400 GeV

• Protons up to 700 GeV

• Electrons+positrons up to 2 TeV(calorimeter alone)

• Light Nuclei (He/Be/C) up to 200 GeV/n

• AntiNuclei search sensitivity of 3x10-8 in He/He

Design Performance

Simultaneous measurement of many cosmic-ray species New energy range Unprecedented statistics


PAMELA: the integration


The Resurs DK-1 spacecraft• Multi-spectral remote sensing of

earth’s surfacenear-real-time high-quality images

• Built by the Space factory TsSKB Progress in Samara (Russia)

• Operational orbit parameters:• inclination ~70o

• altitude ~ 360-600 km (elliptical)

• Active life >3 years • Data transmitted via Very high-

speed Radio Link (VRL)•PAMELA mounted inside a pressurized container•moved from parking to data-taking position few times/year

Mass: 6.7 tonsHeight: 7.4 mSolar array area: 36 m2


PAMELA: in the satellite & launch

• Launch from Baikonur: June 15th 2006, 0800 UTC.Power On: June 21st 2006, 0300 UTC.Detectors operated as expected after launch

• PAMELA in continuous data-taking mode since commissioning phase ended on July 11th 2006• ~600 days of data taking (~73% live-time) • ~10 TByte of raw data downlinked• >109 triggers recorded and under analysis


OrbitOrbit CharacteristicsCharacteristics

70ο

610 km

350 kmSAA

•• LowLow--earth elliptical orbitearth elliptical orbit•• 350 350 –– 610 km610 km•• QuasiQuasi--polar (70polar (70oo inclination)inclination)•• Lifetime >3 years (assisted)Lifetime >3 years (assisted)


Galactic H and He spectraVery high statistics over a wide energy range→ Precise measurement of spectral shape→ Possibility to study time variations and transient phenomena

Statistical errors only

Preliminary


Geomagnetic cutoff

0.4 to 0.51.0 to 1.51.5 to 2.02 to 4

> 1410 to 147 to 104 to 7

Geomagnetic cutoff (GV/c)

•Up-ward going albedo excluded•SAA excluded


Magnetic poles (→ galactic protons)

Secondary Reentrant albedo protons

Magnetic equator


Interstellar spectrum

July 2006August 2007February 2008

Decreasing

solar activity

Increasing G

CR

flux

Solar modulation

sun-spot number

Ground neutron monitorPAMELA


Preliminary


B/C Ratio


Antiparticle Selection in the calorimeter

ee-- ee++

p, dp, dpp

Electron

Hadron

Preliminary


Antiproton:spillover

e- (+ p-bar)

p-bar

p

-1 ← Z → +1

“spillover” p

p (+ e+)

1 GV5 GV

• The main difficulty for the antiproton measurement is the spillover proton bk. At high energy due to the finite deflection resolution of the spectrometer

Deflection:η = 1/R

Preliminary


MDR depends on:• number and distribution of fitted points along the trajectory• spatial resolution of the single position measurements• magnetic field intensity along the trajectory

High-energy antiproton selection

R < MDR/10

p-bar p

10 GV 50 GV

“spillover” p

MDR = 1/ση(evaluated

event-by-event by the fitting

routine)

Prel

imin

ary


Antiproton

GV-1

pp pp

β

GV-1

ee-- ee++

pp ppαα

β

GV-1

ee-- ee++

pp pp

β


Antiproton to Proton RatioAntiproton to Proton Ratio



Preliminary


Positron selection with calorimeter

(e+)

p (non-int)

p (int)

p-bar (int)

e-

p-bar (non-int)

Z=-1

Z=+1

Rigidity: 20-30 GV

Preliminary

Fraction of charge released along the calorimeter track


e+

p

p-bar

e-

Positron selection with calorimeterZ=-1

Z=+1

Rigidity: 20-30 GV

Preliminary


Constrains on:• Energy momentum

match



match• Shower starting-point• Longitudinal profile

e+

p

e-

Positron selection with calorimeterZ=-1

Z=+1

Rigidity: 20-30 GV

Preliminary



Proton background evaluation

e+

p

e-

p

Rigidity: 6-8 GV

Preliminary


match• Shower starting-point• Longitudinal profile



Positron to Electron Fraction

Secondary production Moskalenko & Strong ApJ 493 (1998) 694


Positron to Electron Fraction

End 2007:~20 000 positrons total

Charge signdependent solarmodulation

Preliminary


Charge dependent solar modulation

A > 0 Positive particles

A < 0 Clem J. & Evenson 2007

--- Clem 1995--- Bibier 1999 Drift Model

¯

+

¯

+PAMELA

2006 Preliminary

Preliminary

Preliminary

Secondary production Moskalenko& Strong ApJ 493 (1998) 694


Conclusions

• PAMELA is a permanent cosmic ray space laboratory • Presented preliminary results from ~600 days of data:

• Antiproton charge ratio (~1 GeV ÷100 GeV) • more data to come at lower and higher energies (up to ~150 GeV)

• Positron charge ratio (~400 MeV ÷10 GeV)• more data to come at lower and higher energies (up to ~200 GeV)

• Primary proton and Helium spectra at different geomagnetic cut off latitude and solar activity

• PAMELA is already providing significant experimental results, which will help in understanding and monitorig the flux of CR above the atmosphere

• More exciting results will come in the next future!

PAMELA Space Mission PAMELA CollaborationWiZard activitiesPAMELA SciencePAMELA SciencePAMELA SciencePAMELA ScienceWhy Anti(particle)matter matters?Why Anti(particle)matter matters?Why Anti(particle)matter matters?Why Anti(particle)matter matters?Why Anti(particle)matter matters?PAMELA detectorsPAMELA detectorsDesign PerformancePAMELA: the integrationThe Resurs DK-1 spacecraftPAMELA: in the satellite & launchOrbit CharacteristicsGalactic H and He spectraGeomagnetic cutoffSolar modulationB/C RatioAntiparticle Selection in the calorimeterAntiproton:spilloverHigh-energy antiproton selectionAntiprotonAntiproton to Proton RatioAntiproton to Proton RatioAntiproton to Proton RatioPositron selection with calorimeterPositron selection with calorimeterPositron selection with calorimeterProton background evaluationPositron to Electron FractionPositron to Electron FractionCharge dependent solar modulationConclusions

pamela space mission · • astromag/wizard project (pamela precursor) on board of the space...

Documents