PAMELA: a Satellite Experiment for Antiparticles Measurement in Cosmic Rays PAMELA scientific objectives Detector s overview Subsystems description PAMELA status Massimo Bongi Universita degli Studi di Firenze and INFN Sezione di Firenze The PAMELA collaboration
The PAMELA Collaboration Italy: Bari Florence Frascati Naples Rome Trieste CNR, Florence Russia: USA: GSFC NMSU Moscow St. Petersburg India: Bombay Germany: Siegen Sweden: KTH, Stockholm
PAMELA scientific objectives STUDY OF ANTIMATTER IN COSMIC RAYS Antiprotons spectrum Antiproton flux Positrons spectrum Search for light antinuclei SECONDARY GOALS Modulation of GCRs in the Heliosphere Solar Energetic Particles (SEP) Earth Magnetosphere
PAMELA scientific objectives STUDY OF ANTIMATTER IN COSMIC RAYS Antiprotons spectrum Positron charge ratio Positrons spectrum Search for light antinuclei SECONDARY GOALS Modulation of GCRs in the Heliosphere Solar Energetic Particles (SEP) Earth Magnetosphere
PAMELA scientific objectives STUDY OF ANTIMATTER IN COSMIC RAYS Antiprotons spectrum Positrons spectrum Search for light antinuclei Earth magnetosphere 70.4 o SECONDARY GOALS Modulation of GCRs in the Heliosphere PAMELA 300-600 km Solar Energetic Particles (SEP) Earth Magnetosphere PAMELA will fly on board of RESURS DK1 satellite, which will be launched by a Soyuz 2 rocket from Baikonur launch site in the first half of 2004 for a 3 years long mission
PAMELA scientific objectives STUDY OF ANTIMATTER IN COSMIC RAYS Particle Antiprotons spectrum Number (3 years) Earth magnetosphere Energy range Positrons Protonsspectrum Search for light antinuclei Antiprotons 3 10 8 > 3 10 4 80 MeV 70.4 o 700 GeV 80 MeV 190 GeV Electrons SECONDARY GOALS 6 10 6 50 MeV 2 TeV Modulation of GCRs in the Heliosphere Positrons > 3 10 5 Solar Energetic Particles (SEP) He/He limit 7 10 Earth Magnetosphere -8 PAMELA 300-600 km 50 MeV 270 GeV 80 MeV/n 30 GeV/n
Detector s structure TIME-OF-FLIGHT SCINTILLATORS TRANSITION RADIATION DETECTOR ANTICOUNTER SYSTEM MAGNETIC SPECTROMETER ELECTROMAGNETIC CALORIMETER BOTTOM SCINTILLATOR NEUTRON DETECTOR
Detector s principle of operation AC Trigger and Time-of-Flight Measurement γ Measurement Momentum Measurement Energy Measurement and Bottom scintillator Neutron detector Particle Identification
Time-of-Flight System 3 double layers of Bicron BC-404 plastic scintillator read by Hamamatsu R5900 PMTs 110 ps transit time spread high gain (~106) at 800 V NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
Time-of-Flight System 3 double layers of Bicron BC-404 plastic scintillator read by Hamamatsu R5900 PMTs 110 ps transit time spread high gain (~106) at 800 V Trigger signal Detects albedo particles ~130 ps time resolution de/dx measurement Particle identification up to ~1 GeV/c NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
Transition Radiation Detector 9 planes of 1024 straw tubes each (4 mm ) interleaved with carbon fibres radiators straw tubes use a Xe-CO 2 (80-20)% gas mixture and work at ~ 1400 V
Transition Radiation Detector 9 planes of 1024 straw tubes each (4 mm ) interleaved with carbon fibres radiators straw tubes use a Xe-CO 2 (80-20)% gas mixture and work at ~ 1400 V
Transition Radiation Detector Threshold device: signal from e + and e - no signal from p and p 9 planes of 1024 straw tubes each (4 mm ) interleaved with carbon fibres radiators straw tubes use a Xe-CO 2 (80-20)% gas mixture and work at ~ 1400 V A pion contamination of 5% at an electron discrimination efficiency of ~ 90% has been obtained
Magnetic Spectrometer Silicon Tracker inside a Permanent Magnet Measures particles rigidity: R=p/q 5 Nd-Fe-B alloy magnetic modules in an aluminum structure (132 x 162 x 445) mm 3 cavity 20.5 cm 2 sr geometric factor B = 0.48 T in the center
Magnetic Spectrometer Silicon Tracker inside a Permanent Magnet Measures particles rigidity: R=p/q 6 planes of 300 µm thick silicon sensors 6 microstrip silicon sensors in each plane double sided sensors, with double metalization and 5 Nd-Fe-B alloy magnetic modules in an aluminum structure (132 x 162 x 445) mm 3 cavity 20.5 cm 2 sr geometric factor B = 0.48 T in the center integrated decoupling capacitance strip pitch: 50 µm on X side (bending view), 67 µm on Y side
Magnetic Spectrometer Silicon Tracker inside a Permanent Magnet Measures particles rigidity: R=p/q 6 planes of 300 µm thick silicon sensors 6 microstrip silicon sensors in each plane double sided sensors, with double metalization and 5 Nd-Fe-B alloy magnetic modules in an aluminum structure (132 x 162 x 445) mm 3 cavity 20.5 cm 2 sr geometric factor B = 0.48 T in the center integrated decoupling capacitance strip pitch: 50 µm on X side (bending view), 67 µm on Y side
Magnetic Spectrometer Signal / Noise ratio Y: S/N ~ 26 X: S/N ~ 52 300 GeV/c electron event June 2002 SPS beam test non-bending view bending view
Magnetic Spectrometer Signal Spatial / Noise resolution ratio Y: S/N ~ 26 X: S/N ~ 52 300 GeV/c electron event June 2002 SPS beam test non-bending view bending view Maximum Detectable Rigidity: MDR > 740 GV/c σ X ~ 3 µm, σ Y ~ 13 µm
Electromagnetic Calorimeter Sampling calorimeter made of 22 planes: 16 radiation lengths, 0.9 interaction lengths 2.6 mm thick tungsten absorber between two 380 µm thick macrostrip silicon detector layers Measures energy of e + and e - with E/E = 15% / E 1/2 + 5.5% Reconstructs shower profile both in the longitudinal and in the transverse direction: 10-4 hadron/lepton rejection power Electrons energy up to 2 TeV in self-trigger mode
Electromagnetic Calorimeter Sampling calorimeter made of 22 planes: 16 radiation lengths, 0.9 interaction lengths 2.6 mm thick tungsten absorber between two 380 µm thick macrostrip silicon detector layers Measures energy of e + and e - with E/E = 15% / E 1/2 + 5.5% Reconstructs shower profile both in the longitudinal and in the transverse direction: 10-4 hadron/lepton rejection power Electrons energy up to 2 TeV in self-trigger mode
Anticounter System 4 panels (CAS) of Bicron BC-448 plastic scintillator surrounding the sides of the spectrometer + 1 panel (CAT) on top of it, read by Hamamatsu 5900 PMTs CAS CAT (x4)
Anticounter System 4 panels (CAS) of Bicron BC-448 plastic scintillator surrounding the sides of the spectrometer + 1 panel (CAT) on top of it, read by Hamamatsu 5900 PMTs CAS CAT (x4) Defines the spectrometer acceptance Helps in rejecting spurious triggers
Bottom Scintillator and Neutron Detector Bottom Scintillator 10 mm thick scintillator read by 6 MELZ FEU-85 PMTs Neutron Detector 36 3 He proportional counters + low Z moderator enveloped in a thin cadmium layer n + 3 He p + 3 H + 765 kev The Bottom Scintillator triggers the Neutron Detector, which helps in hadron/lepton identification
All the subdetectors are nearly ready and fulfill the requirements Intense simulation and beam test activities have been performed PAMELA status
All the subdetectors are nearly ready and fulfill the requirements Intense simulation and beam test activities have been performed PAMELA status
All the subdetectors are nearly ready and fulfill the requirements Intense simulation and beam test activities have been performed PAMELA status Integration of the detector is in progress
All the subdetectors are nearly ready and fulfill the requirements Intense simulation and beam test activities have been performed PAMELA status Integration of the detector is in progress Launch from Baikonur on next year