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NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
PAMELA: a Satellite Experiment for PAMELA: a Satellite Experiment for Antiparticles Measurement in Antiparticles Measurement in
Cosmic Rays Cosmic Rays
Massimo BongiUniversita’ degli Studi di Firenze and INFN Sezione di Firenze
The PAMELA collaboration
• PAMELA scientific objectives• Detector’s overview• Subsystems’ description• PAMELA status
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
The PAMELA CollaborationThe PAMELA Collaboration
Bari Florence Frascati
Italy:TriesteNaples Rome CNR, Florence
Russia:
Moscow St. Petersburg
India:
Bombay
Germany:Siegen
Sweden:KTH, Stockholm
NMSU
GSFC
USA:
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
STUDY OF ANTIMATTER IN COSMIC RAYS
AntiprotonsAntiprotons spectrum
PositronsPositrons spectrum
Search for light antinucleiantinuclei
SECONDARY GOALS
•Modulation of GCRs in the Heliosphere
•Solar Energetic Particles (SEP)
•Earth Magnetosphere
PAMELA scientific objectivesPAMELA scientific objectives
Antiproton flux
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
STUDY OF ANTIMATTER IN COSMIC RAYS
AntiprotonsAntiprotons spectrum
PositronsPositrons spectrum
Search for light antinucleiantinuclei
SECONDARY GOALS
•Modulation of GCRs in the Heliosphere
•Solar Energetic Particles (SEP)
•Earth Magnetosphere
PAMELA scientific objectivesPAMELA scientific objectives
Positron charge ratio
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
STUDY OF ANTIMATTER IN COSMIC RAYS
AntiprotonsAntiprotons spectrum
PositronsPositrons spectrum
Search for light antinucleiantinuclei
SECONDARY GOALS
•Modulation of GCRs in the Heliosphere
•Solar Energetic Particles (SEP)
•Earth Magnetosphere
PAMELA scientific objectivesPAMELA scientific objectives
Earth magnetosphere
PAMELA
70.4o
300-600 km
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
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
STUDY OF ANTIMATTER IN COSMIC RAYS
AntiprotonsAntiprotons spectrum
PositronsPositrons spectrum
Search for light antinucleiantinuclei
SECONDARY GOALS
•Modulation of GCRs in the Heliosphere
•Solar Energetic Particles (SEP)
•Earth Magnetosphere
PAMELA scientific objectivesPAMELA scientific objectives
Earth magnetosphere
PAMELA
70.4o
300-600 km
80 MeV/n – 30 GeV/n7•10-8He/He limit
50 MeV – 270 GeV> 3•105Positrons
50 MeV – 2 TeV6•106Electrons
80 MeV – 190 GeV> 3•104Antiprotons
80 MeV – 700 GeV3•108Protons
Energy rangeNumber (3 years)Particle
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
Detector’s structureDetector’s structureTRANSITION RADIATION DETECTOR
MAGNETIC SPECTROMETER
ELECTROMAGNETIC CALORIMETER
NEUTRON DETECTOR
TIME-OF-FLIGHT SCINTILLATORS
ANTICOUNTER SYSTEM
BOTTOM SCINTILLATOR
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
AC
Neutron detectorBottomscintillator
Detector’s principle of operationDetector’s principle of operation• Trigger and
Time-of-Flight Measurement
• γ Measurement
• Momentum Measurement
• Energy Measurement and
Particle Identification
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
TimeTime--ofof--Flight SystemFlight System3 double layers of Bicron BC-404 plastic scintillatorread 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
TimeTime--ofof--Flight SystemFlight System3 double layers of Bicron BC-404 plastic scintillatorread by Hamamatsu R5900 PMTs
• 110 ps transit time spread
• high gain (~106) at 800 V
•• Trigger signalTrigger signal
•• Detects Detects albedoalbedo particlesparticles
•• dEdE//dxdx measurementmeasurement
•• Particle identificationParticle identification
up to up to ~~1 GeV/c1 GeV/c
~130 ps time resolution
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
Transition Radiation DetectorTransition Radiation Detector9 planes of 1024 straw tubesstraw tubes each (4 mm ∅) interleaved with carbon carbon fibres radiatorsfibres radiatorsstraw tubes use a Xe-CO2 (80-20)% gas mixture and work at ~ 1400 V
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
Transition Radiation DetectorTransition Radiation Detector9 planes of 1024 straw tubesstraw tubes each (4 mm ∅) interleaved with carbon carbon fibres radiatorsfibres radiatorsstraw tubes use a Xe-CO2 (80-20)% gas mixture and work at ~ 1400 V
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
Transition Radiation DetectorTransition Radiation Detector9 planes of 1024 straw tubesstraw tubes each (4 mm ∅) interleaved with carbon carbon fibres radiatorsfibres radiatorsstraw tubes use a Xe-CO2 (80-20)% gas mixture and work at ~ 1400 V
Threshold device:
• signal from e+ and e-
• no signal from p and p
A pion contamination of 5% at an
electron discrimination efficiency of
~ 90% has been obtained
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
Magnetic SpectrometerMagnetic SpectrometerSilicon Tracker inside a Permanent MagnetSilicon Tracker inside a Permanent Magnet
Measures particles’ rigidity: R=Measures particles’ rigidity: R=p/qp/q
• 5 Nd-Fe-B alloy magnetic modules in an aluminum structure
• (132 x 162 x 445) mm3 cavity
• 20.5 cm2sr geometric factor
• B = 0.48 T in the center
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
Magnetic SpectrometerMagnetic SpectrometerSilicon Tracker inside a Permanent MagnetSilicon Tracker inside a Permanent Magnet
Measures particles’ rigidity: R=Measures particles’ rigidity: R=p/qp/q
• 5 Nd-Fe-B alloy magnetic modules in an aluminum structure
• (132 x 162 x 445) mm3 cavity
• 20.5 cm2sr geometric factor
• B = 0.48 T in the center
• 6 planes of 300 µm thick silicon
sensors
• 6 microstrip silicon sensorsmicrostrip silicon sensors in
each plane
• double sided sensors, with
double metalization and
integrated decoupling capacitance
• strip pitch: 50 µm on X side
(bending view), 67 µm on Y side
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
Magnetic SpectrometerMagnetic SpectrometerSilicon Tracker inside a Permanent MagnetSilicon Tracker inside a Permanent Magnet
Measures particles’ rigidity: R=Measures particles’ rigidity: R=p/qp/q
• 5 Nd-Fe-B alloy magnetic modules in an aluminum structure
• (132 x 162 x 445) mm3 cavity
• 20.5 cm2sr geometric factor
• B = 0.48 T in the center
• 6 planes of 300 µm thick silicon
sensors
• 6 microstrip silicon sensorsmicrostrip silicon sensors in
each plane
• double sided sensors, with
double metalization and
integrated decoupling capacitance
• strip pitch: 50 µm on X side
(bending view), 67 µm on Y side
s
e
d
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
Signal / Noise ratioSignal / Noise ratioY: S/N ~ 26 X: S/N ~ 52
300 GeV/c electron event300 GeV/c electron eventJune 2002 SPS beam test
non-bending view bending view
Magnetic SpectrometerMagnetic Spectrometer
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
Signal / Noise ratioSignal / Noise ratioY: S/N ~ 26 X: S/N ~ 52
300 GeV/c electron event300 GeV/c electron eventJune 2002 SPS beam test
non-bending view bending view
Magnetic SpectrometerMagnetic SpectrometerSpatial resolutionSpatial resolution
σX ~ 3 µm, σY ~ 13 µm
Maximum Detectable Maximum Detectable Rigidity:Rigidity:
MDR > 740 GV/cMDR > 740 GV/c
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
Electromagnetic CalorimeterElectromagnetic CalorimeterSampling 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/leptonrejection power
Electrons’ energy up to 2 TeV in self-trigger mode
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
(x4)
CASCAT
AnticounterAnticounter SystemSystem4 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
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
(x4)
CASCAT
AnticounterAnticounter SystemSystem4 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
•Defines the spectrometer acceptance•Helps in rejecting spurious triggers
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
BottomBottom ScintillatorScintillator and Neutron Detectorand Neutron DetectorBottom Scintillator
10 mm thick scintillator
read by 6 MELZ FEU-85 PMTs
Neutron Detector
36 3He proportional counters + lowZ moderator enveloped in a thin cadmium layer
n + 3He p + 3H + 765 keV
lot
The Bottom Scintillator triggers the Neutron Detector, which helps in hadron/lepton identification
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
PAMELA statusPAMELA statusAll the subdetectors are nearly ready and fulfill
the requirements
Intense simulation and beam test activities have been performed
Intense simulation and beam test activities have been performed
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
PAMELA statusPAMELA statusAll the subdetectors are nearly ready and fulfill
the requirements
Intense simulation and beam test activities have been performed
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
PAMELA statusPAMELA statusAll the subdetectors are nearly ready and fulfill
the requirements
Intense simulation and beam test activities have been performed
Integration of the detector is in progress
NUCLEAR SCIENCE SYMPOSIUM - Portland, OR - October 20-24, 2003 Massimo Bongi
PAMELA statusPAMELA statusAll the subdetectors are nearly ready and fulfill
the requirements
Intense simulation and beam test activities have been performed
Integration of the detector is in progress
Launch from Baikonur on next
year