Astrophysics with PAMELA cospar 2004

1
Roberta Sparvoli for the PAMELA
Collaboration University of Rome Tor Vergata and
INFN Roma II, Italy
2
PAMELA scientific program
PAMELA is a magnetic spectrometer which will fly
on a Russian satellite by Fall 2005. Its
scientific scope is the measurement of the
antiproton and positron spectra up to few hundred
GeV, of the proton and electron spectra up to 700
GeV and that of light nuclei.

• energy range particles/3 years
• Antiproton flux 80 MeV - 190 GeV gt3 104
• Positron flux 50 MeV 270 GeV gt3 105
• Electron flux up to 400 GeV 6 106
• Proton flux up to 700 GeV 3 108
• Electron/positron flux up to 2 TeV
• Light Nuclei (up to Z6) up to 200 GeV/n
  He/Be/C 4 107/4/5
• AntiNuclei search (sensitivity of 3 10-8 in
  He/He)

• Unprecedented Statistics and new Energy Range in
  Cosmic Rays
• Actual limits antippositrons ? 40 GeV

3
PAMELA detectors
Around the main structure detectors are arranged

• 3 planes of scintillators S1, S2, S3
• Each plane made of 2 crossed layers, segmented in
  X-Y strips
• 48 channels
• ?TOF 110ps
• Used for
• TRIGGER crossing particles
• TOF Particle ID and for
• albedo rejection (upward)
• dE/dx measurements

• 1024 straw tubes arranged in 9 detection planes
• Gas mixture Xe-CO2 (80-20)
• HV 1400 V
• Radiator 10 planes of Carbon fibre (60 g/l)
  interleaved to the detection planes
• Used for
• Redundancy in
• lepton/hadron separation
• Performance
• 5 proton contamination at about 90 electron
  efficiency

• Permanent magnet
• Made of 5 blocks of Nd-B-Fe Alloy
• 0.48 T in internal cavity
• Silicon Tracker
• 6 floors of double sided Si-MicroStrip detectors
  (300 ?m)
• X-Strip 25 ?m implantation pitch / junction side
• Y-Strip 67??m pitch / ohmic side
• R/O pitch 50 ?m in X/Y
• Used to
• Impulse reconstruction
• Charge sign ID
• 3??m resolution in bending view X
• 10 ?m resolution in Y
• ? Max. Ridigity 740 GV

• 22 planes of Tungsten (2.6mm) interleaved with
  double sided MacroStrip detectors (2.4 mm pitch
  along orthogonal directions)
• 16.3 Rad. Lengths, 0.6 Int. Lengths
• Total 4224 channels
• Used for
• Lepton/hadron separation
• Energy determination
• gt104 rejection power for
• p/e (and anti-p/e-)
• Energy resolution 5 at 200 GeV
• Possibility of self-triggering (H.E. electrons
  increased GF used in conjuntion to Shower tail
  catcher)

• Scintillators organized in a TOP paddle and 4
  LATeral paddles
• Detector-efficiency high gt99.9
• Used to
• help rejection of spurios triggers (used offline
  in 2nd level trigger)
• Visit talk dr. Orsi, today aft.

• Bottom Scintillator
• Single square scintillator paddle 10 mm thick
• 6 PMTs
• Dynamic range of 11000 mip
• Used for
• Trigger for ND
• Neutron Detector
• 36 proportional counters filled with 3He, stacked
  in two planes of 18 counters each, oriented along
  the y-axis of the instrument.
• Used for
• Lepton/hadron separation by n. of neutrons
  produced in showers

4
What is PAMELA now?
5
Mass Thermal Model

• PAMELA Mass Thermal Model was assembled in the
  clean room of Rome Tor Vergata (2001-2002) and
  then integrated into the Pressurized Container at
  TsSKB-Progress (Samara/Russia), between March
  2002 and April 2003, for all mechanical
  compatibility tests. It passed thermal and
  dynamical qualification tests.

6
Technological Model

• PAMELA Technological Model was assembled and
  tested (preliminary Acceptance Tests with EGSE
  power ON/OFF, telecommands, data transmission
  through adapter) in the clean room of Rome Tor
  Vergata in 2003-2004.

It was then shipped to Samara inside a special
transport container in April 2004. Magnetic
compatibility tests and Incoming Tests
(stand-alone) already performed. Integration
with satellite and transmission to mass memory
still in progress (Jan 2005).
7
Flight Model Integration

• The final Flight Model integration is in progress
  in Rome clean room since almost 12 months. All
  flight components have been mounted. From
  16/02/2005 a Russian delegation is in Rome for
  official Acceptance tests of PAMELA FM before
  delivery to Samara.

8
Beam tests
From July 2000 until September 2003 PAMELA Flight
Model was extensively exposed to beam tests to
study physical performance. Detectors operated at
CERN PS/SPS test beams as prototypes and in FM
configuration. Final test in Sept. 2003.
9
Dynamic tests
PAMELA FM Model passed a cycle of vibration
tests at IABG/Munich (January 2005) to verify the
final structure. Minimal loads have been imposed
to the instrument. 100 channels were mounted.
All resonance searches confirm the integrity of
the detector after the test.
10
Cosmic ray tracks (Dec. 2004)
Since November 2004 PAMELA is set in cosmic-ray
acquisition during night shifts.
11
First physics results
From the statistics acquired by cosmic-ray
acquisitions we are analyzing PAMELA performance
and comparing with literature.
12
Conclusions already done

• (0) Detectors and Systems are designed ready
• (1) MASS THERMAL MODEL
  ? done
• ? All tests passed ? space qualification!
• (2) TECHNOLOGICAL MODEL
  ? done
• ? Assembly finished in Rome ( 1 yr)
• ? Integration with satellite in Samara
  almost complete (started 05/2004)
• (3) FLIGHT MODEL
• ? SPS BeamTest of almost complete setup
  done in Sept. 2003
• for final calibration alignment
  ? done
• ? Vibration Test (minimal loads) of complete
  setup for final check of structure Munich
  (Jan. 2004) ? done

13
Conclusions to be done
FLIGHT MODEL ? Acceptance tests to be
performed (end by 23 Feb. 2005) ? Cosmic-ray
acquisition (long run) (end by 10 March 2005) ?
Transport to Samara Russia (March 2005) ?
Full integration of PAMELA, ARINA EOS into
satellite (April 2005) ? Tests in Samara
Russia (up to 3 months) ? All final tests
in-situ - Baikonur/Kazahstan (2 3 months)
The PAMELA launch is in Fall 2005