M' Bunerd 1

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In-beam tests of the AMS RICH prototype

• PLAN
• The AMS RICH counter
• Prototype beam tests

Michel Buénerd LPSC GRENOBLE for
The AMS RICH collaboration Bologna, Grenoble,
Lisbon, Madrid, Maryland, Mexico
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Why a RICH in AMS ?
Broad program of Nuclear Cosmic Ray study c
Ion identification (A Z) c Counter optimized
for this purpose c Test with ion beam to
investigate performances
(See talk by J. Casaus, this conf.)
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The RICH inside AMS
CherenkovRadiator
aerogel
NaF
AMS spectrometer
Photo- detectors
ECAL
Radiator(s)
Conical mirror
Photodetectorplane (680 PMTs)
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Radiator plane
Aerogel n1.03-1.05 thickness 30 mm
Sodium Fluoride NaF, n1.33 thickness 5 mm
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Photodetector cell
4x4 Light Guides7.5x7.5mm2

• Front End Electronics
• Charge preamplifier
• Trackhold MPX 16 chan (x2gains)
• ADC
• High voltage divider

Magnetic Shielding profile (Stray field up to
300G)
PMT Hamamatsu R7900_M16 4x4 pixels (4.5x4.5mm2)
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The RICH prototype
½ module of final detector

• 96 PMTs (1536 pixels)
• Light Guides
• FEDAQ
• Radiators
• AGL 1.03 lt n lt 1.05
• NaF n1.33 (CR only)

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Multi-ion beam production
Incident SPS Pb ion beam(20GeV/c/n)
Productiontarget
Br
Fewmrad
Momentumanalysis
Br Cte x g A/Z
Detector
Beam fragmentation è Br Cte x gbeam A/Z
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CERN H8 beam line
Tracker
CREAM
Dispersiondipole
Productiontarget
AnalysisDipole
TOF
Acceptancecollimators
Momentum Analysis
RICH
Imagecollimators
Wall
TOF1
TOF2
Experimental area
?P/P1
-464
-26
0
-352
-150
-420
-80
Position (m)
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Ion selection
Field setting in beam line A/Z2
See D.Casadei et al., this conf.
TOF Z vs RICH Z
N
O
N
B
B
Be
O
C
He
C
Li
He
Li
Be
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Cherenkov RINGS
C
O
Li
6
3
Ca-Fe
16
He
Z
2
gt16
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Velocity reconstruction
??spectra fitting
Ring fitting
For Z1 particles
Aerogel
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Z dependence of b resolution
Aerogel 1.03 Matsushita
N? in the ring Z2
Limit set by pixel size
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Charge resolution

• Dynamics limited by MWPC (Z lt 50 seen in
  dE/dX)
• ?(Z).3 up to Z26

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Ion beam fragments vs Cosmic Ray flux
Beam fragments (A/Z2) (From dE/dX scintillator )
Similarity of the 2 spectra _ controllableCR
equivalent flux
Cosmic Ray flux
J.A. Simpson ARNS 33(1983)323
Nuclear charge Z
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Summary Conclusion

• The study of the AMS RICH prototype with 20GeV/n
  ions has allowed to
• Perform an end-to-end test of the instrument with
  a broad range of nuclear charges (1ltZlt25).
• Measure the performances of the prototype
• Velocity resolution Db/b 0.7 10-3 for Z1
  particles
• Charge resolution s(Z) 0.3
• Next steps
• New beam test Oct-Nov 2003 (158A GeV In ions)
• Counter assembly starting on Aug 2003 (Now !)

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Why beam testing the RICH ?

• End-to-end testing
• Response in charge to ions (large Z)
• Velocity (mass) resolution
• Different radiator samples
• Reconstruction efficiency (Z1)

(Not measurable with CR particles)
_
20 GeV/c/n fragmentation beam from the CERN SPS
(cf CERN report AB-2003-052)
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Ion selection (I)
Field setting in beam line A/Z2
Z
Stable nuclei
N
Be
B
O
He
C
Li
Rigidity Br (A/Z)
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Ion selection (II)
Field setting A/Z7/4
7Be
Zscint.
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Ion selection (III)
Field setting A/Z3/2
3He
Zscint.
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the AMS RICH prototype
In-beam tests of the AMS RICH counter
In-beam tests of
20A GeV/c secondary ions at CERN
AMS
M. Buénerd LPSC Grenoble For the AMS
RICH collaboration

• Plan
• The AMS RICH counter
• Prototype beam tests

The AMS RICH collaboration Bologna, Grenoble,
Lisbon, Madrid, Maryland, Mexico