Improved Cherenkov Threshold detectors

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Improved Cherenkov Threshold detectors for
heavy-ions experiment
P. Martinengo,CERN High-pT Physics at
LHC,Tokaj08
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Can we extend the ALICE PID for hadrons above 5
GeV/c ?
ALICE Club - May 2, 2005 Paolo Martinengo
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What means high-pT ?
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HMPID 3s p/K limit
HMPID TDR
U. Wiedemann, Heavy Ions Forum, 10 February 2004
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yesterday
HMPID 3s p/K limit
HMPID TDR
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start of LHC
yesterday
HMPID 3s p/K limit
HMPID TDR
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first HI collision ?
start of LHC
yesterday
HMPID 3s p/K limit
HMPID TDR
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Conclusion
The HMPID is an excellent detector with a wrong
name !
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Home work

• Identify hadrons with pT 10 GeV/c
  track-by-track
• Inclusive measurement, particle yields,
• especially protons
• Weak identification, i.e. ?,K protons
• can be enough

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N? (cm-1eV-1) sin2? (HMPID 1.5 cm liquid
C6F14)
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2m
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• LHCB RICH1 2.4 m
• LHCB RICH2 2.0 m
• BTeV RICH2 3.0 m
• COMPASS gt 3.0 m
• CBM 2.5 m
• All fixed-target !

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The examples set forth show the great
importance which the radiation caused by
particles moving at a speed greater than that
of light has acquired in experimental physics.
Even so, we have not by a long way exhausted
all the possibilities for their practical use.
There can be no doubt that the usefulness of
this radiation will in the future be rapidly
extended.
End of Cerenkovs Nobel lecture (1958)
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ITC Improved Threshold Cherenkov or TIC Threshol
d Imaging Cherenkov ?
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Nice detector but the radiator is too long (
1m for lt6gt ?s )
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The ?s yield is too low but compact, simple
layout well known and mastered technology ?c
is not measured but ?s are associated to tracks
arobust w.r.t. high multiplicity, noise Is it
possible to improve the ?s yield ?
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Yes, it is
CaF2
IP
C4F10
HMPID CsI photo-cathode
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Quartz cut-off
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The HADES RICH
HMPIDs brother, both sons of RD26
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(No Transcript)
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1.5 m
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Radiator thickness 36 to 65 cm, 12 to 22 ?s
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C4F10 radiator
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Can we do better ?
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Yes, we can
Window less !
CF4
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CF4 CsI give 40 ?s with 50 cm radiator !
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CF4 transparent down to 110 nm !
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Why not a GEM detector ? (perhaps with the
ALTRO R/O)
Nucl. Instrum. Methods Phys. Res., A 535 (2004)
324-329 Nucl. Instrum. Methods Phys. Res., A 523
(2004) 345-354
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CF4 radiator
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Interesting but not exactly what we want
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DOUBLE RADIATOR TIC
Window less !
CF4
C4F10
CaF2 window
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C4F10 CF4 radiators
But Cerenkov angles are very similar ! ( 3o and
1.8o)
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This would work but it is not elegant
C4F10
CF4
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DOUBLE RADIATOR TIC
Window less !
CF4
C4F10
CaF2 window
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50 cm 50 cm
10 cm
C4F10 CF4
2.5 cm
3 cm
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(No Transcript)
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First results from test beam
50 cm 50 cm
of photons
Total charge
C4F10
C4F10 CF4
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Single radiator TIC
CaF2
IP
C4F10
HMPID CsI photo-cathode
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SIMULATION
Cherenkov photons
chamber
Mirror
(Giacomo Volpe)
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SIMULATION
5 GeV/c pions, 366 charged pads
3 GeV/c pions, 189 charged pads
10 GeV/c pions, 564 charged pads
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Blob diameter for C4F10, pad size 0.8x0.8 cm2
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Nikolai Smirnov, Yale Univeristy
More ideas
AeroGel, 10cm
UV Mirror, spherical shape in ZY
Double sided Read-out plane Triple GEM foils with
CsI
50 cm
CF4 gas
CaF2 Window
Y
50 cm
X
C4F10 gas
R position 500 cm. Bz 0.5 T
Z
Particle track UV photons
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Simulation for high Pt p
Flat mirror
Spherical mirror
AeroGel, 10cm
UV Mirror, spherical shape in ZY
Double sided Read-out plane Triple GEM foils with
CsI
CF4 gas
CaF2 Window
C4F10 gas
R
Z
In saturation ltN ph.e.gt ? 25. (C4F10) 30.
(CF4)
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Thick GEM with resistive electrodes (RETGEM)- a
fully spark protected detector
A. Di Mauro et al, Presented at the Vienna Conf.
on Instrum to be published in NIM
Principle of operation
Geometrical and electrical characteristics Holes
diameter 0.3-0.8 mm, pitch 0.7-1.2 mm, thickness
0.5-2 mm. Resitivity200-800kO/? Kapton type
100XC10E
30mm or 70mm
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Fully spark -protected
Summary of the main results obtained with kapton
RETGEMs
1 mm thick
Energy resolution 30FWHM for 6 keV
Discovery kapton can be coated with CsI and
have after high QE
QE30 at ?120nm
Filled symbols-single RETGEM, open symbols
double RETGEMs Stars-gain measurements with
double RETGEM coated with CsI layer.
15 min continues discharge
With increase of the rate the amplitude drop,
but now discharges
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Thick GEMs work even with unconventional gas
mixtures, i.e. pure Neon or Argon and even in dry
air !
(Vladimir Peskov Budapest group)
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Anything wrong with dry air? Cheap! Abundant!
Non flammable! Correct refractive index!
From Olaf Ullalands presentation at the CBM
workshop
Eigenshaften der Materie in Ihren
Aggregatzustanden, 8. Teil Opische Konstanten,
1962
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With a little bit of mixing of CF4 and
Ne Setting (n-1) ?106 350 at 400 nm gives a
mixing ratio of CF4Ne 6733
The Dutch Chemist, c 1780s. Copper engraving
by J Boydell after a painting by J Stein.
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It may work !
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Conclusions (2)

• It is possible to extend the PID capability of
• ALICE up to 30 GeV/c making use of presently
• available technologies at reasonable cost in
• a reasonable time
• But
• it is useless if we dont find a trigger !

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(Olav Ullaland)