Identify hadrons with pT = 10 GeV/c

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GOALS of the VHMPID

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

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First HI collision ?
Start of LHC
Yesterday
HMPID TDR
Urs Wiedemann, HI Forum 10 February 2004
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C Threshold counter ?
THE VHMPID, UPGRADE or DOWNGRADE ?
or TIC ?
RICH ?
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Nice detector but the radiator is too long (1m
for lt6gt photons)
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SIC TRANSIT GLORIA MUNDI
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IMPROVED TIC1 (XXL momentum)
CaF2
IP
C4F10
HMPID CsI photo-cathode
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Quartz cut-off
Data from the HADES RICH (NIM A 433 (1999)
201-206) Radiator thickness 36 to 65 cm, 12 to 22
photons detected
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C4F10 radiator
Momentum Detector resp. Particle id.
lt 3 GeV 0 Who cares?
3 lt p lt 9 1 ?
0 K,p
9 lt p lt 17 1 ?,K
0 p
gt 17 GeV 1 Who knows ?
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1.5 m
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IMPROVED TIC2 (XXXL momentum)
Window less !
CF4 (CH4)
CF4 CsI give 40 photons with 50 cm radiator
! (Nucl. Instrum. Methods Phys.
Res., A 523 (2004) 345-354)
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CF4 transparent down to 110 nm !
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CF4 radiator
But aging needs to be investigated if we want to
get rid of the window
Momentum Detector resp. Particle id.
lt 5 GeV 0 Who cares?
5 lt p lt 16 1 ?
0 K,p
16 lt p lt 30 1 ?,K
0 p
gt 30 GeV 1 Who knows ?
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Amazingly, extremely rapid aging has been
observed for pure CF4 and in Ar/CF4/O2(504010)
mixture, which were expected to have strong
etching abilities.
Finally, it should be noted, that most of the
aging studies in the CF4/hydrocarbon mixtures,
were performed by irradiating a small region of
the wire under well controlled laboratory
conditions. At the same time, several painful
experiences with aging are known from the high
energy experiments.
M.Danilov,
L.Laptin, I.Tichomirov, M.Titov,
Yu.Zaitsev Aging tests of the proportional wire
chambers using Ar/CF4/CH4(74206),
Ar/CF4/CH4(67303) and Ar/CF4/CO2(65305)
mixtures for the HERA-B Muon Detector Moscow
2000
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We are here
In this article we present evidence that the
rapid aging observed is related to chemical
processes at the cathode rather than at the
anode, as previously suggested. J. Wise et al.
J. Appl. Phys. 74 (Q), 1 November 1993
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A word of hope
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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
Much more challenging, a lot of RD required
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TWO STAGES TIC
Window less !
CF4
C4F10
CaF2 window
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C4F10 CF4 radiators
Momentum C4F10 CF4 Particle id.
lt 3 GeV 0 0 Who cares?
3 lt p lt 5 1 0 ?
5 lt p lt 9 1 1 ?
9 lt p lt 16 1 1 ?
1 0 K
0 0 p
16 lt p lt 30 1 1 ?,K
1 0 p
gt 30 GeV 1 1 Who knows?
But Cherenkov angles are very similar !
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2m
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This will work but it would be too long
and complicated
C4F10
CF4
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TWO STAGES TIC
Window less !
CF4
C4F10
CaF2 window
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First results from test beam
50 cm 50 cm
of photons
Total charge
Rad 1
Rad 12
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50 cm 50 cm
10 cm
Radiator 1 Radiator 2
3 cm
2.5 cm
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DELAYED IDENTIFICATION
CaF2
C4F10 / CF4
CF4
Run X days with C4F10 ,Y days with CF4
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CF4 5lt p lt16 N? ,NKp 16lt p lt30
N?K ,Np p gt 30 N?Kp
C4F10 3lt p lt9 N? ,NKp 9lt p lt16 N?K
,Np pgt 16 N?Kp
9ltplt16 N? , NK , Np 16ltplt30 N?K , Np

• Identification
• Identification
• Indirect identification
• Cross-checked

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COST 700 kCHF (from RICH TDR)
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The HADES RICH
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A FERRARI for ALICE
Window less !
C4F10
CF4
CaF2 window
Aerogel detector
Pad chamber, no CsI
For n 1.01 ptrh 1, 3.5, 7 GeV/c for ?, K and
p. If we could reject ? we would have the high
pT trigger we need !
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IMPID VHMPID
Momentum Aerogel C4F10 CF4 Particle id.
lt 1 GeV 0 0 0 Who cares ?
1 lt p lt 3 1 0 0 ?
3 lt p lt 9 1 1 x ?
1 0 x K
0 0 0 p
9 lt p lt 16 1 1 1 ?
1 1 0 K
1 0 0 p
16 lt p lt 30 1 1 1 ?,K
1 1 0 p
gt 30 GeV 1 1 1 Who knows?
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Why I dont like aerogel
Why aerogel does not work

• Momentum range not appropriate
• Poor photons yield low efficiency
• Too sensitive to electron background
• Too sensitive to noise
• Too sensitive to spread in PMTs gain
• Efficiency vs. track position
• Particles traveling through the PMT
• Very expensive

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OPEN QUESTIONS (no matter the technology)
Single or double arm ? Acceptance Do we
need a trigger? How to trigger ?
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Do we know what we do ?
We identify protons by NOT seeing a signal Very
dangerous ! How to convince people that what we
DO NOT see it is the truth ?
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Time scale
Construction cant start before 2006 (not even
prototype) No test beam at CERN before June
2006 Perfect time for simulation and build a
strong physics case
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Conclusions

• 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.
• Two radiators are very suitable.
• Simulation is needed in order to choose and
  optimize
• the detector layout.
• Simulation is needed in order to define the
  physics target
• and understand the physics requirements.
• Laboratory tests are needed in order to
  investigate
• the aging of CF4.

Further work on this subject is incompatible with
the present commitments of the (CERN) HMPID
group.