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A RICH with Aerogel for a hadron machine
On behalf of the LHCb RICH group
Some results and considerations on: Cerenkov angle resolution from aerogel Index of refraction homogeneity in an aerogel tile
And of Budker and Boreskov Institutes of Novosibirsk
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
The RICH of LHCb
p (GeV/c)
radiator Refractive index
2 - 10 Aerogel 1.030
10 – 60 C4F10 1.0014
60 - 160 CF4 1.0005
Momentum
The RICH-1
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
A RICH with aerogel for an hadron machine is a big challengewith respect to experiments like:HERMES (C resolution ~ 9 mrad measured) or
BELLE (RICH upgrade θC resolution ~ 12 mrad expected)
Because of: exposed to high radiation dose
very high multeplicity and background it is mandatory : photoelectron multeplicity as high as possible angular resolution as small as possible
A RICH with aerogel
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RICH-1(aerogel+C4F10)
RICH-2 (CF4)
(Vassily Kandinsky)
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
AEROGEL as Čerenkov radiator
very light, solid quartz-like structure SiO2 low density around 0.15 g/cm3
refractive index n = 1 + 0.21 transparent in the visible region can be hygroscopic or hydrophobic
LHCb choice
T = A e (-C t /4)
A is the long transmittanceand
C is the clarity coefficient
Photon transmission is described by :
where
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
C = 0.0045-0.0065 m4 cm-1
T = 35% for 4 cm tile at 400 nm
Boreskov Institute of Catalysis (Novosibirsk)
AEROGEL
Index of refraction:n = 1.03066n = 1.02982
10 x 10 x 4 cm3 tile (2002)
4 cm
8 cm
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
1 big tile11.6 x 11.6 x 5.5 cm3
successfully produced in 2003 n=1.026 at =400 nm
AEROGEL
C = 0.0057 m4 cm-1
T = 30% for 5 cm at 400 nm
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
AEROGEL as Čerenkov radiator
Tiles20.0 x 20.0 x 5.1 cm3
successfully produced in 2004 n=1.029-1.031 at =400 nm
C = 0.0060 m4 cm-1
T = 30% at 400 nm
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
’sfrom 60Co (ISS)
humidityabsorption
protonsfrom IRRAD-1(CERN-PS)
C and T measurements
after bakingthe tile
neutronsfrom IRRAD-2(CERN-PS)
Aerogel ageing tests
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
Contributions to the angular resolution / :
Č angle resolution
Pixel C/C ~ d/4R (d pixel size, R mirror focal distance)
chromatic dispersion C/C ~ ½ [n/(n-1)] (depends on the
n n(λ) functional behaviour e.g. Sellmeier)
Emission point C/C ~ t sinθC cosθC / L√12 (t rad.thickness, L distance to PD)
Index of refraction C/C ½ [(n-1)/(n-1)]
Tracking C/C depends on precision of tracking
system(+ alignment of optics, optics distortion,…)
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
The RICH of LHCb
Aerogel properties
ČerenkovAngle precision
Photoelectron yield
L [cm]
n
cmax [mrad]
pthres() [GeV/c]
pthres(K) [GeV/c]
5
1.030
242
0.6
2.0
chrom
[mrad]
pixel
emiss [mrad]
track
[mrad]
total [mrad]
N p.e.
2.1
0.6
0.3
1.4
2.6
6.8
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
Measurements of with beams
To measure , separation power, N p.e. use:
Beam from CERN-PS 2 – 10 GeV/c (p/p=1%)
Negative : - Positive : + /protons (50 – 70%)
Photodetectors:
4 pad-HPDs produced at CERN
3 pixel-HPD produced by DEP (final PD of LHCb)
Beam:
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
AEROGEL test beam
with 4 pad-HPD Published in NIMA 519(2004) 493
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
AEROGEL test beam
Aerogel
thickness
with filter (0.3 mm )
C
no filter
C
4 cm 247.1 5.0246.8 3.1
250.0 5.4248.7 4.0
8 cm 245.4 4.8243.7 3.0
246.8 5.8245.0 3.9
4 cm 6.3 ± 0.7 7.4 ± 0.8
9.7 ± 1.011.5 ± 1.2
8 cm 9.4 ± 1.010.1 ± 1.1
12.2± 1.314.7 ±1.6
RESULTS with 4 pad-HPD
C and
N p.e.
DATA and MONTECARLO
Published in NIMA 519(2004) 493
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
Aerogel Mirror
AEROGEL test beam
with 3 pixel-HPD
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
AEROGEL test beam
DATA and MONTECARLO
RESULTS with 3 pixel-HPD
Aerogel
thickness
with filter
C
no filter C
4 cm 237.1 2.8238.1 2.4
238.9 3.3239.1 2.8 N p.e.
9.2 ± 0.8 9.4 ± 1.1
12.8 ± 1.0 14.4 ± 1.6
(preliminary)
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
Measurements of Čerenkov angle resolution
c from test beam data are typically
about 30% larger than expected
Must understand this disagreement(aerogel description in MC, PD behaviour,…???..)
Another possible contribution to C is a dishomogeneity of
n inside an aerogel tile Measure it with 2 methods
Laser beam (lab) electron beam (Č effect) 500 MeV e- at BTF
Č angle resolution in aerogel
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
Measurements performed on a 10×10×4.2 cm3 tile with n=1.031 at L=75.8 cm
n with laser beam
y
y
yyt
nyn
tL
yn
y
n
0
dd
d
~0.35 mradn~0.8∙10-4
=543.5 nm
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
Aerogel
CCD camera
laser
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
n with laser beam
(n-1)/(n-1)~1.3%
n ≈ 4.6∙10-4 ≈ 1.8 mrad
Result for this tile:
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
Aerogel Photographic Analysis by Cherenkov Emission
n with e- beam
500 MeV electron beam at the DANE Beam Test Facility (LNF – Frascati) B&W photographic films as photodetectors
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
n with e- beam Film Mirror
Aerogel
Scan of the aerogel tile:
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
Mirror Aerogel
e- beam
Film
APACHE
Aerogel ring
N2 ring
• Cherenkov ring width dominated by chromaticity n=n(l)• (n-1)/(n-1)=1% → (θC)=1.17 mrad
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
Aerogel ring
N2 ring
Hit-by-hit retracking algorithm to build the distribution of the reconstructed C angleResolution: ~0.3 mrad
n with laser beam
DATA
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
n with laser beam
Result for this tile:
≈ 1.14 mrad (n-1)/(n-1) < 1%
Nitrogen Aerogel
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
Summary and plans
RICH with aerogel is an essential detector component for b-physics program of LHCb (p/K/p separation in the 2-10 GeV range)
Aerogel for a RICH at LHC is a big challenge: needs excellent optical quality to perform an excellent angular resolution and photoelectron yield
Measured angular resolution not yet completely described by MonteCarlo simulation aerogel simulation needs to be improved to understand fully the intrinsic angular resolution homogeneity in n across a tile must be known
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
Bern Museum of Art
exhibition ‘La legerete de l’art’ (31 july – 17 august 2003)
(by Veronica Jenssen)
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
Spare slides
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
The LHCb detector
Forward single-arm spectrometer
RICH 1RICH 2
YZ view
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi
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RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi