a rich with aerogel for a hadron machine on behalf of the lhcb rich group some results and...

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

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

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

RICH-1(aerogel+C4F10)

RICH-2 (CF4)

(Vassily Kandinsky)

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

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

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

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

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

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,…)

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

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:

RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi

AEROGEL test beam

with 4 pad-HPD Published in NIMA 519(2004) 493

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

RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi

Aerogel Mirror

AEROGEL test beam

with 3 pixel-HPD

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)

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

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

RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi

Aerogel

CCD camera

laser

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:

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

RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi

n with e- beam Film Mirror

Aerogel

Scan of the aerogel tile:

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

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

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

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

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)

RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi

Spare slides

RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi

The LHCb detector

Forward single-arm spectrometer

RICH 1RICH 2

YZ view

RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi

RICH2004 30 Nov. – 5 Dec. 2004 Clara Matteuzzi