GSI meeting 20-21 November 2003 Afanasiev S.V. JINR Dubna

Aerogel Cherenkov counters for CBM

S.V.Afanasiev

VBLHE JINR

Dubna

GSI meeting 20-21 November 2003 Afanasiev S.V. JINR Dubna

The envisaged CBM physics program

• Signatures of chiral symmetry restoration. Probes: Dilepton pairs, D mesons.

• The deconfinement phase transition. Probes: charmonium, strangeness, collective flow.

• The critical point. Probes: event-by-event fluctuations (K/pi ratio)

• Exotic states of matter. Probes: strange and multistrange particles, K/ ratio

GSI meeting 20-21 November 2003 Afanasiev S.V. JINR Dubna

AEROGEL PROPERTIES

• Silica aerogels are a colloidal form of glass. They are solid, very light, transparent and refraction index can be in range 1.1 - 1.002.

Ya.Wang and W.L.Wolf, J.Opt.Soc.Am., Vol.73, No.11 (1983)

GSI meeting 20-21 November 2003 Afanasiev S.V. JINR Dubna

Silica aerogels of low refractive index (n=1.012-1.028) arefound to be radiation-hard at least up to 9.8 Mrad of gamma

ray radiation.

S.K.Sahu et al. NIM A382(1996)

GSI meeting 20-21 November 2003 Afanasiev S.V. JINR Dubna

KEDR aerogel system

• 160 counters• 800 liters of aerogel • refractive index

n=1.05• p and K separation in

the momentum range 0.6 - 1.5 GeV/c.

M.Yu.Barnykov et al., NIM. A 453(2000)

GSI meeting 20-21 November 2003 Afanasiev S.V. JINR Dubna

BELLE ACC

• 1188 counters• 2000 litters of aerogel • refractive index

n=1.03-1.01• p and separation in

the momentum range up to 3.5 GeV/c.

T.Sumiyoshi et al. J.Non-Crys. Sol. 225(1998)369

GSI meeting 20-21 November 2003 Afanasiev S.V. JINR Dubna

PHENIX ACC

• 160 counters• 420 liters of aerogel • refractive index

n=1.012 • K and separation in

the momentum range 0.2 - 2.0 GeV/c.

M.Yu.Barnykov et al., NIM. A 453(2000)

GSI meeting 20-21 November 2003 Afanasiev S.V. JINR Dubna

GSI meeting 20-21 November 2003 Afanasiev S.V. JINR Dubna

5 - 91 - 5 n=1.012Aerogel

17 -5 - 17 n=1.00044RICH

- 50 - 2.5 ~100 psTOF

K-p separation-K separation

0 4 8

0 4 8

0 4 8

0 4 8

0 4 8

0 4 8

The PHENIX ACCtogether with TOF can extend the PID capability upto 10 GeV/c

GSI meeting 20-21 November 2003 Afanasiev S.V. JINR Dubna

JINR ACC test

Secondary particles p of the nuclotron beam

Large TOF base for particle separation

V.F.Peresedov et al. Proc. Of the RNP Int. Workshop,Slovak Rep. Stara Lesna, 2003

GSI meeting 20-21 November 2003 Afanasiev S.V. JINR Dubna

• Clear separation of protons and pions observed.PID by TOF successful

Pions

Protons

+2 GeV/c

Proton

Pion

d

K

Aerogel Signal for protons and pions

GSI meeting 20-21 November 2003 Afanasiev S.V. JINR Dubna

Potentialities of ACC

To see the threshold momenta for the different indices of AEROGEL, the expected number of emitted photon arecalculated through empirical equation

N p.e. = 55 L {1-(1/n2)}

GSI meeting 20-21 November 2003 Afanasiev S.V. JINR Dubna

Particle densityN/100 cm2 along the horizontalaxis (black line) and along thevertical axis (red line) within 10cm wide windows which cross thecenter of the detector

GSI meeting 20-21 November 2003 Afanasiev S.V. JINR Dubna

Qlab. N/cm2 area [m2] cell size [cm2] No. of cells

1o – 5o 510-2 – 210-2 1.2 - - 5o – 10o 210-2 – 610-3 2.6 100 26010o – 15o 610-3 – 210-3 4.8 200 24015o – 25o 210-3 – 510-4 21.5 400 540

Emission angle, charged particle density, detector surface, pad size and number of cells per aerogel layer. The numbers refer to a central Au+Au collision at 25 GeV/u and an occupancy below 5%.

Segmentation of Aerogel

GSI meeting 20-21 November 2003 Afanasiev S.V. JINR Dubna

Aerogel RICH

GSI meeting 20-21 November 2003 Afanasiev S.V. JINR Dubna

CONCLUSIONS

• refractive index 1.1 - 1.005

• radiation-hard• stable• compact size

• refractive index <1.01• physical and chemical

properties

The Aerogel Threshold Cherenkov detector can be used as bridge between TOF and gas RICH detectors

For study