-- DvD - 07 Apr 2006

LHCb Silica Aerogel: the database

In this web page you can find the database of all the LHCb Silica Aerogel tiles delivered, with a list of mechanical and optical properties from the manufacturer and from the measurements done in Milano Bicocca optical Laboratory.

Silica Aerogel 981-1

• Technical description (manufacturer)
  • dimensions: (200.0-0.1) x (200.0-0.3) x (51.3±0.5) mm³
  • horizontal angle accuracy: 90° ± 0.05°
  • vertical angle accuracy: 90° ± 0.10°
  • index of refraction: n = 1.305 (density controlled)
  • density: ρ = 0.1415 g⁄cm³
  • scattering length at 400 nm: L = 47 mm
  • delivered: 25.06.2004
• Optical characterization
  • 31.03.2005
    • C = (0.005385 ± 0.000232) µm⁴⁄cm
    • A = (96.36 ± 4.03)%
    • n = 1.02885 ± 0.00027 - laser λ = 543.50 nm
    • n = 1.02871 ± 0.00027 - laser λ = 632.80 nm
  • 17.11.2005
    • C = (0.005717 ± 0.000054) µm⁴⁄cm
    • A = (98.16 ± 0.06)%
    • n = 1.02871 ± 0.00027 - laser λ = 543.50 nm
  • 14.02.2006
    • n = 1.02874 ± 0.00027 - laser λ = 632.80 nm
    • σ(n-1) ⁄ (n-1) = (1.19 ± 0.01)% - laser λ = 632.80 nm

Silica Aerogel 981-2

• Technical description (manufacturer)
  • dimensions: (200.0−0.1) x (200.0−0.25) x (50.8±0.5) mm³
  • horizontal angle accuracy: 90° ± 0.05°
  • vertical angle accuracy: 90° ± 0.10°
  • index of refraction: n = 1.309 (density controlled)
  • density: ρ = 0.1434 g⁄cm³
  • scattering length at 400 nm: L = 46 mm
  • delivered: 25.06.2004
• Optical characterization
  • Not yet characterized...

Silica Aerogel 985-3

• Technical description (manufacturer)
  • dimensions: (200.0+0.35) x (200.0+0.2) x (51.4±0.7) mm³
  • horizontal angle accuracy: 90° ± 0.05°
  • vertical angle accuracy: 90° ± 0.10°
  • index of refraction: n = 1.316 (density controlled)
  • density: ρ = 0.1466 g⁄cm³
  • scattering length at 400 nm: L = 41 mm
  • delivered: 25.06.2004
• Optical characterization
  • 13.10.2004
    • C = (0.005789 ± 0.000105) µm⁴⁄cm
    • A = (96.03 ± 2.06)%
  • 15.11.2004
    • n = 1.0324 ± 0.0003 - APACHE II method
    • σ(n-1) ⁄ (n-1) = (0.76 ± 0.01)% - APACHE II method
    • T. Bellunato et al., Nucl. Instrum. Methods Phys. Res., A 556, Issue 1 (2006) 140-145
  • 15.03.2006
    • C = (0.006191 ± 0.000111) µm⁴⁄cm
    • A = (96.75 ± 0.13)%
    • σ(n-1) ⁄ (n-1) = (1.05 ± 0.01)% - laser λ = 632.80 nm

Silica Aerogel 65-1

• Technical description (manufacturer)
  • dimensions: 199.8 x 200.0 x 51.4 mm³
  • index of refraction: n = 1.031 (density controlled)
  • density: ρ = 0.145 g⁄cm³
  • scattering length at 400 nm: L = 49 mm
  • delivered: 28.05.2005
• Optical characterization
  • 21.12.2005
    • C = (0.005769 ± 0.000054) µm⁴⁄cm
    • A = (93.34 ± 0.15)%
    • n = 1.02927 ± 0.00027 - laser λ = 543.50 nm
    • n = 1.02962 ± 0.00027 - laser λ = 543.50 nm

Silica Aerogel 89-1

• Technical description (manufacturer)
  • dimensions: 199.7 x 199.6 x 52.1 mm³
  • index of refraction: n = 1.029 (density controlled)
  • density: ρ = 0.135 g⁄cm³
  • scattering length at 400 nm: L = 52 mm
  • delivered: 28.05.2005
• Optical characterization
  • 18.11.2005
    • C = (0.005364 ± 0.000134) µm⁴⁄cm
    • A = (96.67 ± 0.67)%
    • n = 1.02679 ± 0.00025 - laser λ = 543.50 nm

Summary of all the measurements

Serial Number	Clarity	Refractive Index	Homogeneity
981-1	OK	OK	OK
981-2	-	-	-
985-3	OK	OK	OK
65-1	OK	OK	-
89-1	OK	OK	-

The Optical Laboratory Conditions

In this section a few plots about the relative humidity and the temperature of the laboratory where the optical characterization of LHCb silica aerogel is done are listed. The laboratory is located at the Università degli Studi di Milano-Bicocca, Dipartimento di Fisica "G. Occhialini". The monitoring of the lab has started on 2003 and it is stil going on.

Natural Ageing Test

In the following section

C₄F₁₀ Gas Compatibility Test

Since the silica aerogel radiator will be in contact with the C₄F₁₀ gas inside the Gas Enclosure of the RICH 1 detector, a compatibility test has been started in 2005. Ths test is going on.

Varnish Compatibility Test

The gas enclosure of RICH 1 will be painted black. Possible effects due to the interaction of varnish vapour with the aerogel is under study, considering a couple of black paint varnish.