1. Optical Characterization and Performances of Aerogel Radiator L.Barion, G.Battaglia, M. Contalbrigo, P. Lenisa, A.Movsisyan, L. Pappalardo, M. Turisini INFN Ferrara CLAS12 RICH internal review Frascati: June 24

2. 2 Introduction Aram Movsisyan, June 24 2015 Single photon angular resolution: Direct light (mrad) Reflected light (mrad) Emission Point1.7 Readout Accuracy2.11.0 Mirror System-<1 Chromatic Aberration3.02.5 Aerogel Optical Prop.~1~2 Required criteria for the aerogel tiles: Scattering Length> 43 mm Absorption> 95% Density0.224< <0.244 g/cm 3 Planarity<1.5 mm

3. 3 Aerogel Characteristics in the Air Aram Movsisyan, June 24 2015 Monitoring the time dependence of the weight of aerogel tile in environment of non-zero humidity. Monitoring the time dependence of the transmission of aerogel tile in environment of non-zero humidity.

4. 4 Aerogel Characteristics in the Air Aram Movsisyan, June 24 2015

5. 5 Aerogel Characteristics in the Dry Box Aram Movsisyan, June 24 2015 Monitoring the recovery of the weight of aerogel tile in dry box.

6. 6 Measurements with Spectrophotometer Aram Movsisyan, June 24 2015

7. 7 Aerogel Surface Measurement Aram Movsisyan, June 24 2015 30 mm Screen Laser Beam normal in lab. frame [10º-50º] R Surface reflection CCD Camera Aerogel Description of the setup

8. 8 Aerogel Surface Measurement Aram Movsisyan, June 24 2015 30 mm Screen Laser Beam normal in lab. frame [10º-50º] R Surface reflection CCD Camera Aerogel Description of the setup............. Scan of aerogel surface CCD camera [ThorLabs DCU 224c] Sensitive area [ 5.95 - 4.76 mm]. Sensitive area [ 5.95 - 4.76 mm]. Resolution [ 1280 - 1024 pixels]. Resolution [ 1280 - 1024 pixels]. Pixel size 4.65 m. Pixel size 4.65 m.

9. 9 Aerogel Surface Measurement Aram Movsisyan, June 24 2015 30 mm Screen Laser Beam normal in lab. frame [10º-50º] R Surface reflection CCD Camera Aerogel Description of the setup............. Scan of aerogel surface CCD camera [ThorLabs DCU 224c] Sensitive area [ 5.95 - 4.76 mm]. Sensitive area [ 5.95 - 4.76 mm]. Resolution [ 1280 - 1024 pixels]. Resolution [ 1280 - 1024 pixels]. Pixel size 4.65 m. Pixel size 4.65 m. Distributions of X & Y positions of the spot

10. 10 Aerogel Surface Measurement Aram Movsisyan, June 24 2015 30 mm Screen Laser Beam normal in lab. frame [10º-50º] R Surface reflection CCD Camera Aerogel Description of the setup [rad]

11. 11 Aerogel Surface Measurement Aram Movsisyan, June 24 2015 [mm]

12. 12 Aerogel Surface Measurement Aram Movsisyan, June 24 2015 Comparison of current measurements with the results provided by producer [mm]

13. 13 Light Dispersion Measurement Aram Movsisyan, June 24 2015 30 mm Mirror Screen Laser Beam normal in lab. frame symmetric reflection meas. reflection R ΔxΔx CCD Camera Description of the setup [10º-50º] Setup reflects realistic experimental conditions. Setup reflects realistic experimental conditions. Reference measurement taken without aerogel. Reference measurement taken without aerogel. Deviation of the laser spot position around the reference point provides a measure of light dispersion. Deviation of the laser spot position around the reference point provides a measure of light dispersion.

14. 14 Light Dispersion Measurement Aram Movsisyan, June 24 2015 Impact of the surface shape on the light dispersion: Contribution of the surface shape on light dispersion can be approximated: Refraction from the ideal surface: Refraction from the surface with certain gradient:

15. 15 Aram Movsisyan, June 24 2015 Light Dispersion Measurement Measurement at 10˚: light dispersion after double passage through double passage through the aerogel light dispersion after reflection from the aerogel surface

16. 16 Angular Dependence of Light Dispersion Aram Movsisyan, June 24 2015 Simulated light dispersion as a function of incident angle: Current measurement of light dispersion as a function of incident angle:

17. 17 Forward Scattering Aram Movsisyan, June 24 2015 30 mm CCD Camera Laser Beam R Scattering of the light in the medium due to the anisotropy of the dielectric properties caused by the microscopic fluctuations. Scattering of the light in the medium due to the anisotropy of the dielectric properties caused by the microscopic fluctuations. Description of the setup Examples of X & Y profiles of the spot [mm] Analysis steps. Analysis steps. Reference measurement taken without aerogel. Reference measurement taken without aerogel. Extract angular dependence of the intensity after passage trough the aerogel. Extract angular dependence of the intensity after passage trough the aerogel. Extract an increase of the width of laser beam compared with reference measurement. Extract an increase of the width of laser beam compared with reference measurement.

18. 18 Forward Scattering Aram Movsisyan, June 24 2015 Angular dependence of the measured intensity: Differential of the measured intensity:

19. 19 Conclusion Aram Movsisyan, June 24 2015 Tools for measurements and monitoring of the aerogel characteristics are operational and have stable performance. Mismatch between the measurements done in Novosibirsk and in Ferrara was observed, indicating the necessity to bake the aerogel before delivery. Corresponding agreement was obtained with the producer. Ongoing measurements attempt to optimize the specifications vs production rate. Currently 25% of the main production is ready for delivery.