present: A. Kiselev, M. Contalbrigo, S. Dalla Torre, M. Posik, B. Surrow, B. Zihlmann
goal: assess status of the Aerogel R&D efforts and discuss documentation of test procedures and results
At Temple (Matt):
- measured transmittance at 3 fixed wave length with 3 different LED at 430nm, 530nm and 625nm
- measured index of refraction with prism method in all 4 corners, result is average of 4 measurement.
- compare results with BNL and Japan (Manufacturer)
- one Test tile measured 2 more to go in March
- plans for upgrade of the system with additional LEDs in other frequencies and individual power supplies for the different LEDs.
questions:
- how does the manufacturer measure the transmittance?
- how big is the effect of deflected light on the surfaces vs. direct undisturbed transmission?
- what is the LED spot size of the transmission test?
- the spot size incident on the face of the aerogel is about 7mm diameter. The spot size grows to about 16mm diameter as it enters the integrating sphere.
- propose to use integrating sphere to be positioned in front of sample looking at "back scattering light" not to be done for all samples but for some.
- what is the acceptable level of variation in the index of refraction?
- accuracy (statistical) of n i< 0.002 (systematic uncertainty not know at this point)
- what is the acceptable accuracy in the transmission measurement?
Meeting got cut short because of overlap with PID cross cutting meeting. Need to continue this meeting at some other time (possible in two weeks)
Action items:
- Ask manufacturer if the tiles were water cut in any way?
- How is the quoted number for n determined by the manufacturer?
- Answer from Manufacturer:
- They measured directly at the four corners of the tiles using a laser with a 405 nm wavelength (then averaged tile by tile).
- The tiles have not been cut at all. The tile size was 110 mm, and the mold size was 116 mm. A shrinkage of 6 mm occurred during the production process.
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