1. Inserire curva di attenuation length normale Warning do not trust the error Warning Preliminary results 0.8 mm 250 ppm part 1 - measure 2 Fit from 0 to 17 m 3 August 2006 Preliminary  1 = 7620 +/- 400 mm  2 = 3580 +/- 1000 mm The first measurement on this fiber, made on half the points only : Fit from 0 to 17 m 0.8 mm 250 ppm part 1 - measure # 2 18 August 2006 why to fit from 0 till 17 m only ? The data were fitted to the functional form:

2. Fit from 0 to 9 m Fit from 9 to 24 m 0.7 mm 150 ppm part 1 - measure 01 9 August 2006 18 August 2006

3. 1 ( m ) 0.60.70.8 150 8.79 ± 0.10 ± ??? 8.61 ± 0.08 ± ??? 200 250 8.44 ± 0.06 ± ??? 300 8.46 ± 0.11 ± ??? 2 (m ) 0.60.70.8 150 3.54 ± 0.14 ± ???3.19 ± 0.14 ± ??? 200 250 2.58 ± 0.1+/-??? 300 2.66 ± 0.06 ± ??? Preliminary results 18 August 2006

4. Riproducibility on 1 meter of fiber measurement 18 August 2006 3.13 3.44 3.28 3.19 3.26 Avg 0.13std dev 0,13 / 3,26 = 4,0% Study the systematics Estimate the measurement reproducibility To be further investigated: Systematic in the measurement increase of the length of the motorized bench to 1.5 m Upgrade of the apparatus: more focussed and better shielded led spot

5. N. Moggi, S. Zucchelli and A. Barbieri ISOF- CNR Bologna Measurements performed at ISOF CNR-Bologna on a 25 meter 0.8 mm 200 ppm ( reference) fiber. Spectral response as function of distance along the fiber 18 August 2006 The light source was a Helium- Cadmium Kimmon S3522 laser 442 nm continous emission laser, 37 mW, beam spot diameter ~0.94 mm, laser stability ~ +/- 2%. The fiber was coupled to an Avantes - AVA Spec 2048 spectrometer.

6. 18 August 2006 Fit to a single exponential: inverse of attenuation length as function of wavelenght

8. Plan for the immediate future: Next: Pseudocumene from Borexino shall arrive in Bologna by end of August. Start test of fiber survival in pseudocumene Start aging test Complete on all the fibers the measurements of attenuation length. 0.6 mm fiber is next. 0.6 150 ppm should be under way right now. Measure relative light yeald Measure spectral response. Test of fiber response as function of bending radius Results foreseen for next Nova Collaboration meeting in November 06 18 August 2006