Light Intensity Measuring System Ver2 NOA-NESTOR Institute, Athens-U and NCMR By A. Belias. (Tasos) KM3NeT, Catania 2008

Light Intensity Measuring System Objective: To measure sedimentation on the KM3NeT glass housings. Concept: Shine light into glass sphere and measure the response of photodiodes inside the glass sphere. LED Beacon (UP) Glass sphere LED Beacon (Down) KM3NeT, Catania 2008

LED Beacon (UP) with Photodiode LED Beacon (Down) with Photodiode KM3NeT, Catania 2008

PHOTODIODES POSITION KM3NeT, Catania 2008

TSLB257 LINEARITY TEST SS KM3NeT, Catania 2008

MASTER CARD KM3NeT, Catania 2008 ANALOG SIGNAL INPUT ANALOG SWITCH (4X1) ATMega8535 Microcontroller 256 Kbit EEPROM MAX232 (RS232 LINE DRIVER) RS232 PC – PORT LED OUTPUT KM3NeT, Catania 2008

MASTERCARD LOGIC PC READ-OUT PROGRAM ANALOG SWITCH ADC CONVERTER EEPROM 512KBit RS232 PORT CONTROL LOGIC ANALOG SESNSORS MASTERCARD LOGIC PC READ-OUT PROGRAM KM3NeT, Catania 2008

5 MONTHS WORTH OF DATA FROM 4 LIMS DEPLOYED AT SITES Nestor 5 5 MONTHS WORTH OF DATA FROM 4 LIMS DEPLOYED AT SITES Nestor 5.2 AND Nestor 4.5 MORE DATA EXPECTED FROM ANOTHER 4 LIMS DEPLOYED AT SITES Nestor 5.2 AND Nestor 4.5 P Scale: 425m/mm in A4 paper, always check A4: Location at 4500m depth A5: Location at 5200m depth P: Pylos M: Methoni M Name, Date, Position Sea bottom, Instr. Depth LIMS201 17.5.2007-21.10.2007 36o 34.483’ N, 21o 08.692’ E 5120m, 3870m LIMS202 17.5.2007-21.10.2007 5120m, 4261m LIMS203 18.5.2007-20.10.2007 36o 32.501’ N, 21o 28.550’ E 4520m, 3564m LIMS204 18.5.2007-20.10.2007 4520m, 4132m A5200 A4500 Grid, points EGA 2 LIMS with AEGAEO at 4520m sea bed, 4132m and 3564m 2 LIMS with AEGAEO at 5120m sea bed, 4261m and 3870m KM3NeT, Catania 2008

Nestor site 5.2 Nestor site 4.5 KM3NeT, Catania 2008

Post deployment tests After recovery the LIMS were placed in dark room for 6 weeks and operated like in the sea. The distribution of the response over 6 weeks is used to quantify Stability as RMS/Mean for each Photodiode. LIMS 201 site Nestor 5.2 LIMS 203 site Nestor 4.5 KM3NeT, Catania 2008

Raw data LIMS 201 (site Nestor 5.2) 10 degrees Data treatment Photodiode Response (mV) The response of each photodiode is divided by the reference photodiode  intensity normalized response After the first 5 days each response is divided by the average response of the first 5 days. Measurement Count KM3NeT, Catania 2008

Normalized Response of Photodiodes Azimuth 0o Azimuth 55o Normalized Response of Photodiodes over 5 months at various azimuth angles at site Nestor 5.2 Azimuth 10o Azimuth -90o Azimuth 20o Azimuth 30o Azimuth -80o KM3NeT, Catania 2008 Azimuth 40o Azimuth -70o

Shadowed neighboring photodiodes A local dip observed in neighboring photodiodes at the same azimuth angle a few cm apart. This dip is not attributed to sedimentation but due to shadowing caused by …(?) KM3NeT, Catania 2008

LIMS 203: 21 PDs LIMS 204: 20 PDs LIMS 201: 20 PDs LIMS 202: 17 PDs KM3NeT, Catania 2008

The average responses of the last 5 days and the last 15 days show no significant difference. KM3NeT, Catania 2008

Conclusions 5 months of LIMS data at Nestor site 5.2 and 4.5 are analyzed More data are expected Local and temporal dips were observed About 15% Light Intensity drop was measured independent of the azimuth angle in 5 months KM3NeT, Catania 2008