1. NEMO PHASE II RATE MONITORING AND CORRELATIONS M.G. Pellegriti INFN-LNS KM3 collaboration meeting Roma 12-13 november 2013

2. Outlook  Rate measurement from slow-control  Long Term monitoring (median values over 15 min)  Burst fraction study  Correlation with the oceanographic parameters M.G. Pellegriti INFN-LNS KM3 collaboration meeting

3. PMT Counting rate Rate from slow control The rate is sampled once per second by the front-end electronics Rate is measured in a time window ∆t=10ms No “dead time” effects tt 1s 10 ms M.G. Pellegriti INFN-LNS KM3 collaboration meeting Data are stored in the database when they differ from the previous stored entry by a set threshold value (in the case of the rate this value is 1kHz) Before to proceed with the analysis, it is necessary to recover these «missing» values Rate analysis has been performed by using the code TestSite (PhaseI) download rate files from DataBase correct files from missing values perform the analisys

4. Average rates from slow control 4 Baseline value = 52 kHz Burst >100 kHz = 1.6% Run 412 File 0, file duration ~2h43m Floor 1 PMT1 rate occurrence Mean value Gaussian mean value (fit) Median Burst-fraction (2 options) For a given time window

5. Rate monitoring PMT1 –FLOOR5 26 April – 4 November Baseline (kHz) B. F. >100 kHz (%) Analysis interval  t= 15 min Median values  Baseline values are quite costant for over 6 months  There is a small burst percentage

6. Median and burst fractions Background rates floor panoramic Baseline (kHz) Burst fraction > 100 kHz (%) Horizontally outwards looking PMTs FLOOR8 – PMT1 Time (days) FLOOR7 – PMT1 FLOOR6 – PMT1 FLOOR5 – PMT1 FLOOR4 – PMT1 FLOOR3 – PMT1 FLOOR2 – PMT1 FLOOR1 – PMT1 6

7. M.G. Pellegriti INFN-LNS KM3 collaboration meeting Background rates floor panoramic

8. 20/09/2013 04/10/2013 Preliminary burst fraction analysis 1st method: b.f. higher then a given rate threshold 1048576 sec  12,14 days SAMPLE Analysis interval  t b.f. >100kHz b.f. >200kHz b.f. >1000kHz cut-off 6544 kHz 6549 kHz 6475 kHz rate threshold normalization factor

9. Preliminary burst fraction analysis 2nd method: b.f. in a given rate costant window ∆R=5kHz 1048576 sec  12,14 days CAMPIONE Analysis interval  t normalization factor ∆R=5kHz ∆R=100kHz Renormalized to the 5kHz region  6500 kHz cut-off is more clear  Flat behavior for rate>3000 kHz

10. M.G. Pellegriti INFN-LNS KM3 collaboration meeting  Similar behavior for other PMT’s

11. M.G. Pellegriti INFN-LNS KM3 collaboration meeting Rate periodic behaviors  Daily periodicity is more evident in the burst fraction behavior with respect to the rate median values Inertial currents impact (about 20h period) Burst frations >100 kHz  t=15 min B. F. >100 kHz (%) B. F. >100 kHz (%) B. F. >100 kHz (%)

12. Luminescence vs heading and current Current (cm/s) B. F. >100 kHz (%) Heading (deg) M.G. Pellegriti INFN-LNS KM3 collaboration meeting Inertial currents are evident at the same time in b.f., current intensity and heading variations

13. Current intensity averaged over 15 min Current (cm/s) Time (s) 1/07/2013 4/11/2013

14. Heading-current correlation 5/07/2013 15/07/2013 Current (cm/s) Heading (deg) Time (s) Heading (deg) Current (cm/s) preliminary In this selected time interval C language code that correct for missing values, correlates and averages two parameters from DB (in the case of rate, calculates media Time (s) B. F. >70 kHz (%)

15. Comparison with the CTD measurements Intensity correlations with temperature to be further investigated

16. Conclusions  Long term rate monitoring Very low background rates (about 60kHz) Compatible with a 40K background with few bioluminescence bursts  Burst fraction parametrization under study  Correlation between rates and the other instrumentation outputs (compass, CTD, current-meter) under study M.G. Pellegriti INFN-LNS KM3 collaboration meeting