Amsterdam 29 March 2011

1. KM3NeT Optical Calibration Laser Beacon and Nanobeacon Status Fernando Urbano IFIC (CSIC – Universidad de Valencia) Amsterdam 29 March 2011

2. KM3NeT TIME CALIBRATION PROPOSAL (Reminder) • Decoupling within the same D.U. (intra- D.U.) and between D.U. (inter-D.U.) calibration systems • INTRA D.U. Calibration: Two Nanobeacon per DOM. Looking upwards and downwards • Less expensive and high redundancy • Either external or internal trigger • Frequency of several kHz depending on the DAQ system (300 Hz @ ANTARES) • Avoid cumbersome synchronization process, only one LED per Nanobeacon

3. KM3NeT TIME CALIBRATION PROPOSAL (Reminder) • Decoupling within the same D.U. (intra- D.U.) and between D.U. (inter-D.U.) calibration systems • INTRA D.U. Calibration: Two Nanobeacon per DOM. Looking upwards and downwards • Less expensive and high redundancy • Either external or internal trigger • Frequency of several kHz depending on the DAQ system (300 Hz @ ANTARES) • Avoid cumbersome synchronization process, only one LED per Nanobeacon • INTER D.U. Calibration: Laser Beacons @ 532 nm • Higher in intensity and shorter pulses < 1 ns • No synchronization needed • More expensive but less redundancy required • Tunable by Liquid Crystal Optical attenuator • Collimated beam -> Diffusion device needed

4. NANOBEACON STATUS - ELECTRONICS • Two electronic components: • Pulser:It contains and flashes the LED with the control boards commands • Control Board: • Selectsthe LED Light intensity • Selects the trigger (external or internally generated in the control board) • Provides a trigger signal to the pulser • Selects the frequency of the generated trigger. To be fixeddepends on the DAQ. 10 KHz possible? • Several improvements performed: • The Nanobeacon Control Board can work either at 5 V or 3.3 V • The external trigger signal now is LVDS • The trigger selection, between internal or external trigger, has been improved and the jitter has been substantially reduced (From µs to ns)

5. NANOBEACON STATUS - ELECTRONICS INPUTS OUTPUTS

6. NANOBEACON STATUS - PPM The Nanobeacon will be included in 4 of the DOM allocated in the 2 active storeys of the PPM (Storey 20 and 19). Nanobeacons of storey 20 will look horizontally to the other DOM in the same storey.

7. NANOBEACON – PPM OPENING ANGLE A 15°opening angle is sufficient to illuminate OMs above the beacon even in perpendicular arrangement including potential misalignment 40m 3 m

8. NANOBEACON STATUS - PPM Regarding the Nanobeacons it would be better to have the second active storey in position 17 instead of 19. If possible this option is recommended by us. BEST OPTION FOR NANOBEACON TEST

9. NANOBEACON – PPM PLANNING

10. NANOBEACON STATUS – NEMO TOWER PHASE 2 • The installation of some Nanobeacons on the NEMO Tower to be deployed this summer at Capo Pasero has been approved by the NEMO Technical board. • WorktoadapttheNanobeacon, mechanically and electronically, totheNemoExperiment are underway. • The final number of Nanobeaconisnotdecidedyet.

11. NANOBEACON STATUS – NEMO TOWER PHASE 2 Nanobeacon mechanics (ONLY FOR NEMO): Two pieces in PVC: 1.- Glued to the glass sphere (fixed) 2.- Screwed (in) to the first one: Holds the LED + Electronics Protects the PMT from the Nano-Beacon light Easy to be replaced

12. NANOBEACON STATUS – NEMO TOWER PHASE 2 MECHANICAL SUPPORT PULSER CONTROL BOARD

13. LASER BEACON – COMPONENTS • Titanium Container • Attenuator • LASER • Anti-Biofuling System • Slow Control Inteface • Photodiode Signal Connector

14. LASER BEACON -CONTAINER Cylinder of 542 mm long, with a diameter of 142 mm that holds the laser, the liquid crystal optical attenuatorand the electronics. It is made of Titanium grade 5 (Ti6Al4V)

15. LASER BEACON – NEMO PHASE 2 • One laser is going to be deployed in NEMO PHASE 2 • A complete different electronics has been developed as: • Only RS-232 connection available • There is a power limitation: 12 V @ 200 mA which has been overcome with a battery system • Read-out of the internal photodiode removed for simplicity • The laser is a STG-03E-1S0 from Teemphotonics which emits light with a wavelength of 532 nm after frequency doubling of the original Nd-YAG wavelength of 1064 nm.

16. LASER BEACON – KM3NeT • A more powerful laser is under study. Selected model PNG-B02010 • A different container will be probably needed • Completelly different electronics from the Nemo one. • Photodiode signal read-out really important • Also research with blue lasers is ongoing.

17. Conclusions • INTRA DU Calibration. Nanobeacon • 4 Nanobeacons on 2 Active Storeys of the PPM • Several Nanobeacons on the NEMO Phase 2 • Last design: supply, LVDS trigger and jitter signal improved • Final frequency range depens on the DAQ • INTER DU Calibration. Laser beacon • Laser Beacon ready to be integrated in NEMO Phase 2 • Looking for a more powerful green and blue lasers for KM3NeT • New design of electronics and Titanium container will be needed

18. TIME CALIBRATION PROPOSAL THANKS FOR YOUR ATTENTION!

19. KM3NeT LASER STUDIES - SPECTRUM Measurements carried out with the Spectrometer Ocean Optics HR4000 Both Lasers of Teemphotonics, present the main spectrum at 532 nm as expected

20. KM3NeT LASER STUDIES - SPECTRUM • Measurements of an ALPHALAS, GmbH blue laser • Present 3 peaks @ 485 nm, 808 nm and 945 nm • The undesired emission peaks must be filtered out:

21. LASER STABILITY The lasers @ 532 nm are quite stable The laser @ 485 nm is not so stable More tests are under progress to determine is the instability is due to the 485 nm emission or to the infrared peaks @ 808 nm and 945 nm