Umberto Emanuele IFIC (CSIC-UV), Valencia (Spain) Status of Time Calibration System forKM3NeT

Digital Optical Module (DOM) 31 PMTs/DOM - 40 DOM/Line 300 lines (in two separated groups) Digital Optical Module (DOM) 31 PMTs/DOM - 40 DOM/Line 300 lines (in two separated groups)

INTER D.U. Calibration : Laser Beacons - High intensity ( > 20 μJ ) and short pulses (< 1 ns) - Collimated beam -> Diffusion device needed INTER D.U. Calibration : Laser Beacons - High intensity ( > 20 μJ ) and short pulses (< 1 ns) - Collimated beam -> Diffusion device needed

Control Electronic board: Select the intensity of flashing Select the trigger (external or auto-trigger) Provides an external trigger signal Select the frequency of the external trigger Control Electronic board: Select the intensity of flashing Select the trigger (external or auto-trigger) Provides an external trigger signal Select the frequency of the external trigger Pulser: Auto-triggered – External clock not needed Controlled by one (or two) DC Voltage: - LED intensity and frequency non-correlated Pulser: Auto-triggered – External clock not needed Controlled by one (or two) DC Voltage: - LED intensity and frequency non-correlated

Two PVC made pieces: One piece glued to the glass sphere (fixed) The second one screwed (in) to the first one: Holds the LED + Electronics Protect the PMT from the Nano-Beacon Light Possibility of replacement Two PVC made pieces: One piece glued to the glass sphere (fixed) The second one screwed (in) to the first one: Holds the LED + Electronics Protect the PMT from the Nano-Beacon Light Possibility of replacement

A 15°opening angle is sufficient to illuminate OMs above the beacon even in perpendicular arrangement including potential misalignment 3m 40m

Summary for information: InstrumentsNumber needed DOM4 DIM2 Compass6 FFR2 Hydrophone5 Nanobeacon6 NDLM20 Piezo6 Tilt meter6 Temperaturesome autonomous real time Storey DOMs, 2 hydrophones Storey NDLM Storey NDLM Storey DOMs, 2 hydrophones Storey NDLM Storey NDLM Storey NDLM Storey NDLM Storey NDLM Storey NDLM Storey NDLM Storey NDLM+OFM Stoery NDLM Storey NDLM Storey NDLM Storey NDLM Storey NDLM Storey NDLM Storey NDLM Storey NDLM Spacer 280 NDLM Spacer 140 NDLM Base≤2 NDLM Dead weight0 NDLM+Base container

INTER D.U. Calibration : Laser Beacons - High intensity ( > 20 μJ ) and short pulses (< 1 ns) - Collimated beam -> Diffusion device needed INTER D.U. Calibration : Laser Beacons - High intensity ( > 20 μJ ) and short pulses (< 1 ns) - Collimated beam -> Diffusion device needed

 Titanium Container  Anti-Biofouling System  Connector  Slow Control Inteface  Sequence of Commands  Photodiode Signal  LASER  Attenuator

The Laser Beacon source is a diode pumped Q-switched Nd-YAG Teem Photonics laser which produces very short light pulses, ~ 400 ps (FWHM), of high intensity (~20 μJ) and at a wavelength of 532 nm (green). It is housed in a titanium container and can be fixed to numerous seafloor structures (for example secondary junction boxes or detection unit sea floor anchors) The Laser Beacon source is a diode pumped Q-switched Nd-YAG Teem Photonics laser which produces very short light pulses, ~ 400 ps (FWHM), of high intensity (~20 μJ) and at a wavelength of 532 nm (green). It is housed in a titanium container and can be fixed to numerous seafloor structures (for example secondary junction boxes or detection unit sea floor anchors)

GLASS ROD TITANIUM COVER MECHANICA L FIXING DIFFUSE R LASER BEAM -A voltage controlled optical attenuator -A linear polarizer followed by a liquid- crystal retarder and a second linear polarizer. -Since the light from the Laser Beacon is linearly polarized, the attenuation can be achieved with only one linear polarizer. -A voltage controlled optical attenuator -A linear polarizer followed by a liquid- crystal retarder and a second linear polarizer. -Since the light from the Laser Beacon is linearly polarized, the attenuation can be achieved with only one linear polarizer. The laser head has a built-in photodiode that provides the exact time of the laser light emission

TO BE TESTED few lasers would be enough to cover all detector

How will affect the LED light to the OM PMT? It does not damage the PMT The detected light is good enough for giving the temporal reference How will affect the LED light to the OM PMT? It does not damage the PMT The detected light is good enough for giving the temporal reference Measured in air Measured in water

How will affect the LED light to the OM PMT? It does not damage the PMT The detected light is good enough for giving the temporal reference How will affect the LED light to the OM PMT? It does not damage the PMT The detected light is good enough for giving the temporal reference RMS ~ 1 ns Trigger signal w.r.t. OM signal

Codes for the “TimeSlices” data format have to be optimized for the analysis. However first information is obtained from GuiBeacon code.

The feeding voltage of the NB is well correlated wit the OM rates At 280 – 300 meters light is observed Short runs (4 min) in ANTARES trigger setup give good statistic The feeding voltage of the NB is well correlated wit the OM rates At 280 – 300 meters light is observed Short runs (4 min) in ANTARES trigger setup give good statistic It is confirmed? It’s enough? Final analysis on photon and charge of the hits has to be performed Does the higher frequency of KM3NeT strongly reduce the duration of runs (~sec)? It is confirmed? It’s enough? Final analysis on photon and charge of the hits has to be performed Does the higher frequency of KM3NeT strongly reduce the duration of runs (~sec)? The Nanobeacon seems not to saturate/damage the OM

The Nanobeacon prototype was successfully tested on the CEA CLB: 1.- The I 2 C communication worked properly 2.- The internal trigger worked properly 3.- The external trigger provided through the CLB worked properly 4.- The geometry of the Nanobeacon was tested and some minor changes in the position of the holes was agreed. 5.- It was also agreed to change the trigger connector to a coaxial lemo in order to reduce the induced noise. The Nanobeacon prototype was successfully tested on the CEA CLB: 1.- The I 2 C communication worked properly 2.- The internal trigger worked properly 3.- The external trigger provided through the CLB worked properly 4.- The geometry of the Nanobeacon was tested and some minor changes in the position of the holes was agreed. 5.- It was also agreed to change the trigger connector to a coaxial lemo in order to reduce the induced noise.

Some Nanobeacons will be integrated in the Nemo Tower, in order to test: the integration inside of an OM glass sphere the computations of the range of the light as simulated using the specifications of the angular distribution of the light emitted by the LEDs and measurements the communications between the main control board and light emitting sources the reliability of the electronics in general Some Nanobeacons will be integrated in the Nemo Tower, in order to test: the integration inside of an OM glass sphere the computations of the range of the light as simulated using the specifications of the angular distribution of the light emitted by the LEDs and measurements the communications between the main control board and light emitting sources the reliability of the electronics in general

The integration of a Laser Beacon in NEMO Tower is under study. A Laser Beacon was built (with integrated the acoustic system) High pressure tests were performed A stand-alone rechargeable battery system was developed Supports have been built, in order to mount the Laser Beacon on the anchor A real setup test and corresponding validation by NEMO people is needed The integration of a Laser Beacon in NEMO Tower is under study. A Laser Beacon was built (with integrated the acoustic system) High pressure tests were performed A stand-alone rechargeable battery system was developed Supports have been built, in order to mount the Laser Beacon on the anchor A real setup test and corresponding validation by NEMO people is needed

Track reconstruction requires the knowledge of the relative arrival times of the Cherenkov photons at the PMTs and therefore only their time offsets. The time elapsed between the incidence of a photon on the photocathode of the PMT and the time stamping of the associated signal must be determinated. The main goal of the clock system is to provide a common signal to synchronize the readout of the OMs In situ measurement of the time offsets of all the OMs is performed with the Optical Beacon (OB) system (two kind of complementary devices): - LED beacons that emit blue light (470 nm) - Laser beacons that emit green light (532 nm) Track reconstruction requires the knowledge of the relative arrival times of the Cherenkov photons at the PMTs and therefore only their time offsets. The time elapsed between the incidence of a photon on the photocathode of the PMT and the time stamping of the associated signal must be determinated. The main goal of the clock system is to provide a common signal to synchronize the readout of the OMs In situ measurement of the time offsets of all the OMs is performed with the Optical Beacon (OB) system (two kind of complementary devices): - LED beacons that emit blue light (470 nm) - Laser beacons that emit green light (532 nm)

Time residuals should be characterized by mean values well centered at zero 24 storey 2 storey 9 storey 15 storey 21 Line 2 However, there is a linear delay due to the combination of Early photon + Walk effect Deviations from the straight line are used for calibration OM 0OM 1OM 2 storey LOB-ARS (ns)

LED mode l Rise tim e (ns) (n m) FWH M (º) Inten sity (pJ) AVAGO CB AVAGO CB NSPB5 00S AVAGO AB LED candidates have been tested in the laboratory, and four models were preselected. Following the recovery and redeployment of ANTARES line 12, these new models were incorporated in one of the LED optical beacons of the line and tested in situ. The selected LED was the NSPB500S, due to the higher range end the angular distribution. Based on these results, several NanoBeacons will be integrated in the forthcoming deployment of a pre-production KM3NeT DU LED candidates have been tested in the laboratory, and four models were preselected. Following the recovery and redeployment of ANTARES line 12, these new models were incorporated in one of the LED optical beacons of the line and tested in situ. The selected LED was the NSPB500S, due to the higher range end the angular distribution. Based on these results, several NanoBeacons will be integrated in the forthcoming deployment of a pre-production KM3NeT DU