KM3NeT - Blog

KM3NeT blog posts

New publication: The KM3NeT broadcast optical system

1 February 2023 – Via a long-distance electro-optical network the more than 6000 optical modules of KM3NeT in the deep sea are provided with a point-to-point connection to the control station on shore. The optical layer is presented in full details:

S. Aiello et al. 2023 JINST 18 T02001 DOI 10.1088/1748-0221/18/02/T02001

Abstract:

The optical data transport system of the KM3NeT neutrino telescope at the bottom of the Mediterranean Sea will provide more than 6000 optical modules in the detector arrays with a point-to-point optical connection to the control stations onshore. The ARCA and ORCA detectors of KM3NeT are being installed at a depth of about 3500 m and 2500 m, respectively and their distance to the control stations is about 100 kilometers and 40 kilometers. In particular, the two detectors are optimised for the detection of cosmic neutrinos with energies above about 1 TeV (ARCA) and for the detection of atmospheric neutrinos with energies in the range 1 GeV–1 TeV (ORCA). The expected maximum data rate is 200 Mbps per optical module. The implemented optical data transport system matches the layouts of the networks of electro-optical cables and junction boxes in the deep sea. For efficient use of the fibres in the system the technology of Dense Wavelength Division Multiplexing is applied. The performance of the optical system in terms of measured bit error rates, optical budget are presented. The next steps in the implementation of the system are also discussed.

The architecture of the KM3NeT broadcast optical system
The architecture of the optical layer connecting the ARCA detector of KM3NeT in the deep sea with the control station on shore.

ORCA enlarged with 4 new detection units

12 December 2022 – During a sea campaign performed last week, ORCA has been enlarged by means of 4 new detection units. This brings the total of detection units deployed in ORCA to 15, comprising more than 7,500 photomultipliers.

The operation was performed with the Castor ship of Foselev, for deployment of the detection units, and with the Janus II of SAAS (formerly Comex), equipped with a deep-sea remotely operated vehicle, for submarine operations.

The KM3NeT Collaboration congratulates the crews on the two ships, the team who performed careful checks from the shore station during the campaign, and all the teams who contributed to the construction of the detection units, for the success of the operation.

One of the ORCA detection units starting its journey from the Castor to the sea floor, 2500 m below. In the background is the Janus II.

 

Sonar map of ORCA, showing 14 detection units (the 15th one is beyond the boundary of the map). The 4 in the bottom part of the picture are the new ones installed.

Major upgrade of ARCA’s seafloor network

22 November 2022 – After 4 years of  activities carried out by the Italian funding agency INFN and Alcatel Submarine Networks, part of Nokia, the new subsea network for KM3NeT ARCA, funded under the Idmar regional project in Italy, is now complete.

The new system comprises a 100 km long electro-optical cable, equipped with 48 optical fibres for detector control and data communication and two electrical conductors for power distribution, connected to the shore station control and power feeding equipment, that can deliver up to 80 kW offshore. The cable is bifurcated in order to serve the two building blocks foreseen in ARCA.

During a 10 days long sea operation, which ended on November 17th, a cable termination frame (CTF) was installed on the northern branch of the cable. To this purpose the end of the cable, which was deployed already in 2020, was recovered from the sea floor and connected to the CTF onboard the deployment ship – the Ile d’Ouessant of Alcatel Submarine Networks. Then the CTF was carefully deployed to the target position on the sea floor. Extensive tests were done before and after the deployment to ensure its nominal behaviour.

The CTF is a large-size, 12-ton component which is equipped with four medium voltage converters and a total of 16 electrical and optical subsea connectors for connecting a set of submarine junction boxes to which the detection units will be in turn connected.

With this installation the connectivity and power transmission capabilities of the network have been increased by a factor four compared to the first part of the network, used to run the set of junction boxes and the first 30 detection units of ARCA Phase 1. This will allow for the completion of the construction of the first building block of ARCA and prepares the field for the installation of a second CTF on the other branch of the cable for the second building block.

The CTF at the end of the integration.
CTF onboard Ile d’Ouessant.
Overboarding of the CTF.

New sea campaigns at both KM3NeT sites

12 September 2022 – New sea campaigns were performed last week for both ARCA and ORCA. The purpose was to prepare the field for next installation phases of the detectors as well as to deploy new detection units and acoustic beacons – the latter are autonomous calibration devices which run on batteries and need to be replaced after some time.

The number of detection units in operation in the deep sea has been increased to 32 (comprising almost 18,000 photomultipliers): 21 in ARCA and 11 in ORCA.

After installation of a third junction box at the ARCA site, this site is now fully equipped for hosting the so-called Phase-1 of the project, comprising the first 31 detection units and the calibration unit of the apparatus.

The ARCA sea campaign represented the final action of the IDMAR project in Italy, supported by Regione Sicilia.

These operations were made possible by the dedication of hardware teams and the onshore and offshore teams at the two sites – the Collaboration is very grateful to them.

The newly added junction box of ARCA on the sea bottom.
Detection unit deployment at the ORCA site.

New publication: The KM3NeT multi-PMT optical module

27 July 2022 – Long-term operation in the deep sea puts challenging requirements on detectors. A review of the design and construction of the KM3NeT optical module has been published:

S. Aiello et al. 2022 JINST 17 P07038 DOI 10.1088/1748-0221/17/07/P07038

Abstract:

The optical module of the KM3NeT neutrino telescope is an innovative multi-faceted large area photodetection module. It contains 31 three-inch photomultiplier tubes in a single 0.44 m diameter pressure-resistant glass sphere. The module is a sensory device also comprising calibration instruments and electronics for power, readout and data acquisition. It is capped with a breakout-box with electronics for connection to an electro-optical cable for power and long-distance communication to the onshore control station. The design of the module was qualified for the first time in the deep sea in 2013. Since then, the technology has been further improved to meet requirements of scalability, cost-effectiveness and high reliability. The module features a sub-nanosecond timing accuracy and a dynamic range allowing the measurement of a single photon up to a cascade of thousands of photons, suited for the measurement of the Cherenkov radiation induced in water by secondary particles from interactions of neutrinos with energies in the range of GeV to PeV. A distributed production model has been implemented for the delivery of more than 6000 modules in the coming few years with an average production rate of more than 100 modules per month. In this paper a review is presented of the design of the multi-PMT KM3NeT optical module with a proven effective background suppression and signal recognition and sensitivity to the incoming direction of photons.

Rendering of a KM3NeT DOM
Rendering of a KM3NeT optical module with bollards attached to mechanically supporting cables in the deep-sea. In the cut out, the interior of the module with photomultipliers and electronics is visible. The black break-out box connects to the electro-optical network for electrical power and long-distance data communication toward the control station on shore.

KM3NeT at ICHEP 2022

For the first time, the International Conference on High Energy Physics was organized in Italy. This major conference in our field was the opportunity for KM3NeT and ANTARES members to present the latest updates from our experiments.

Some of our collaborators were also involved in the organization of the conference being held in Bologna.

The various talks and posters are available on the website of the conference:

Group picture of some of the KM3NeT members attending ICHEP (showing how seriously they considered this great opportunity!)

Rebecca Gozzini summarizing the potential of ANTARES and KM3NeT for indirect dark matter searches.

Valentin Pestel describing the KM3NeT sensor technology that allows the collaboration to carry out oscillation neutrino studies.

An overview of the recent results of ARCA presented by Piotr Kalczyński.

Victor Carretero presenting his work on the search for new physics in the neutrino sector.

Maurizio Spurio getting ready to present the latest highlights from ANTARES.


Isabel Goos before presenting the potential of KM3NeT for supernova neutrino searches.

Gwenhael W De Wasseige talking about KM3NeT during her plenary talk on multi-messenger physics.

Sea campaign for ARCA concluded: welcome, KM3NeT/ARCA19!

14 June 2022 – The sea campaign for enlarging the KM3NeT/ARCA submarine telescope has been completed with full success!

During the last few days, all detection units loaded on Handin Tide for the second phase of the operation were carefully installed on the sea bottom. This was achieved at a record-breaking speed, with 7 detection units installed, connected and unfurled in less than 48 hours!

As a result of the campaign, the size of ARCA has more than doubled. It now comprises 19 detection units in operation, equipped with more than 10,000 photomultipliers,

We thank the teams which worked tirelessly offshore and onshore to reach this remarkable success. And we can’t forget that this was made possible by the hard work ongoing in the almost 30 integration sites of the Collaboration.

The activities at sea went around the clock during the campaign.

The shore station during the campaign – more than 30 people were involved in the onshore team for this campaign.

Activities at sea being resumed at the ARCA site

11 June 2022 – Due to the adverse weather conditions of the last days, the schedule of the sea campaign had to be redefined.

Here is the updated plan:

  • the ship left Malta this afternoon, to be back at the ARCA site tonight
  • the deep sea activities will be started already during the night
  • DU deployments will be started tomorrow
  • end of the operation is foreseen for early next week

Good luck to our offshore and onshore teams!

Empty LOMs (the launcher vehicles used for deployment and unfurling of the detection units) on the dock in the Malta port after the first phase of the sea campaign.
The deck of the Handin Tide loaded with detection units and their cable trays for the second phase of the campaign.
The Handin Tide leaving the port of Malta this afternoon.

Intermediate outcome of the ARCA campaign: 2 junction boxes and 12 detection units operational

6 June 2022 – The first round of activities of the ongoing sea campaign at ARCA has been completed.

In a summary, in the past week-end:

  • we installed two submarine junction boxes, one of which in replacement of the temporary junction box that we have used so far
  • the temporary junction box has been safely recovered
  • we moved all connections of the detection units already installed on the sea bed onto the new junction boxes
  • we installed 4 new detection units (where, by installation, one should understand that each detection unit was lowered to the bottom of the sea, carefully placed on the sea bottom, connected to the junction box and unfurled to reach its nominal, upright configuration)

Each of the steps above comprised dedicated tests, requiring careful coordination of the activities of the onshore and offshore teams.

And… the campaign is not yet finished! The ship is now heading back to Malta to load an additional set of detection units to install.

Stay tuned, as there will be more to report in the next days!

Preparation to deployment of the first detection unit to be installed during the campaign. On the right of it is one of the junction boxes awaiting installation, on the left the temporary junction box recovered from the sea floor.

 

The first detection unit installed in this campaign gracefully splashes into the water, to start its journey down to 3,500 m depth.

 

New sea operation started at ARCA

3 June 2022 – A new sea operation was started yesterday aiming at a significant enlargement of the ARCA neutrino telescope.

This is a major step forward for the Collaboration, as this is the first time ever that we launch a 2-weeks campaign. The scope of the operation in fact is twofold: upgrade the submarine network, by installing 2 brand-new junction boxes in replacement of the junction box that we have been operating so far, and to install new detection units (DUs). The operation will therefore take place in two steps: after the first round of activities for installation of the junction boxes and the first 4 DUs, the ship will come back to shore to pick up an additional set of DUs.

Handin Tide, which has already performed the previous sea campaign for KM3NeT ARCA last year, is the ship which will conduct this operation.

The ship left the port of Malta yesterday afternoon.

Remain connected, as we will be posting news about the operation while the action goes on – on our blog and on our social channels.

A set of KM3NeT DUs ready for deployment in the port of Malta earlier this week.

 

Loading of a KM3NeT DU onto the Handin Tide.

The Handin Tide sailing off from Malta in the afternoon of yesterday, June 2.