KM3NeT - Deployment

Three more detection units for KM3NeT/ORCA

1 May 2023 – During a two days sea operation, 27-28 April 2023, three detection units were successfully connected to the ORCA detector of KM3NeT in a record time of just over 24 hours. In addition, an acoustic beacon was recovered for battery replacement. The total number of deployed ORCA units is now 18, as visible in the sonar scan above.

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

Many thanks to the crews offshore as well as to the team who performed the functional tests of the new detection units from the shore station!

ARCA enlarged with 3 new detection units!

14 September 2021 – the ARCA telescope is now enlarged with 3 new detection units.

The procedure for installing a detection unit in ARCA is as follows: firstly the detection unit is lowered from the deck of the ship. When it reaches a low level above the sea floor, the ROV (the submarine vehicle operated from the ship) comes in play: it takes a bridle and helps to guide the detection unit to its target position on the sea bottom; it also rotates it so that the panel for connection of the submarine cable faces the direction of the submarine junction box. Only at that point, the detection unit is lowered on the sea floor. After a quick visual check, the ROV detaches the deployment line. The ROV then picks up the cable which had been previously routed on the sea bottom and which is connected to the junction box on the opposite end, and plugs it to the detection unit. Then the onshore team is asked to perform a first round of test to ensure that the detection unit meets its functional requirements. After that, the ROV opens a release mechanism that lets the deployment vehicle on which the detection unit is furled free to go. The vehicle is buoyant and starts coming up; while doing so, it rotates, leaving the detection unit, which is tied to the anchor on the sea floor, upright – a sort of giant, and reversed yo-yo!

After unfurling, the deployment vehicle is recovered from the ship, to be reused for next deployments.

A final test of the newly installed and unfurled detection unit is then performed to confirm that the detection unit works as expected.

This happened three times today!

An optical spectrum analyzer is used in the shore station for a check of the quality of the communications with the detection unit (almost 100 km away, 3,500 m deep). Each signal (in the form of a peak) in the plot corresponds to one of the optical modules of the detection unit. Believe it: when this plot appears on the screen of the instrument, it is a fantastic reward for all the hard work done in the sea campaign and before!

 

 

 

 

 

 

 

 

 

 

Liveblog about the ongoing sea operation for ARCA

10 September 2021 – In the evening of September 10, five new detection units of KM3NeT, onboard the Handin Tide, will sail from Malta headed to the KM3NeT/ARCA detection site. This site is located 80 km off the coast of Capo Passero, Sicily (Italy). During a 1-week operation, the detection units will be deployed and connected to the ARCA neutrino telescope at 3,500 m depth, adding up to the six already in operation.

The expectation is high for this new, important step in the construction of KM3NeT. Despite the pandemic, the Collaboration has worked hard to keep the high integration speed needed for such an ambitious project. The detection units include components prepared in various European laboratories, and also the integration, testing and installation of the units on their deployment vehicles was a joint effort of many different KM3NeT teams.

As we write this note, the detection units are safely restrained on the deck of Handin Tide, the ship crew and the KM3NeT offshore team are onboard and ready, and the ship is about to set sail. Onshore, everything is ready in the control station in Portopalo di Capo Passero. The motivation, everywhere, is very high.

We look forward to several days packed with hard work and documented with extraordinary images from the sea surface and the deep sea.

Follow the action while it takes place through our social media channels and our ARCA-blog!

 

 

The detection units awaiting deployment on the deck of Handin Tide. Note that the equipment has been already prepared in the order in which it will be moved off the ship: first, two tripods carrying an acoustic beacon each (partially visible in the picture) for the acoustic positioning system, then the reels carrying long cables for connection to the existing submarine network on the sea floor, then the detection units.

Handin Tide left the harbour of Malta

10 September 2021 – the Handin Tide left the port of Malta around 5 p.m. CEST.

The navigation to the KM3NeT site is estimated to take about 10 hours.

The weather forecast is good. The activity on site will start early morning tomorrow.

Keep following the  ARCA-blog.

New paper: Deep-sea deployment of the KM3NeT neutrino telescope detection units by self-unrolling

20 November 2020 – The KM3NeT Collaboration has published a new paper, in which we describe in detail the innovative deployment method for KM3NeT detection units.

No standard moorings

A custom design was necessary, because the KM3NeT mooring – the detection unit -is different from moorings typically used for oceanography.

For instance, in KM3NeT moorings the instrumentation is contained in transparent and thus unprotected glass spheres. That makes them vulnerable during deployment. Moreover, we use a long, thin and soft tube with optical fibres and thin copper wires for data transmission and electrical power for the instruments. That makes the units even more vulnerable.

On top of that, because we use thin Dyneema ropes as strength members in stead of a standard steel cable the mooring is not strong enough to carry the weight of the anchor during deployment.

All this makes it more difficult to deploy the unit without breaking it and we needed a customised deployment method.

Different from other telescopes

Compared to other neutrino telescopes such as ANTARES in the Mediterranean Sea and GVD in Lake Baikal, we designed the KM3NeT detection unit even more slender to minimise the amount of material used for support of the sensor modules. An other – economical – difference is that we have to deploy hundreds of units more for KM3NeT in a period of a few years while keeping the costs for sea operations at a minimum. These are even more reasons for innovation of the deployment method.

The LOM

We developed a custom-made, fast deployment method. Despite the length of the detection unit of several hundreds of metres, we managed to compact it into a small, re-usable spherical launching vehicle instead of deploying it weight down from a surface vessel – the standard method in oceanography. We dubbed the vehicle LOM for Launcher of Optical Modules.

The tric

Once the LOM has reached the seafloor, the innovative tric begins. The buoyant LOM rolls upwards along the Dyneema ropes. While doing so, it spits out the glass spheres with instrumentation attached to the ropes. As a result, while floating to the surface, the LOM leaves the detection unit behind at the seabed, unfurled to its full vertical length. Ready for data taking during many years to come.

Cost effective

The LOM has two economical advantages. First, it does not take a lot in space. Therefore, during a sea operation many LOMs can be stored on deck of a ship. Secondly, we can lower the LOM to the seabed at high speed. As a result, we need less expensive ship time for the installation of the KM3NeT telescope.

Cooperation

As far as we know, the method of compact deployment of moorings with a LOM is unique. The method is the result of close cooperation between engineers and scientists in the KM3NeT Collaboration from both oceanographic and astrophysics institutes. We hope it will inspire oceanographic scientists for the design and deployment of their future moorings.

Details

In the paper, we describe the details of the design of the LOM, the loading with a detection unit, and its underwater self-unrolling. You find the reference below.

LOM in pictures

Pictures below reflect the  process from idea to realisation. First an impression of the initial ideas for deployment by @Marijn van der Meer/Quest. Followed by the technical design of the KM3NeT detection units that must be installed and the design of the LOM launcher vehicle. Finally, photos of the first prototype of the LOM and the final version that is now regularly used for the installation of the detection units of the ARCA and ORCA detectors of the KM3NeT telescope.

 


 

Reference

Deep-sea deployment of the KM3NeT neutrino telescope detection units by self-unrolling

The KM3NeT Collaboration: S. Aiello et al 

2020 JINST 15 P11027

https://doi.org/10.1088/1748-0221/15/11/P11027

ORCA is operational

8 March 2019 – Last month, the KM3NeT team of CPPM, Marseille together with the ship crews successfully installed an ORCA detection unit. It was the first unit connected to the refurbished main electro-optical cable to shore. After a few weeks of technology tests, the unit is given free for physics runs. ORCA is operational!

Unfortunately, after the deployment of one unit, the winch of the heavy lift line failed and three other units could not be deployed. They will be deployed during the next sea campaign.

In the mean time, KM3NeT researchers have taken up the duty of 24/7 shifts overlooking proper functioning of the detection units at both the ORCA and ARCA site. It is a pleasure to watch good quality data streaming to shore.

Pictures below: Four detection units in their deployment mode on deck of RV Castor (left), the package with the detection unit hanging on the heavy weight lift line just above the water surface (middle) and a plot of the signals that a down-going muon particle leaves in the detection unit: height vs the time of the recorded light signals (right).