KM3NeT - ARCA sea campaigns

Liveblogs during sea campaigns for ARCA

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.

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.

Time to resume data taking in ARCA

15 September 2021 – after the recovery of two old detection units, already left disconnected after previous sea campaigns – the so-called PPM-DU (Pre-Production Model of Detection Unit), a 3-digital optical module unit used for qualification of the project in the sea as early as in 2014, and one of the first prototype full-size detection units deployed in spring 2016, the sea campaign of ARCA has been completed today.

A lot of good work has been done in this intense week – and we are very grateful for that to the onshore and offshore teams. We also thank all the various institutes which contributed to the construction and preparation to deployment of the detection units – in next entries on this blog we will report on these demanding activities.

As a summary, during this sea campaign:

  • the positioning system has been maintained by installing two acoustic beacons and recovering an exhausted one (these are autonomous devices running on batteries which need to be refurbished in due time)
  • five interlink cables were installed on the sea bottom
  • three new detection units were installed, i.e.: deployed to the sea bottom, connected to the submarine infrastructure, unfurled to their nominal shape (standing for almost 700 m above the sea floor) and proved to work
  • the launcher vehicles of the three installed detection units and the cable trays used for deploying the cables were of course recovered, to be reused for next campaigns

After completing this set of operations, Handin Tide safely sailed back to the port of Malta.

Note that it was decided not to install the remaining two detection units which were onboard the ship, due to a mechanical issue that will be solved. These two detection units have been taken back to shore. After adequate refurbishment, they will be added to those already in preparation. Nothing is lost therefore: they will be included in the next sea campaign.

In the end… it’s time to resume detector operation of ARCA now!

The KM3NeT Collaboration is very grateful to the onshore (in the picture) and offshore teams for their hard work, instrumental for the success of this sea campaign – note that the full operation was performed respecting all applicable rules against COVID-19: our onshore team got so close together only for the time of a… “cheese”!

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!

 

 

 

 

 

 

 

 

 

 


A very busy day, offshore and onshore

13 September 2021 – Still a day packed of activities today!

The status at the moment is that all interlink cables have been layed down on the sea floor and two detection units have been deployed and connected to the junction box. The detection units are still furled on their launcher vehicles; they will be allowed to unfurl tomorrow – since the launcher vehicle has to be recovered from the ship after it reaches the surface, it is better to perform this operation in the daylight.

Pre-unfurling functional tests performed from the onshore control station show that those first two detection units are in good order.

Deployments of the next detection units will continue during the night.

The onshore team in the control station at Portopalo di Capo Passero, Sicily, Italy.

 

 

 

 

 

 

 

 


Good progress, despite adverse sea condition

12 September 2021 – there has been good progress in the operation so far!

The two cable reels are also deployed. The cables for connecting four detection units are already layed on the sea bottom and connected to the junction box. There is only one cable left to install.

While proceeding with these activities, however, the weather conditions worsened. The sky was still sunny, but waves mounted high: “We have a lot of sun here, but we are dancing a lot” commented Daniele Vivolo, who is among the KM3NeT team onboard the ship.

In such situation the risks when putting the equipment in water increase significantly. It was therefore decided to put the operation on hold, waiting for an improvement of the sea state.

In late afternoon, the sea had calmed down significantly, and the operations were resumed.

As we write this post, the first detection unit of the set of five included in this campaign is already in water, travelling into the deep, dark sea, down to 3,500 meters depth. There it will meet the ROV (the submarine vehicle operated from the ship), which will take care of the next steps: to assist in carefully positioning the detection unit on the sea bottom and to connect it to the cable already in place. Have a safe trip!

In the movie: the first detection unit is prepared for deployment.


First day of deployments at the ARCA site

11 September 2021 – operations are proceeding smoothly on Handin Tide.

The two new optical beacons of the positioning system are already placed on the sea bottom – these are autonomous devices not requiring a connection to the sea-floor network.

The deployment of the two reels carrying the long interlink cables for the detection units is proceeding. Installation of these cables requires time, because once a reel has reached the sea bottom, each cable has to be spooled off and layed down on the sea floor. These cables will be later used for connecting each detection unit to the submarine junction box which is already at the site (and connected to the 6 detection units already installed).

Once installation of the cables is completed, the deployment of the detection units can start – tomorrow!

The deck of the Handin Tide at the start of the operations (note that the yellow vehicle on the left is the Remotely Operated Vehicle – ROV – to be used for underwater operations).