28 October 2024 – The latest sea campaigns at both the KM3NeT’s ARCA and ORCA sites have led to major progress in expanding detector installations and improving calibration systems.
The number of detection units in operation in the deep sea has been increased to 57: 33 in ARCA and 24 in ORCA.
Despite bad weather at the ARCA site, the so-called Phase-1 part of the apparatus was completed, while construction of Phase-2 was started with the installation of two new junction boxes, three detection units (exploiting a new data acquisition architecture), and calibration components. The operations also included important maintenance tasks, such as recovering and replacing acoustic beacons. All optical modules of the deployed strings are fully operational. KM3NeT/ARCA now comprises 33 detection units.
At the ORCA site, a 60-hour calm weather window allowed the team to deploy the Calibration Unit (Calibration Base+Instrumentation Unit) and to install an additional detection unit. After these successful installations, node 1 of ORCA is complete and fully functional, an important milestone in the construction of ORCA. The total number of functional detection units at ORCA has now reached 24.
These recent efforts at both sites underscore KM3NeT’s expanding capability in detecting and studying neutrinos from the sea’s depths. The whole Collaboration extends its gratitude to the offshore and onshore teams whose hard work made these successful operations possible.
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.
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.
14 June 2022 – The sea campaign for enlarging the KM3NeT/ARCA submarine telescope which was started on June 2, has been completed today with a full success. As a result, data taking with ARCA has been resumed with 19 detection units in operation!
This represents a major step forward for the collaboration, as this was the first time that a 2-weeks campaign was performed. The scope of the operation in fact was twofold: to upgrade the submarine network, by installing 2 new junction boxes in replacement of the junction box that we had been operating so far, and to install 11 new detection units (DUs). The operation therefore took place in two steps: after the first round of activities for installation of the junction boxes and the first 4 DUs, the ship went back to shore to pick up the remaining set of 7 DUs.
The campaign was performed with Handin Tide, of the FUGRO company, which had already performed the previous sea campaign for KM3NeT/ARCA last year, sailing off from Malta.
All planned activities were performed with full success, including ancillary operations such as the replacement of one autonomous acoustic beacon on the sea floor. A speed record was also established, 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,
The KM3NeT collaboration wishes to thank the Handin Tide crew for their top-level performance, the KM3NeT teams which worked tirelessly offshore and onshore to reach this remarkable success, as well as all teams which work so hard at the almost 30 integration sites of the collaboration to produce the DUs for building the apparatus.
Below is a gallery of pictures from the campaign. A log of the activities while the operation was ongoing is available on our blog.
Deployment of one of the junction boxes installed in the campaign.
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!
The first detection unit installed in this campaign gracefully splashes into the water, to start its journey down to 3,500 m depth.
Fifty years ago, in 1972, the first neutrino conference was held in Hungary, because the organisers were not satisfied with the subdued position of neutrino interactions at the international conferences at that time. Nowadays, the neutrino conference is one of the major conferences in neutrino (astro)particle physics. Neutrino2022 took place in virtual Seoul, 30 May-4 June, 2022 and of course KM3NeT was there to show the results of data taking with the first detection units of ARCA and ORCA.
Aart Heijboer, physics coordinator of KM3NeT, showed the results of one year of data taking with ORCA6 and 100 days with ARCA6. The ‘6’ refers to the number of detection units in a detector used in the data analysis.
The ORCA detector is optimised to measure the oscillation parameters of neutrinos travelling through the Earth. Neutrino oscillation is a quantum mechanical phenomenon in which a neutrino created with a particular flavour – electron, muon or tau neutrino – can be later measured to have changed its flavour. In figure 1 below, it is evident that the data does NOT follow the flat blue horizontal line indicating the absence of neutrino oscillations. In other words, already with only six detection units, the ORCA6 detector ‘sees’ oscillations. In the second figure two oscillation parameters are plotted against each other. Clearly, the contour of ORCA6 is still wider than that of other experiments. More data with more detection units will make it narrower.
Also the ARCA detector, optimised for the search of high energy neutrinos from sources in the Universe, is well underway pushing the limits of the potential to discover sources of neutrinos down towards the expected limits of the full detector.
In the poster sessions KM3NeT physicists presented the details of many analyses being performed with the ARCA and ORCA detectors.
Aart Heijboer concluded at the plenary session that ARCA and ORCA will span eight decades in energy, that there is a rich variety of data analyses going on in the collaboration and that construction of the detectors is ramping up. Promising conclusions.
Very nice to have been invited to share the progress of KM3NeT with the community of neutrino (astro)physicists!
The KM3NeT Collaboration thanks the organisers of Neutrino2022 for an excellent edition of the conference. See you in two years time in Milano.
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.
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!
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.