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”!