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on our universe
21 December 2020 – Just in time for the winter break, a nice Christmas present was delivered to KM3NeT: the second main cable between the ARCA detector site and the shore station in the lovely village of Porto Palo di Capo Passero at the isle of Sicily, Italy has been installed. It is an important step in the program of upgrading the ARCA seafloor network for the ARCA detector near Sicily, Italy.
13 December 2020 – Have a look at the banner pictures of the KM3NeT home page. During December 2020 and January 2021, we display amazing drawings of the three neutrino-flavours: muon-neutrinos, electron-neutrinos and tau-neutrinos.
The drawings are made by the winners of the KM3NeT contest ‘Draw me a neutrino‘. We invited everyone from young to old to use their imagination and picture a neutrino.
About 500 people from Ecuador, France, Georgia, Greece, India, Italy, Morocco, Netherlands, Switzerland, Russian Federation, Spain and the UK took up the challenge.
The best drawings are now on display in an online exhibition in our Virtual Neutrino Art Centre (hub.link/ZZwzhf7).
You can find the drawings and the names of their authors here.
And a high resolution version of the drawings .
Enjoy!
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.
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.
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.
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.
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.
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.
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.
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.
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.
Deep-sea deployment of the KM3NeT neutrino telescope detection units by self-unrolling
The KM3NeT Collaboration: S. Aiello et al
19 August 2019 – Since this spring, the KM3NeT telescopes are routinely operating with five detection units: four at the ORCA site, one at the ARCA site. First data results have been reported on the international conferences and workshops.
For the ORCA detector, off shore the French Provencal coast, four units were installed and connected to the seabed network. An earlier deployed unit was damaged during inspection and had to be recovered for repair in the labs of the Collaboration. It will be re-deployed in a next sea campaign. Also during the Spring-campaigns, three autonomous acoustic beacons were deployed at the seabed in the vicinity of the ORCA array. They are used for acoustic positioning of the optical modules in the detection units that move with the slowly varying deep sea currents. Sea campaigns for further expansion of the ORCA detector are scheduled after the summer break.
Offshore Sicily at the site of ARCA, after a fix of the seabed network, a detection unit that was deployed three years ago, could be revived and is again taking data since. Currently, the seabed network is being re-designed to allow for the extension of the ARCA detector to more than 200 detector units. The successful though temporary fix of the existing network makes connection of more detection units possible, while waiting for the implementation of the upgraded network.
Differences between ARCA and ORCA
The technology used for the ARCA and ORCA detectors is almost identical, but the difference in volume and height of the detectors and the density of optical modules in the detectors are strikingly different. When finished, the volume of ARCA will be more than 100 times larger then that of ORCA. ARCA will have a volume of about 1 Gton and ORCA ‘only’ about 8 Mton, while the number of optical modules in ARCA will only be twice that of ORCA: about 4000 vs about 2000. Consequently, module density in ORCA will be about five times larger than that in ARCA. How is that achieved? In both detectors, eighteen optical modules are attached to each vertical detection unit. In ARCA, the distance between the lowest and the highest module is about 600. In ORCA this is about 150 m. Also the horizontal spacing between detection units is different: about 90 m in ARCA vs about 20 m in ORCA. Although, ARCA will have only twice the number of detection units, its foot print on the sea bed is much larger that that of ORCA.
The geometrical differences reflect the main scientific purpose for which the detectors will be used. These are also visible in the first character of their names: ARCA stands for ‘Astroparticle Research with Cosmics in the Abyss’. The sparsely instrumented detector is optimised for the detection of high-energy cosmic neutrinos from distant sources in the Universe. ORCA is the acronym for ‘Oscillation Research with Cosmics in the Abyss’. The more densily instrumented detector is optimised to measure lower energy neutrinos, thus providing data for the study of neutrinos oscillating between the three known neutrino flavours. The words ‘in the Abyss’ refer to the locations of the detectors several kilometres deep in the Mediterranean Sea.
28 July 2019 – The bi-annual International Cosmic Ray Conference (ICRC) is one of the most important conferences where astroparticle physicists share their latest results. This year’s conference, the 36th edition, is organised in Madison, Wisconsin, USA, from 24 July – 1 August.
Together, the ANTARES and KM3NeT Collaborations present their results in a highlight talk by Rosa Coniglione and in total 35 talks and posters.
Below a gallery of contributions presented at #icrc2019 on be half of the KM3NeT Collaboration. They comprise technical work, calibration work, data analysis, software developments and predictions of sensitivities of the detectors and theoretical limits. Click on the images for the proceedings.
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).
During November and December 2018, KM3NeT will follow with great interest the sea operations of the finalists of the Shell Ocean Discovery XPRIZE.
The Shell Ocean Discovery XPRIZE is a global competition for innovation in deep sea technology. The challenge for the nine teams in the final competition is to explore and map within 24 hours and with a resolution of at least five metres a large area of the seafloor of the Mediterranean Sea, off-shore the city of Kalamata on the Peleponnese peninsula of Greece.
The selected area is about 500 km2 with depths up to 4000 m. The teams must explore at least 250 km2 of the area with their self-developed autonomous technology. The autonomous devices will be launched from a control centre in Kalamata, where they must be recovered again at the end of their explorative mission.
Fortunately for KM3NeT the selected area includes the future third installation site of KM3NeT. The high-resolution bathymetric map resulting from the measurements of the finalists will be made available to NCSR-Demokritos, one of the founding partners of KM3NeT and the managing institute of the KM3NeT-Gr installation site. The high-resolution map is a fantastic contribution to the implementation of the KM3NeT-Gr site.
The KM3NeT Collaboration wishes all finalists good luck in their challenging endeavour!
31 May 2018 – Each KM3NeT optical sensor module contains 31 photomultiplier tubes. Each KM3NeT detection unit comprises 18 optical modules, i.e. a total of 18 x 31 = 558 photomultipliers. Together the ARCA and ORCA detectors of KM3NeT will comprise a total of 345 detection units, i.e. 345 x 558 =192,510 photomultipliers. So, you can imagine that it is important to very well understand the characteristics of these photomultipliers. Read more
On 22 September 2017, after a two day long sea operation, the first detection unit of the ORCA neutrino telescope came online. This marks an important milestone of the scientific and technological endeavour of the international KM3NeT Collaboration.
26 October 2017 – The KM3NeT Collaboration congratulates Giovanna Ferrara of INFN/LNS and the University of Catania, Italy with the award of the best poster presented at the Conference for Neutrino and Nuclear Physics, CNNP2017, in Catania, Italy.
With the poster ‘First results of the KM3NeT/ARCA detector‘, she presents the preliminary results of detailed studies comparing Monte Carlo predictions and the measurements collected in about a year of data taking with two ARCA detection units. In particular, she shows that the measured dependency of the flux of down going muon particles with the depth in the sea is in agreement with prediction. The results confirm that the ARCA detection units are well calibrated.
Giovanna presented the poster on behalf of the KM3NeT Collaboration. Co-author was Simone Biagi, INFN/LNS, Catania, Italy
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