KM3NeT - Recent News

Latest news items.

Data taking with KM3NeT

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.

 

KM3NeT-ARCA and ORCA
KM3NeT: Comparison of the physical size of the ARCA and ORCA detectors.

 


KM3NeT at #icrc2019

 

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.

 

 

 


 

 

 

 

 

 

 

 

 

 

 

 

 

 


For the experts:

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.

Talks:

Posters:

 


KM3NeT is growing

28 May 2019 – The KM3NeT/ORCA detector is now running with two detection units. The two units were installed during a recent deployment campaign. The KM3NeT researchers are eagerly analysing the recorded signals, while preparing the deployment of a further set of detection units.

For deployment, the units are packed in a compact configuration and lowered the 2.5 km from the deployment vessel to the sea floor. Using an acoustic system based on a set of acoustic transponders anchored on the sea floor, they are positioned to within 1 m of their nominal position. After connection to the sea floor network, a ROV triggers the detection unit to unfurl to its vertical position. For ORCA, the units are horizontally spaced by 20-23 m from each other. Vertically, the optical light sensors are attached to the unit with a spacing of about 9 m.

Height versus the time of the recorded light signals seen in both detection units for a down-going muon particle created in the atmosphere.

 

 

 

 

 

 

 

Sea science instrumentation module

In addition to the two units for neutrino research, also a sea science instrumentation module was installed. This unit, built by the technical division of INSU for EMSO-France, hosts sensors that provide real-time monitoring of a variety of environmental parameters including temperature, pressure, conductivity, oxygen, turbidity and sea current. The module also incorporates an acoustic modem that, in the near future, will communicate acoustically with an autonomous ‘Albatross’ line; an instrumentation line dedicated to the oceanographic studies of the full 2.5 km water column.

The instrumentation module.
Time series of the pressure variations on the sea floor due to the tidal action.

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).


ARCA is alive again

29 January 2019 – KM3NeT had a good start of 2019. Data taking of the first detection unit of ARCA could be resumed, after the operation of the unit had to be stopped in 2017, because of a fault in the seafloor cable network. Thanks to a fix of the network early January, the ARCA unit is operational again and data taking runs smoothly since. The first events could be reconstructed immediately after switch-on. This first ARCA detection unit was installed on 3 December 2015 and has been operational until data-taking had to be halted in 2017. It remained unattended in the deep sea for more than a year and celebrated last December its 3rd anniversary at its location at a depth of 3400 m without any ceremony. KM3NeT is happy the unit is back into operation again.

Below, screenshots of the computers in the shore station at Porto Palo di Capo Passero during installation of the unit in 2015. Above: the first reconstructed event after resuming data taking in 2019.

  

 


Workshop on simulation and data analysis

23 January 2019 – An internal KM3NeT workshop on ‘Simulation and Data Analysis’ was organised at INFN – Istitutio Nazionale di Fisica Nucleare in Genova, Italy. In the last two years the ARCA and ORCA sites were equipped with the first detection units which allowed for obtaining the first calibration data. The data comprises many measurements of muons created in the atmosphere. These measurements, although background to the neutrino signal, are extremely useful for the understanding of the detector performance and improving detector calibration and simulations of the detector response. The aim of the workshop was to review the currently existing simulation software tools and tuning them to reach agreement with the collected data on a new precision level.

Simulation of background events comprises very computationally intensive tasks, which must be run on the GRID and cloud infrastructures. For this, automatic workflows for the software deployment and running on different computer infrastructures were discussed and tests have been started. The simulation workflows also should keep provenance of the data to allow for repetition  and tracing of each simulated event. Automisation of the quality control of the data and simulation is yet another key task addressed at the workshop.