27 May 2025 – Do you know how the optical modules of KM3NeT are built? This has been shown and practised in the second edition of the Digital Optical Module (DOM) integration workshop which took place last week.
In total 30 people participated in the workshop. They came from the eight KM3NeT integration labs, including the new lab in Salerno, Italy. Experts from the KM3NeT steering committee and the central and local quality management were also present.
The workshop was purely hands-on! Each phase of mounting a DOM was scrutinised, while the participants shared their experience and the procedures were discussed.
The workshop took place in the CAPACITY laboratory in Caserta, Italy, taking advantage of the new facilities which were recently inaugurated.
The construction of the KM3NeT optical modules consists of many phases, comprising several delicate operations. The final product is a pressure-resistant glass sphere which contains 31 photomultipliers and various electronics devices for the power supply and acquisition and transmission of data.
In addition, the optical modules contain important calibration devices, such as a compass, a piezoacoustic sensor and a fast LED pulser, the nanobeacon. They are fundamental for pushing the performance of the apparatus.
The two hemispheres which compose a module are assembled and tested separately. When everything is installed and all functional tests are passed, it is time to proceed to non-reversible steps of integration, such as pouring optical gel in the interface between the photomultipliers and the glass of the hemispheres. Finally the optical module can be closed and sealed. After undergoing a last acceptance test, the module is ready for being integrated in a detection line.
All integration and test procedures strictly comply with the high quality standards of KM3NeT.
And what if a problem occurs in a completed and sealed optical module? Is it possible to open it? The answer is yes! But with a very very delicate procedure.
Below are some pictures taken during the workshop.
