Nucleus Bubbles
Learn more about NUCLEUS in a fun way by reading our dedicated comic strip!
News & Updates
The Muon Veto moves to Chooz
November, 2025
After the installation of the Muon Veto panels in Chooz, the Muon Veto was commissioned by our teams in November.
Once the acquisition systems, cabling and panel calibration were in place, we were finally able to take very successful first-light measurements in Chooz! Comparisons with the Summer 2024 Commissioning Run and previous simulations confirm that the Muon Veto is working as expected. It is now patiently waiting for its colleagues to move from Munich to the Very Near Site!
MDM-COV integration
September-October, 2025
After several months of hard work, screwing, unscrewing, sweat (and much patience) in TU Munich's labs, the Minimal Detector Module (MDM, an array of four CaWO4 crystals) and the cryogenic outer veto were successfully operated with good performances in two independent cryostats!
Now it's time to combine them together in a brand-new support structure, whose nickname within the collaboration is "the Cage”, equipped with a new thermalization system. The Cage serves as mechanical support for the six cryogenic outer veto's high-purity germanium crystals, which enclose the four CaWO4 detectors, each equipped with two Transition Edge Sensors.
The simultaneous operation of the two subsystems is a critical milestone in view of the next steps of the experiment. And we are also validating a new data acquisition hardware and software, which will allow us to acquire much more data than during the previous runs! Prepare your hard disks to be filled with voltage traces…
Collaboration meeting in Chooz
March 10-11, 2025
The collaboration travelled again to the Ardennes to gather in Chooz and discuss the current status and the outlook of the experiment.
The latest developments in hardware, simulations and data analysis were presented.
The planning of the tests to be carried out on the cryogenic detectors and on the cryogenic outer veto at TU Munich was discussed. 2025 will be a crucial year for operating these two systems simultaneously in the same cryostat! This is a fundamental milestone to be reached before the move of the experiments' subsystems and cryostat to Chooz, planned for 2026.
It also was an excellent occasion to toast together to the results of the Technical Run of Summer 2024.
Finally, the Early Career Members group of the collaboration was also established, with the goal of enhancing the exchange of ideas and views between different generation of scientists and strengthen the ties among the youngest members of NUCLEUS.
NUCLEUS’s first commissioning run
August, 2024
For the first time in NUCLEUS, two cryogenic detectors (one CaWO4 and one Al2O3 crystals) were tested together with the experiment’s active and passive shielding systems in a 2 months-long run at the Technical University of Munich (TUM).
Within the collaboration, this run is known as the Long Background Run (LBR). In reality, it was much more: it was a run in which we commissioned different subsystems of the experiment; that’s why we also call it the Commissioning Run. All detector subsystems operated with stable performance, and background measurements were conducted, providing important benchmarks for modeling background sources at the reactor site — a major milestone for NUCLEUS. But the party is not over just yet! The LBR was conducted with a simplified version of the setup, and its successful validation now paves the way for the commissioning and validation of the final configuration, an ongoing process that brings new and exciting challenges!
Read more about our Commissioning run in the Publications section of the website.
A clean room around the NUCLEUS setup
June, 2024
We have installed a clean room around the NUCLEUS cryostat. This ensures a pristine environment, preventing dust and contaminants from entering the cryostat.
Additionally, the cryostat has been thoroughly cleaned and is now ready for future measurements!
Collaboration and detector meetings in Munich
February - April, 2024
Meetings focused on the detector development and the collaboration meeting took place February and April 2024. It was the occasion to define more precisely the goals of the Long Background Data taking foreseen in summer 2024.
Collaboration meeting in Vienna
October, 2023
The NUCLEUS collaboration met in Vienna in October 2023.
The meeting was focused on the preparation of the long background data taking, that will happen in 2024 in the TUM and the preparation of the strategy for the move of the experiment in Chooz.
The shielding and the cryostat reunited at TUM
May, 2023
Until now, the shielding and the cryostat were staring at each other without talking. But the cryostat has finally been moved inside the cryostat and it seems that they are getting along quite well.
A great story is starting with those two. A perfect match which starts to look like the final NUCLEUS setup!
Installation of the polyethylene shielding
April, 2023
The borated polyethylene (no that's not a washing machine...) has arrived at TUM and has been successfully installed inside the lead shielding. With this last step, the NUCLEUS external shielding (Muon Veto, mechanical structure, lead and polyethylene) is complete!
Collaboration meeting at Chooz
March 6, 2023
Exactly three years after the first collaboration meeting at Chooz, the collaboration gathered again in March at the nuclear power plant.
Even if the site was quite disturbed by some strikes, this meeting has been the occasion for most of the members to visit the VNS and the power plant. It was a really productive meeting, which helped to define the goals of the commissioning that is bound to happen in the next months at TUM, other than start planning the moving to Chooz.
The muon veto has arrived at TUM
December 8, 2022
The installation of the NUCLEUS Muon Veto has been performed in December 2022 by the CEA team. The 28 panels have been successfully assembled on the mechanical structure. The cabling will follow in the beginning of 2023.
All the process went quite smoothly!
First layer of shielding
September 1, 2022
The mechanical structure and the lead shielding, the first layers of the NUCLEUS passive shileding was installed in the UnderGround Lab (UGL) at TUM. The other layers of external shielding (passive and active with the Muon Veto) will follow in the mounting procedure of the experiment.
Collaboration meeting at Bracciano
July 6, 2022
In July, the collaboration meeting took place at Bracciano near the lake of the same name, close to Roma. A great environment to work on the blank assembly and the commissioning of the experiment.
Commissioning of a brandnew Bluefors cryostat for NUCLEUS
November 19, 2021
A new dry dilution refrigerator from Bluefors has just been delivered to TUM, and will be commissioned during the next weeks. The cryostat will be used for R&D of several NUCLEUS components, before (soon) hosting the first NUCLEUS target detectors.
Detector meeting at TUM
October 20, 2021
A special meeting focused on the NUCLEUS detectors took place at TUM. It was the first in-presence meeting (although a hybrid one in fact...) after a long time. It was the occasion to talk about the detector technologies and the decide the next key steps for the development of the experiment.
The NUCLEUS cryostat receipt at TUM
April 24, 2020
The NUCLEUS dry dilution refrigerator has arrived and has been mounted at TUM. The NUCLEUS cryogenic detectors are tested and operated in this cryostat: the Cryogenic Outer Veto, the silicon Inner Veto, the TESs used to read out the CaWO4 and Al2O3 crystals.
Collaboration meeting at Chooz
March 5, 2020
NUCLEUS members met at Chooz in March, just in the beginning of the coronavirus pandemic. The occasionfor many members to discover the power plant for the first time.
Collaboration Meeting at Paris-Saclay
May 22, 2019
The CEA Paris-Saclay welcomed the collaboration for a two-day meeting. Design of the shielding, planning of the experiment and challenges to face have been discussed.
Kick-off meeting at TUM
November, 2018
The NUCLEUS collaboration started during this kick-off meeting in 2018 at TUM. The name, the collaboration agreements, the experimental site and the concept of the experiment were defined at this meeting.
