Missions

Dark matter is one of the great enigmas of fundamental physics today. Its contribution to the total mass of the Universe is 85%, but it cannot be explained within the framework of the Standard Model of particle physics (SM). However, several candidates for dark matter exist in theories beyond the SM: this is the case of the axion, one of the best-motivated candidates as it also explains the absence of CP violation in the strong interaction.
The discovery of axions requires the invention of new experimental techniques. Several proposals have emerged in recent years. MADMAX is one of the few that is sensitive to the mass domain around 100 micro-eV, favored by theory. For this reason, it has attracted the attention of the scientific community since 2016, when it was first proposed. Today, MADMAX is a collaboration of 50 scientists from German and French laboratories (including CPPM since 2019) and is part of the DMLab International Research Laboratory, installed at DESY-Hamburg. Based on the innovative concept of dielectric haloscope, MADMAX will consist of a booster made of 80 1-meter-diameter disks that need to be positioned to micrometer precision at a temperature of 4 degrees Kelvin and in a magnetic field of 9 T. In order to realize this detector, which will take data at DESY after 2030, the MADMAX collaboration is in an R&D phase, which will be concluded by the construction and operation of a prototype whose main aim is to demonstrate the feasibility of the dielectric booster concept.
The aim of the postdoc, paid by the ANR PRCI grant HALOX, is to conduct a search for axions in an uncharted phase space by participating to the commissioning and data analysis of the prototype. The booster is presently being assembled in an experimental hall on the DESY campus. It will be inserted in a stainless-steel cryostat during fall 2025 and tested at liquid helium temperature in 2025-26. The prototype and the cryostat will then be sent to CERN in October 2026. A long-term test in a 1.6 T magnetic field will take place during the first half of 2027, under the supervision of CPPM. More details about the CPPM Dark Matter team can be found at this link: https://www.cppm.in2p3.fr/web/en/research/particle_physics/index.html#Dark%20Matter

Activités

The candidate will be involved in all experimental aspects, from setting up to operating the dielectric haloscope, as well as data analysis. In particular, the CERN test will enable to search for axions around 100 micro-eV using the innovative concept of the dielectric haloscope, with unprecedented sensitivity to axion-photon coupling.

Compétences

Candidates must have a recent thesis in experimental particle or astroparticle physics, or accelerator physics when starting the position, and have a maximum of two years' professional experience after the thesis. Hardware, signal processing and data analysis skills will be required. Previous experience in the field of radio frequencies will be an asset. A solid knowledge of Python and/or C++ is also essential for this position. Finally, a good command of spoken and written English is required.

Contexte de travail

Located in the heart of the Parc National des Calanques, on the Luminy campus, the CPPM is a joint research laboratory of the CNRS and Aix-Marseille University, with around 180 researchers, engineers and PhD students. The laboratory studies subjects ranging from particle physics to astroparticle physics and cosmology, with a strong technological focus on electronics, mechanics, instrumentation and computing, enabling the design and construction of cutting-edge detection systems, often called upon to operate under extreme conditions: in the depths of the sea, in space or underground. Most of our research is carried out as part of leading international scientific collaborations, and our contributions are recognized worldwide. CPPM is committed to conducting ethical research and promoting diversity and inclusion in the workplace, and provides administrative and logistical support for newcomers (https://www.cppm.in2p3.fr/web/fr/index.html).
The successful candidate will be part of the dark matter team, which comprises a dozen members. The position is funded by the ANR HALOX project, approved in 2024 for 3 years from 2025 to 2027.
During his/her thesis, the student will travel regularly to the DESY lab in Hamburg and CERN in Geneva LNGS to participate to the integration and run for the prototype.