A new cryostat made of a glass epoxy laminate (G11) has been designed, produced and commissioned together with the Central Cryogenic Laboratory (Cryolab) at CERN. The inner diameter of the inner vessel is 342 mm, thus allowing to install different setups inside it. This non-magnetic cryostat will allow to cool down our setups, e.g. CB100 (shown in the photograph), inside the MORPURGO magnet to temperatures below 10 K for several hours. This will improve significantly the sensitivity reach of our prototypes.
Three commissioning runs were performed at the CERN Cryolab in March, April and May 2023, demonstrating that a temperature below 10 K could be reached for 23 hours.
In March and April, a Closed Booster with 3 fixed 100 mm diameter discs (CB100) was inserted in the MORPURGO dipole magnet at CERN. A very stable magnetic field around 1.6 Tesla was maintained for 21 days. The online monitoring of the power frequency data indicates that the system stability is sufficient to extract a limit on ALP photon coupling for an ALP mass of 80 μeV.
Prof. Dr. Erika Garutti (UHH) explains in the 21st episode of the podcast "Exzellent erklärt. Spitzenforschung für alle" (Excellent Explained. Cutting-edge research for all) how MADMAX aims to search for dark matter. Only in German.
"Exzellent erklärt" podcast about dark matter
Photo: Jens Rüßmann / QU
After three years of Zoom meetings, the MADMAX collaboration members have finally met in person in a three-day meeting in Hamburg. Besides many very interesting presentations and scientific discussions, the collaboration members had also the chance to visit the SHELL laboratory (UHH) and the HERA North Hall at DESY, the future home of the MADMAX experiment.
MADMAX is recognised as a central project of the "CNRS Helmholtz Dark Matter Laboratory", DMLab, an International Research Laboratory (IRL) between the CNRS/IN2P3 and the Helmholtz Association whose scientific kickoff took place in December 2021. DMLab aims to address various challenges in dark matter physics in French-German cooperation.
Formally, DMLab is an CNRS research laboratory outside France sited at DESY, which will act as a scientific and administrative hub extending over the four Helmholtz centres (DESY, Forschungszentrum Jülich, GSI Helmholtzzentrum für Schwerionenforschung, and Karlsruher Institut für Technologie). DMLab will offer resources for the organisation of workshops, training events, and travel. The projects encompassed by DMLab are expected to be funded and staffed by IN2P3, Helmholtz as well as universities and other partner institutes. DMLab has been created for renewable periods of 5 years.
In March and April, a successful series of radio frequency interference (RFI) measurements were conducted in the area surrounding the 1.6 Tesla MORPURGO magnet at CERN. The aim was to identify and remove unwanted interference signals that may interfere with the feeble power coming from a potential axion signal. The CB100, or Closed Booster 100 mm in reference to its diameter, was inserted into the MORPURGO magnet and data were recorded at 1.6 T.
Image: CB100 prepared to enter the 1.6 Tesla MORPURGO magnet
The 9 T MADMAX magnet will be one of the most challenging magnets ever designed. One of the main challenges in the design of any new superconductor magnet is to prevent quenches. For this purpose, the MADMAX Coil for Quench Understanding (MACQU), a solenoid magnet using a novel conductor, has been produced and tested by Bilfinger-Noell and CEA-Saclay, respectively. Quench propagation velocity tests with the MACQU coil were successfully performed showing a velocity of several meters per second. This velocity is fast enough for a quench to be detected before the magnet is damaged. With these tests, one of the main risks in the design of the MADMAX magnet has been mitigated.
P200 has been tested for the first time in a strong magnetic field in the MORPURGO magnet at CERN. The feasibility of moving a sapphire disc in a 1.6 T field has been verified. No differences in the disc movement were observed when the magnet was in operation.
P200 has been tested for the first time at cryogenic temperatures in the Cryolab at CERN. In the first test, three of the MADMAX piezoelectrical motors were driven together in a coordinated way at approximately 20 K (first tests performed with no disc). The movement and positioning of the motors were monitored using a cryo-compatible laser interferometer. First results confirm the feasibility of moving a disc in these extreme conditions using the piezo motors designed by the company JPE.
In a second experimental run, three piezo motors have moved a sapphire disc of 200 mm diameter inside the cryostat.
In the final MADMAX experiment, approximately 80 dielectric disks will be moved, and positioned, by high-precision motors. These motors will have to withstand very low temperatures (~4 K) and a strong magnetic field (~9 T). MADMAX's first piezoelectric motor, developed by the company JPE, has been successfully tested in a 5.3 T magnetic field at approximately 5.1 K, thus demonstrating its capabilities. The tests were carried out at DESY in one of the ALPS-II test magnets.
Project 200 (P200) is MADMAX's first mechanics prototype. It consists of an aluminium structure holding a copper mirror fixed in position and a dielectric disc. The position of the disc can be adjusted with the help of very precise piezoelectric motors supplied by the company JPE. With this setup, MADMAX aims to verify the feasibility of moving the MADMAX discs with the required precision at very low temperatures (~4 K) and, eventually, also in a magnetic field. In the photo, one can see the structure, the Cu mirror, the tiled disc attached to three motors via a ring, as well as the ceramic rails along which the motors move.
Néel Institute, Grenoble has now become a full member of the MADMAX collaboration.
CERN has endorsed the MADMAX prototype tests in the Morpurgo magnet located in the Prevessin North Area. This is the outcome of the CERN Research Board, that took place 16-Sep, after the positive recommendations from the SPS committee in June 2020. These tests will be an important milestone for the MADMAX collaboration. They will allow to realize and test the dielectric booster concept for the first time in a significant B-field. The prototype should be sensititive to ALPs (axion-like particles) in a mass domain around 100 μeV, as illustrated in the Figure. read more (external)
CPPM is now a full member of the MADMAX collaboration.
The new Shielded Experimental Hall (SHELL) in Hamburg provides an electromagnetic quite laboratory for the BRASS experiment and MADMAX R&D. Using ferroconcrete walls with a thickness of 3m it shieldes electromagnetic radiation from outside, like radio stations, mobile phone signals, WiFi and others. read more (external)
Néel Institute are developing Josephson junction-based pre-amplifiers that can work at 10-30 GHz and reach near quantum limited performance. Such amplifiers, if successfully integrated into MADMAX, can reduce the system noise temperature by ~50% and therefore significantly increase the overall sensitivity of MADMAX.
"The European Physical Journal C" (EPJC) has put our sensitivity projection on their journal cover page for March 2019. The MADMAX collaboration is very happy and wishs to thank the EPJC for this special honor.
A new experimental approach to probe QCD axion dark matter in the mass range above 40μeV,
MADMAX Collaboration, Brun, P., Caldwell, A. et al. Eur. Phys. J. C (2019) 79: 186. https://doi.org/10.1140/epjc/s10052-019-6683-x
CPPM Marseille has become associate member of the MADMAX collaboration. CPPM is currently looking into the possibility to help the MADMAX collaboration as a full collaboration member by investigating how the prototype booster can be scaled to its final size. CPPM has already taken over the task to characterizing the flatness of the individual prototype-booster disks to µm level.
On the 8th of May 2018 the MADMAX-Collaboration inaugurated their official logo, originally proposed by the group at the University of Tübingen. It outlines three dielectric disks in orange surrounded by the acronym MADMAX.
On the 18th of October 2017 the MADMAX-Collaboration was founded. Founding Insitutes are the Max-Planck-Institut für Physik in Munich, the Universities of Aachen, Hamburg, and Tübingen in Germany the University of Zaragoza in Spain, the CEA-IRFU in Saclay, France, and the Deutsche-Elektronen-Synchrotron (DESY) in Hamburg.