With the objective of carrying out major scientific projects related to origins, the LABEX LIO has, since its creation, launched an investment program in new innovative experimental and technical facilities at the cutting edge of technology. This has given rise, among other things, to the Common Cryogenics and Integration Facility (CCIF) which includes, in addition to an assembly hall at CRAL, three facilities installed at IP2I: a liquid argon tank unique in France, for ultra-sensitive neutrino detection, a “dark matter” platform, a center for the development of cryogenic semi-conducting and super-conducting detectors, for the detection of very rare events, and a clean room to optimize the integration of high-tech detectors.

The LIO Cryogenic Dark Matter technical facility has been deployed in 2015 in the newly refurbished so-called CRYOLAB of the Institut de Physique des 2 Infinis de Lyon (IP2I). More than 10 researchers, technical staffs, teachers and students of the MANOIR group and INSTRUMENTATION service are working in germanium cryogenic detectors development and associated low noise instrumentation (low capacitance and low microphonics cabling, low noise cold electronics, low radioactivity material).

Scientific goals are focus on direct Dark Matter searches (low mass – sub-GeV – WIMPs, Axion-Like Particle, Dark Photon) within the EDELWEISS experiment and recently application to new physics studies with Coherent Elastic Neutrino-Nucleus Scattering (CENNS) within the Ricochet experiment.

The main feature of the facility is a He3-He4 “dry” dilution cryostat able to reach 10 mK. The fridge has been designed in collaboration with the French CryoConcept company. It is based on a commercial PT410 Pulse Tube cryo-cooler from the US Cryomech company. The cryo-cooler has a cooling power of 1.0 W at 4.2 K and 40 W at 45 K and thus the dilution cryostat is running “DRY”, without any liquid helium or nitrogen.

The weak point of “DRY” dilution refrigerators is the vibrations generated by the pulse tube cold head. Even if the valve motor is remote, the helium gas expansion in the cold head is generating a wide range of very nasty vibrations for most of the experiments.

The only definitive solution to cut all vibrations is to mechanically decouple completely the cold head and its valve motor from the dilution unit. The big challenge is to maintain the cooling performance of the refrigerator with no physical contact from the cold head first and second stages to the whole stages of the dilution refrigerator down to the mixing chamber.

This unique performance is completed within the Ultra Quiet Technology ™ developed by Cryoconcept and first tested in the IP2I Cryolab in summer 2015.

Since then, the detector cabling, the electronics and acquisition softwares have been developed and installed with the great help of the technical services.

The LIO Clean room was built to optimize the construction and integration of high-technology detectors. It is located at the IP2I in the Van de Graaf building. Thanks to the labex LIO, a two-floor workshop was completely refurbished and the Clean room was delivered in 2018. As a first step, the Clean room will be used to host the construction and integration of the future CMS Tracker Endcap for the High Luminosity LHC (HL-LHC, starting in 2027). The project is called TEDD (Tracker Endcap Double Discs).

The labex LIO funding was used to equip the Clean room with crucial instruments: a high precision machining centre to produce key construction elements, partition walls to ensure insulation at the second floor, a large cold room able to hold the mechanical structures for the thermal measurements down to -35°C (see Fig.1), a 3D measurement arm to perform precise mechanical measurements, and a gantry crane to elevate the mechanical structures to the second floor (see Fig.2).

Fig 1-1 LIO Clean room after delivery, first floor (March 2019)

Fig 1-2 LIO Cold room installed, first floor (January 2020)

Fig 2-1 Gantry crane elevating a Dee transport box up to the second floor

Fig 2-2 First full-size Dee prototype (2.2m diameter) and 3D measurement arm