Conceptual Design of the Cryostat for a Highly Radiation Transparent 2 T Superconducting Detector Solenoid for FCC-ee⁺

The Future Circular Collider electron-positron version (FCC-ee$^{+}$) may be the next step towards a next generation of particle colliders. It may include an Experiment for probing ee$^{+}$ collisions using the IDEA (International Detector for Electron-positron Accelerator), or a similar detector, requiring a solenoid enclosing the inner tracking detector. An innovative 2 T superconducting solenoid with 4 m bore and 6 m long has been accepted as baseline. Positioning the solenoid in between tracker and calorimeter requires an ultra-thin and highly radiation transparent cold mass. Likewise, a thin and radiation transparent cryostat is needed. The set value for the solenoid's maximum radiation length is 1 × X0. The cryostat is designed as a sandwich of thin Aluminum alloy inner and outer shells, eventually locally reinforced, for achieving vacuum tightness, and layers of innovative insulation material providing lowest thermal conductivity and sufficient mechanical resistance. Cryogel Z, a composite blanket of silica aerogel and reinforcing fibers, has a density of 160 kg/m$^{3}$ and would allow a 250 mm cryostat thickness. As an alternative, glass spheres (e.g., K1 type, manufactured by 3M, with a 65μm diameter and a 125 kg/m$^{3}$ density), or similar material, can be dispersed between the vacuum vessel thin-walls providing structural support. Besides the cryostat conceptual design, we outline the setup developed at CERN to represent the real-case cryostat and to measure the heat load transferred through the above-mentioned materials and we present the test results for Cryogel Z

New national and regional Annex I Habitat records: from #60 to #82

New Italian data on the distribution of the Annex I Habitats are reported in this contribution. Specifically, 8 new occurrences in Natura 2000 sites are presented and 49 new cells are added in the EEA 10 km × 10 km reference grid. The new data refer to the Italian administrative regions of Campania, Calabria, Marche, Piedmont, Sardinia, Sicily, Tuscany and Umbria. Relevés and figures are provided as Supplementary material respectively 1 and 2

Towards cryogel®Z and glass spheres insulated cryostats for superconducting detector solenoids: R&D in the frame of the 2014-2020 future circular collider study at CERN

In the frame of the Future Circular Collider (FCC) study, the FCC-ee+ IDEA detector magnet comprises a solenoid installed around the inner tracker directly, thus inside the dual-readout calorimeter, saving about a factor 4 in stored magnetic energy and roughly a factor 2 in cost. The radiation thickness of the solenoid must then be minimized to allow the particles emanated from the interaction point to reach the calorimeter. The concept can eventually be adapted for the longer-term FCC-hh. This thesis work constitutes a feasibility study of a cryostat concept for this “ultra-thin” detector solenoid. The 20 mm thick uniform plate that constitutes the cryostat’s outer vessel wall is here replaced by an aluminum foil of some 100 μm thickness. The thin foil must ensure vacuum tightness but is not required to withstand the atmospheric pressure, nor the weight of the cold mass. Instead, the typical multi-layer insulation (MLI) is replaced by an insulation material that fills the empty space inside the vacuum vessel completely and thus provides the required mechanical support against the atmospheric pressure. The outer wall is allowed to “corrugate” under vacuum and to rest on the enclosed insulation. Through cold mass supports, the weight of the solenoid, its thermal contraction and the vacuum pressure are transferred to the end flanges and then further to the main detector support structure. Cryogel® Z and 3M™ glass microspheres type K1 are chosen as insulation materials. Their radiation transparency, compression strength and thermal conductivity are investigated. The experimental results are used to design a mock-up cryostat manufactured in-house. Filled with an insulation material of choice, it allows to estimate the heat fluxes transferred to the thermal shield and to the cold mass of a real-case cryostat for different vacuum levels, boundary temperatures and compression loads applied to the insulation layers. Size, radiation thickness and thermal budget are then estimated for a conceptual cryostat insulated with Cryogel® Z and are compared to those of alternative designs in order to make a critical evaluation of the feasibility of such a cryostat concept for large-scale detector magnets

Conceptual Development of a Novel Ultra-Thin and Transparent 2 T Superconducting Detector Solenoid for the Future Circular Collider

In the frame of the ongoing Future Circular Collider (FCC) Study, a novel ultra-thin and maximum radiation transparent solenoid for next generation particle detectors is under development. Actually, two versions providing 2 T and 3 T for the FCC-ee and FCC-hh detectors, respectively, are engineered, but here we report on the 2 T version only. Essential aspects of the design are presented. The mechanical and thermal stability of the cold mass is investigated. New, very high-yield stress Al-stabilized NbTi/Cu conductors are required to allow a 0.4 ∗ X 0 radiation thickness. For conductor production, welding of dissimilar aluminum alloys will be necessary. Electron beam and friction stir welding techniques were tested to connect the Ni-doped pure Aluminum stabilizer to the very high-yield strength Al-7068 alloy. The welding results and their applicability are presented and discussed. The proposed conduction-based cold mass cooling scheme using heat drains, and quench protection were analyzed and results are presented

Ultra-thin solenoid and cryostat development for novel detector magnets

In the scope of the Future Circular electron positron Collider study (FCC-ee), the IDEA detector is developed. It comprises a superconducting solenoid with free bore of 4 m, 6 m long and a central magnetic field of 2 T. The positioning of the magnet between the inner tracker and the electronic calorimeter heavily constrains the magnet design, as it is required to have the lowest possible radiation length, so minimum thickness and lowest density material. With respect to the classical solution of a solenoid enclosing the calorimeters, a cost reduction of about 50% is expected due to size reduction. An optimization of the different components of the magnet system has been carried out, resulting in the development of a new composite high-strength conductor that can be used to build a 30 mm thin solenoid. The quench analysis of the solenoid will be presented as it is of critical importance given the high energy density in the magnet of 21 kJ/kg. A cryostat made of concentric aluminium shells would account for about 50% of the radiation length of the magnet and most of this material is used in the outer vacuum shell of the cryostat to prevent buckling. In order to further reduce the radiation length, two fundamentally different approaches are being analysed. The first method focuses on reducing drastically the outer shell thickness. This leads to use honeycomb composites, reinforcing bars and corrugated shells for the outer shell of the cryostat. The second approach consists of supporting very thin cryostat shells directly on the solenoid cold mass using proper support. This can be achieved by replacing the thick walls and MLI insulation by a material that can sustain 1 atm while having low radiation length and low thermal conductivity. Cryogel Z has shown promising properties and its suitability for this project is being analysed. This novel approach has never been used so far for superconducting magnets

Superconducting detector magnets baseline designs for particle physics experiments at the Future Circular Collider

International audienceIn early 2014 a design study started at CERN for a Future Circular Collider. A new tunnel with a circumference of about 100 km for the collider magnets is foreseen as well as new general-purpose particle detectors to probe electron-positron (e$^-$e$^+$), electron-hadron (eh), and hadron-hadron (hh) collisions, housed in large underground caverns. In the last four years baseline designs for the various detector magnets were developed. For the FCC-ee detector two magnet variants were defined: a 7.6-m bore and 7.9-m-long classical 2 T solenoid with 600 MJ stored energy, surrounding the calorimeters, and also a very challenging 4-m bore, 6-m-long, some 100-mm-thick ultrathin and radiation transparent 2 T solenoid with a stored energy of some 170 MJ, that surrounds only the inner tracker of the detectors. For the FCC-eh detector, the detector solenoid is combined with forward and backward dipole magnets required to guide the electron beam in and out of the collision point. This detector requires a 3.5 T solenoid, 2.6-m free bore and 9.2-m length with about 230 MJ of stored energy. Most demanding is the FCC-hh detector with a 14 GJ stored energy magnet system comprising three series connected solenoids, requiring 4 T in the main solenoid with 10-m free bore and a length of 20 m, in line with two 3.2 T forward solenoids with 5.1-m free bore and 4-m length. A quite challenging series of detector magnets is proposed, that needs to be further engineered in the coming years. The superconductor technology though is essentially the same in all the solenoids proposed: conductors comprising Rutherford type cables made of NbTi/Cu strands, stabilized by nickel doped pure aluminum and structurally reinforced with a high yield strength aluminum alloy. The cold masses are conduction cooled through helium cooling pipes welded to their outer support cylinder. The designs of the various baseline magnets as well as their engineering are presented

Fabrication and Test of the Fourth Prototype of the D2 Orbit Corrector Dipole for HL-LHC

As part of the High-Luminosity upgrade project (HL-LHC) for the Large Hadron Collider (LHC) at CERN, new double-aperture beam orbit corrector magnets will be installed near the recombination dipole (D2). These magnets are 2.2 m long Nb–Ti dipoles based on the Canted Cosine-Theta (CCT) design. They provide an in bore magnetic field of 2.60 T at 394 A in a 105 mm aperture with an integrated field of 5 Tm. The fourth full-length prototype was built and tested at CERN. Its design is based on the best engineering practices from previous prototypes. In this paper we first report on recent improvements in the manufacturing process, focusing on the feedback from winding and on the optimization of the impregnation phase. The magnetic measurements carried out at warm and cold temperatures are then reported. Finally, the results of powering tests at 1.9 K and 4.5 K are presented. The magnet meets the dimensional, electrical and magnetic requirements, and is a valid reference for the HL-LHC series production that is currently being carried out in collaboration between CERN and Institute of High Energy Physics (IHEP)

Design of the Optional Forward Superconducting Dipole Magnet for the FCC-hh Detector

International audienceA 4-T, 10-m free bore and 20-m long central solenoid is proposed as the main magnet in the baseline detector for the future circular collider (FCC) hadron–hadron collisions physics program. Besides the 4-T axial magnetic field around the interaction point in the center of the main solenoid, additionally, magnetic field is required in the forward directions. This provides sufficient bending power for particles traveling at small angles from the beam axis as well. Using forward solenoids is the baseline. Here, we present the option of using forward dipole magnets. A previously published design foresaw cone-shaped dipole magnets as well as force and torque balanced. This design, however, evolved to a more practical design, where the cryostat occupies the same space as in the baseline with forward solenoids, meaning that the vacuum vessel dimensions in solenoid and dipole designs are the same