Superfluid helium cryogenics for the large hadron collider project at CERN

Abstract

A . -S (fg { LHC Note 274 CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH elevation differences of up to 22 m. OCR Output producing and distributing refrigeration to the adjacent half-octants, over a length of 1.7 km and across other. As a consequence, the LHC cryogenic system is based on eight octant cryogenic plants, each from 50 to 150 m below ground, with eight evenly-spaced access areas at a distance of 3.3 k.rn from each geometry: a quasi-circular tunnel composed of eight octants, on a slope of 1.4 % and at a depth ranging machine will reuse civil engineering and infrastructure from LEP, and is thus constrained by the existing The basic design parameters of the LHC, operating as proton collider, are listed in Table 1. The integrate them reliably in a high-energy accelerator with high-intensity beams.cryogenics to an unprecedented scale, to develop them well beyond their present state-of-the-art, and to rests on the ability to push the key technologies of applied superconductivity and large-capacity helium below 1.9 K, for guidance and focusing of the stiff hadron beams. The technical success of the project thus use of high-field, twirr-aperture superconducting magnets, operating in pressurized superfluid heliumThe LHC also represents a major technical challenge for accelerator builders. It will make intensive long-standing tradition of efficient international collaboration.injectors, the infrastructure of a large laboratory and the technical expertise of an experienced staff with a accelerator complex, the LHC will make optimal use of existing resources, such as the efficient network of the predominance of matter over antimatter in today's universe. As the latest addition to the CERN concems fundamental issues such as the origin of mass and the breaking of symmetry, which accounts for the way for progress beyond the range of the "standard model" of modern physics, in particular as exploration of the structure of matter and of the basic forces acting between its constituents, thus opening particle physics community now agrees that the LHC is the most adequate instrument to continue the matter at the very fine scale of 10·19 m, i.e. to resolve the quarks which constitute the nucleons. The protons and ions at higher energies than ever achieved before. This will allow to probe the structure of tunnel of the existing LEP collider (Figure 1), will accelerate and bring into collision intense beams of physics [1]. This machine, to be installed close to Geneva (Switzerland) in the 26.7 km circumference CERN is preparing to build the Large Hadron Collider (LHC), a unique research facility for particle

Cryogenic operation and testing of the extended LHC Prototype Magnet String

“…On the 1.4 % slope, the 1.8 K liquid flow in the 4.15-cm inner-diameter corrugated tube is blocked at a vapor velocity of 6 m/s, corresponding to a heat load of 46 W, i.e. above the nominal demand of the LHC half-cells [3]. Although occurring at higher mass flow-rate between 4.5 and 2.2 K, blocking of the liquid flow in the heat exchanger tube may increase time for cool-down of the string from 4.5 K. Strategy for fast cool-down is to optimize the saturation conditions as a function of magnet temperature, in order to work with high-density, low velocity vapor, while preserving sufficient driving temperature difference.…”

Thermodynamics of computation and linear stability limits of superfluid refrigeration of a model computing array

“…The motivation is quantum computation, which must be carried out at very low temperature, in order to maximize as much as possible the duration of quantum coherent states of the system [7], [8], [9], [10]. Amongst the refrigeration techniques, the use of superfluid helium is one of the most practical possibilities [11], [12], [13], [14], as also confirmed by its use as refrigerator at CERN 0 E-mail addresses: michele.sciacca@unipa.it (M. Sciacca), ant.sellitto@gmail.com (A. Sellitto), luca.galantucci@newcastle.ac.uk (L. Galantucci), david.jou@uab.cat (D. Jou).…”

Final Design and Experimental Validation of the Thermal Performance of the LHC Lattice Cryostats

“…The superconducting magnets operate in a bath of pressurized 1.9 K superfluid helium, and are cooled via a separate cryogenic distribution line (QRL) running parallel to the main cryostat, to which is linked every cell, as shown on Figure 1 [1] and [2]. The LHC machine comprises 8 arc cryostats.…”