118122719
DESIGN, TEST AND PERFORMANCE OF THE LIQUID HELIUM CRYOSTATS FOR THE LEP SUPERCONDUCTING QUADRUPOLE MAGNETS
The experimental areas of LEP, the high-energy electron-positron collider presently under construction at CERN, will be equipped with eight superconducting quadrupole magnets, housed in liquid helium cryostats embedded in the complex detector set-ups. To comply with transverse space restrictions, the 2.5 m-long slender cryostats feature a 130 mm diameter warm bore and a horizontally-oriented service funnel at one end, equipped with 2000 A current leads. The cryostats have been designed by CERN, manufactured and assembled by industry, and tested in the laboratory. Besides design principles and constructional features, results of tests and comparative performance data are presented.
120725124
Application of liquid helium cryoplants at CERN
In 1992, the liquid-helium cooling capacity installed at CERN was nearly tripled, passing from 6.8 to 19.7 kW/4.5 K (entropy equivalent*). Further tripling is expected in 1993. While the 6.8 kW available in 1991 were produced by 14 plants of moderate size (500 W/4.5 K average), two of the four plants added in 1992 have unit capacities of 6 kW/4.5 K. Four plants of 12 kW/4.5 K, upgradable to 18 kW/4.5 K in a later phase, are presently being installed. Most of the smaller plants are associated with particle physics experiments, cooling superconducting magnets of particle detectors and high-gradient focusing magnets of colliding-beam experiments. Six plants provide liquid helium for development laboratories and test facilities. The recently acquired multi-kW plants will be integral parts of the collider itself. Their present function is to cool superconducting RF cavities designed to increase the beam energy of the Large Electron Positron collider LEP from 50 to above 90 GeV. In the future, the same and additional plants will be available for the cooling of the superconducting magnet ring of the planned Large Hadron Collider LHC. To this end, they will be equipped with complementary 1.8 K final stages.
122643839
A pulsed superconducting magnet for a static magnetic refrigerator operating between 1.8 K and 4.5 K
Superfluid helium is increasingly used as a technical cooling medium in large-scale research projects involving high-field superconducting magnets, such as the CERN Large Hadron Collider (LHC). For refrigeration cycles operating below the normal boiling point of helium, a potentially interesting alternative to vapour compression is magnetic refrigeration, pioneered decades ago. In the framework of development for an industrial-size 1.8 K magnetic refrigerator using a static active material, we have designed, built and tested a pulsed superconducting magnet producing up to 3 T at a ramping rate of 6.5 T/s. The solenoid-type coil, wound with low-loss superconducting wire (small-filament NbTi in a composite Cu/Cu-Ni matrix), is internally cooled by normal boiling helium, and installed inside a toroidal yoke, made of tapered laminations of commercially pure iron. After describing design and construction of the magnet, we present test results and measurements of performance, field quality and pulsed-operation losses. >
117360197
The prototype superconducting quadrupole magnet for the CERN Intersecting Storage Rings
108668199
Operational Experience with a Cryogenic Axial-Centrifugal Compressor
The Large Hadron Collider (LHC), presently under construction at CERN, requires large refrigeration capacity at 1.8 K. Compression of gaseous helium at cryogenic temperatures is therefore inevitable. Together with subcontractors, Linde Kryotechnik has developed a prototype machine. This unit is based on a cryogenic axial-centrifugal compressor, running on ceramic ball bearings and driven by a variable-frequency electrical motor operating at ambient temperature. Integrated in a test facility for superconducting magnets, the machine has been commissioned without major problems and successfully gone through the acceptance test in autumn 1995. Subsequent steps were initiated to improve efficiency of this prototype. This paper describes operating experience gained so far and reports on measured performance prior and after constructional modifications.
122695581
TOWARDS COST-TO-PERFORMANCE OPTIMISATION OF LARGE SUPERFLUID HELIUM REFRIGERATION SYSTEMS
The field range of superconducting devices may be extended by lowering their operating temperature, using superfluid helium refrigeration systems which have to deliver working pressures down to 1.6 kPa. The corresponding pressure ratio can be produced by integral cold compression or using a combination of cold compressors in series together with "warm" compressors at room temperature. The optimisation of such a system depends on the number, arrangement and characteristics of cold and warm machines as well as on the operating scenario and turndown capability. The aim of this paper is to compare relative investment and operating costs of different superfluid helium cryogenic systems, with the aim of optimising their cost-to-performance ratio within the constraints of their operating scenario.
62352767
ASPECTS OF SCIENTIFIC VISUALIZATION FOR HEP ANALYSIS AT FERMILAB
56333052
Benchmarking/Crosschecking DFS in the ILC Main Linac
In an effort to compare beam dynamics and create a ''benchmark'' for Dispersion Free Steering (DFS) a comparison was made between different ILC simulation programs while performing DFS. This study consisted of three parts. First, a simple betatron oscillation was tracked through each code. Secondly, a set of component misalignments and corrector settings generated from one program was read into the others to confirm similar emittance dilution. Thirdly, given the same set of component misalignments DFS was performed independently in each program and the resulting emittance dilution was compared. Performance was found to agree exceptionally well in all three studies.
122661128
A first approach to mechanical construction and cooling of a composite 3D silicon vertex detector
Abstract This paper presents first results on mechanical and cooling studies for a 3D silicon vertex detector designed for B physics at a hadron collider. Prototype modules were built from raw silicon wafers. One module was instrumented with resistors to simulate readout electronics. Both module movement and temperature variations were recorded. A cooling method utilizing simple air/helium flow was investigated, but proved inadequate because of too large temperature anisotropies.
120234331
Performances of a preamplifier-silicon photodiode readout system associated with large BGO crystal scintillators
Abstract The characteristics of a hybridized low noise preamplifier are described. Performances of the preamplifier in combination with silicon photodiodes are discussed and results from laboratory tests and test runs with an assembly of large BGO crystals are presented.
36127671
Double field flip cooling channel for the neutrino factory
A 220 m long ionization cooling system consisting of three solenoids with two field-flip sections, is proposed as a cooling channel for the neutrino factory. The reduction of transverse emittance is achieved using 87 liquid hydrogen absorbers (30-40 cm long), and 87 (2 m long) 200 MHz linacs. The first flip is performed at relatively small magnetic field, B = 3 T, to keep the longitudinal motion under control. The field is then increased adiabatically up to 7 T and a second field flip performed. The cooler was studied and simulated in detail. Preceded by a 16 GeV proton driver, a carbon target, a mini-cooler and a buncher, the system provides about 0.082 muons per incident proton.