Series-produced Helium II Cryostats for the LHC Magnets: Technical Choices, Industrialisation, Costs

Assembled in 8 continuous segments of approximately 2.7 km length each, the He II cryostats for the 1232 cryodipoles and 474 Short Straight Sections (SSS housing the quadrupoles) must fulfil tight technical requirements. They have been produced by industry in large series according to cost-effective industrial production methods to keep expenditure within the financial constraints of the project and assembled under contract at CERN. The specific technical requirements of the generic systems of the cryostat (vacuum, cryogenic, electrical distribution, magnet alignment) are briefly recalled, as well as the basic design choices leading to the definition of their components (vacuum vessels, thermal shielding, supporting systems). Early in the design process emphasis was placed on the feasibility of manufacturing techniques adequate for large series production of components, optimal tooling for time-effective assembly methods, and reliable quality assurance systems. An analytical review of the costs of the cryostats from component procurement to final assembly, tests and interconnection in the machine is presented and compared with initial estimates, together with an appraisal of the results and lessons learned

The Assembly of the LHC Short Straight Sections at CERN: Work Organization, Quality Assurance and Lessons Learned

After 4 years of activity, the assembly of approximately 500 Short Straight Sections (SSS) for the LHC has come to an end at the beginning of 2007. This activity, which was initially foreseen in European industry, was in-sourced at CERN because of the insolvency of the prime contractor. While the quadrupole cold masses were produced in industry, the assembly within their cryostats was transferred to CERN and executed by an external company under a result-oriented contract. CERN procured cryostat components, set up a dedicated 2000 m2 assembly hall with all the specific assembly equipment and tooling and defined the assembly and testing procedures. The contractor took up responsibility for the delivery, on time, of assemblies according to the required quality. A dedicated CERN production and quality assurance team was constituted. A specific quality assurance plan was set up involving 2 additional contractors responsible for weld inspections on a total of about 20'000 assembly welds and the execution of about 3300 leak detection tests. This paper presents the organizational aspects of the activity and the experience gained throughout the production. The learning curves and statistics by type of non-conformities detected and general quality assurance aspects are presented and discussed. The main lessons learnt are summarized, in an attempt to draw some conclusions which could be useful in making strategic choices for the cryostat assembly in future large-scale accelerators

Leak-Tight Welding Experience from the Industrial Assembly of the LHC Cryostats at CERN

The assembly of the approximately 1700 LHC main ring cryostats at CERN involved extensive welding of cryogenic lines and vacuum vessels. More than 6 km of welding requiring leak tightness to a rate better than 1.10-9 mbar.l.s-1 on stainless steel and aluminium piping and envelopes was made, essentially by manual welding but also making use of orbital welding machines. In order to fulfil the safety regulations related to pressure vessels and to comply with the leak-tightness requirements of the vacuum systems of the machine, welds were executed according to high qualification standards and following a severe quality assurance plan. Leak detection by He mass spectrometry was extensively used. Neon leak detection was used successfully to locate leaks in the presence of helium backgrounds. This paper presents the quality assurance strategy adopted for welds and leak detection. It presents the statistics of non-conformities on welds and leaks detected throughout the entire production and the advances in the use of alternative leak detection methods in an industrial environment

Fault Detection and Identification Methods Used for the LHC Cryomagnets and Related Cabling

Several methods for electrical fault location have been developed and tested. As part of the electrical quality assurance program for the LHC, certain wires have to be subjected to a (high) DC voltage for the testing of the insulation. With the time difference of spark-induced electromagnetic signals measured with an oscilloscope, fault localization within ± 10 cm has been achieved. Another method used, and adapted for particular needs, is the synthetic pulse time-domain reflectometry (TDR) with a vector network analyzer (VNA). This instrument has also been applied as a low frequency sweep impedance analyzer in order to measure fractional capacitances of cable assemblies where TDR was not applicable

Prospectus, August 9, 1988

https://spark.parkland.edu/prospectus_1988/1018/thumbnail.jp

High levels of women's satisfaction and compliance with transdermal contraception: results from a European multinational, 6-month study

Objective. To investigate compliance, satisfaction, and preference in women using a transdermal contraceptive patch. Methods. Women (18–46 years) from eight European countries used contraceptive patches (norelgestromin 6 mg, ethinylestradiol 600 mg) for six, 4-week treatment cycles. Compliance, satisfaction, and preference were assessed after 3 and 6 cycles and study completion using self-report methods. Results. Of the 778 participants, 36.8 % (n 287) used no contraception at baseline. The most common methods were oral contraceptives (67.9%, n 334) and barrier methods (21.5%, n 106). Of oral contraception users, 63.5 % (n 212) were satisfied or very satisfied with their previous method, but compliance was poor with 77.8 % (n 260) reporting missed doses. After 3 and 6 cycles,480 % of all included women were satisfied or very satisfied with the patch. At study completion, most participants (73.7%) reported a preference for the patch compared to their previous method. Of 4107 cycles, 3718 (90.5%) were completed with perfect compliance. Two pregnancies occurred during this study, representing a Pearl Index of 0.63. No new safety issues were identified and the patch was well tolerated. Conclusion. Women were highly satisfied with transdermal contraception and preferred this form of family planning over their previous method. Transdermal contraception represents a valuable addition to contraceptive options with potential t

The LHC Cryomagnet Supports in Glass-Fiber Reinforced Epoxy: A Large Scale Industrial Production with High Reproducibility in Performance

The about 1700 LHC main ring super-conducting magnets are supported within their cryostats on 4700 low heat in leak column-type supports. The supports were designed to ensure a precise and stable positioning of the heavy dipole and quadrupole magnets while keeping thermal conduction heat loads within budget. A trade-off between mechanical and thermal properties, as well as cost considerations, led to the choice of glass fibre reinforced epoxy (GFRE). Resin Transfer Moulding (RTM), featuring a high level of automation and control, was the manufacturing process retained to ensure the reproducibility of the performance of the supports throughout the large production. The Spanish aerospace company EADS-CASA Espacio developed the specific RTM process, and produced the total quantity of supports between 2001 and 2004. This paper describes the development and the production of the supports, and presents the production experience and the achieved performance

Motile dislocations knead odd crystals into whorls

The competition between thermal fluctuations and potential forces governs the stability of matter in equilibrium, in particular the proliferation and annihilation of topological defects. However, driving matter out of equilibrium allows for a new class of forces that are neither attractive nor repulsive, but rather transverse. The possibility of activating transverse forces raises the question of how they affect basic principles of material self-organization and control. Here we show that transverse forces organize colloidal spinners into odd elastic crystals crisscrossed by motile dislocations. These motile topological defects organize into a polycrystal made of grains with tunable length scale and rotation rate. The self-kneading dynamics drive super-diffusive mass transport, which can be controlled over orders of magnitude by varying the spinning rate. Simulations of both a minimal model and fully resolved hydrodynamics establish the generic nature of this crystal whorl state. Using a continuum theory, we show that both odd and Hall stresses can destabilize odd elastic crystals, giving rise to a generic state of crystalline active matter. Adding rotations to a material’s constituents has far-reaching consequences for continuous control of structures and transport at all scales.The National Science Foundation (NSF) under award no. DMR-2011854. NSF DMR-1905974, NSF EFRI NewLAW 1741685 and the Packard Foundation. NSF grants DMR-1420073 (NYU-MRSEC) and DMR-2004469. ARN grant WTF and IdexLyon Tore. The National Science Foundation Graduate Research Fellowship under grant no. 1746045. D.B. The Chicago-France FACCTS programme. ‘la Caixa’ Foundation (ID 100010434), fellowship LCF/BQ/PI20/11760014 and from the European Union’s Horizon 2020 research and innovation programme under Marie Skłodowska-Curie grant agreement no. 847648. NSF DMR-1828629 and US NSF grant no. DMR-201185

Total synthesis and biological evaluation of the tetramic acid based natural product harzianic acid and its stereoisomers

Financial support for this project was provided by Cancer Research UK (Grant No. C21383/A6950)The bioactive natural product harzianic acid was prepared for the first time in just six steps (longest linear sequence) with an overall yield of 22%. The identification of conditions to telescope amide bond formation and a Lacey-Dieckmann reaction into one pot proved important. The three stereoisomers of harzianic acid were also prepared, providing material for comparison of their biological activity. While all of the isomers promoted root growth, improved antifungal activity was unexpectedly associated with isomers in the enantiomeric series opposite that of harzianic acid.Publisher PDFPeer reviewe

Prospectus, August 1988

https://spark.parkland.edu/prospectus_1988/1000/thumbnail.jp