Search

MOP010; International audience; Assembly and tests of the SPIRAL2 superconducting linac's cryomodules at CEA/Saclay and IPN/Orsay have now reached cruising speed after having faced a series of problems, among them contamination. 19 cryomodules are composing the whole Linac and IPN Orsay is in charge of the 7 cryomodules B, housing two 88 MHz, beta 0.12 Quarter-Wave Resonators. Threecryomodules have been assembled and successfullytested up to the nominal gradient of 6.5 MV/m for all cavities with also cryogenic losses withinspecifications. Two of them are fully qualified and already delivered to GANIL. The thirdone showed misalignment ofone cavity which could lead to partial disassembly if needed. This paper presents the results of those cryomodules tests as well as the status of the remaining ones.

Because the brush-border (BB) of the renal proximal tubule shares antigens with other epithelia including glomerular epithelial cells (GEC) and the visceral yolk sac (VYS) of the embryo, immune reactions directed to BB antigens can induce glomerulonephritis (GN), such as Heymann's nephritis, a rat model of membranous GN (MGN) and teratogenic effects. To identify the responsible antigens, we have raised monoclonal antibodies against the BB, selected those exhibiting cross-reactivity with the GEC and/or the VYS, and tested their pathogenicity in vivo. This led us to characterize the target antigen of Heymann's nephritis as a 330 kD glycoprotein closely associated with clathrin in the intermicrovillar areas of the BB and the coated pits of the GEC. Induction of the characteristic electron -dense deposits is a dynamic process including redistribution of the antigen on the surface of GEC triggered by cross-linking by polyclonal antibodies, followed by shedding of the immune complexes from the cell membrane, and increased antigen synthesis. Gp330 is not detected in human GEC and therefore is probably not implicated in the pathogenesis of MGN in man. Other antigenic candidates for the in situ formation of epimembranous deposits in the glomerular capillary wall are dipeptidyl peptidase IV (gp90) and naeutral endopeptidase (gp85, CALLA), two enzymes shared by the BB and the GEC in numerous species including man. Using the same ""monoclonal approach"", we have identified another coated pit glycoprotein, gp280, as the main target antigen of teratogenic anti-kidney antibodies. Injection of any of the anti-gp280 monoclonal antibodies induces in a dose-dependent manner embryonic resorption and malformations in the surviving fetuses. Preliminary experiments suggest that the teratogenic effects are due to alterations of the endocytotic process that plays a key role in providing nutrients to the developing embryo. These observations indicate that binding of a monoclonal antibody to a single epitope can be pathogenic by blocking the function of the antigen. BB antIgens are thus implicated in various immune diseases affecting other structures than the renal tubule; full-blown expression of the disease may be observed with monoclonal antibodies or require polyclonal immune response, depending on the nature of the molecular mechanisms triggered by the deposition of the specific antibodies.

Piezoelectric actuators, which are integrated into the cold tuning system and used to compensate the small mechanical deformations of the cavity wall induced by Lorentz forces due to the high electromagnetic surface field, may be located in the radiation environment during particle accelerator operation. In order to provide for a reliable operation of the accelerator, the performance and life time of piezoelectric actuators (~24.000 units for ILC) should not show any significant degradation for long periods (i.e. machine life duration: ~20 years), even when subjected to intense radiation (i.e. gamma rays and fast neutrons). An experimental program, aimed at investigating the effect of fast neutrons radiation on the characteristics of piezoelectric actuators at liquid helium temperature (i.e. T~4.2 K), was proposed for the working package WP#8 devoted to tuners development in the frame of CARE project. A neutrons irradiation facility, already installed at the CERI cyclotron located at Orléans (France), was upgraded and adapted for actuators irradiations tests purpose. A deuterons beam (maximum energy and beam current: 25 MeV and 35µA) collides with a thin (thickness: 3 mm) beryllium target producing a high neutrons flux with low gamma dose (~20%): a neutrons fluence of more than 1014 n/cm2 is achieved in ~20 hours of exposure. A dedicated cryostat was developed at IPN Orsay and used previously for radiation hardness test of calibrated cryogenic thermometers and pressure transducers used in LHC superconducting magnets. This cryostat could be operated either with liquid helium or liquid argon. This irradiation facility was upgraded for allowing fast turn-over of experiments and a dedicated experimental set-up was designed, fabricated, installed at CERI and successfully operated for radiation hardness tests of several piezoelectric actuators at T~4.2 K. This new apparatus allows on-line automatic measurements of actuators characteristics and the cryogenic parameters. Further, the test-cell and actuators are equipped with high purity Ni foils for measuring the total neutrons dose by an activation method. In this report, the details of the irradiation test facility will be described then the experimental data will be analyzed and discussed.

IPN Orsay participates, in the frame of the CARE project activities supported by EU, to the development of a fast cold tuning system for SRF cavities. The main task of IPN is the full characterization of piezoelectric actuators at low temperature T, and the study of their behaviour when subjected to fast neutrons radiation at T=4.2 K. In order to compare the performance of various industrial piezoelectric actuators, a new apparatus was developed and successfully used for measuring their electromechanical and thermal properties for T in the range 1.8 K-300 K. Different parameters were investigated as function of T: piezoelectric constant, dielectric and thermal properties including heating ΔT due to dielectric losses vs. modulating voltage Vmod and frequency f. We observed a decrease of the maximum displacement ΔX of the actuators tested from ΔX ~40μm @ 300K down to 1.8μm-3.5 μm @ 1.8K, depending on both material and fabrication process of the piezostacks. Besides, both material and fabrication process have a strong influence on the shape of the characteristics ΔX vs. T dependence. Finally a dedicated facility located at CERI institute (Orléans, France) for radiation hardness tests of actuators with fast neutrons at T=4.2 K was developed and the first beam tests results are summarized.

International audience; OBJECTIVE AND METHODS: The aim of this study was to describe the main features of sclerosing peritonitis, using a retrospective study in 10 patients. RESULTS: The main causes of sclerosing peritonitis were continual ambulatory peritoneal dialysis (n = 3), peritoneal chemotherapy (n = 2) and liver cirrhosis (n = 2). Sclerosing peritonitis was revealed by acute or chronic bowel obstruction (n = 8). Small bowel X-rays and abdominal tomodensitometry showed a small bowel dilatation with a normal mucosa (n = 7), ascites (n = 5) as well as agglutination and fixation of small bowel loops within a cocoon (n = 3). Surgical viscerolysis was performed in 9 patients and allowed prolonged clinical remission in 4; 3 patients died postoperatively (1 had a cirrhosis and 2 were treated with continuous ambulatory peritoneal dialysis), 1 patient had a complicated postoperative course with recurrent enterocutaneous fistulae. CONCLUSION: Sclerosing peritonitis may be suspected in a patient who presents a combination of bowel obstruction, small bowel dilatation without mucosal disease and ascites. Surgical viscerolysis is a dangerous operation associated with high mortality in patients with renal failure or cirrhosis.

International audience

International audience