CVD diamond detector with interdigitated electrode pattern for time-of-flight energy-loss measurements of low-energy ion bunches.

Ion stopping experiments in plasma for beam energies of few hundred keV per nucleon are of great interest to benchmark the stopping-power models in the context of inertial confinement fusion and high-energy-density physics research. For this purpose, a specific ion detector on chemical-vapor-deposition diamond basis has been developed for precise time-of-flight measurements of the ion energy loss. The electrode structure is interdigitated for maximizing its sensitivity to low-energy ions, and it has a finger width of 100 µm and a spacing of 500 µm. A short single α-particle response is obtained, with signals as narrow as 700 ps at full width at half maximum. The detector has been tested with α-particle bunches at a 500 keV per nucleon energy, showing an excellent time-of-flight resolution down to 20 ps. In this way, beam energy resolutions from 0.4 keV to a few keV have been obtained in an experimental configuration using a 100 µg/cm2 thick carbon foil as an energy-loss target and a 2 m time-of-flight distance. This allows a highly precise beam energy measurement of δE/E ≈ 0.04%-0.2% and a resolution on the energy loss of 0.6%-2.5% for a fine testing of stopping-power models.

High-resolution quasi-monochromatic X-ray imaging using a Fresnel phase zone plate and a multilayer mirror.

High-resolution, high-sensitivity X-ray imaging is a real challenge in laser plasma diagnostic to attain reliable data in high-energy density plasma experiments. In this context, ultra-high-intensity lasers generate hot and dense plasma but only in a small volume. An experiment has been performed at the LULI2000 laser facility to diagnose such plasma conditions from thermal spectroscopic data. To image the emission zone plasma's Al Heß, a Fresnel-lens-based X-ray imager has been developed. It features a 846 µm-diameter Fresnel Phase Zone Plate (FPZP) and a Pd/B4C multilayer mirror (thickness d = 5.1 nm). This association can be used between 1500 eV and 2100 eV. The FPZP's efficiency was measured on a synchrotron facility (SOLEIL) and its spatial resolution in a laser facility (EQUINOX). The mirror reflectivity was measured on the synchrotron facility BESSY II. With experimental conditions, the system resolution reaches 3.8 ± 0.6 µm with an adequate efficiency in the 1800 eV-1900 eV energy range with a solid angle of 9 × 10-6 sr. Consequently, a FPZP is an excellent optics setup for high-resolution quasi-monochromatic X-ray imaging and provides a good collection angle. Bragg-Fresnel lenses, based on the principle of FPZP and mirrors, are currently designed for an X-ray imager at the Laser MégaJoule facility.

Performance of Laser Megajoule's x-ray streak camera.

A prototype of a picosecond x-ray streak camera has been developed and tested by Commissariat à l'Énergie Atomique et aux Énergies Alternatives to provide plasma-diagnostic support for the Laser Megajoule. We report on the measured performance of this streak camera, which almost fulfills the requirements: 50-µm spatial resolution over a 15-mm field in the photocathode plane, 17-ps temporal resolution in a 2-ns timebase, a detection threshold lower than 625 nJ/cm2 in the 0.05-15 keV spectral range, and a dynamic range greater than 100.

Picosecond X-ray streak camera dynamic range measurement.

Streak cameras are widely used to record the spatio-temporal evolution of laser-induced plasma. A prototype of picosecond X-ray streak camera has been developed and tested by Commissariat à l'Énergie Atomique et aux Énergies Alternatives to answer the Laser MegaJoule specific needs. The dynamic range of this instrument is measured with picosecond X-ray pulses generated by the interaction of a laser beam and a copper target. The required value of 100 is reached only in the configurations combining the slowest sweeping speed and optimization of the streak tube electron throughput by an appropriate choice of high voltages applied to its electrodes.

First set of gated x-ray imaging diagnostics for the Laser Megajoule facility.

The Laser Megajoule (LMJ) facility located at CEA/CESTA started to operate in the early 2014 with two quadruplets (20 kJ at 351 nm) focused on target for the first experimental campaign. We present here the first set of gated x-ray imaging (GXI) diagnostics implemented on LMJ since mid-2014. This set consists of two imaging diagnostics with spatial, temporal, and broadband spectral resolution. These diagnostics will give basic measurements, during the entire life of the facility, such as position, structure, and balance of beams, but they will also be used to characterize gas filled target implosion symmetry and timing, to study x-ray radiography and hydrodynamic instabilities. The design requires a vulnerability approach, because components will operate in a harsh environment induced by neutron fluxes, gamma rays, debris, and shrapnel. Grazing incidence x-ray microscopes are fielded as far as possible away from the target to minimize potential damage and signal noise due to these sources. These imaging diagnostics incorporate microscopes with large source-to-optic distance and large size gated microchannel plate detectors. Microscopes include optics with grazing incidence mirrors, pinholes, and refractive lenses. Spatial, temporal, and spectral performances have been measured on x-ray tubes and UV lasers at CEA-DIF and at Physikalisch-Technische Bundesanstalt BESSY II synchrotron prior to be set on LMJ. GXI-1 and GXI-2 designs, metrology, and first experiments on LMJ are presented here.

Development of an x-ray imaging system for the Laser Megajoule (LMJ).

This imaging system aims at recording images of the core size and shape of an imploding deuterium-tritium (DT) microballoon on LMJ inertial confinement fusion (ICF) experiments. Image acquisition is difficult due to the harsh surrounding created by the fusion reaction, which affects system specifications. This one is made of a scintillator, an optical relay, and a CCD camera shielded from the surrounding. The system was tested on different facilities at CEA/DIF, where a spatial resolution of 120 µm was achieved and gamma dose up to 20 rad effects were measured. Setup and performed test are described.

The x-ray calibration facility of the laser integration line in the 0.9-10 keV range: the high energy x-ray source and some applications.

The laser integration line (LIL) located at CEA-CESTA is equipped with x-ray plasma diagnostics using different kinds of x-ray components such as filters, mirrors, crystals, detectors, and cameras. The CEA-DAM of Arpajon is currently developing x-ray calibration methods and carrying out absolute calibration of LIL x-ray photodetectors. To guarantee LIL measurements, detectors such as x-ray cameras must be regularly calibrated close to the facility. A new x-ray facility is currently available to perform these absolute x-ray calibrations. This paper presents the x-ray tube based high energy x-ray source delivering x-ray energies ranging from 0.9 to 10 keV by means of an anode barrel. The purpose of this source is mainly to calibrate LIL x-ray cameras but it can also be used to measure x-ray filter transmission of plasma diagnostics. Different x-ray absolute calibrations such as x-ray streak and framing camera yields, x-ray charge-coupled device quantum efficiencies, and x-ray filter transmissions are presented in this paper. A x-ray flat photocathode detector sensitivity calibration recently performed for a CEA Z-pinch facility is also presented.

A versatile high-resolution x-ray imager (HRXI) for laser-plasma experiments on OMEGA.

A high-resolution x-ray imager (HRXI) devoted to laser-plasma experiments combines two state-of-the-art technologies developed in France: a high-resolution x-ray microscope and a high-speed x-ray streak camera. The resulting streaked imager achieves spatial and temporal resolutions of approximately 5 microm and approximately 10 ps, respectively. The HXRI has recorded enhanced spatial and temporal resolution radiographs of indirectly driven targets on OMEGA. This paper describes the main features of the instrument and details the activation process on OMEGA (particularly the alignment). Recent results obtained on joint CEA/LLE radiographic OMEGA experiments will also be presented.

X-ray diagnostic calibration with the tabletop laser facility EQUINOX.

The broadband x-ray emission of a target irradiated by a laser can be used to check the calibration of detectors. At CEA-DIF we have a tabletop picosecond laser facility called EQUINOX with 0.3 J at 800 nm. The laser is focused inside a target chamber onto a solid target and produces bright radiation in the 100-2000 eV spectral range. The x-ray source is routinely monitored with a pinhole camera for source dimension measurement and with x-ray diodes for flux measurement. In addition an x-ray transmission grating spectrometer, a crystal spectrometer, and a single count charge coupled device camera measure the x-ray spectrum between 100 eV and 15 keV. The absolute calibration of those sets of spectrometers allows us to fully characterize x-ray emission spectra. Typical duration is less than 100 ps. The spectrum can be tuned by changing target material, pulse length, and x-ray filters. An application to checking the calibration of x-ray diodes used in the broad band spectrometer DMX with single shots will be presented.

Diagnostics hardening for harsh environment in Laser Megajoule (invited).

The diagnostic designs for the Laser Megajoule (LMJ) will require components to operate in environments far more severe than those encountered in present facilities. This harsh environment will be induced by fluxes of neutrons, gamma rays, energetic ions, electromagnetic radiations, and, in some cases, debris and shrapnel, at levels several orders of magnitude higher than those experienced today on existing facilities. The lessons learned about the vulnerabilities of present diagnostic parts fielded mainly on OMEGA for many years, have been very useful guide for the design of future LMJ diagnostics. The present and future LMJ diagnostic designs including this vulnerability approach and their main mitigation techniques will be presented together with the main characteristics of the LMJ facility that provide for diagnostic protection.

X-ray imaging with grazing-incidence microscopes developed for the LIL program.

This article describes x-ray imaging with grazing-incidence microscopes, developed for the experimental program carried out on the Ligne d'Integration Laser (LIL) facility [J. P. Le Breton et al., Inertial Fusion Sciences and Applications 2001 (Elsevier, Paris, 2002), pp. 856-862] (24 kJ, UV-0.35 nm). The design includes a large target-to-microscope (400-700 mm) distance required by the x-ray ablation issues anticipated on the Laser MégaJoule facility [P. A. Holstein et al., Laser Part. Beams 17, 403 (1999)] (1.8 MJ) which is under construction. Two eight-image Kirkpatrick-Baez microscopes [P. Kirkpatrick and A. V. Baez J. Opt. Soc. Am. 38, 766 (1948)] with different spectral wavelength ranges and with a 400 mm source-to-mirror distance image the target on a custom-built framing camera (time resolution of approximately 80 ps). The soft x-ray version microscope is sensitive below 1 keV and its spatial resolution is better than 30 microm over a 2-mm-diam region. The hard x-ray version microscope has a 10 microm resolution over an 800-microm-diam region and is sensitive in the 1-5 keV energy range. Two other x-ray microscopes based on an association of toroidal/spherical surfaces (T/S microscopes) produce an image on a streak camera with a spatial resolution better than 30 microm over a 3 mm field of view in the direction of the camera slit. Both microscopes have been designed to have, respectively, a maximum sensitivity in the 0.1-1 and 1-5 keV energy range. We present the original design of these four microscopes and their test on a dc x-ray tube in the laboratory. The diagnostics were successfully used on LIL first experiments early in 2005. Results of soft x-ray imaging of a radiative jet during conical shaped laser interaction are shown.

[Joint prosthesis infection with Staphyococcus lugdunensis: 7 cases]. / Infections à Staphylocoque lugdunensis sur prothèses articulaires: à propos de 7 cas.

Staphylococcus lugdunensis was described in Lyon in 1988. This coagulase-negative staphylococcus is the cause of diverse infections which are often severe, particularly in the field cardiology where numerous publications are available for reference. The severity of S. lugdunensis infection is related to specific virulence factors associated with significant adherence properties despite good sensitivity to antibiotics. Publications dealing with joint prosthesis infections are sparse and the reports available have noted failure of treatment unless the prosthesis is removed. S. lugdunensis can easily be identified with an Api Id 32 Staph battery from BioMerieux. We analyzed seven cases of joint prosthesis infections with S. lugdunensis observed between 1991 and 2005. Four chronic infections were managed using the classical schema of implant removal then reimplantation, using a two-stage procedure for three and a single stage for one. Combined with adequate antibiotic treatment, this method was successful in all four cases. We did however have three cases of failure (two were secondary to a probable hematogenic infection and the other an early postoperative infection); these cases were operated on by early lavage and antibiotic therapy without success.

[Ten-year surveillance of nosocomial surgical site infections in an orthopedic surgery department]. / Bilan de 10 ans de surveillance du taux d'infections du site opératoire dans un service d'orthopédie.

PURPOSE OF THE STUDY: Surveillance of nosocomial surgical site infections was instituted in our department in June 1991. We report our first nine years experience. MATERIAL AND METHODS: This study concerned the first 9 years (June 1991-June 2000) of a surveillance program designed to monitor nosocomial surgical site infections in our orthopedic surgery department. During this period 9,696 patients underwent surgery, including 2745 for hip replacements and 1016 for knee replacements. The diagnosis of infection was based on the Centers of Disease Control criteria. Beginning in 1997, the program was widened to include all indications for prophylactic antibiotics, being limited before that time to indications for arthroplasty and spinal surgery. RESULTS: The overall rate of infection was 1.25%; 0.55% for hip arthroplasty and 1.77% for knee arthroplasty. The rate of infection among hip surgery patients over the last 5 years was much higher for prosthesis revision (2.37%) than for first-intention implantations (0.16%). The majority of the isolated strains were Gram-positive (84%) including Staphylococcus sp. found in 65% of the cases. Multiple-strains were found in 23% of the infections. The rate of infection improved very significantly over the last five years both for knee arthroplasty and spinal surgery. The rate remained unchanged for hip arthroplasty. DISCUSSION: This 10-year survey enabled us to analyze the difficulties encountered and pinpoint errors or insufficiencies in data recording. We were also able to identify measures to be taken concerning patient follow-up. The improvement in the rate of infection over time appears to be multifactorial, undoubtedly related to wider use of prophylactic antibiotics, progress in hygiene and sterilization methods with institution of a quality assurance program, and team awareness. CONCLUSION: Surveillance of nosocomial infections is a recommended practice. We have found that the information provided can be beneficial if the data is statistically sound, pointing out the need for progress in patient follow-up.

[Revision of infected total hip prostheses by ablation reimplantation of an uncemented prosthesis. 57 case reports]. / Reprise des prothèses totales de hanche infectées par ablation réimplantation d'une prothèse sans ciment. Expérience de 57 cas.

PURPOSE OF THE STUDY: 57 cases of infected total hip prosthesis treated by removal of the implant and implantation of unncemented prosthesis, were studied to evaluate functional and sepsis results. MATERIAL AND METHODS: 57 patients treated by reimplantation of an uncemented total hip prosthesis after removal of the infected prosthesis were observed. 16 patients underwent a single-stage exchange, 41 a two-stage reimplantation. 46 cases were analysed for infection findings (clinical, radiological and biological assessment) and only 34 cases for functional evaluation (PMA scale, Harris score) with a mean follow-up of 6.6 years. The antibiotic therapy was adapted to each patient but generally, the treatment was prolonged. RESULTS: At follow-up time (which might be too short in time), only 2 patients had a recurrence of infection. One had a single-stage exchange (reoperated by two stage exchange with a good final result at 6 years follow-up), the other a two-stage exchange. In both cases we found that postoperative antibiotic therapy was inadequate. Functional results were better with PMA scale (23 good results of 34) than with Harris score (14 excellent or good results only). 5 patients were reoperated for mechanical implant failure. DISCUSSION: Since 1991, we adopted a standardized procedure to treat chronic infected total hip prosthesis including: routine preoperative aspiration of symptomatic prosthesis; removal of the implant and around debridement followed at a later date (6 weeks) by reimplantation using uncemented implants (hydroxyapatite coated implant). Postoperative antibiotic therapy has to be massive (parenteral bitherapy for at least 21 days after each operative stage) and has to last 6 months after reimplantation. This procedure seems reliable and corroborate the validity of two-stage treatment. The using of uncemented implants allows a good bone reconstruction and does not seem to increase the risk of septic recurrence. CONCLUSION: It is quite difficult to find a hard and fast rule in infected prosthesis treatment, because many factors can influence results. The proposed procedure seems reliable, even if antibiotherapy is long and hard, but requires a strong collaboration between bacteriologist infectiologist and surgeon.

Treatment of 112 bone and joint infections with teicoplanin.

Teicoplanin was used in three hospitals over 6 years in 112 cases of bone or joint infection and the results were reviewed retrospectively. Teicoplanin was used at a dose of 400 mg/day, after a 3-day loading regimen, in combination with other agents, usually netilmicin at the beginning of the treatment. Most infections were chronic (mean duration = 20.9 months) and had failed previous antibiotic or surgical treatment. Gram-positive organisms were isolated in 120/137 identified strains (64 methicillin-resistant Staphylococcus aureus or coagulase négative Staphylococci) and all were susceptible to teicoplanin except one (intermediate for NCCLS norms). Median of follow-up was 17.3 months. The final outcome was clinical cure in 89/98 evaluable cases (91%). There were one improvement, four failures and four recurrences. Adverse events occurred in 11 patients (10%) but did not require any change in treatment. Despite the limitations of a retrospective study, teicoplanin appeared to be effective, well tolerated and easy to use with only one daily injection.RéSUMé: Une étude rétrospective, non comparative, de l'utilisation de la teicoplanine sur 112 cas d'infection ostéo-articulaire pendant 6 ans dans trois hopitaux Français est rapportée. La teicoplanine a été utilisée à la dose de 400 mg/j, après une dose de charge de 3 jours, en association avec d'autres antibiotiques (le plus souvent la netilmycine en début de traitement). Ces infections étaient chroniques (durée d'évolution moyenne de 20,9 mois) et avaient déjà fait l'objet de traitements antérieurs médicaux ou chirurgicaux. Cent vingt cocci gram positif étaient retrouvés sur les 137 souches isolées (64Staphylococus Aureus ou Epidermidis résistant à la methicillin) et tous sauf une (intermédiaire selon les normes NCCLS) étaient sensibles à la teicoplanine. Après une durée de suivi moyenne à 17,3 mois, 89 des 98 cas evaluables (91 %) étaient considérés comme guéris. On retrouvait également 1 amélioration, 4 échecs et 4 récurrences. Un effet secondaire a été noté chez 11 patients (10 %) mais n'a jamais necessité un changement de traitement témoignant ainsi de la bonne tolérance observée avec cette molécule facile à utiliser gràce à une seule injection par jour.

[Neutropenia during treatment with fusidic acid: analysis of 5 cases]. / Neutropénies au cours de traitements par l'acide fusidique: analyse de cinq observations.

Two cases of moderate neutropenia and 3 cases of severe neutropenia in the course of fusidic acid treatment for sepsis related to a hip prothesis or septic osteitis are reported. Neutropenia was always observed following routine blood cell count, after a mean of 21 days' treatment (16 to 27 days). Moderate fever was observed only once, in a patient with profound neutropenia. A complete recovery of blood cell count was noted in all cases, 5 to 9 days upon discontinuation of fusidic acid. A sternal bone-marrow aspiration was performed in 4 cases, showing normocellularity or hypercellularity in two cases, and moderate hypoplasia of granulocytic cells. The respective roles of other treatments are discussed. Overall, these five cases suggest that reversible granulocytopenia can be caused by protracted treatment with fusidic acid. Although nine different associated drugs could also have been involved in four patients, the causal relationship was less suggestive for three of them due to chronological events. In other cases, the drugs never or very rarely caused neutropenia. Finally, the possibility of vancomycin-induced neutropenia cannot be excluded in one case.

[Serum and bronchial concentrations of netilmicin during its continuous intratracheal administration]. / Etude des concentrations sériques et bronchiques au cours de l'administration continue de nétilmicine intratrachéale.

Respiratory tract infections in intensive care units have a high fatality rate, perhaps as a result of the poor diffusion into bronchial secretions of aminoglucosides given by a systemic route. Endotracheal administration of aminoglycosides has been advocated but the optimal dosage remains to be determined. To investigate this problem we studied 13 patients free of renal failure and 6 patients with renal failure. Netilmicin was given by continuous endotracheal infusion in a daily dosage of 3 to 30 mg/kg. A good correlation was found between infused doses and serum concentrations; very high bronchial secretion concentrations were consistently found. There is a significant risk of accumulation in patients with renal failure. The characteristics of the respiratory tract secretions had no influence on the passage of netilmicin into the bloodstream. The dosages we advocate on the basis of our results are 8 mg/kg/day in patients free of renal failure and 4 mg/kg/day in patients with renal failure; serum netilmicin concentrations should not exceed 1 microgram/ml.