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203 result(s) for "Maillard, O"
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Recent Developments on Precise Timing with the PICOSEC Micromegas Detector
The PICOSEC-Micromegas detector was developed for precise timing of the arrival of charged particles with a resolution bellow 30 ps. This contribution, after a brief introduction presents results concerning the PICOSEC-Micromegas response to single photoelectrons, estimation of the photoelectron yield of various photocathode types, as well as its performance to time the arrival of test beam muons. In addition, results based on detailed simulation studies and a stochastic model developed for the understanding of the detector are presented. Finally, results of studies related to the development of large scale PICOSEC-Micromegas detector for practical applications are also presented, in particular, the timing performance of a multi-channel PICOSEC prototype.
Micromegas for beam loss monitoring
The early detection of beam losses and the alarm to the machine protection system in accelerators are crucial for the safe operation of the machine. In the low energy region of the hadron accelerators, only neutrons and photons are produced in the case of a beam loss. However, photons are also emitted by electrons at the RF cavities, becoming a natural background for losses identification. A new kind of beam loss monitors have been conceived to extend the sensitivity to the low energy region of the high intensity hadron accelerators. They are based on Micromegas detectors sensitive to fast neutrons. The appropriate configuration of the Micromegas operating conditions will allow a fast response, a sensitivity to small beam losses and a suppressed sensitivity to photons. In this paper the operation principle and the system developed for the European Spallation Source will be presented, with focus on the results obtained at different irradiation facilities. First time proof of operation in real conditions, with the detection of beam losses, will be also shown with measurements performed at LINAC4 (CERN).
Comparing the effects of self-selected music versus predetermined music on patient anxiety prior to gynaecological surgery: a study protocol for a randomised controlled trial
Background Patients undergoing gynaecological surgery are known to experience anxiety. While the use of music selected by patients based on their personal taste has hardly been evaluated, a recent study suggests that musical preferences significantly alter the anxiolytic and relaxing effects of music. Our study aims to determine whether self-selected music decreases patient anxiety prior to gynaecological surgery, as compared with predetermined music from a software programme such as MUSIC CARE®. Methods The study will consist of a clinical trial comparing the effects of self-selected music versus predetermined music on patient anxiety prior to gynaecological surgery. A minimum of 170 patients will be randomised in a 1:1 ratio. Inclusion criteria will be: women aged 18–55 years, awaiting scheduled gynaecological surgery under general/local anaesthesia or under sedation; having created a personal 20-min playlist; and not having received anxiolytic drugs prior to surgery. The primary outcome will be the difference between the preoperative anxiety score taken 15 to 20 min before the music-listening session and the preoperative anxiety score taken shortly after the session, as measured with the STAI for state anxiety. Discussion This study should help to identify more effective non-medical treatments for preoperative anxiety, as well as to adapt music therapy to the cultural context of patients. Trial registration ClinicalTrials.gov, ID: NCT03226834 . Registered on 24 July 2017.
Emergence of High Ampicillin-Resistant Enterococcus faecium Isolates in a Kidney Transplant Ward: Role of Antibiotic Pressure and Cross Transmission
The epidemiology of patients associated with ampicillin-resistant Enterococcus faecium (ARE) was investigated by combining both clinical approach and molecular analysis in a kidney transplant patient's ward. A case–control study was performed to identify risk factors for ARE by matching each patient with ARE with two control patients without any isolated E. faecium strain. ARE isolates were characterized by pulsed-field gel electrophoresis. From June 2004 to May 2006, 18 cases with clinical ARE samples were detected and compared with 35 control patients. By univariate analysis, recurrent urinary tract infections (UTIs) (odds ratio [OR], 4.9; 95% confidence interval [CI], 1.0–25.6), mean number of hospitalization days in the last year ( p  < 0.003), pyelonephritis or UTI (OR, 9.6; 95% CI, 2.2–46.1), oral third-generation cephalosporin use (OR, 12.42; 95% CI, 2.04–109.1), and fluoroquinolone use (OR, 4.4; 95% CI, 1.1–18.2) were significantly associated with ARE urinary tract colonization. By conditional logistic regression, hospitalization >21 days within 1 year (adjusted OR [aOR], 6.9; 95% CI, 1.0–46.5), recent medical history of pyelonephritis or UTI (aOR, 8.6; 95% CI, 1.5–49.1), and prior oral third-generation cephalosporin use (aOR, 13.1; 95% CI, 1.2–142.6) were identified as independent factors associated with ARE urinary tract colonization. Genotyping revealed a heterogeneous epidemiological situation with two major clones in patients hospitalized in successive rooms and 10 different single pulsotypes. Emergence of highly resistant enterococcal strains is a collateral damage from antibiotic prescription and represents a potential source of patient-to-patient transmission. Combining epidemiological approach and molecular analysis is a powerful tool to delineate mechanisms of emerging resistance. Improving our knowledge on ARE emergence in high antibiotic pressure hospital wards is a key factor to better control these colonizations/infections and to prevent the emergence of vancomycin-resistant E. faecium .
Precise timing and recent advancements with segmented anode PICOSEC Micromegas prototypes
Timing information in current and future accelerator facilities is important for resolving objects (particle tracks, showers, etc.) in extreme large particles multiplicities on the detection systems. The PICOSEC Micromegas detector has demonstrated the ability to time 150\\,GeV muons with a sub-25\\,ps precision. Driven by detailed simulation studies and a phenomenological model which describes stochastically the dynamics of the signal formation, new PICOSEC designs were developed that significantly improve the timing performance of the detector. PICOSEC prototypes with reduced drift gap size (\\(\\sim\\)\\SI{119}{\\micro\\metre}) achieved a resolution of 45\\,ps in timing single photons in laser beam tests (in comparison to 76\\,ps of the standard PICOSEC detector). Towards large area detectors, multi-pad PICOSEC prototypes with segmented anodes has been developed and studied. Extensive tests in particle beams revealed that the multi-pad PICOSEC technology provides also very precise timing, even when the induced signal is shared among several neighbouring pads. Furthermore, new signal processing algorithms have been developed, which can be applied during data acquisition and provide real time, precise timing.
Timing performance of a multi-pad PICOSEC-Micromegas detector prototype
The multi-pad PICOSEC-Micromegas is an improved detector prototype with a segmented anode, consisting of 19 hexagonal pads. Detailed studies are performed with data collected in a muon beam over four representative pads. We demonstrate that such a device, scalable to a larger area, provides excellent time resolution and detection efficiency. As expected from earlier single-cell device studies, we measure a time resolution of approximately 25 picoseconds for charged particles hitting near the anode pad centers, and up to 30 picoseconds at the pad edges. Here, we study in detail the effect of drift gap thickness non-uniformity on the timing performance and evaluate impact position based corrections to obtain a uniform timing response over the full detector coverage.
Charged particle timing at sub-25 picosecond precision: the PICOSEC detection concept
The PICOSEC detection concept consists in a \"two-stage\" Micromegas detector coupled to a Cherenkov radiator and equipped with a photocathode. A proof of concept has already been tested: a single-photoelectron response of 76 ps has been measured with a femtosecond UV laser at CEA/IRAMIS, while a time resolution of 24 ps with a mean yield of 10.4 photoelectrons has been measured for 150 GeV muons at the CERN SPS H4 secondary line. This work will present the main results of this prototype and the performance of the different detector configurations tested in 2016-18 beam campaigns: readouts (bulk, resistive, multipad) and photocathodes (metallic+CsI, pure metallic, diamond). Finally, the prospects for building a demonstrator based on PICOSEC detection concept for future experiments will be discussed. In particular, the scaling strategies for a large area coverage with a multichannel readout plane, the R\\&D on solid converters for building a robust photocathode and the different resistive configurations for a robust readout.
PICOSEC: Charged particle timing at sub-25 picosecond precision with a Micromegas based detector
The prospect of pileup induced backgrounds at the High Luminosity LHC (HL-LHC) has stimulated intense interest in developing technologies for charged particle detection with accurate timing at high rates. The required accuracy follows directly from the nominal interaction distribution within a bunch crossing (\\(\\sigma_z\\sim5\\) cm, \\(\\sigma_t\\sim170\\) ps). A time resolution of the order of 20-30 ps would lead to significant reduction of these backgrounds. With this goal, we present a new detection concept called PICOSEC, which is based on a \"two-stage\" Micromegas detector coupled to a Cherenkov radiator and equipped with a photocathode. First results obtained with this new detector yield a time resolution of 24 ps for 150 GeV muons, and 76 ps for single photoelectrons.