Performance of prototypes for the ALICE electromagnetic calorimeter

The performance of prototypes for the ALICE electromagnetic sampling calorimeter has been studied in test beam measurements at FNAL and CERN. A $4\times4$ array of final design modules showed an energy resolution of about 11% /$\sqrt{E(\mathrm{GeV})}$ $\oplus$ 1.7 % with a uniformity of the response to electrons of 1% and a good linearity in the energy range from 10 to 100 GeV. The electromagnetic shower position resolution was found to be described by 1.5 mm $\oplus$ 5.3 mm /$\sqrt{E \mathrm{(GeV)}}$. For an electron identification efficiency of 90% a hadron rejection factor of $>600$ was obtained.Comment: 10 pages, 10 figure

Progress Report on Target Development

The present document is the D08 deliverable report of work package 1 (Target Development) from the MEGAPIE TEST project of the 5th European Framework Program. Deliverable D08 is the progress report on the activities performed within WP 1. The due date of this deliverable was the 5th month after the start of the EU project. This coincided with a technical status meeting of the MEGAPIE Initiative, that was held in March 2002 in Bologna (Italy). The content of the present document reflects the status of the MEGAPIE target development at that stage. It gives an overview of the Target Design, the related Design Support activities and the progress of the work done for the safety assessment and licensing of the target

Anisotropic Magnetic Resonance in Random Nanocrystal Quantum Dot Ensembles

Magnetic anisotropy critically determines the utility of magnetic nanocrystals (NCs) in new nanomagnetism technologies. Using angular-dependent electron magnetic resonance (EMR), we observe magnetic anisotropy in isotropically arranged NCs of a nonmagnetic material. We show that the shape of the EMR angular variation can be well described by a simple model that considers magnetic dipole-dipole interactions between dipoles randomly located in the NCs, most likely due to surface dangling bonds. The magnetic anisotropy results from the fact that the energy term arising from the magnetic dipole-dipole interactions between all magnetic moments in the system is dominated by only a few dipole pairs, which always have an anisotropic geometric arrangement. Our work shows that magnetic anisotropy may be a general feature of NC systems containing randomly distributed magnetic dipoles

LiSoR, a liquid metal loop for material investigation under irradiation

LiSoR is a liquid metal loop that will use PSI's 72 MeV Philips cyclotron to irradiate stressed steel specimens in contact with flowing lead-bismuth with 50µA proton beam. LiSoR is a joint effort of PSI and SUBATECH with the support from CNRS and the Institute of Physics from Riga. It has been initiated to explore whether or not liquid metal corrosion and liquid metal embrittlement are enhanced under irradiation in the presence of stress. Numerical simulations showed that the damage levels and gas production in thin specimens induced by 72 MeV protons are, within reasonable limits, comparable to those on the inside of the beam window of a spallation target at 600 MeV, while much less radioactivity is produced. The paper describes the basic features of the experiment, the technical concept of the liquid metal loop with a special emphasis on the test section exposed to the proton beam and some of the relevant safety aspects

XEMIS2: A liquid xenon Compton camera to image small animals

International audienc

Studies and optimization of scintillation light measurements for the development of the 3-gamma medical imaging XEMIS2 liquid xenon compton camera

International audienceWe report the studies and optimization of scintillation light measurements in an updated version of the XEMIS1 prototype for the development of the XEMIS2 camera. A novel monolithic liquid xenon Compton camera, named XEMIS2 (XEnon Medical Imaging System), attempts to achieve low-activity small-animal imaging using the 3-gamma imaging technique. This emerging detector relies on the time projection chamber technique: it will be able to perform a simultaneous detection of the three γ-rays emitted by a specific radionuclide, such as scandium-44, and to produce a good quality image with a remarkable diminution of radiopharmaceutical activity at the same time. Vacuum Ultraviolet (VUV) scintillation light and ionization charge carriers generated from the recoiling particles within the detector are detected and used to reconstruct the interaction position and deposited energy. A cost-effective self-triggering scintillation signal read-out and data acquisition (DAQ) system has been developed to achieve a continuous data read-out with negligible electronics dead time. The DAQ prototype has been installed and qualified in an updated version of the XEMIS1 detector. It reaches the performance specifications in scintillation light measurements. Moreover, scintillation signals can also be used for the virtual segmentation of the monolithic detection volume through the matching algorithm of the scintillation and ionization signals based on the Light Collection Map (LCM). This spatial pre-localization of the physical events, called the virtual fiducialization of the active volume, is used to lower the detector occupancy rate when the administered activity is increased to lessen the examination time. The XEMIS1 experimental LCMs indicate that each PMT owns an individual field of view so as to segment the active volume virtually. The preparation work for the XEMIS2 camera operation has been completed in the updated XEMIS1 detector while the XEMIS2 scintillation light measurement system is under commissioning in Nantes Centre Hospitalier Universitaire. •The XEMIS2 camera oriented to the whole-body small animal 3-gamma medical imaging is presented.•The XEMIS2 system is a monolithic liquid xenon Compton camera with a 24 cm axial field of view.•A cost-effective 16-channel self-triggering scintillation signal front-end read-out electronics named XSRETOT is reported.•The XEMIS1 experimental light collection maps can be used for the virtual segmentation of the monolithic detection volume

Physiotherapist prediction of extubation outcome in the adult intensive care unit.

ObjectiveMost patients requiring intubation and mechanical ventilation are extubated successfully at the first attempt; however, a minority experience extubation failure, which is associated with increased risk of ventilator-associated pneumonia, prolonged intensive care unit (ICU) length of stay and mortality. Physiotherapists have expertise to assess cough strength, work of breathing, respiratory muscle strength, and respiratory secretion load, which are important factors in the outcome of extubation. Accurate prediction of extubation outcome could help to inform management plans pre-extubation and postextubation. The primary objective of this service evaluation was to report the accuracy of physiotherapists' prediction of extubation outcome in the adult ICU.MethodsA single-centre case note review was undertaken. All subjects who received a physiotherapy assessment of extubation suitability prior to extubation between January and March 2016 in the adult ICU of a large teaching hospital in the United Kingdom were included. Assessment, by both specialist and nonspecialist physiotherapists-which included risk stratification of extubation failure as "high," "moderate," or "low"-was undertaken prior to extubation. Logistic regression analysis was performed to determine which pre-extubation factors were predictive of extubation outcome.ResultsDuring the evaluation period, 68 subjects were extubated following a physiotherapy assessment. Physiotherapy risk stratification as "high risk" (OR 4; 95% confidence interval, CI, [1.312]; p=0.009) and "inappropriate" neurological status (OR 3.3; 95% CI [1.0410]; p=0.037) were the only pre-extubation factors significantly associated with extubation failure. Assessment by specialist physiotherapists demonstrated greater sensitivity (100% vs. 22%) but lower specificity (68% vs. 95%) to detect extubation failure compared with the assessment performed by nonspecialist physiotherapists.ConclusionPatients classified as "high risk" of extubation failure by a physiotherapist are significantly more likely to fail extubation. Specialist physiotherapists should be involved in the decision to extubate patients in the adult ICU

XEMIS2: A liquid xenon detector for small animal medical imaging

International audienceWe report a new liquid xenon Compton camera, called XEMIS2 (XEnon Medical Imaging System), developed to image for the first time small animals using 3 γ imaging. This technique proposes an alternative to reduce the administered radiopharmaceutical activity while preserving diagnostic image quality using liquid xenon as detection medium. Given the success of its predecessor, a small dimension liquid xenon time projection chamber called XEMIS1, we are currently building a larger scale detector for preclinical applications. This second prototype, XEMIS2, is a single phase liquid xenon cylindrical camera with a large axial field of view for full-body small animal imaging. XEMIS2 holds around 200 kg of xenon and it has been designed to enable high-efficiency and simultaneous detection of the three γ -rays emitted by a 44Sc radionuclide. The innovative geometry of XEMIS2 will allow to discriminate and measure the position and deposited energy of most Compton interactions inside the detector. In order to manage such a large quantity of xenon, an innovative high-pressure subsystem known as ReStoX has been developed and successfully qualified. ReStoX allows to maintain the xenon in liquid state at the desired temperature and pressure, transfer the xenon into XEMIS2 and store it during long term periods. XEMIS2 will be installed at a non controlled radioactive area of Nantes Hospital. The goal is to evaluate image quality of a 20 min whole-body preclinical exam with an injected activity of 20 kBq

XEMIS: Liquid Xenon Compton Camera for 3γ Imaging

International audienceAn innovative liquid xenon Compton camera project, XEMIS (XEnon Medical Imaging System) has been proposed by SUBATECH laboratory, for a new functional medical 3γ imaging technique based on the detection in coincidence of 3 γ-rays. The purpose of this 3γ imaging modality is to obtain a 3D image using 100 times less activity than in current PET systems. The combination of a liquid xenon time projection chamber (LXe TPC) and a specific (β$^{+}$, γ) radionuclide emitter$^{44}$Sc is investigated in this concept. In order to provide an experimental demonstration for the use of a LXe Compton camera for 3γ imaging, a succession of R&D programs, XEMIS1 and XEMIS2, have been carried out using innovative technologies. The first prototype XEMIS1 has been successfully validated showing very promising results for energy, spatial and angular resolutions with an ultra-low noise front-end electronics. The second phase dedicated to a 3D imaging of small animals, XEMIS2, is now under installation and qualification, while the characterizations of ionization signal using Monte Carlo simulation has shown preliminary good performances for energy measurement

Scintillation Signal in XEMIS2, a Liquid Xenon Compton Camera with 3γ Imaging Technique

International audienceThe XEMIS project (XEnon Medical Imaging System), which makes use of 3γ imaging technique and liquid xenon Compton camera, aims to make a precise 3D localization of a specific radioactive emitter and to reduce drastically (100 times less) the injected activity to the patient in cancer diagnosis. The 3γ imaging is characterized by the simultaneous detection of 3 γ-rays emitted by$^{44}$Sc which is a (β+, γ) emitter. The second prototype XEMIS2 is a liquid xenon cylindrical camera for small animal imaging. The active volume of XEMIS2 is surrounded by a set of VUV-sensitive Hamamatsu photomultipliers, for the scintillation signals detection. A pulse-shaping amplifier was tested in XEMIS1 for the readout of the scintillation signal of the PMT. The typical output pulse shows a relatively good performance of the pulse-shaping amplifier providing a possible solution for XEMIS2 scintillation DAQ. Meanwhile, the pulse-shaping amplifier and the constant fraction discriminator (CFD) have lay the foundation of the preliminary design of XEMIS2 scintillation signal detection chain