The intrinsic electronic properties of diamond make it suitable for radiation-hard and very fast detector development with good signal to noise ratios. With the advent of new generations of ion ...accelerators either for physics (nuclear and high energy physics) or medical applications (hadrontherapy and synchrotron radiation radiotherapy) there is a need for a very accurate beam monitoring in high radiation environments. Diamond is particularly suited to these applications. Fast pulse detection mode for time stamp, and current integration mode for operation as beam monitors at high particle rates are targeted. Commercial single-crystal, polycrystalline and heteroepitaxial diamonds produced by Chemical Vapor Deposited (CVD) method are analyzed and compared by means of X-ray Beam Induced Current (XBIC). Their performance as particle detectors is investigated using a 8.5 keV X-ray photon micro-bunch beam at ESRF (European Synchrotron Radiation Facility). This facility provides a focused (~1 μm) pulsed beam (100 ps bunch duration), producing an almost uniform energy deposit along the beam irradiated volume in the detector, therefore closely mimicking the interaction of single charged particles. The XBIC set-up of the ID21 beamline enabled us to draw 2D response maps of detectors with disk- and strip metal contact patterns. Using the pulse-synchronized XBIC measurements, a time resolution of 150 ps RMS and bunch detection efficiency of ~100% were evaluated at the contact strip crossing points of a first prototype polycrystalline beam monitor.
Display omitted
•Diamond double stripped beam monitor prototypes for hadrontherapy monitoring.•Chemical Vapor Deposited diamond detector performance evaluated under X-rays.•2D current maps evaluated on diamond metallized surface using X-rays micro beams.•Time resolution and bunch detection efficiency at contact strip crossing points.
Radiation tolerance of diamond detectors Bäni, L; Artuso, M; Bachmair, F ...
Journal of physics. Conference series,
11/2022, Volume:
2374, Issue:
1
Journal Article
Peer reviewed
Open access
Diamond is used as detector material in high energy physics experiments due to its inherent radiation tolerance. The RD42 collaboration has measured the radiation tolerance of chemical vapour ...deposition (CVD) diamond against proton, pion, and neutron irradiation. Results of this study are summarized in this article. The radiation tolerance of diamond detectors can be further enhanced by using a 3D electrode geometry. We present preliminary results of a poly-crystalline CVD (pCVD) diamond detector with a 3D electrode geometry after irradiation and compare to planar devices of roughly the same thickness.
In the context of online ion range verification in particle therapy, the CLaRyS collaboration is developing Prompt-Gamma (PG) detection systems. The originality in the CLaRyS approach is to use a ...beam-tagging hodoscope in coincidence with the gamma detectors to provide both temporal and spatial information of the incoming ions. The ion range sensitivity of such PG detection systems could be improved by detecting single ions with a 100ps (σ) time resolution, through a quality assurance procedure at low beam intensity at the beginning of the treatment session. This work presents the investigations that led to assessment of the Chemical Vapor Deposition (CVD) diamond detectors performance to fulfill these requirements. A 90Sr beta source, 68MeV protons, 95 MeV/u carbon ions and a synchrotron X-ray pulsed beam were used to measure the time resolution, single ion detection efficiency and proton counting capability of various CVD diamond samples. An offline technique, based on double-sided readout with fast current preamplifiers used to improve the signal-to-noise ratio, is also presented. The different tests highlighted Time-Of-Flight resolutions ranging from 13ps (σ) to 250ps (σ), depending on the diamond crystal quality and the particle type and energy. The single 68MeV proton detection efficiency of various large area polycrystalline (pCVD) samples was measured to be >96% using coincidence measurements with a single-crystal reference detector. Single-crystal CVD (sCVD) diamond proved to be able to count a discrete number of simultaneous protons while it was not achievable with a polycrystalline sample. Considering the results of the present study, two diamond hodoscope demonstrators are under development: one based on sCVD, and one of larger size based on pCVD. They will be used for the purpose of single ion as well as ion bunches detection, either at reduced or clinical beam intensities.
Background: Two opioid regimens, computer‐simulated to provide optimal general anesthesia in combination with propofol, were compared using clinical criteria.
Methods: Fifty patients undergoing ...thyroid surgery were blindly, prospectively and randomly allocated to receive either (a) i.v. remifentanil (1.5 µg kg−1, followed by 0.2 µg kg−1 min−1) or (b) i.v. sufentanil (0.2 µg kg−1 followed by 0.2 µg kg−1 h−1). Remifentanil infusion was stopped at the last skin suture. Sufentanil infusion was stopped 30 min before the end of surgery. Intravenous propofol was titrated to keep BIS at 50±5. Remifentanil and sufentanil groups were compared with regards to (a) propofol delivery, (b) hemodynamic and recovery variables, and (c) effect‐site propofol levels during a steady‐state period for effect‐site remifentanil and sufentanil levels. P<0.05 was significant.
Results: Groups were similar in demographic data; types and durations of surgery; total propofol consumption; and response, extubation and emergence times. During the steady‐state period for the opioid delivery, the remifentanil and sufentanil effect‐site levels were 5.3 ng ml−1 and 0.18 ng ml−1, respectively (potency ratio=30). In both opioid groups, in accordance with previous computer‐simulations, the effect‐site propofol concentrations remained (a) within a narrow range unaffected by surgical stimuli, (b) significantly smaller in the remifentanil group than in the sufentanil group, but (c) smaller than expected from previous computer‐simulations. More patients required ephedrine following induction of anesthesia in the remifentanil compared with the sufentanil group.
Conclusions: The present clinical trial conducted in thyroid surgery is consistent with previous computer‐simulated opioid‐propofol combinations with respect to intraoperative and recovery variables. Effect‐site propofol ranges were, however, lower than expected.
This paper discusses a detailed design approach to determine the optimal input impedance ( Z_{in} ) and bandwidth (BW) for current preamplifiers in Front End Electronics (FEE) of high-accuracy time ...measurement systems used in particle detection. Our study shows the effect of Z_{in} including the parasitic interconnection inductances of bonding wires between the detector and the FEE. We explain also the development of a new mathematical model for the estimation of the timing jitter of the current preamplifier in the case of using a low capacitor detector ( C_{d} ) as diamond. Tests and measurements of the response of a transimpedance amplifier (TIA) designed in a 130 nm 1P8M CMOS technology are used to demonstrates the accuracy of the design approach and the timing jitter estimation model.
Anesthesia may acutely reveal angle-closure glaucoma. This complication is an ophthalmologic emergency. However, symptoms of acute glaucoma may be overlooked or misinterpreted in a sedated or ...comatose patient, and this may result in delayed treatment. Immediate diagnosis and appropriate treatment should be done to prevent visual loss.
This work reports the testing of a Forward Calorimeter (FoCal) prototype based on an n-type Si pad array detector at the CERN PS accelerator. The FoCal is a proposed upgrade in the ALICE detector ...operating within the pseudorapidity range of 3.2 < \(\mathrm{\eta}\) < 5.8. It aims to measure direct photons, neutral hadrons, vector mesons, and jets for the study of gluon saturation effects in the unexplored region of low momentum fraction x (\(\mathrm{\sim10^{-5} - 10^{-6}}\)). The prototype is a \(\mathrm{8\times9}\) n-type Si pad array detector with each pad occupying one cm\(^2\) area, fabricated on a 6-in, 325~\(\mathrm{\pm 10 \thinspace \mu}\)m thick, and high-resistivity (\(\sim\)7 k\(\Omega \thinspace\) cm) Si wafer which is readout using HGCROCv2 chip. The detector is tested using pion beams of energy 10~GeV and electron beams of energy 1-5~GeV. The measurements of the Minimum Ionizing Particle (MIP) response of pions and the shower profiles of electrons are reported.
Nous rapportons un cas de pneumothorax bilatéral suffocant survenu chez un homme de 36 ans au décours d'une jet ventilation à haute fréquence (JVHF) utilisée pour une endoscopie à visée diagnostique. ...Le patient avait été traité par radiochimiothérapie concomitante deux ans auparavant pour un adénocarcinome oropharyngé, puis par chirurgie pour récidive. L'accident est survenu après l'arrêt de la JVHF au moment du retrait du cathéter transtrachéal de Ravussin. Nous discutons ici les facteurs de risque favorisant la survenue d'un pneumothorax lors de la JVHF avec une attention particulière pour l'effet
trapping et la fibrose pulmonaire.
We report a bilateral tension pneumothorax which occurred in a 36-year-old man after high-frequency jet ventilation (HFJV) for panendoscopy. The patient had been treated with radiotherapy and chimiotherapy two years ago for an oropharyngeal adenocarcinoma, and by surgery for a recurrence. The incident occurred after a cough episode triggered by the withdrawal of the Ravussin transtracheal catheter. We are discussing the risk factors and the mechanisms of pneumothorax during HFJV with special emphasize on trapping and lung fibrosis.
PDF
