Etude d'une matrice de photodiodes a avalanche associee a des cristaux scintillants (LSO et LuAP)

CM

Photon detection with CMOS sensors for fast imaging

International audiencePixel detectors employed in high energy physics aim to detect single minimum ionizing particle with micrometric positioning resolution. Monolithic CMOS sensors succeed in this task thanks to a low equivalent noise charge per pixel of around 10 to 15 e-, and a pixel pitch varying from 10 to a few 10 s of microns. Additionally, due to the possibility for integration of some data treatment in the sensor itself, readout times of have been reached for 100 kilo-pixels sensors. These aspects of CMOS sensors are attractive for applications in photon imaging. For X-rays of a few keV, the efficiency is limited to a few % due to the thin sensitive volume. For visible photons, the back-thinned version of CMOS sensor is sensitive to low intensity sources, of a few hundred photons. When a back-thinned CMOS sensor is combined with a photo-cathode, a new hybrid detector results (EBCMOS) and operates as a fast single photon imager. The first EBCMOS was produced in 2007 and demonstrated single photon counting with low dark current capability in laboratory conditions. It has been compared, in two different biological laboratories, with existing CCD-based 2D cameras for fluorescence microscopy. The current EBCMOS sensitivity and frame rate is comparable to existing EMCCDs. On-going developments aim at increasing this frame rate by, at least, an order of magnitude. We report in conclusion, the first test of a new CMOS sensor, LUCY, which reaches 1000 frames per seco

Performance study of a MegaPixel single photon position sensitive photodetector EBCMOS

International audienceThis development is related to the design and the integration of a Monolithic Active Pixel Sensor (MAPS) into a photosensitive proximity focusing vacuum-based tube. This EBCMOS project is dedicated to the fluorescent and the bioluminescent high speed imaging. The results of the full characterization of the first prototype are presented. Comparative tests with different fluorescent dyes have been performed in biology laboratories. Preliminary conclusions on the ability of EBCMOS to perform fast single-molecule tracking will be given

Test beam results for an upgraded forward tagger of the L3 experiment at LEP II

We have tested new scintillator modules with silicon photodiode readout for the upgraded Active Lead Rings (ALR) of the L3 detector at LEP II. Results are presented from data recorded in muon and electron test beams with particular emphasis on the light production and collection as a function of the particle impact position on the scintillator modules. The results from the beam test data will be used for the design of the readout and trigger electronics in conjunction with the required ALR performance as an electron tagger and beam background monitor at LEP II

First results from the Development of a New Generation of Hybrid Photon Detectors: EBCMOS

International audienceThe proximity focusing Hybrid Photon Detector (HPD) concept is implemented to develop a single photon sensitive Electron Bombarded CMOS (EBCMOS). The first demonstrator has been produced by the collaboration between the EBCMOS group of IPNL, the CMOS sensor group of IPHC and the R&D department of PHOTONIS. The prototype characteristics (dark current, gain, spatial and energy resolutions) are presented. The futur developments of this type of photo detector are discussed

Radiation hardness qualification of PbWO4 scintillation crystals for the CMS Electromagnetic Calorimeter

This is the Pre-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2010 IOPEnsuring the radiation hardness of PbWO4 crystals was one of the main priorities during the construction of the electromagnetic calorimeter of the CMS experiment at CERN. The production on an industrial scale of radiation hard crystals and their certification over a period of several years represented a difficult challenge both for CMS and for the crystal suppliers. The present article reviews the related scientific and technological problems encountered

Intercalibration of the barrel electromagnetic calorimeter of the CMS experiment at start-up

Calibration of the relative response of the individual channels of the barrel electromagnetic calorimeter of the CMS detector was accomplished, before installation, with cosmic ray muons and test beams. One fourth of the calorimeter was exposed to a beam of high energy electrons and the relative calibration of the channels, the intercalibration, was found to be reproducible to a precision of about 0.3%. Additionally, data were collected with cosmic rays for the entire ECAL barrel during the commissioning phase. By comparing the intercalibration constants obtained with the electron beam data with those from the cosmic ray data, it is demonstrated that the latter provide an intercalibration precision of 1.5% over most of the barrel ECAL. The best intercalibration precision is expected to come from the analysis of events collected in situ during the LHC operation. Using data collected with both electrons and pion beams, several aspects of the intercalibration procedures based on electrons or neutral pions were investigated

Orthopedic in-training examination question metrics and resident test performance

First administered in November 1963, the orthopedic in-training examination (OITE) is now distributed to more than 4000 residents in over 20 countries and has become important for evaluation of resident fund of knowledge. Several studies have assessed the effect of didactic programs on resident performance, but only recently has it become possible to assess detailed testtaking metrics such as time spent per question. Here, we report the first assessment of resident OITE performance utilizing this full electronic dataset from two large academic institutions. Full 2015 OITE score reports for all orthopedic surgery residents at two institutions were anonymized and compiled. For every question answered by each resident, the resident year, question content or domain, question result (correct or incorrect), and answer speed were recorded. Data were then analyzed to determine whether resident year, result, or domain affected answer speed and whether performance in each subspecialty domain varied based on resident year in training. Data was available for 46 residents and 12,650 questions. Mean answer speed for questions answered correctly, 54.0±48.1 s, was significantly faster than for questions answered incorrectly, 72.2±61.2 s (P<0.00001). When considering both correct and incorrect answers, PGY-1s were slower than all other years (P<0.02). Residents spent a mean of nearly 80 seconds on foot and ankle and shoulder and elbow questions, compared to only 40 seconds on basic science questions (P<0.05). In education, faster answer speed for questions is often considered a sign of mastery of the material and more confidence in the answer. Though faster answer speed was strongly associated with correct answers, this study demonstrates that answer speed is not reliably associated with resident year. While answer speed varies between domains, it is likely that the majority of this variation is due to question type as opposed to confidence. Nevertheless, it is possible that in domains with more tiered experience such as shoulder, answer speed correlates strongly with resident year and percentage correct

Search for New Physics with Jets and Missing Transverse Momentum in pp collisions at sqrt(s) = 7 TeV

A search for new physics is presented based on an event signature of at least three jets accompanied by large missing transverse momentum, using a data sample corresponding to an integrated luminosity of 36 inverse picobarns collected in proton--proton collisions at sqrt(s)=7 TeV with the CMS detector at the LHC. No excess of events is observed above the expected standard model backgrounds, which are all estimated from the data. Exclusion limits are presented for the constrained minimal supersymmetric extension of the standard model. Cross section limits are also presented using simplified models with new particles decaying to an undetected particle and one or two jets