2,880 research outputs found

    A laser diode based system for calibration of fast time-of-flight detectors

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    A system based on commercially available items, such as a laser diode, emitting in the visible range ∼400\sim 400 nm,and multimode fiber patches, fused fiber splitters and optical switches may be assembled,for time calibration of multi-channels time-of-flight (TOF) detectors with photomultipliers' (PMTs') readout. As available laser diode sources have unfortunately limited peak power, the main experimental problem is the tight light power budget of such a system. In addition, while the technology for fused fiber splitters is common in the Telecom wavelength range (λ∼850,1300−1500\lambda \sim 850, 1300-1500 nm), it is not easily available in the visible one. Therefore, extensive laboratory tests had to be done on purpose, to qualify the used optical components, and a full scale timing calibration prototype was built. Obtained results show that with such a system, a calibration resolution (σ\sigma) in the range 20-30 ps may be within reach. Therefore, fast multi-channels TOF detectors, with timing resolutions in the range 50-100 ps, may be easily calibrated in time. Results on tested optical components may be of interest also for time calibration of different light detection systems based on PMTs, as the ones used for detection of the vacuum ultraviolet scintillation light emitted by ionizing particles in large LAr TPCs.Comment: submitted to JINS

    Radiation Hardness tests with neutron flux on different Silicon photomultiplier devices

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    Radiation hardness is an important requirement for solid state readout devices operating in high radiation environments common in particle physics experiments. The MEGII experiment, at PSI, Switzerland, investigates the forbidden decay μ+→e+γ\mu^+ \to \mathrm{e}^+ \gamma. Exploiting the most intense muon beam of the world. A significant flux of non-thermal neutrons (kinetic energy Ek≥0.5 MeVE_k\geq 0.5 ~MeV) is present in the experimental hall produced along the beamline and in the hall itself. We present the effects of neutron fluxes comparable to the MEGII expected doses on several Silicon PhotoMulitpliers (SiPMs). The tested models are: AdvanSiD ASD-NUV3S-P50 (used in MEGII experiment), AdvanSiD ASD-NUV3S-P40, AdvanSiD ASD-RGB3S-P40, Hamamatsu and Excelitas C30742-33-050-X. The neutron source is the thermal Sub-critical Multiplication complex (SM1) moderated with water, located at the University of Pavia (Italy). We report the change of SiPMs most important electric parameters: dark current, dark pulse frequency, gain, direct bias resistance, as a function of the integrated neutron fluency.Comment: 9 pages, 6 figures. Proceedings from Instrumentation for colliding Beam Physics (INSTR-17) 27-02-2017/03-03-2017 Novosibirsk (R

    Design and test of an extremely high resolution Timing Counter for the MEG II experiment: preliminary results

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    The design and tests of Timing Counter elements for the upgrade of the MEG experiment, MEG II,is presented. The detector is based on several small plates of scintillator with a Silicon PhotoMultipliers dual-side readout. The optimisation of the single counter elements (SiPMs, scintillators, geometry) is described. Moreover, the results obtained with a first prototype tested at the Beam Test Facility (BTF) of the INFN Laboratori Nazionali di Frascati (LNF) are presented.Comment: 10 pages, 7 figures. Presented at the 13th Topical Seminar on Innovative Particle and Radiation Detectors (IPRD13) 7-10 October 2013 Siena, Ital

    The Timing Counter of the MEG experiment: calibration and performance

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    The MEG detector is designed to test Lepton Flavor Violation in the μ+→e+γ\mu^+\rightarrow e^+\gamma decay down to a Branching Ratio of a few 10−1310^{-13}. The decay topology consists in the coincident emission of a monochromatic photon in direction opposite to a monochromatic positron. A precise measurement of the relative time te+γt_{e^+\gamma} is crucial to suppress the background. The Timing Counter (TC) is designed to precisely measure the time of arrival of the e+e^+ and to provide information to the trigger system. It consists of two sectors up and down stream the decay target, each consisting of two layers. The outer one made of scintillating bars and the inner one of scintillating fibers. Their design criteria and performances are described.Comment: Presented at the 12th Topical Seminar on Innovative Particle and Radiation Detectors (IPRD10) 7 - 10 June 2010, Siena. Accepted by Nuclear Physics B (Proceedings Supplements) (2011)tal

    Behaviour in Magnetic Fields of Fast Conventional and Fine-Mesh Photomultipliers

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    The performance of both conventional and fine-mesh Hamamatsu photomultipliers has been measured inside moderate magnetic fields. This has allowed the test of effective shielding solutions for photomultipliers, to be used in time-of-flight detectors based on scintillation counters. Both signal amplitude reduction or deterioration of the timing properties inside magnetic fields have been investigated

    Agranulocytosis and hepatic toxicity with ticlopidine therapy: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Ticlopidine is a platelet inhibitor used to prevent thrombosis in patients with cerebrovascular or coronary artery disease. The most common side effects are mild and transitory: diarrhea, dyspepsia, nausea and rashes. More serious, but less frequent, adverse effects are hematological dyscrasia and cholestatic hepatitis. We report a rare case of agranulocytosis associated with hepatic toxicity, probably related to the use of ticlopidine.</p> <p>Case presentation</p> <p>A 70-year-old Caucasian woman, with no previous history of hematological or liver diseases, was treated with ticlopidine 250 mg twice daily immediately after a vertebrobasilar stroke. Upon admission, her blood tests were normal. About four weeks later she developed agranulocytosis and hepatic toxicity. Ticlopidine was discontinued immediately, and aspirin 25 mg and dipyridamole 200 mg were given twice daily. She was treated with hematopoietic growth factors (granulocyte colony stimulating factor), with a rapidly increased white blood count and progressive normalization of liver tests as a result.</p> <p>Conclusion</p> <p>In the first three months following initiation of ticlopidine therapy, regular monitoring of complete blood cell count and of liver function tests is essential for the early detection of serious and unpredictable side effects.</p


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    Presentazione del concorso e del progetto PROMENADE DELL'ARTE E DELLA CULTURA INDUSTRIALE di Politecnico di Torino , Accademia Albertina di Belle Arti e Città di Torino, finanziato nell'ambito del Fondo Europeo di Sviluppo Regionale 2007/2013 - Por Fesr. In www.contemporarytorinopiemonte.it/.../ Portale di Città di Torino, Regione Piemonte e Fondazione per l'Arte Moderna e Contemporanea - CR

    Circularly Polarized Resonant Rayleigh Scattering and Skyrmions in the ν\nu = 1 Quantum Hall Ferromagnet

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    We use the circularly polarized resonant Rayleigh scattering (RRS) to study the quantum Hall ferromagnet at ν\nu = 1. At this filling factor we observe a right handed copolarized RRS which probes the Skyrmion spin texture of the electrons in the photoexcited grounds state. The resonant scattering is not present in the left handed copolarization, and this can be related to the correlation between Skymionic effects, screening and spin wave excitations. These results evidence that RRS is a valid method for the study of the spin texture of the quantum Hall states
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