3,230 research outputs found
First results on radiation damage in PbWO4 crystals exposed to a 20 GeV/c proton beam
We have exposed seven full length production quality crystals of the
electromagnetic calorimeter (ECAL) of the CMS detector to a 20 GeV/c proton
beam at the CERN PS accelerator. The exposure was done at fluxes of 10**12
p/cm**2/h and 10**13 p/cm**2/h and integral fluences of 10**12 p/cm**2 and
10**13 p/cm**2 were reached at both rates. The light transmission of the
crystals was measured after irradiation and suitable cooling time for induced
radioactivity to decrease to a safe level. First results of these measurements
are shown. The possible damage mechanisms are discussed and simulations based
on one possible model are presented. The implications for long-term operation
of CMS are discussed and it is shown that in the whole barrel and at least most
of the ECAL endcap hadron damage alone - even if cumulative - should not cause
the crystals to fail the CMS specification of an induced absorption coefficient
muIND < 1.5 /m during the first 10 years of LHC operation.Comment: 5 pages, to be published in Proc. ICATPP Conference on Astroparticle,
Particle, Space Physics, Detectors and Medical Physics Applications (Como,
Italy, 6 to 10 October 2003
High-energy proton induced damage study of scintillation light output from PbWO4 calorimeter crystals
Eight PbWO4 crystals produced for the electromagnetic calorimeter of the CMS
experiment at LHC have been irradiated in a 20 GeV/c proton beam up to fluences
of 5.4 E13 p/cm2. The damage recovery in these crystals, stored in the dark at
room temperature, has been followed for over a year. Comparative irradiations
with 60Co photons have been performed on seven other crystals using a dose rate
of 1 kGy/h. The issue whether hadrons cause a specific damage to the
scintillation mechanism has been studied through light output measurements on
the irradiated crystals using cosmic rays. The correlation between light output
changes and light transmission changes is measured to be the same for
proton-irradiated crystals and for gamma-irradiated crystals. Thus, within the
precision of the measurements and for the explored range of proton fluences, no
additional, hadron-specific damage to the scintillation mechanism is observed.Comment: 7 pages, 4 figure
Young children’s experiences of music and soundings in museum spaces: lessons, trends and turns from the literature
This article considers the value and role of early years music and sound activities in museum spaces – in relation to children themselves, as well as to their families and wider communities. The article reviews literature around early years music and sound activities; early childhood and the museum; and the use of music and sound in museum spaces – reflecting on reconceptualisation’s of the child within museum spaces and in relation to music and sound. In particular, the article highlights gaps in the literature that present an opportunity to explore the role of music and sound with young children (and particularly with so-called ‘hard-to-reach’ communities or families) within museums
Aristoteles, retoriikka ja sijoittajasuhteet
Aristoteleen Retoriikka ei edelleenkään ole
pelkkä historiallinen kuriositeetti. Paitsi että
se on tärkeä oman aikansa merkkiteos, sen
sivut kuluvat myös tämän päivän retorisesta
vaikuttamisesta kiinnostuneiden käsissä. Aristoteleen
ajatukset ja keskeiset käsitteet ovat
säilyttäneet voimansa, mutta samalla niiden
historiallinen painolasti asettaa omat haasteensa
niiden käytölle. Tämä artikkeli käsittelee
talouselämän retoriikan avulla sitä, miten
historian haasteeseen voi yrittää vastata. Lähtökohtani
on, että Aristoteleen oppi puheen
lajeista voi toimia omalle ajallemme ajankohtaisessa,
sijoittajasuhdeviestinnän piiriin kuuluvassa materiaalissa
Electrical conduction mechanisms of metal / high- T c superconductor (YBCO) interfaces
Current-voltage characteristics of Au/YBa2Cu3Ointerfaces (Au/YBCO), built on optimally-doped YBCO thin films, grown by pulsed laser deposition, were measured as a function of temperature in the 50 K to 270 K range, for two different resistance states. A non-trivial equivalent circuit model is proposed, which reveals the existence of a highly inhomogeneous scenario composed by two complex layers: one presenting both a non-linear Poole-Frenkel conduction as well as variable range hopping localization effects (probably associated with YBa2Cu3O6) mixed with a minor metallic phase, while the other is also composed by a mixture of YBCO with different oxygen contents, where a metallic ohmic phase still percolates. A microscopic description of the effects produced by the resistance switching is given, showing the evolution of carrier traps, localization effects and dielectric behavior for each state. The dielectric behavior is interpreted in terms of a Maxwell-Wagner scenario.Fil: Lanosa, Leandro Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Huhtinen, H. University of Turku; FinlandiaFil: Paturi, P. University of Turku; FinlandiaFil: Acha, Carlos Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentin
Wire scanners in low energy accelerators
Fast wire scanners are today considered as part of standard instrumentation
in high energy synchrotrons. The extension of their use to synchrotrons working
at lower energies, where Coulomb scattering can be important and the transverse
beam size is large, introduces new complications considering beam heating of
the wire, composition of the secondary particle shower and geometrical
consideration in the detection set-up. A major problem in treating these
effects is that the creation of secondaries in a thin carbon wire by a
energetic primary beam is difficult to describe in an analytical way. We are
here presenting new results from a full Monte Carlo simulation of this process
yielding information on heat deposited in the wire, particle type and energy
spectrum of secondaries and angular dependence as a function of primary beam
energy. The results are used to derive limits for the use of wire scanners in
low energy accelerators.Comment: 20 pages, 8 Postscript figures, uses elsart.cl
Sacral Neuromodulation: Foray into Chronic Pelvic Pain in End Stage Endometriosis
Copyright (C) 2017 Maija Lavonius et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Excision of all endometriotic lesions is the method of choice in the treatment of severe endometriosis resistant to medical therapy. The infiltrating nature of the disease as well as extensive surgery may, however, cause chronic pain that cannot be relieved by either surgery or hormonal treatment. As a pilot treatment, we tested the effect of sacral neuromodulation (SNM) for four endometriosis patients suffering chronic pelvic pain and pelvic organ dysfunction after radical surgical treatment. Three out of four patients reported improvement in their symptoms during the neuromodulation testing period and a permanent pulse generator was installed. After 2.5 years, all three patients report better quality of life and want to continue with SNM
Transport properties of resistive switching in Ag/Pr0.6Ca0.4MnO3/Al thin film structures
Thin films of Pr0.6Ca0.4MnO3 were prepared by pulsed laser deposition with an asymmetric pair of Ag and Al metal electrodes in order to study their resistive switching properties. The devices exhibited stable voltage controlled bipolar switching which proved to be reliable and non-volatile. The resistive states show a well-defined dependence on the write voltage, which was used to achieve several intermediate states, indicating that the devices could be utilized in hardware implementations of neuromorphic computing. The switching mechanism was attributed to the electric-field assisted migration of oxygen vacancies at the Al-electrode interface, resulting in a formation and modulation of a rectifying interfacial AIO(x) layer. The current-voltage characteristics were analyzed by means of the power exponent representation, which hinted to a device state dependent interplay of bulk-limited Poole-Frenkel conduction and interface-limited Schottky conduction. A deeper understanding of resistive switching characteristics in Ag/Pr0.6Ca0.4MnO3/Al will lead towards further advances in manganite-based neuromorphic circuits. (C) 2019 The Authors. Published by Elsevier B.V
Effect of ex situ Post-annealing Treatments on Sr2FeMoO6 Thin Films
Magnetoresistive Sr2FeMoO6 thin films were grown by pulsed laser deposition at optimized deposition atmosphere and temperature. Films were then ex situ post-annealed in different atmospheres and by vacuum annealing at temperatures between 500 A degrees C and 1100 A degrees C. Ar and air annealed samples were destroyed by ex situ post-annealing treatment, due to formation and dominance of SrMoO4 impurity phase. X-ray diffraction showed no impurities and full texturation of vacuum and ArH2 (5%) annealed samples. Those samples showed also similar magnetic and magnetoresistive behavior like as-deposited sample. Neither magnetic, magnetotransport nor structural properties could be improved by ex situ post-annealing treatments
- …