8,173 research outputs found

    Analytical method for designing grating compensated dispersion-managed soliton systems

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    This paper was published in Journal of Optical Society of America B and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/abstract.cfm?URI=JOSAB-21-4-706. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law. Ā© 2004 The Optical Society.Peer reviewedPublisher PD

    The Radon Monitoring System in Daya Bay Reactor Neutrino Experiment

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    We developed a highly sensitive, reliable and portable automatic system (H3^{3}) to monitor the radon concentration of the underground experimental halls of the Daya Bay Reactor Neutrino Experiment. H3^{3} is able to measure radon concentration with a statistical error less than 10\% in a 1-hour measurement of dehumidified air (R.H. 5\% at 25āˆ˜^{\circ}C) with radon concentration as low as 50 Bq/m3^{3}. This is achieved by using a large radon progeny collection chamber, semiconductor Ī±\alpha-particle detector with high energy resolution, improved electronics and software. The integrated radon monitoring system is highly customizable to operate in different run modes at scheduled times and can be controlled remotely to sample radon in ambient air or in water from the water pools where the antineutrino detectors are being housed. The radon monitoring system has been running in the three experimental halls of the Daya Bay Reactor Neutrino Experiment since November 2013

    Space-charge-limited flows in the quantum regime

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    This paper reviews the recent developments of space-charge-limited (SCL) flow or Child-Langmuir (CL) law in the quantum regime. According to the classical CL law for planar diodes, the current density scales as 3/23āˆ•2ā€™s power of gap voltage and to the inverse squared power of gap spacing. When the electron de Broglie wavelength is comparable or larger than the gap spacing, the classical SCL current density is enhanced by a large factor due to electron tunneling and exchange-correlation effects, and there is a new quantum scaling for the current density, which is proportional to the 1/21āˆ•2ā€™s power of gap voltage, and to the inverse fourth-power of gap spacing. It is also found that the classical concepts of the SCL flow such as bipolar flow, transit time, beam-loaded capacitance, emitted charge density, and magnetic insulation are no longer valid in quantum regime. In the quantum regime, there exists a minimum transit time of the SCL flows, in contrast to the classical solution. By including the surface properties of the emitting surface, there is a threshold voltage that is required to obtain the quantum CL law. The implications of the Fowler-Nordheim-like field emission in the presence of intense space charge over the nanometer scale is discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87757/2/056701_1.pd

    UTJECAJ RELIGIOZNOSTI I DUHOVNOSTI NA SVAKODNEVNU PRAKSU SOCIJALNIH RADNIKA

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    Although social work can trace the roots of its establishment as a profession to religion/spirituality, the relationship between social work and religion/spirituality has deteriorated due to the formerā€™s professionalisation and secularisation. Nevertheless, religious/spiritual values are important for many social work services and for the practice of the profession. It is, hence, worth demarcating the role of religion/spirituality for frontline social workers. In the current qualitative study, repeated interviews were conducted with 11 Chinese social workers from diverse social work settings. It was noted that Eastern and Western religion/spirituality can instil meaning and value in the professionā€™s nature.Iako se uspostavljanje socijalnog rada kao profesije temelji na religIoznosti/duhovnosti, odnos između socijalnog rada i religioznosti/duhovnosti naruÅ”en je zbog profesionalizacije i sekularizacije socijalnog rada. Usprkos tome, religiozne/duhovne vrijednosti važne su za mnoge usluge socijalnog rada i za praksu socijalnog rada kao profesije. Stoga je važno utvrditi ulogu religioznosti/duhovnosti za najizloženije socijalne radnike. U ovom kvalitativnom istraživanju provedeni su ponovljeni razgovori s 11 kineskih socijalnih radnika iz različitih područja socijalnog rada. Uočeno je da istočnjačka i zapadnjačka religioznost/duhovnost mogu unijeti značenje i vrijednost u prirodu profesije

    Measurement of Cosmic-ray Muons and Muon-induced Neutrons in the Aberdeen Tunnel Underground Laboratory

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    We have measured the muon flux and production rate of muon-induced neutrons at a depth of 611 m water equivalent. Our apparatus comprises three layers of crossed plastic scintillator hodoscopes for tracking the incident cosmic-ray muons and 760 L of gadolinium-doped liquid scintillator for producing and detecting neutrons. The vertical muon intensity was measured to be IĪ¼=(5.7Ā±0.6)Ɨ10āˆ’6I_{\mu} = (5.7 \pm 0.6) \times 10^{-6} cmāˆ’2^{-2}sāˆ’1^{-1}srāˆ’1^{-1}. The yield of muon-induced neutrons in the liquid scintillator was determined to be Yn=(1.19Ā±0.08(stat)Ā±0.21(syst))Ɨ10āˆ’4Y_{n} = (1.19 \pm 0.08 (stat) \pm 0.21 (syst)) \times 10^{-4} neutrons/(Ī¼ā‹…\mu\cdotgā‹…\cdotcmāˆ’2^{-2}). A fit to the recently measured neutron yields at different depths gave a mean muon energy dependence of āŸØEĪ¼āŸ©0.76Ā±0.03\left\langle E_{\mu} \right\rangle^{0.76 \pm 0.03} for liquid-scintillator targets.Comment: 14 pages, 17 figures, 3 table

    Scattering of positrons and electrons by alkali atoms

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    Absolute total scattering cross sections (Q sub T's) were measured for positrons and electrons colliding with sodium, potassium, and rubidium in the 1 to 102 eV range, using the same apparatus and experimental approach (a beam transmission technique) for both projectiles. The present results for positron-sodium and -rubidium collisions represent the first Q sub T measurements reported for these collision systems. Features which distinguish the present comparisons between positron- and electron-alkali atom Q sub T's from those for other atoms and molecules (room-temperature gases) which have been used as targets for positrons and electrons are the proximity of the corresponding positron- and electron-alkali atom Q sub T's over the entire energy range of overlap, with an indication of a merging or near-merging of the corresponding positron and electron Q sub T's near (and above) the relatively low energy of about 40 eV, and a general tendency for the positron-alkali atom Q sub T's to be higher than the corresponding electron values as the projectile energy is decreased below about 40 eV
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