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Neutron scattering experiments on well-staged graphite - FeCl/sub 3/

Description: This paper reports results of a neutron diffraction study on both the magnetic and the lattice dynamic structure of graphite-FeCl/sub 3/. The FeCl/sub 3/ system was selected for this study because of the interesting magnetic properties previously reported for this system. Of particular interest is the low temperature magnetic phase transition, which has been shown to be stage dependent. Special emphasis was given to the study of the low temperature magnetic state of the Fe/sup 3 +/ spins and to… more
Date: January 1, 1981
Creator: Axe, J.D.; Majkrzak, C.F.; Passell, L.; Satija, S.K.; Dresselhaus, G. & Mazurek, H.
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Partner: UNT Libraries Government Documents Department
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Martensitic transformation of CsFeS/sub 2/ driven by the singlet to Neel state transition

Description: CsFeS/sub 2/ is regarded as an example of the quasi one-dimensional alternating antiferromagnetic Heisenberg chain above about 70K. In accordance with this picture, an energy gap of 10MeV was observed for the singlet to triplet excitation at a zone center near the transition temperature by our neutron measurements. Large excitation width implies a strong coupling of excitons to phonons, and LA phonons along <001> direction become ill-defined for q greater than 0.3. At about 70K, the first order… more
Date: January 1, 1985
Creator: Ito, Y.; Nishi, M.; Passell, L.; Majkrzak, C.F. & Shirane, G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Polarizing multilayer spectrometer for neutrons

Description: Polarizing neutron monochromators were prepared by sputtering thin-film multilayers with d-spacings from 40 to 85A on large float-glass substrates. Peak reflectivities as great as 90% and polarizing efficiencies of 98% were measured. Increased angular acceptances were obtained by fabricating multilayers with multiple d- spacings. A planned polarized beam spectrometer which incorporates the multilayers and which has a variable energy resolution independent of angular beam divergence is described. more
Date: January 1, 1981
Creator: Majkrzak, C.F.; Passell, L. & Saxena, A.M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Rebuilding the Brookhaven high flux beam reactor: A feasibility study

Description: After nearly thirty years of operation, Brookhaven`s High Flux Beam Reactor (HFBR) is still one of the world`s premier steady-state neutron sources. A major center for condensed matter studies, it currently supports fifteen separate beamlines conducting research in fields as diverse as crystallography, solid-state, nuclear and surface physics, polymer physics and structural biology and will very likely be able to do so for perhaps another decade. But beyond that point the HFBR will be running o… more
Date: January 1, 1995
Creator: Brynda, W. J.; Passell, L. & Rorer, D. C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Optimization of the Hyspec Design Using Monte Carlo Simulations.

Description: HYSPEC is a direct geometry spectrometer to be installed at the SNS [1] on beamline 14B where it will view a cryogenic coupled hydrogen moderator, The ''hybrid'' design combines time-of-flight spectroscopy with focusing Bragg optics to provide a high monochromatic flux on small single crystal samples, with a very low background at an extended detector bank. The instrument is optimized for an incident energy range of 3-90meV. It will have a medium energy resolution (2-10%) and will provide a flu… more
Date: April 25, 2005
Creator: Ghosh, V. J.; Hagen, M. E.; Leonhardt, W. J.; Zaliznyak, I.; Shapiro, S. M. & Passell, L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The Methods of Producing and Analyzing Polarized Neutron Beams for Hyspec at the SNS.

Description: The Hybrid Spectrometer (HYSPEC), under construction at the SNS on beam line 14B, is the only inelastic scattering instrument designed to enable polarization of the incident and the scattered neutron beams. A Heusler monochromator will replace the graphite crystal for producing polarized neutrons. In the scattered beam it is planned to use a collimator--multi-channel supermirror bender array to analyze the polarization of the scattered beam over the final energy range from 5-20 meV. Other metho… more
Date: April 25, 2005
Creator: Shapiro, S. M.; Passell, L.; Zaliznyak, A.; Ghosh, V. J.; Leonhardt, W. L. & Hagen, M. E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Absolute measurement of the critical scattering cross section in cobalt

Description: Small-angle neutron scattering techniques have been used to study the angular distribution of the critical scattering from cobalt above T/sub c/. These measurements have been put on an absolute scale by calibrating the critical scattering directly against the nuclear incoherent scattering from cobalt. In this way the interaction range r$sub 1$, which appears in the classical and modified Ornstein--Zernike expressions for the asymptotic form of the spin pair correlation function and is related t… more
Date: January 1, 1975
Creator: Glinka, C. J.; Minkiewicz, V. J. & Passell, L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Preliminary analysis of gain measurements at the HFBR liquid hydrogen moderator

Description: The High Flux Beam Reactor (HFBR) is a 60 MW steady state neutron source. As part of the facility a cold neutron source is included in one of the beam tubes (H-9). The arrangement of this source is shown in Figure 1, which shows the reactor core, beam tube H-9, and the cold source with its attached helium cooling lines and hydrogen feed lines. The liquid hydrogen chamber is in the shape of an oblate spheroid and has a volume of 1.466 liters, and an aspect ratio of 1:3. Aluminum is used as the m… more
Date: May 1, 1998
Creator: Ludewig, H.; Aronson, A.; Todosow, M.; Passell, L. & Wildgruber, U.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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