Optimum velocity of a phase-space transformer for cold-neutron backscattering spectroscopy

2011 ◽  
Vol 44 (3) ◽  
pp. 467-472 ◽  
Author(s):  
Marcus Hennig ◽  
Bernhard Frick ◽  
Tilo Seydel
Keyword(s):  
Phase Space ◽  
Cold Neutron ◽  
Inelastic Neutron Scattering ◽  
Bragg Reflection ◽  
Analytical Framework ◽  
High Energy ◽  
Inelastic Neutron ◽  
High Energy Resolution ◽  
Rotating Disc ◽  
Incident Wavelength

Cold-neutron backscattering spectrometers are designed for inelastic neutron scattering experiments at a high energy resolution, where 0.5 µeV FWHM can routinely be achieved at the incident wavelength λ ≃ 6.3 Å. The phase-space transformation (PST) technique can be used to enhance the neutron flux at the sample position of such backscattering spectrometers at the expense of an acceptable increase of the beam divergence. Technically, the PST is achieved by a rotating disc carrying mosaic crystals on its circumference. Here a new analytical framework to describe the Bragg reflection of a divergent polychromatic beam from a moving mosaic crystal is discussed. Results obtained using this framework are compared with detailed Monte Carlo numerical simulations. The results presented here provide a deeper understanding of the PST and in particular of the optimum circumferential crystal speed of a PST device.

High Energy-Resolution Inelastic Neutron Scattering Experiments on Triplet Bound State Excitations in SrCu2(BO3)2

2005 ◽  
Vol 74 (8) ◽  
pp. 2189-2192 ◽  
Author(s):  
Naofumi Aso ◽  
Hiroshi Kageyama ◽  
Katsuyuki Nukui ◽  
Masakazu Nishi ◽  
Hiroaki Kadowaki ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Energy Resolution ◽  
Inelastic Neutron Scattering ◽  
Bound State ◽  
High Energy ◽  
Inelastic Neutron ◽  
High Energy Resolution

scholarly journals Inelastic Neutron Scattering from Ice and Other Proton-containing Substances

1978 ◽  
Vol 21 (85) ◽  
pp. 231-240 ◽  
Author(s):  
Bruno Dorner
Keyword(s):  
Neutron Scattering ◽  
Phonon Dispersion ◽  
Inelastic Neutron Scattering ◽  
Rotational Diffusion ◽  
High Energy ◽  
Inelastic Neutron ◽  
High Energy Resolution ◽  
Very High Energy ◽  
Proton Disorder ◽  
The Difference

Abstract A brief introduction to neutron scattering is given with special emphasis on the difference between coherent and incoherent contributions. The following report of recent work on ice contains the determination and verification of some phonon dispersion curves, and outlines the state of the art on diffuse scattering due to the proton disorder. Results on “two-dimensional ice” in copper formate tetrahydrate are of great interest as this system exhibits a phase transformation below which the protons are ordered. The study of rotational diffusion and of the tunnel splitting of the rotational ground state of molecules which contain protons is discussed in some detail. These investigations are now possible with very high energy resolution ΔE ≈ 5 × 10-8 eV (4 • 10-4 cm- 1 or 12 MHz).

Inelastic Neutron Scattering from Ice and Other Proton-containing Substances

1978 ◽  
Vol 21 (85) ◽  
pp. 231-240
Author(s):  
Bruno Dorner
Keyword(s):  
Neutron Scattering ◽  
Phonon Dispersion ◽  
Inelastic Neutron Scattering ◽  
Rotational Diffusion ◽  
High Energy ◽  
Inelastic Neutron ◽  
High Energy Resolution ◽  
Very High Energy ◽  
Proton Disorder ◽  
The Difference

AbstractA brief introduction to neutron scattering is given with special emphasis on the difference between coherent and incoherent contributions. The following report of recent work on ice contains the determination and verification of some phonon dispersion curves, and outlines the state of the art on diffuse scattering due to the proton disorder. Results on “two-dimensional ice” in copper formate tetrahydrate are of great interest as this system exhibits a phase transformation below which the protons are ordered. The study of rotational diffusion and of the tunnel splitting of the rotational ground state of molecules which contain protons is discussed in some detail. These investigations are now possible with very high energy resolution ΔE ≈ 5 × 10-8 eV (4 • 10-4 cm- 1 or 12 MHz).

scholarly journals Probing high-energy electronic excitations in NiO using inelastic neutron scattering

2011 ◽  
Vol 84 (8) ◽  
Author(s):  
Young-June Kim ◽  
A. P. Sorini ◽  
C. Stock ◽  
T. G. Perring ◽  
J. van den Brink ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Inelastic Neutron Scattering ◽  
High Energy ◽  
Inelastic Neutron ◽  
Electronic Excitations

Design of a High-Flux Backscattering Spectrometer for Ultra-High Resolution Inelastic Neutron Measurements

1994 ◽  
Vol 376 ◽  
Author(s):  
P. M. Gehring ◽  
C. W. Brocker ◽  
D. A. Neumann
Keyword(s):  
Phase Space ◽  
High Resolution ◽  
Dynamic Range ◽  
Cold Neutron ◽  
Pyrolytic Graphite ◽  
Inelastic Neutron ◽  
Radius Of Curvature ◽  
High Flux ◽  
Research Facility ◽  
Flux Increase

ABSTRACTWe discuss the design of a new backscattering spectrometer to be installed at the Cold Neutron Research Facility at the National Institute of Standards and Technology. Si (111) crystals cover both monochromator and analyzer which are spherically bent to a radius of curvature of ~ 2 m to focus the incident and scatterered neutron beams. The bending increases the intrinsic lattice gradient of Si beyond its Darwin limit, resulting in an energy resolution of ~ 0.75 μeV FWHM. The monochromator is Doppler-driven, allowing users access to a dynamic range of ±60 μeV. The elastic Q-range covers 0.15 to 1.8 Å-1. The most novel aspect of this design lies in the incorporation of a phase-space-transform chopper. This device rotates at 4700 rpm while neutrons are Bragg-diffracted from sets of pyrolytic graphite crystals affixed to its periphery. The process enhances the neutron flux at the backscattering energy of 2.08 meV, but at the expense of a larger horizontal divergence. Computer simulations indicate a resultant flux increase of order 3 should be obtained.

Sign in / Sign up

Export Citation Format

Share Document