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Title: Superconducting Wollaston Prism for Spin Echo Scattering Angle Measurement

Authors:
 [1];  [2]
  1. Adelphi Technology, Inc., Redwood City, CA (United States)
  2. Indiana Univ., Bloomington, IN (United States)
Publication Date:
Research Org.:
Adelphi Technology, Inc., Redwood City, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1367570
Report Number(s):
DOE Phase II STTR Final Report
DOE Contract Number:
SC0009584
Type / Phase:
STTR
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; Neutron Spin Echo Scattering Angle Measurement; Neutron Wollaston Prism; Neutron Reflectometry; Neutron Diffractometry; Neutron Phase Contrast Radiography

Citation Formats

Cremer, Jay Theodore, and Pynn, Roger. Superconducting Wollaston Prism for Spin Echo Scattering Angle Measurement. United States: N. p., 2017. Web.
Cremer, Jay Theodore, & Pynn, Roger. Superconducting Wollaston Prism for Spin Echo Scattering Angle Measurement. United States.
Cremer, Jay Theodore, and Pynn, Roger. Sat . "Superconducting Wollaston Prism for Spin Echo Scattering Angle Measurement". United States. doi:.
@article{osti_1367570,
title = {Superconducting Wollaston Prism for Spin Echo Scattering Angle Measurement},
author = {Cremer, Jay Theodore and Pynn, Roger},
abstractNote = {},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Apr 15 00:00:00 EDT 2017},
month = {Sat Apr 15 00:00:00 EDT 2017}
}

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  • A magnetic Wollaston prism can spatially split a polarized neutron beam into two beams with different neutron spin states, in a manner analogous to an optical Wollaston prism. Such a Wollaston prism can be used to encode the trajectory of neutrons into the Larmor phase associated with their spin degree of freedom. This encoding can be used for neutron phase-contrast radiography and in spin echo scattering angle measurement (SESAME). In this paper, we show that magnetic Wollaston prisms with highly uniform magnetic fields and low Larmor phase aberration can be constructed to preserve neutron polarization using high temperature superconducting (HTS)more » materials. The Meissner effect of HTS films is used to confine magnetic fields produced electromagnetically by current-carrying HTS tape wound on suitably shaped soft iron pole pieces. The device is cooled to ∼30 K by a closed cycle refrigerator, eliminating the need to replenish liquid cryogens and greatly simplifying operation and maintenance. A HTS film ensures that the magnetic field transition within the prism is sharp, well-defined, and planar due to the Meissner effect. The spin transport efficiency across the device was measured to be ∼98.5% independent of neutron wavelength and energizing current. The position-dependent Larmor phase of neutron spins was measured at the NIST Center for Neutron Research facility and found to agree well with detailed simulations. The phase varies linearly with horizontal position, as required, and the neutron beam shows little depolarization. Consequently, the device has advantages over existing devices with similar functionality and provides the capability for a large neutron beam (20 mm × 30 mm) and an increase in length scales accessible to SESAME to beyond 10 μm. With further improvements of the external coupling guide field in the prototype device, a larger neutron beam could be employed.« less
  • We describe experiments in which the neutron spin echo technique is used to measure neutron scattering angles. We have implemented the technique, dubbed spin echo scattering angle measurement (SESAME), using thin films of Permalloy electrodeposited on silicon wafers as sources of the magnetic fields within which neutron spins precess. With 30-{mu}m-thick films we resolve neutron scattering angles to about 0.02 deg. with neutrons of 4.66 A wavelength. This allows us to probe correlation lengths up to 200 nm in an application to small angle neutron scattering. We also demonstrate that SESAME can be used to separate specular and diffuse neutronmore » reflection from surfaces at grazing incidence. In both of these cases, SESAME can make measurements at higher neutron intensity than is available with conventional methods because the angular resolution achieved is independent of the divergence of the neutron beam. Finally, we discuss the conditions under which SESAME might be used to probe in-plane structure in thin films and show that the method has advantages for incident neutron angles close to the critical angle because multiple scattering is automatically accounted for.« less
  • Heavy direct coal liquefaction products are known to exhibit rapidly increasing viscosities upon prolonged exposure to oxygen. Small angle x-ray scattering has been used to monitor changes in the colloidal structure of a coal liquid subjected to accelerated aging under an oxygen atmosphere for a total period of eight weeks. The data are consistent with an agglomeration model for the formation of large colloidal size scattering centers which are partially responsible for the rapidly increasing viscosity of the coal liquid. 2 figures.