PONTO—An instrument for imaging with polarized neutrons

Treimer, W.; Ebrahimi, O.; Karakas, N.; Seidel, Sophie

doi:10.1016/j.nima.2011.01.009

Cited by 21 publications

(8 citation statements)

References 10 publications

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“…The detailed description of the instrument can be found in ref. 78 . For the present study, the graphite monochromator was positioned so as to reflect a mean wavelength of 0.32(1) nm towards an optical bench.…”

Section: Methodsmentioning

confidence: 99%

Thermodynamics of Meissner effect and flux pinning behavior in the bulk of single-crystal La2−xSrxCuO4 ( x=
Dhiman
¹
,
Ziesche
²
,
Anand
³

et al. 2017
Phys. Rev. B
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We have studied the evolution of magnetic flux pinning behavior in the Meissner phase and the mixed state for the high-Tc single crystal La2xSrxCuO4 (x = 0.09) superconductor using the polarized neutron imaging method with varying magnetic field and temperature. In the Meissner state expulsion of magnetic field (switched on during the measurements) is visualized, and the signatures of mixed state with increasing temperature are observed. While, for flux pinning behavior between 5 K  T  15 K and Hext = 63.5 mT (switched o↵ during the measurements), the evolution of fringe pattern indicates magnetic flux pinning inside the bulk of the sample. At 25 K  T  32 K, a continuous decrease of inhomogeneously distribution pinned magnetic flux is observed, with the sample reaching a normal conducting state at Tc (⇡ 32 K). The flux pinning behavior is also explored as a function of Hext, at T = 5 K. As expected, with increasing Hext an increase in fringe density is observed, indicating an increase in magnetic flux pinning in the bulk of the sample. Comparison between calculated and experimentally visualized pinned magnetic flux shows good agreement. This implies quantification of pinned magnetic flux inside the sample, which is not possible with any other technique on bulk samples.

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Section: Methodsmentioning

confidence: 99%

Thermodynamics of Meissner effect and flux pinning behavior in the bulk of single-crystal La2−xSrxCuO4 ( x=
Dhiman
¹
,
Ziesche
²
,
Anand
³

et al. 2017
Phys. Rev. B
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0
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“…The polarization state of the neutron beam was the most crucial part of all studies. The overall polarization P of the instrument was measured several times using the shim-method and spin rotation method [31].…”

Section: Experimental Set-up and Coil Experimentsmentioning

confidence: 99%

Polarized neutron imaging and three-dimensional calculation of magnetic flux trapping in bulk of superconductors

et al. 2012

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“…The use of a mosaic monochromator increased the L/D ratio by a factor of 2.2 from L/D(pin hole) = 573 to L/D (mosaic monochromator) = 1270, which has already been demonstrated with another instrument [41]. The spatial resolution for unpolarized neutrons at PONTO II was determined to be 57(3) µm for an object at a distance of 5 mm from the detector, which is an improvement from earlier measurements (80 µm) [35].…”

Section: Discussionmentioning

confidence: 52%

“…For radiography (and tomography) using polarized neutrons the magnetic spatial resolution is always associated with change of the neutron spin orientation due to a magnetic field. Polarized neutron imaging is used in many experiments and has been published, e.g., [29][30][31][32][33][34][35][36][37][38][39][40], but all have in common a spin analysis system which determines the resolution of the imaging system.…”

Section: Introductionmentioning

confidence: 99%

Determination of the Spatial Resolution in the Case of Imaging Magnetic Fields by Polarized Neutrons

Treimer

Köhler

2021

Applied Sciences

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One of the most important parameters characterizing imaging systems (neutrons, X-rays, etc.) is their spatial resolution. In magnetic field imaging, the spatial resolution depends on the (magnetic) resolution of the depolarization of spin-polarized neutrons. This should be realized by different methods, but they all have in common that a spin-polarizing and spin-analyzing system is part of the resolution function. First a simple and useful method for determining the spatial resolution for unpolarized neutrons is presented, and then methods in the case of imaging with polarized neutrons. Spatial resolution in the case of polarized neutron imaging is fundamentally different from ‘classical’ spatial resolution. Because of π-periodicity, the shortest path along which a spin-flip can occur is a measure of ‘magnetic’ spatial resolution. Conversely, the largest detectable magnetic field (B-field) within a given path length is also a measure of magnetic spatial resolution. This refers to the spatial resolution in the flight direction of the neutrons (Δy). The Δx and Δz refers to the spatial resolution in x- or z-direction; however, in these cases a different method must be used. Therefore, two independent methods are used to distinguish longitudinal and lateral spatial resolution, one method to determine the modulation transfer function (MTF) by recording the frequency-dependent fringe contrast of magnetic field images of a coil (longitudinal spatial resolution), and the second method, to observe the fringe displacement at the detector as a function of magnetic motion, provided that the accuracy of the motion is much better than the pixel size (at least half the pixel size) of the detector (lateral spatial resolution). The second method is a convolution of the fringe pattern with the pixel array of the detector.

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PONTO—An instrument for imaging with polarized neutrons

Cited by 21 publications

References 10 publications

Thermodynamics of Meissner effect and flux pinning behavior in the bulk of single-crystal La2−xSrxCuO4 ( x=
Dhiman
¹
,
Ziesche
²
,
Anand
³

et al. 2017
Phys. Rev. B
Self Cite
8
1
4
0
View full text Add to dashboard Cite

Thermodynamics of Meissner effect and flux pinning behavior in the bulk of single-crystal La2−xSrxCuO4 ( x=
Dhiman
¹
,
Ziesche
²
,
Anand
³

et al. 2017
Phys. Rev. B
Self Cite
8
1
4
0
View full text Add to dashboard Cite

Polarized neutron imaging and three-dimensional calculation of magnetic flux trapping in bulk of superconductors

Determination of the Spatial Resolution in the Case of Imaging Magnetic Fields by Polarized Neutrons

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PONTO—An instrument for imaging with polarized neutrons

Cited by 21 publications

References 10 publications

Thermodynamics of Meissner effect and flux pinning behavior in the bulk of single-crystal La2−xSrxCuO4 ( x=Dhiman1, Ziesche2, Anand3 et al. 2017Phys. Rev. BSelf Cite8140View full textAdd to dashboardCite

Thermodynamics of Meissner effect and flux pinning behavior in the bulk of single-crystal La2−xSrxCuO4 ( x=Dhiman1, Ziesche2, Anand3 et al. 2017Phys. Rev. BSelf Cite8140View full textAdd to dashboardCite

Polarized neutron imaging and three-dimensional calculation of magnetic flux trapping in bulk of superconductors

Determination of the Spatial Resolution in the Case of Imaging Magnetic Fields by Polarized Neutrons

Contact Info

Product

Resources

About

Thermodynamics of Meissner effect and flux pinning behavior in the bulk of single-crystal La2−xSrxCuO4 ( x=
Dhiman
¹
,
Ziesche
²
,
Anand
³

et al. 2017
Phys. Rev. B
Self Cite
8
1
4
0
View full text Add to dashboard Cite

Thermodynamics of Meissner effect and flux pinning behavior in the bulk of single-crystal La2−xSrxCuO4 ( x=
Dhiman
¹
,
Ziesche
²
,
Anand
³

et al. 2017
Phys. Rev. B
Self Cite
8
1
4
0
View full text Add to dashboard Cite