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<p>Dear colleagues,<br>
<br>
you are welcome to the KFN Neutron Webinar on</p>
<h2>Wide angle neutron polarization analysis time of flight
spectroscopy: An Introduction</h2>
<h3>Dr. Ross Stewart, ISIS<br>
<span>Friday, <strong>30 January 2026</strong>, 11:00 - 12:00 CET</span></h3>
<p><span lang="EN-GB" style="mso-ansi-language: EN-GB">Zoom link: <a
class="v1moz-txt-link-freetext moz-txt-link-freetext"
href="https://fz-juelich-de.zoom-x.de/j/61006517600?pwd=YiKR1xsor31wFo9EGRV7FNsiysGBBJ.1"
target="_blank" rel="noreferrer">https://fz-juelich-de.zoom-x.de/j/61006517600?pwd=YiKR1xsor31wFo9EGRV7FNsiysGBBJ.1</a><br>
Meeting ID: 610 0651 7600<br>
Passcode: 983794</span></p>
<p>In recent years, polarised neutron spectroscopy on multi-detector
spectrometers has become possible with the advent of wide-angle
neutron spin analysers, either using polarizing supermirror arrays
(e.g. D007 (ILL), HYSPEC (SNS)) or 3He spin-filters (LET (ISIS),
PASTIS (ILL)). Wide-angle neutron polarization analysis is
particularly useful for studying materials with short-range or
non-crystalline order. Most commonly, it has been employed to
separate magnetic scattering in disordered magnetic materials from
nuclear scattering using XYZ polarization analysis developed by
Schärpf [1] in the mid-80s. At the same time, it was realised that
polarized neutrons could also be employed in the study of
soft-matter and biological materials due to their ability to
distinguish single-particle dynamics (such as diffusion) from
co-operative correlated motions via the separated coherent and
incoherent neutron cross-sections in hydrogenous materials. </p>
<p>In this webinar, Ross Stewart will introduce the technique of
uniaxial polarization analysis and its application to high
resolution spectroscopy (QENS) studies using LET at ISIS, and on
the proposed SHERPA spectrometer. Since neutron polarization
experiments always come with a major flux and counting-rate
penalty, he’ll discuss when (and when not) polarized neutrons are
really necessary in QENS measurements, using examples from LEΤ.
Future prospects for high-resolution magnetic spectroscopy with
polarization analysis will also be discussed.</p>
<p>[1] O. Schärpf and H. Capellmann (1993). The XYZ‐Difference
Method with Polarized Neutrons and the Separation of Coherent,
Spin Incoherent, and Magnetic Scattering Cross Sections in a
Multidetector. <i>Physica Status Solidi (A)</i>, <i>135</i>(2),
359–379. <a class="external-link"
href="https://doi.org/10.1002/pssa.2211350204" target="_blank"
title="">https://doi.org/10.1002/pssa.2211350204<br>
</a><br>
For the general background, see <br>
<a
href="https://www.oxfordneutronschool.org/2024/Lectures/Stewart_polarized%20neutrons.pdf"
rel="noreferrer" target="_blank"
class="MIME-application MIME--pdf external-link">https://www.oxfordneutronschool.org/2024/Lectures/Stewart_polarized%20neutrons.pdf<br>
</a><br>
R. M. Moon, T. Riste, and W. C. Koehler. Polarization Analysis of
Thermal-Neutron Scattering. Phys. Rev. 181, 920 (1969)<br>
<a href="https://journals.aps.org/pr/pdf/10.1103/PhysRev.181.920"
rel="noreferrer" target="_blank"
class="external-link moz-txt-link-freetext">https://journals.aps.org/pr/pdf/10.1103/PhysRev.181.920</a></p>
<p>----</p>
<p>The lecture will be recorded, and there is information on data
protection at <br>
<a class="v1moz-txt-link-freetext moz-txt-link-freetext"
href="https://www.sni-portal.de/en/files/kfn-neutron-webinar-data-protection"
target="_blank" rel="noreferrer">https://www.sni-portal.de/en/files/kfn-neutron-webinar-data-protection</a><br>
<br>
On the website<br>
<a class="v1moz-txt-link-freetext moz-txt-link-freetext"
href="https://www.sni-portal.de/en/user-committees/committee-research-with-neutrons/neutron-webinar"
target="_blank" rel="noreferrer">https://www.sni-portal.de/en/user-committees/committee-research-with-neutrons/neutron-webinar</a><br>
you will find announcements of upcoming lectures.<br>
<br>
Kind regards,<br>
<br>
Frank Schreiber and Thomas Gutberlet (Webinar organization)<br>
Mirijam Zobel (KFN chair)</p>
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