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Development of a novel neutron spin filter

Applicant Hautle Patrick
Number 143297
Funding scheme Project funding (Div. I-III)
Research institution Paul Scherrer Institut
Institution of higher education Paul Scherrer Institute - PSI
Main discipline Technical Physics
Start/End 01.08.2013 - 31.08.2016
Approved amount 183'541.00
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Keywords (6)

Dynamic Nuclear Polarization; Neutron Optics; Neutron Physics; Photo-excited triplet states; Spin Filters; Polarized Targets

Lay Summary (German)

Lead
Spin polarisierte Neutronen sind ein mächtiges Werkzeug in der Neutronenstreunung und der Fundamental Physik. Besonders attraktiv zur Polarisierung von Neutronen ist die Verwendung von polarisierten Protonen, da die starke spin-abhängige Neutron-Proton Wechselwirkung bis in den sub-MeV Bereich verwendbar ist. Nutzt man optisch angeregte Triplet Zustände zur Polarisierung von Protonen, sind tiefe Temperaturen und hohe Magnetfelder nicht nötig und technisch einfachere Systeme werden realisierbar.
Lay summary

Wir haben kürzlich gezeigt, dass die Triplet DNP Methode benutzt werden kann um ein zuverlässig funktionierendes Spin Filter zu bauen. Interessante Möglichkeiten für ein solches Triplet Spin Filter eröffnen sich nun durch neueste Entwicklungen in der Neutronenoptik die Strahlgeometrie mittels fokussierenden Leitern exakt auf die Probengrösse abzustimmen. 

Das Ziel dieses Projektes ist das Potential der Triplet Spin Filter Technik für Neutronenstreuexperimente zu erforschen. Ein Schwerpunkt wird die Studie der optimalen Integration des Filters in Neutronenoptische Komponenten sein. Wir beabsichtigen Monte Carlo Simulationen von Neutronenoptischen Konzepten für Standard Streuexperimente durchzuführen und diese in ausgewählten Fällen experimentell zu bestätigen. Zudem beabsichtigen wir die Performance des Filters kontinuierlich zu verbessern indem wir die im Labor gefundenen Erkenntnisse implementieren.

Direct link to Lay Summary Last update: 05.07.2013

Responsible applicant and co-applicants

Employees

Name Institute

Publications

Publication
Magnetic microstructure of a textured Nd-Fe-B sintered magnet characterized by small-angle neutron scattering
Perigo E. A., Mettus D., Gilbert E. P., Hautle P., Niketic N., van den Brandt B., Kohlbrecher J., McGuiness P., Fu Z., Michels A. (2016), Magnetic microstructure of a textured Nd-Fe-B sintered magnet characterized by small-angle neutron scattering, in JOURNAL OF ALLOYS AND COMPOUNDS, 661, 110-114.
Polarization analysis in neutron small-angle scattering with a novel triplet dynamic nuclear polarization spin filter
N. Niketic, B. van den Brandt, W. TH. Wenckebach, J. Kohlbrecher, P. Hautle (2015), Polarization analysis in neutron small-angle scattering with a novel triplet dynamic nuclear polarization spin filter, in Journal of Applied Crystallography, 48(5), 1514-1521.
Neutron spin filtering with dynamically polarized protons using photo-excited triplet states
Eichhorn T. R., Niketic N., van den Brandt B., Hautle P., Wenckebach W. Th. (2014), Neutron spin filtering with dynamically polarized protons using photo-excited triplet states, in International Workshop on Neutron Optics and Detectors (NOP&D 2013), IsmaingIOP Publishing, Bristol, UK.
Proton polarization above 70% by DNP using photo-excited triplet states, a first step towards a broadband neutron spin filter
Eichhorn T. R., Niketic N., van den Brandt B., Filges U., Panzner T., Rantsiou E., Wenckebach W. Th., Hautle P. (2014), Proton polarization above 70% by DNP using photo-excited triplet states, a first step towards a broadband neutron spin filter, in NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND, 754, 10-14.

Collaboration

Group / person Country
Types of collaboration
Prof. W.Th. Wenckebach / academic guest PSI Netherlands (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Dr. Joachim Kohlbrecher / PSI Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Prof. A. Michels Luxembourg (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
The 2015 International Workshop on Polarized Sources, Targets & Polarimetry (PSTP 2015) Talk given at a conference Dynamic Nuclear Polarization using short-lived photo-excited triplet states: experiments and applications 13.09.2015 Bochum, Germany Hautle Patrick; van den Brandt Ben; Niketic Nemanja;
European Conference on Neutron Scattering (ECNS 2015) Poster Polarization analysis in small-angle neutron scattering with a novel triplet DNP spin filter 30.08.2015 Zaragoza, Spain van den Brandt Ben; Hautle Patrick; Niketic Nemanja;
Physics Seminar, University of Luxembourg Individual talk Dynamic nuclear polarization - recent developments and novel applications 17.12.2014 Luxemburg, Luxembourg Hautle Patrick;
2014 PSI Summer School on Condensed Matter Research Poster Neutron spin filter based on polarized protons using photo-excited triplet states 09.08.2014 Zug, Switzerland van den Brandt Ben; Hautle Patrick; Niketic Nemanja; Filges Uwe;
SPS Annual Meeting 2014 Talk given at a conference A technically simple broadband neutron spin filter based on dynamically polarized protons using photo-excited triplet states 30.06.2014 Fribourg, Switzerland van den Brandt Ben; Niketic Nemanja; Hautle Patrick; Filges Uwe;
European Magnetic Resonance Conference (Euromar 2014) Talk given at a conference DNP using photo-excited triplet states: above 70% proton spin polarization at moderate magnetic field and temperature 29.06.2014 Zürich, Switzerland Niketic Nemanja; van den Brandt Ben; Hautle Patrick;
Annual meeting of the MPNS Cost Action TD 1103, Eurpoean Network of Hyperpolairzation Physics and Methodology in NMR and MRI Poster DNP using photo-excited triplet states: above 70% proton spin polarization at moderate magnetic field and temperature 27.06.2014 Zürich, Switzerland Niketic Nemanja; Filges Uwe; Hautle Patrick; van den Brandt Ben;
American Conference on Neutron Scattering (ACNS 2014) Talk given at a conference A technically simple broadband neutron spin filter based on dynamically polarized protons using photo-excited triplet states 01.06.2014 Knoxville, United States of America Hautle Patrick; Niketic Nemanja; van den Brandt Ben;


Self-organised

Title Date Place

Associated projects

Number Title Start Funding scheme
124901 Methodology in Dynamic Nuclear Polarization 01.10.2009 Project funding (Div. I-III)
165496 A novel device for neutron polarization analysis 01.12.2016 Project funding (Div. I-III)

Abstract

The use of spin-polarized neutrons is a powerful tool to study a wide range of scientific phenomena with neutron scattering and in fundamental physics. It provides indispensible information for many current areas of research as magnetism, superconductivity, correlated electron systems, and also particle physics and cosmology.The most common techniques to polarize and analyze neutron beams are based on neutron optical mirror reflection. They are systematically restricted in angular acceptance and to neutron energies of the cold region only. Alternatively, polarized nuclei provide a way to build broad-band spin filters with a large acceptance. Optically polarized 3He is often considered the best choice; however its energy-dependent neutron absorption cross-section makes it difficult to optimise the filter thickness in a large range. With the advent of megawatt-class pulsed spallation sources (SNS, JSNS, ESS), alternatives to the well established neutron polarization techniques used at steady sources have to be found and the use of polarized protons as spin filter is recalled, as the large spin dependent neutron scattering cross section for protons is useful up to the sub-MeV region.Proton polarization is normally created employing the classical scheme of dynamic nuclear polarization (DNP). One polarizes electron spins by cooling them down to low temperature (~ 1K) and applying a strong magnetic field (2.5 - 5 T) and then transfers their high polarization to the nuclear spins by means of a microwave field. These stringent conditions can be relieved with a more recent and very promising DNP method that uses optically excited triplet states. Here the triplet electron spin is polarized as a result of the optical selection rules. Then the requirements for the cryogenic equipment and the magnetic field are significantly relaxed making technically simpler systems with open geometries possible. We have recently proved that the triplet DNP method can be used to build a reliably working neutron spin filter [1]. Besides the pioneering work of Uesaka et al [2], this is the only time that an instrument based on this technique has been employed in a long term experiment on a particle beam. Interesting possibilities for a triplet spin filter are opened by the recent trend in neutron optics to adapt with focusing guides to the sample which is often only available in very small size [3]. It is the goal of the present proposal to assess the potential of the triplet spin filter technique for polarized neutron scattering experiments. A key point will be the investigation of the filter integration with neutron optical devices. We intend to perform numerical simulations of neutron optics concepts for standard scattering schemes and to experimentally prove their feasibility for selected cases.
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