ESS and Reflectometry SAC Report 22 nd May 2014

The Reflectometry STAP John Ankner (SNS) Richard Campbell (ILL) Bob Cubitt (ILL) Robert Dalgliesh (ISIS) Karen Edler (Bath University) Giovanna Fragneto (ILL) Bjorgvin Hjorvarsson (Uppsala University) Chuck Majkrzak (NIST) Chris Marrows (Leeds University) Peter Mueller-Buschbaum (Technische Universität München) Andrew Nelson (Ansto) Roger Pynn (Indiana University) Masayasu Takeda (JPARC) Ali Zarbakhsh (Queen Mary University London) Suzanne te Velthuis (ANL) Until 2013

The Case for Neutron Reflectometry at ESS Powerful probe for soft matter particularly with isotopic substitution – Enables unique determination of structures in multicomponent systems. Unique probe for buried interfaces and magnetism – Unique information from magnetic nanostructures that cannot be obtained by any other means. Well matched to the ESS source characteristics.

Comparison to the ESS Science Case Life science – Pharmacy – Protein behaviour – Membrane Physics Soft condensed matter – Surfactants – Polymer physics – Electrochemistry – Templated nanostructures – Liquid-liquid interfaces Energy research – Display screen and OLED technologies – Hydrogen storage – Lithium intercalation Magnetic and electronic phenomena – Spintronics – Superconductors Engineering materials – Surface chemistry of metals

Huge Range of Science

Free Liquids

Small Samples

Polarised Beams

STAP Priorities Fast Kinetics Small Samples Liquid-liquid interfaces GISANS Thin film “spintronics” Magnetic reference layers for soft matter

The instrument suite All major facilities have at least 2 reflectometers optimised for different science SNS ILL ISIS JPARC FRMII

Characteristics of a TOF Reflectometer FluxResolution Background Simultaneous Dynamic Range Focussing

Technical Problems STAP Challenges to the instrument teams for the last 3 years. Inherent resolution – 30m instrument >10% resolution at 2Å – Need <5% for many samples High energy backgrounds – Specular reflectivity occurs at 1 angle only. – It is not possible to ignore the prompt pulse and to collect data over multiple frames without care. Broad simultaneous Q range is essential.

A Reflectometer at ESS FluxResolution Background Simultaneous Dynamic Range Focussing

STAP Prioritised Ranking 1.FREIA 2.Estia 3.Veritas 4.Thor

Very Challenging Decision All the instruments could be built. At least 2 instruments are required to meet the full science case. At least one must enable the study of free liquid surfaces. Another must allow the use of high field cryomagnets (>2T) and enable continuous Q coverage out to high angle. – This is much more easily achieved with a vertical sample geometry.

Thor Broad simultaneous Q range with frame skipping Variable resolution through WFM Free liquid surfaces Liquid-liquid interfaces to high Q Considerable flexibility for add ons and design flexibility.

Veritas Broad simultaneous Q range Conventional focussing for small samples Vertical sample for magnetism and large continuous Q coverage Variable resolution on a short instrument. Proven polariser and GISANS design concept from MARIA at Julich.

Estia Broad dynamic Q range Strong focussing for very small samples Very low backgrounds Vertical sample for magnetism Step change in the size of samples that can be studied.

FREIA Broad dynamic range without moving the sample for fast kinetics or small samples Free liquid surfaces Liquid-liquid interfaces Largely known technology GISANS, polarisation and WFM options are part of the case

Spin-Echo Add on Can be incorporated into any of the designs if considered early enough. Technique is ideally suited to the ESS pulse structure ESS Flux will offer new scientific possibilities

Grazing Incidence SANS The ESS source characteristics are perfectly suited to GISANS. Science should match the strengths of neutron scattering – Isotopic substitution in soft matter – Magnetism – Buried interfaces in complex SE and liquid-liquid interfaces In-plane length scales >100nm should be accessible so an instrument capable of up to 12m-12m L1-L2 would be ideal. None of the current NR or SANS instruments is well suited. The ability to deflect the beam up or down slightly is required.

Conclusions Neutron Reflection at ESS will be world leading with >10 gain factors over current instrumentation for all the concepts. 4 well developed designs which could all be constructed. FREIA was the clear highest priority of the STAP and will provide world class science for a broad spectrum of science from day one. At least 2 instruments are required to for the science case. Estia is an exciting concept that offers the possibility of a step change in capability for small samples. None of the SANS or NR concepts presented to date are ideal for GISANS. However, the ESS source is, so an instrument optimised for this technique should be built.

Thank you for your attention. Thanks to the work packages.

Shielding ChipIr at ISIS The sample has no direct view of the source