MIRACLES

Life sciences, molecular dynamics and water dynamics

• Degenerative diseases: Alzheimer, Parkinson, Cancer
• Protein dynamics and enzyme catalysis
• Pharmaceutical studies: drug implementation/delivery

Energy sciences:

• Fuel cells and H2 storage (hydrides)
• Proton diffusion in MOFs
• Catalysis

Polymer sciences:

• Viscoelasticity
• Morphology-performance connections in e.g. organic electronic devices

Climate change:

• Ice formation
• Portland-alternative cements (water dynamics)

Next-generation magnetic materials:

• Molecular nanomagnets
• Spin dynamics in novel magnetic materials (spin ice, large SOC)

MIRACLES is the time-of-flight backscattering spectrometer of the ESS. It will be one of the ESS long instruments (travel of the neutrons from source to sample: 162.5 m) located at the west sector.

ESS-Bilbao is the primary partner in the design, construction and commissioning of the instrument, with close collaborations between ESS-Bilbao, the University of Copenhagen and the European Spallation Source.

The design of the primary spectrometer (that tailors the energy and shape of the neutron pulse arriving to the sample) is essentially simple, but smartly designed to transport cold neutrons with a neutron wavelength between 2 and 20 Å. The neutron beam extraction system has been optimized for an efficient neutron collection and transport, according to its view of the ESS butterfly moderator. The guide presents a curve, extended throughout the bunker and the D03 hall, to avoid direct line of sight of unwanted fast neutrons, thus minimizing the spectral background.

A key characteristic of the performance of the MIRACLES instrument is the outstanding flexibility to cover a wide range of neutron beam energy probing the sample for quasielastic and inelastic neutron scattering experiment (QENS and INS), taking advantage of the long pulse of the ESS neutron source with an optimized chopper cascade to tailor this neutron pulse and select the required energy range.

The core of the instrument is the sample-analyzer-detector near-backscattering geometry of this type of instrument. High resolution will be achieved using a 150º coverage panel of Si(111) analyzer bent crystals, with a fixed analyzer radius of 2.5 m. A ³He detector array will be strategically located around the sample chamber to collect efficiently the backscattered neutrons, with recent efforts oriented to reduce, to a minimum dimension achievable, the distance between the sample and the detectors, and improving the backscattering geometry.

Future upgrade will include full analyzer coverage, with a Si(311) analyzer of the same size, to the other side of the vessel, aimed to explore high resolution QENS and INS measurements centered at higher energies.

• The dynamic bandwidth range provided by the pulse-definition choppers ranges Dl=1.6 Å, providing a matchless energy transfer range, centered at the Si(111) elastic line (l=6.267 Å) of DE=1.1 meV. This dynamic wavelength range of MIRACLES can be shifted within the interval of 2–20 Å. to allow measurement at low-energy inelastic excitations.
• MIRACLES will provide a variable elastic energy resolution, δ(ℏω), between 2 and 32 μeV when using a wavelength of λ = 6. 267 Å (E=2.08 meV, Si(111) reflection), with the possibility of collecting extensive inelastic neutron spectra (INS) along an energy transfer range between +2 and -18 meV.
• Commissioning tests will be performed prior to user operations to test the feasibility of utilizing the Si(333) reflection [λ = 2.080 Å; E=18.908 meV]. Finally, future upgrade to full scope will include implementation of a Si(311) crystal analyzer, covering similar angles for experiments at higher energies with respect to the standard Si(111) analyzer.

Lead Scientist: Felix J. Villacorta (ESS-Bilbao)

Lead Engineer: Paula Luna (ESS-Bilbao)

ESS dedicated Technical Coordinator: Clara I. Lopez (ESS)

Team: Heloisa N. Bordallo (KU) and Melissa Sharp (ESS), Jorge Aguilar, Monica Huerta, Octavio González del Moral, Miguel Magan, Marita Mosconi, Estefania Abad, Ander Serrano, Fernando Sordo (ESS-Bilbao)

• N. Tsapatsaris, R. E. Lechner, M. Marko and H. N. Bordallo, “Conceptual design of the time-of-flight backscattering spectrometer, {MIRACLES}, at the European Spallation Source”, Rev. Sci. Instrum. 87 (8), 085118 (2016).
• N. Tsapatsaris; P. K. Willendrup, R. E. Lechner and H. N. Bordallo, “From BASIS to MIRACLES: Benchmarking and perspectives for high-resolution neutron spectroscopy at the ESS”, Qens/wins 2014 - 11th International Conference on Quasielastic Neutron Scattering and 6th International Workshop on Inelastic Neutron Spectrometers Volume: 83 (2015)