VESUVIO is the only instrument of its kind in the entire world, using high-energy (epithermal) neutrons for the technique of neutron Compton scattering (NCS) [1-3]. The NCS technique, unlike other neutron techniques, measures nuclear momentum distributions (NMDs) of one atom at a time, thereby enabling the elucidation of potentials of mean force (PMF) and mean force constants (MFC) of individual atomic species.
Knowing the values of MFCs, one can assess the mechanical properties of condensed matter systems, such as cohesion and fracture toughness, as well as thermodynamic properties. Knowing the shapes of PMFs, one can assess nuclear quantum effects (NQEs), such as nuclear quantum tunnelling (NQT) and delocalisation (NQD). NQT and NQD are important for characterising solid-state diffusion of nuclei and nuclear dynamics of hydrogen bonds (HBs), with important ramifications in biology, chemical physics, and materials science.
Uniquely, on VESUVIO, neutrons of all energies reach the sample and can be scattered or adsorbed. Namely, VESUVIO, unlike many other direct or indirect neutron spectrometers, employs a noninvasive final-neutron-energy filter. This means that scattered neutrons of all energies and other particles, such as gamma rays, are produced within the sample and then reach the detectors and can be counted. This is in opposition to direct geometry instruments, where incident neutron energies are selected using choppers, and inverted geometry instruments, where intermediate reflections select the scattered neutrons on the filter. In these cases, the secondary path is not a straight line connecting the sample and the detector, with the latter actually shielded against direct radiation from the sample. This unique VESUVIO detection setup makes it possible to concurrently perform NCS, neutron diffraction (ND), neutron transmission (NT), and gamma spectroscopy based on resonant neutron absorption followed by gamma emission [through techniques such as Neutron Resonance Capture Analysis (NRCA) and Prompt Gamma Activation Analysis (PGAA)][3, 12].
For the past 10
years, this realisation has motivated and driven all efforts towards a paradigm
change in the VESUVIO community and amongst VESUVIO stakeholders from a
single-technique niche spectrometer towards a much more versatile
thermal-to-epithermal neutron station. These efforts have resulted in new
research directions and themes aided by the much-awaited upgrade in the data
treatment schemes and software [2, 3, 12].
Further metrics of the scientific paradigm change on VESUVIO include:
1. Publication of over 250 scientific papers from the VESUVIO community in the period 2011-2021, with an average of 25 publications per year being higher than ISIS average per instrument in the same period (18.2). The distribution of VESUVIO scientific output is now characterised by an increased number of papers that explore many techniques and an increased number of papers in which NCS tackles multiple scientific problems. VESUVIO has been used to explore novel solid-state materials for the hydrogen-based economy, leading to the revision of hydrogen storage capabilities of many materials using criteria that include NQEs. The concurrent measurement of ND and NCS on VESUVIO enabled the finding of the best temperature and moisture content values for optimal food storage. The mass-selective nature of the NCS technique on VESUVIO allowed for performing non-destructive quantitation of hydrogen and water in bulk materials and devices.
2. An increased number of studies where NCS had been used to investigate systems beyond water and hydrogen. Two key areas have become prominent (i) the investigation of vibrational properties of glassy and other disordered materials, and (ii) nuclear quantum effects in hydrogen-bonded systems beyond water. NCS investigations of the effects of disorder on the mechanical properties of glasses were used for the optimisation of tailored advanced multifunctional devices. Moreover, VESUVIO was used to revisit phase diagrams and revise the views on the phase polymorphism in hydrogen-bonded crystals.
3. VESUVIO has always been one of the key focus points of the ISIS-Italy partnership (with the current ISIS-Italy agreement worth €15M to ISIS over a six-year period). This partnership has been reinforced with a new set of work packages defined within the PANACEA (300k£) project financed through the ISIS-Italy partnership where VESUVIO plays a central role;
4. Introduction of new active collaborations with the extended VESUVIO community in countries like China, the USA, Russia, Germany, France, Poland, the Czech Republic, and Hungary. VESUVIO and ISIS science were championed during the VII International Workshop on Electron-Volt Neutron Spectroscopy [7–8 November 2017, Rome, Italy] with 67 participants from 8 countries, 17 oral presentations, and 28 posters (mostly from early-career researchers).
[1] Andreani C, Colognesi D, Mayers J, Reiter G and Senesi R 2005 Measurement of momentum distribution of light atomstatoms and molecules in condensed matter systems using inelastic neutron scattering Advances in Physics 54 377-469
[2] Andreani C, Krzystyniak M, Romanelli G, Senesi R and Fernandez-Alonso F 2017 Electron-volt neutron spectroscopy: beyond fundamental systems Advances in Physics 66 1-73
[3] Andreani C, Senesi R, Krzystyniak M, Romanelli G and Fernandez-Alonso F 2017 Experimental Methods in the Physical Sciences, ed F Fernandez-Alonso and D L Price: Academic Press) pp 403-57
[4] Senesi R, Andreani C, Bowden Z, Colognesi D, Degiorgi E, Fielding A L, Mayers J, Nardone M, Norris J, Praitano M, Rhodes N J, Stirling W G, Tomkinson J and Uden C 2000 VESUVIO: a novel instrument for performing spectroscopic studies in condensed matter with eV neutrons at the ISIS facility Physica B 276 200-1
[5] Andreani C, Pietropaolo A, Senesi R, Gorini G, Perelli-Cippo E, Tardocchi M, Rhodes N and Schooneveld E M 2004 A resonant detector for high-energy inelastic neutron scattering experiments Appl Phys Lett 85 5454-6
[6] Perelli Cippo E, Gorini G, Tardocchi M, Andreani C, Pietropaolo A, Senesi R, Rhodes N J and Schoonveld E M 2008 Advances on detectors for low-angle scattering of epithermal neutrons Measurement Science and Technology 19 047001
[7] Schooneveld E M, Mayers J, Rhodes N J, Pietropaolo A, Andreani C, Senesi R, Gorini G, Perelli-Cippo E and Tardocchi M 2006 Foil cycling technique for the VESUVIO spectrometer operating in the resonance detector configuration Review of Scientific Instruments 77 095103
[8] Tardocchi M, Gorini G, Pietropaolo A, Andreani C, Senesi R, Rhodes N and Schooneveld E M 2004 YAP scintillators for resonant detection of epithermal neutrons at pulsed neutron sources Review of Scientific Instruments 75 4880-90
[9] Seeger P A, Taylor A D and Brugger R M 1985 Double-difference method to improve the resolution of an eV neutron spectrometer Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 240 98-114
[10] Mayers J 2011 Calculation of background effects on the VESUVIO eV neutron spectrometer Measurement Science and Technology 22 015903
[11] Mayers J and Reiter G 2012 The VESUVIO electron volt neutron spectrometer Measurement Science and Technology 23
[12] Romanelli G, Krzystyniak M, Senesi R, Raspino D, Boxall J, Pooley D, Moorby S, Schooneveld E, Rhodes N and Andreani C 2017 Characterisation of the incident beam and current diffraction capabilities on the VESUVIO spectrometer Measurement Science and Technology 28 095501
