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Title: VESPA: The vibrational spectrometer for the European Spallation Source

Abstract

VESPA, Vibrational Excitation Spectrometer with Pyrolytic-graphite Analysers, aims to probe molecular excitations via inelastic neutron scattering. It is a thermal high resolution inverted geometry time-of-flight instrument designed to maximise the use of the long pulse of the European Spallation Source. The wavelength frame multiplication technique was applied to provide simultaneously a broad dynamic range (about 0-500 meV) while a system of optical blind choppers allows to trade flux for energy resolution. Thanks to its high flux, VESPA will allow the investigation of dynamical and in situ experiments in physical chemistry. Here we describe the design parameters and the corresponding McStas simulations.

Authors:
 [1];  [2];  [3]; ; ;  [4]; ;  [1];  [3]; ;  [5];  [1]
  1. Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen Ø (Denmark)
  2. (Italy)
  3. (Sweden)
  4. Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, 50019 Sesto Fiorentino (Italy)
  5. European Spallation Source ESS AB, SE-221 00 Lund (Sweden)
Publication Date:
OSTI Identifier:
22597988
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 87; Journal Issue: 6; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; DESIGN; ENERGY RESOLUTION; EUROPEAN SPALLATION SOURCE; EXCITATION; GEOMETRY; GRAPHITE; INELASTIC SCATTERING; MEV RANGE 100-1000; NEUTRON DIFFRACTION; NEUTRON REACTIONS; NEUTRONS; PHYSICAL CHEMISTRY; PULSES; SPALLATION; SPECTROMETERS; TIME-OF-FLIGHT METHOD; WAVELENGTHS

Citation Formats

Fedrigo, Anna, E-mail: anna.fedrigo@nbi.ku.dk, Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, 50019 Sesto Fiorentino, European Spallation Source ESS AB, SE-221 00 Lund, Colognesi, Daniele, Grazzi, Francesco, Zoppi, Marco, Bertelsen, Mads, Strobl, Markus, European Spallation Source ESS AB, SE-221 00 Lund, Hartl, Monika, Deen, Pascale P., and Lefmann, Kim. VESPA: The vibrational spectrometer for the European Spallation Source. United States: N. p., 2016. Web. doi:10.1063/1.4952430.
Fedrigo, Anna, E-mail: anna.fedrigo@nbi.ku.dk, Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, 50019 Sesto Fiorentino, European Spallation Source ESS AB, SE-221 00 Lund, Colognesi, Daniele, Grazzi, Francesco, Zoppi, Marco, Bertelsen, Mads, Strobl, Markus, European Spallation Source ESS AB, SE-221 00 Lund, Hartl, Monika, Deen, Pascale P., & Lefmann, Kim. VESPA: The vibrational spectrometer for the European Spallation Source. United States. doi:10.1063/1.4952430.
Fedrigo, Anna, E-mail: anna.fedrigo@nbi.ku.dk, Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, 50019 Sesto Fiorentino, European Spallation Source ESS AB, SE-221 00 Lund, Colognesi, Daniele, Grazzi, Francesco, Zoppi, Marco, Bertelsen, Mads, Strobl, Markus, European Spallation Source ESS AB, SE-221 00 Lund, Hartl, Monika, Deen, Pascale P., and Lefmann, Kim. 2016. "VESPA: The vibrational spectrometer for the European Spallation Source". United States. doi:10.1063/1.4952430.
@article{osti_22597988,
title = {VESPA: The vibrational spectrometer for the European Spallation Source},
author = {Fedrigo, Anna, E-mail: anna.fedrigo@nbi.ku.dk and Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, 50019 Sesto Fiorentino and European Spallation Source ESS AB, SE-221 00 Lund and Colognesi, Daniele and Grazzi, Francesco and Zoppi, Marco and Bertelsen, Mads and Strobl, Markus and European Spallation Source ESS AB, SE-221 00 Lund and Hartl, Monika and Deen, Pascale P. and Lefmann, Kim},
abstractNote = {VESPA, Vibrational Excitation Spectrometer with Pyrolytic-graphite Analysers, aims to probe molecular excitations via inelastic neutron scattering. It is a thermal high resolution inverted geometry time-of-flight instrument designed to maximise the use of the long pulse of the European Spallation Source. The wavelength frame multiplication technique was applied to provide simultaneously a broad dynamic range (about 0-500 meV) while a system of optical blind choppers allows to trade flux for energy resolution. Thanks to its high flux, VESPA will allow the investigation of dynamical and in situ experiments in physical chemistry. Here we describe the design parameters and the corresponding McStas simulations.},
doi = {10.1063/1.4952430},
journal = {Review of Scientific Instruments},
number = 6,
volume = 87,
place = {United States},
year = 2016,
month = 6
}
  • In this work, we present the conceptual design of the backscattering time-of-flight spectrometer MIRACLES approved for construction at the long-pulse European Spallation Source (ESS). MIRACLES’s unparalleled combination of variable resolution, high flux, extended energy, and momentum transfer (0.2–6 Å{sup −1}) ranges will open new avenues for neutron backscattering spectroscopy. Its remarkable flexibility can be attributed to 3 key elements: the long-pulse time structure and low repetition rate of the ESS neutron source, the chopper cascade that tailors the moderator pulse in the primary part of the spectrometer, and the bent Si(111) analyzer crystals arranged in a near-backscattering geometry in themore » secondary part of the spectrometer. Analytical calculations combined with instrument Monte-Carlo simulations show that the instrument will provide a variable elastic energy resolution, δ(ħ ω), between 2 and 32 μeV, when using a wavelength of λ ≈ 6.267 Å (Si(111)-reflection), with an energy transfer range, ħ ω, centered at the elastic line from −600 to +600 μeV. In addition, when selecting λ ≈ 2.08 Å (i.e., the Si(333)-reflection), δ(ħ ω) can be relaxed to 300 μeV and ħ ω from about 10 meV in energy gain to ca −40 meV in energy loss. Finally, the dynamic wavelength range of MIRACLES, approximately 1.8 Å, can be shifted within the interval of 2–20 Å to allow the measurement of low-energy inelastic excitations.« less
  • The design update of the European Spallation Source (ESS) accelerator is almost complete and the construction of the prototype of the microwave discharge ion source able to provide a proton beam current larger than 70 mA to the 3.6 MeV Radio Frequency Quadrupole (RFQ) started. The source named PS-ESS (Proton Source for ESS) was designed with a flexible magnetic system and an extraction system able to merge conservative solutions with significant advances. The ESS injector has taken advantage of recent theoretical updates and new plasma diagnostics tools developed at INFN-LNS (Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare). Themore » design strategy considers the PS-ESS and the low energy beam transport line as a whole, where the proton beam behaves like an almost neutralized non-thermalized plasma. Innovative solutions have been used as hereinafter described. Thermo-mechanical optimization has been performed to withstand the chopped beam and the misaligned focused beam over the RFQ input collimator; the results are reported here.« less
  • In 2003 the joint European effort to design a European Spallation Source (ESS) resulted in a set of reports, and in May 2009 Lund was agreed to be the ESS site. The ESS Scandinavia office has since then worked on setting all the necessary legal and organizational matters in place so that the Design Update and construction can be started in January 2011, in collaboration with European partners. The Design Update phase is expected to end in 2012, to be followed by a construction phase, with first neutrons expected in 2018-2019.
  • The European Spallation Neutron Source (ESS) delivers high-intensity pulsed particle beams with 5-MW average beam power at 1.3-GeV incident proton energy. This causes sophisticated demands on material and geometry choices and a very careful optimization of the whole target system. Therefore, complex and detailed particle transport models and computer code systems have been developed and used to study the nuclear assessment of the ESS target system. The purpose here is to describe the methods of calculation mainly based on the Monte Carlo code to show the performance of the ESS target station. The interesting results of the simulations of themore » mercury target system are as follows: time-dependent neutron flux densities, energy deposition and heating, radioactivity and afterheat, materials damage by radiation, and high-energy source shielding. The results are discussed in great detail. The validity of codes and models, further requirements to improve the methods of calculation, and the status of running and planned experiments are given also.« less
  • A study group has started to develop a conceptual design for a European Spallation Source (ESS). This pulsed 5 MW source presently consists of a 1.334 GeV linac and two compressor rings. In the following mainly the high intensity linac part will be discussed, which has some features of interest for accelerators for transmutation of radioactive waste too.