Optimization of moderators and beam extraction at the ESS

Andersen, K.H.; Bertelsen, Mads F.; Zanini, L.; Klinkby, E. B.; Schönfeldt, Troels; Bentley, Phillip M.; Šaroun, Jan

doi:10.1107/s1600576718002406

Cited by 58 publications

(59 citation statements)

References 14 publications

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“…At a pulsed facility, these methods can be applied at full counting statistics. The ESS cold moderator will provide a 50 times higher peak brightness and a two times higher time-averaged brightness than the cold sources of the leading continuous facility (the high flux reactor of the Institut Laue-Langevin ILL) [10]. In spite of the substantially smaller viewed area of the ESS cold moderator, pulsed experiments at the ESS should gain more than one order of magnitude in counting rate compared to the ILL.…”

Section: Localisation Of Neutron Pulse In Timementioning

confidence: 99%

ANNI – A pulsed cold neutron beam facility for particle physics at the ESS

et al. 2019

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Pulsed beams have tremendous advantages for precision experiments with cold neutrons. In order to minimise and measure systematic effects, they are used at continuous sources in spite of the related substantial decrease in intensity. At the European Spallation Source ESS these experiments will profit from the pulse structure of the source and its 50 times higher peak brightness compared to the most intense reactor facilities, making novel concepts feasible. Therefore, the cold neutron beam facility for particle physics ANNI was proposed as part of the ESS instrument suite. The proposed design has been re-optimised to take into account the present ESS cold moderator layout. We present design considerations, the optimised instrument parameters and performance, and expected gain factors for several reference experiments.

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Section: Localisation Of Neutron Pulse In Timementioning

confidence: 99%

ANNI – A pulsed cold neutron beam facility for particle physics at the ESS

et al. 2019

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“…We consider here the most general case of diffuse scattering, for which there is no correlation between the trajectories of the neutron beam before and after the sample. 1 In that case the variance of the sum of two normally distributed variables is the sum of individual variances, i.e. σ 2 ϕ = σ 2 ϕ 1 + σ 2 ϕ 2 .…”

Section: Introductionmentioning

confidence: 99%

“…where J is the magnetic field integral along a specific trajectory and .. stands for the averaging over the neutron beam. 1 The neutron beam trajectories before and after the sample are one-to-one correlated in the case of the direct beam (the part of the beam that has not been scattered by the sample) and the Bragg peaks. This feature is very important for the design and operation of SESANS [5,13] and Larmor diffraction [12] instruments.…”

Section: Introductionmentioning

confidence: 99%

“…In the following we will consider the separation of those two sources in a more general way and apply the results to assess the implications of the "pancake" moderator which is currently planned for the European Spallation Source (ESS) on an NSE instrument design [1,16]. The novelty of this moderator design is that it will produce high-intensity neutron beams over cross sections that are significantly smaller compared to research reactors.…”

Section: Introductionmentioning

confidence: 99%

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Semi-analytical calculations of intrinsic field magnetic field inhomogeneities for a Neutron Spin Echo spectrometer at the ESS

Kusmin

Pappas

2020

JNR

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Neutron Spin Echo methods (NSE) use Larmor labelling to measure the precession phase of the neutron beam polarization around well-defined magnetic fields. Scattering by a sample can affect the resulting precession phase providing information on the sample's structure and dynamics with high accuracy and resolution. A major limitation for the performance of Neutron Spin Echo instruments is the homogeneity of the precession magnetic fields. Here we investigate the influence of the new "pancake" moderator, which is being built at the European Spallation Source, on the design of a Neutron Spin Echo spectrometer. The calculations show clear gains when the height to width ratios of the rectangular beam cross-sections mimic those of the ESS "pancake" moderator beams. In such a case the homogeneity of the magnetic field integrals could improve by at least 30%. However, the calculations show that will not be possible to preserve a high resolution and at the same time reduce the length of the instrument. Consequently, NSE spectrometers will perform better at the ESS but they will not be substantially compacter than at other neutron sources e.g. ILL or FRM2.

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“…The world's brightest pulsed neutron source is currently under construction in Lund, Sweden [1]. The European Spallation Source (ESS) will be the first long-pulsed neutron source and novel instrument concepts have been developed to utilize the unique time structure [2][3][4][5]. Many instruments will be optimally placed at long distances, ∼170 m, from the moderator [3,6].…”

Section: Introductionmentioning

confidence: 99%

Optimization of Performance, Price, and Background of Long Neutron Guides for European Spallation Source

Holm-Dahlin

Olsen

Bertelsen

et al. 2019

QuBS

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We describe a systematic approach for the design of long, ballistic cold, and thermal neutron guides for the European Spallation Source (ESS). The guides investigated in this work are 170 m long and are required to have a narrowing point with room for a pulse shaping chopper placed 6 m from the moderator. In addition, most guides avoid line-of-sight from the moderator to the sample. The guides are optimized in order to find a reasonable trade-off between neutronics performance and construction price. The geometries simulated are closely related to the thermal-neutron multi-length-scale diffractometer HEIMDAL and the cold-neutron multi-analyser spectrometer BIFROST. For the cold-neutron guide an inexpensive solution was found that maintains good transport properties, while avoiding line-of-sight. However, for the thermal-neutron guide the losses when avoiding line-of-sight are large and it seems a good choice to stay in line-of-sight, even though this will increase both the shielding costs and fast-neutron background. The results are of general relevance for the understanding of the relation between transport, background, and price of long neutron guides.

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Optimization of moderators and beam extraction at the ESS

Abstract: All instruments at the European Spallation Source (ESS), Lund, Sweden, are served by a carefully optimized moderator assembly, providing world-leading performance and excellent flexibility and upgradeability.

Cited by 58 publications

References 14 publications

ANNI – A pulsed cold neutron beam facility for particle physics at the ESS

ANNI – A pulsed cold neutron beam facility for particle physics at the ESS

Semi-analytical calculations of intrinsic field magnetic field inhomogeneities for a Neutron Spin Echo spectrometer at the ESS

Optimization of Performance, Price, and Background of Long Neutron Guides for European Spallation Source

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