Advanced geometries for ballistic neutron guides

Schanzer, Christian; Böni, P.; Filges, Uwe; Hils, Thomas

doi:10.1016/j.nima.2004.04.178

Cited by 99 publications

(37 citation statements)

References 7 publications

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“…As already shown in previous works, elliptic mirrors [1]- [4] are well suited to focus neutron and xray beams at the sample. With the rather dramatic increase of the reflection angles of supermirrors exceeding m = 8 times the critical angle of reflection of Ni [5], neutrons encompassing a wide range of wavelengths and large divergence can be directed towards the sample position.…”

Section: Introductionmentioning

confidence: 99%

Variable focusing system for neutrons

Schanzer¹,

Schneider²,

Filges

et al. 2018

J. Phys.: Conf. Ser.

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Abstract. We have developed a variable focusing system for neutrons that allows varying the vertical and horizontal beam size at the sample position independently. It is based on a focusing parabolic neutron guide coated with supermirror m = 6 times the critical angle of reflection of Ni. The divergence of the incident beam is adjusted by solid-state collimators with horizontally and vertically arranged absorbing blades. The performance of the prototype set-up has been benchmarked at the beamline BOA at SINQ confirming the expected behavior. In particular we show that the beam size at the sample position can be varied between 0.6 and 2 mm without exchanging the focusing guide or by introducing a beam-defining aperture between the exit of the guide and the sample, i.e. the beam size can be adapted more than half a meter away from the sample. IntroductionThe investigation of novel materials using neutron scattering techniques is challenging because these materials are often only available in small quantities, e.g. encompassing a volume of a few mm³. Moreover, special experimental conditions, e.g. high pressure, high/low temperatures and/or high magnetic fields can only be realized for small volumes. Confining the neutron beam to such small areas using slits reduces the number of neutrons delivered by the rather large neutron beams (e.g. 50-100 cm²) significantly because for the minimization of the background, the penumbra must be suppressed too, to reduce scattering of neutrons from the sample environment. Moreover, it would require an aperture that is placed close to the sample which is usually not compatible with the sample environment. Therefore, it is desirable to focus the neutrons precisely to an area corresponding to the given size of the sample. Ideally, the useful neutrons would be selected already far away from the sample area using neutron optical devices. As already shown in previous works, elliptic mirrors [1]-[4] are well suited to focus neutron and xray beams at the sample. With the rather dramatic increase of the reflection angles of supermirrors exceeding m = 8 times the critical angle of reflection of Ni [5], neutrons encompassing a wide range of wavelengths and large divergence can be directed towards the sample position. While adjusting the beam size at the sample with Montel mirrors [6] is straightforward using an aperture at the focal point at the entrance of the mirror [6], the selection of the beam size using elliptic or parabolic guides is more complicated and essentially given by the design of the optics [7]. In the following we propose a combination of a focusing parabolic guide with a variable collimation stage in front of the entrance of the guide that allows varying the size of the beam spot at the sample position in the horizontal and

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Section: Introductionmentioning

confidence: 99%

Variable focusing system for neutrons

Schanzer¹,

Schneider²,

Filges

et al. 2018

J. Phys.: Conf. Ser.

Self Cite

View full text Add to dashboard Cite

show abstract

“…With the addition of the super-mirror coating in the seventies [4,5], another vital step in the improvement of neutron guides was taken, increasing dramatically the reflection angle and thus the divergence and intensity transported by the guide. In recent years ballistic guides with straight tapering [6,7], parabolic tapering [8,9] and full elliptical [8][9][10][11] geometries have been investigated and implemented with the aim of reducing transport losses and improving divergence profiles in guide systems.…”

Section: Introductionmentioning

confidence: 99%

Neutron guide-split: A high performance guide bundle concept for elliptical guides

Holm

Rasmussen

Høpfner

et al. 2015

Nuclear Instruments and Methods in Physics Research Section A:

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“…Significant developments have been made in the area of neutron optics in the intervening years since HRPD was first designed. Most notable is the concept of neutron supermirrors [3,4] and 'ballistic' guide designs [5,6] along with technological advances in the large-scale production of supermirror coatings [7]. Modern Monte Carlo simulation codes, for example McSTAS [8,9], NISP [10], etc., have also evolved and now enable more novel and potentially risky designs to be rigorously and reliably tested.…”

Section: Introductionmentioning

confidence: 99%

Design and performance of the new supermirror guide on HRPD at ISIS

Ibberson

2009

Nuclear Instruments and Methods in Physics Research Section A:

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Advanced geometries for ballistic neutron guides

Cited by 99 publications

References 7 publications

Variable focusing system for neutrons

Variable focusing system for neutrons

Neutron guide-split: A high performance guide bundle concept for elliptical guides

Design and performance of the new supermirror guide on HRPD at ISIS

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