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

TY - JOUR

T1 - Neutron guide-split

T2 - A high performance guide bundle concept for elliptical guides

AU - Holm, Sonja Lindahl

AU - Rasmussen, Nina

AU - Høpfner, Louise

AU - Bertelsen, Mads

AU - Voigt, Jörg

AU - Andersen, Ken H.

AU - Lefmann, Kim

PY - 2015/5/11

Y1 - 2015/5/11

N2 - We present a new guide-split concept for transporting cold and thermal neutrons to multiple instruments from a single beam port at a neutron facility without compromising the useful neutron brilliance notably for any of the instruments. Elliptical guides are capable of transporting an almost completely filled phase space within a large divergence (±2° for cold neutrons). It is therefore possible to place several secondary guides side by side pointing in slightly different directions using the end of a primary guide as a virtual source. The instruments placed at the secondary guides hence exploit different parts of the phase space transported by the primary guide. In addition, the resulting kink between the primary and secondary guide eliminates line of sight. Using ray-tracing simulations of three different set-ups (with two, four, and eight secondary guides) we show that it is possible to illuminate at least eight sample positions from one beam port with a brilliance transfer above 90% on each sample on a 150 m long instrument. This has been done for a phase space volume comprised of an area of 1×1 cm2 and a maximum divergence of±0.5° within a wavelength band of 4.25-5.75 Å. We show, by a full virtual experiment, an example of applying the guide-split concept to an instrument proposed for the European Spallation Source, namely a magnetism diffractometer.

AB - We present a new guide-split concept for transporting cold and thermal neutrons to multiple instruments from a single beam port at a neutron facility without compromising the useful neutron brilliance notably for any of the instruments. Elliptical guides are capable of transporting an almost completely filled phase space within a large divergence (±2° for cold neutrons). It is therefore possible to place several secondary guides side by side pointing in slightly different directions using the end of a primary guide as a virtual source. The instruments placed at the secondary guides hence exploit different parts of the phase space transported by the primary guide. In addition, the resulting kink between the primary and secondary guide eliminates line of sight. Using ray-tracing simulations of three different set-ups (with two, four, and eight secondary guides) we show that it is possible to illuminate at least eight sample positions from one beam port with a brilliance transfer above 90% on each sample on a 150 m long instrument. This has been done for a phase space volume comprised of an area of 1×1 cm2 and a maximum divergence of±0.5° within a wavelength band of 4.25-5.75 Å. We show, by a full virtual experiment, an example of applying the guide-split concept to an instrument proposed for the European Spallation Source, namely a magnetism diffractometer.

U2 - 10.1016/j.nima.2015.01.045

DO - 10.1016/j.nima.2015.01.045

M3 - Journal article

SN - 0168-9002

VL - 782

SP - 1

EP - 8

JO - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

JF - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

ER -