Beamline parameters

The NEUTRA beamline consists of evacuated neutron flight-tubes looking through a fixed 20mm diameter pinhole into the D2O SINQ moderator tank. This implements a pinhole optic forming an almost "parallel" neutron beam, where beam divergence decreases with increasing distance from the pinhole. Due to this divergence a geometric unsharpness in the images results , which is in the order of ug = lsample2detector / (L/D). In a flight-tube neutron flux decreases with increasing distance from the pinhole and is proportional to the pinhole area and the proton current (~1.5 mA) irradiating the SINQ target.

NEUTRA positions for experiments 1 2 3
Distance from the n-aperture L [mm] 3820 7292 10547
Beam diameter [mm] 150 290 400
Neutron flux / cm2 / sec / mA 3.68 107 9.8 106 5.1 106
Collimation ratio L/D 200 350 550
Position Lens Field of view [mm] Nominal pixe size [mm] Exposure time [sec]
NEUTRA 2 Macro 65 x 65 0.032 60
NEUTRA 2 Normal 150 x 150 0.104 12
NEUTRA 3 Macro 131 x 131 0.064 50
NEUTRA 3 Normal 306 x 306 0.15 8