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Kennedy, S.J.

Paper Title Page
MOPEB067 The Novel Method of Focusing-SANS with Rotating Magnetic Sextupole Lens and Very Cold Neutrons 427
 
  • M. Yamada, M. Ichikawa, Y. Iwashita, T. Kanaya, H. Tongu
    Kyoto ICR, Uji, Kyoto
  • K.H. Andersen, P.W. Geltenbort, B. Guerard, G. Manzin
    ILL, Grenoble
  • M. Bleuel
    RID, Delft
  • J.M. Carpenter, L. Jyotsana
    ANL, Argonne
  • M. Hino, M. Kitaguchi
    KURRI, Osaka
  • K. Hirota
    RIKEN, Wako, Saitama
  • S.J. Kennedy
    ANSTO, Menai
  • K. Mishima, H.M. Shimizu, N.L. Yamada
    KEK, Tsukuba
 
 

We have developed a motorized magnetic lens for focusing of pulsed white neutron beams. The lens is composed of two concentric permanent magnet arrays, in sextupole geometry, with bore of 15 mm and magnet length of 66 mm. The inner magnet array is stationary, while the outer array is rotated (the frequency of the modulation of magnetic field inside the bore ν ≤ 25Hz), providing a sextupole magnetic field gradient range of 1.5x104T/m2 ≤ g' ≤ 5.9x104T/m2. By synchronization of a pulsed neutron beam with the sinusoidal modulation of the magnetic field in the lens, the beam is focused, without significant chromatic aberration, over a wide neutron wavelength band. We have constructed a focusing-SANS (Small Angle Neutron Scattering) test bed on the PF2-VCN (Very Cold Neutron) beam line at the Institut Laue-Langevin in Grenoble. The beam image size matched the source size (≈ 3mm) over of wavelength range of 30Å ≤ λ ≤ 48Å with focal length of ~ 2.3 m. Further, we have demonstrated the performance of this device for high resolution time-of-flight (tof) SANS for a selection of polymeric & biological samples, in a compact geometry of just 5 m.