Neutron spectrometer at FRM II
A broad spectrum of first-class scattering instruments at the MLZ (Heinz Maier-Leibnitz Zentrum) makes it possible to pursue a wide variety of scientific questions, for example in physics, chemistry, biology, engineering or materials science. The MLZ supports national and international scientists in solving fundamental current issues facing our society.
The branch of the Jülich neutron research institute JCNS operates and develops several instruments at the MLZ that utilise the neutrons generated at the FRM2 research reactor. The ZEA-1 institute provides significant support for the further expansion of the neutron instruments and the further development of new types of neutron spectrometers.
KWS-3 is a diffractometer for very small scattering angles (VSANS) that works with a focussing mirror. The instrument is set up in the Neutron Guide Hall West of FRM2 and focussed on cold neutrons.
New measurement modes were developed for the small-angle scattering spectrometer KWS 3, which made it necessary to redesign the second sample location. For this purpose, a new mount for the vacuum chamber at sample location 2 was developed in the ZEA-1.
By shifting the existing vacuum chamber of the 2nd sample location by 500 mm in the reactor direction, an optimisation of the measurement data resolution is achieved. The so-called Q-range of the 2nd sample position is in the range of 0.0006 to 0.012/A after the shift. For many measurement modes performed at the KWS3 instrument, the increased distance to the detector allows measurements to be performed with low Q and high flux.
The reconstruction also stabilises the mechanical construction. As the axis of rotation of the lifting table in the new design is identical to the axis of rotation of the vacuum chamber, there are no additional external bending moments on the structure, unlike in the previous design. The lead shielding of the detector is mounted on a separate mounting frame and is separated from the detector mount. This ensures that the weight of the shielding does not influence the position of the detector and the execution of the measurements. ZEA-1 carried out the engineering, design, manufacturing and assembly on site. The mechanical conversion of the 2nd sample location was successfully completed in spring 2022.
The project represents the excellent collaboration between the institutes JCNS and ZEA-1 and it was entirely designed and realised during the pandemic.