MultiFLEXX

In 2016, the construction of the new multi-analyzer MultiFLEXX (see Fig. 1) was completed [1]. It consists of 31 angular segments that each contain 5 vertically scattering analyzers [2], which are placed one after the other in the beam path as seen in Fig. 2. The analyzers are made from pyrolytic graphite, which is highly transparent to long-wavelength neutrons. Each analyzer is set to a fixed wavelength, corresponding to final energies of 2.5, 3, 3.5, 4 and 4.5 meV. The 31 channels are separated by 2.5° leading to a total angular coverage of 77°. Thus, MultiFLEXX allows a large region of reciprocal space to be measured simultaneously by simply rotating the sample. Switching between FLEXX and MultiFLEXX takes only half an hour, and all usual sample environment set-ups are compatible with MultiFLEXX. An oscillating radial collimator ensures low background counts. MultiFLEXX is thus a convenient new tool for parametric overview studies of excitations as a function of field or temperature.

MultiFLEXX with oscillating radial collimator

Fig. 1: Photo of MultiFLEXX.

MultiFLEXX analyzers

Fig. 2: Schematic drawing of one angular channel of MultiFLEXX, showing the vertical scattering geometry with 5 analyzers.


References

[1] S. Meng, R. Toft-Petersen, L. Hao, K. Habicht, multiflexxlib: A Python package for data reduction and visualization for the cold-neutron multi energy wide angle analyzer MultiFLEXX, SoftwareX 7 (2018) 309.

[2] F. Groitl, R. Toft-Petersen, D.L. Quintero-Castro, S. Meng, Z. Lu, Z. Huesges, M.D. Le, S. Alimov, T. Wilpert, K. Kiefer, S. Gerischer, A. Bertin, K. Habicht, MultiFLEXX - The new multianalyzer at the cold triple-axis spectrometer FLEXX, Sci. Rep. 7 (2017) 13637.

[3] R. Toft-Petersen, F. Groitl, M. Kure, J. Lim, P. Čermák, S. Alimov, T. Wilpert, M. D. Le, D. Quintero-Castro, C. Niedermayer, A. Schneidewind, K. Habicht, Experimental characterization of a prototype secondary spectrometer for vertically scattering multiple energy analysis at cold-neutron triple axis spectrometers, Nucl. Instrum. Methods Phys. Res. A 830, 338-344 (2016).