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First test measurements at the new structure powder diffractometer (SPODI) at the FRM-II

Zeitschrift Fur Kristallographie: 183-188

Autoren/Herausgeber: Gilles R
Hoelzel M
Schlapp M
Elf F
Krimmer B
Boysen H
Fueß H
Erschienen: 2006

In framework of a cooperation between the Technische Universitat Darmstadt and the Ludwig-Maximilians-Universitdt Munchen, funded by German government (BMBF), the new Structure Powder Diffractometer (SPODI) has been built at the neutron source FRM-II in Garching near Munchen (see figure 1). The instrument operates in the angle-dispersive mode with a pre-selected wavelength. This contribution gives an overview of the status and the innovations of new components included in the concept [1-2]. Particular highlights of the set-up are, for example, the sophisticated supermirror neutron guides (trumpet shape) for thermal neutrons, the high take-off angle of 155 degrees realized with 17 individual modules of an unconventional orientation (5 5 1) of the germanium monochromator (each module consists of 37 wafers !), the 300 mm high collimators with tapered sidewalls to enlarge the effective detection area, the position sensitive detector providing 2D array detection with multifarious evaluation procedures and the space optimized shielding with different special materials (to improve the signal to background ratio) etc. The realization of this layout aims at higher intensity, improved resolution and better profile shapes. Monte Carlo simulations of the complete instrument including the sample were carried out to match all components.