Authors: Kaudia Hradil, H. Schneider, G. Eckold, J. Neuhaus

Abstract
The triple axis spectrometer PUMA with a view on the thermal source of FRM II is build up within a cooperation of the University of Göttingen and the Physics Department E13 of the Technical University of Munich. After the commissioning phase and first ”friendly user” experiments, the instrument is now available to the user community within the proposal system of the FRM II. An overload factor of about 2 already for the first proposal rounds reveals the high demand and acceptance of the instrument.

The main characteristics of PUMA can be summarised as follows: high neutron flux on sample position; flexible and straightforward change of components as collimation, monochromators/analysers; Eularian cradle for flexible scattering plane adjustment; equipment for time resolved measurements; diverse and powerful sample environment. At present, PG(002) and Cu(220) monochromators and PG(002) as analyser, manufactured at IPC, are provided, covering an energy transfer range up to 80 meV. A multi-analyser/detector option is under construction which allows survey measurements in (Q, w) space and provides new features for time-resolved measurements of excitations. The high quality of the Cu(220) is displayed by the beam profiles at sample position (figure 1). Phonon measurements for larger energy transfers proved the high flux at sample position.

Beside the standard sample environment of FRM II a closed-cycle cryostat (3-300K), a cryo furnace (3-800K), a high temperature furnace (-1300K) for the Eularian cradle and a high-pressure cell Paris-Edinburgh type VX3 (10 GPa) is available. In the context of this contribution, characteristics, current status of the instrument and a survey of the first measurements on PUMA will be presented.

This project has been funded by the German Federal Ministry of Education and Research under contract no. 03EC6GO1

Authors Description
IPC Universität Göttingen
ZWE FRM II, Technische Universität München