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Methoden und Instrumentierung Poster: Mi., 14:00–16:30 M-P65
BRISP - a new thermal neutron Brillouin scattering spectrometer
W.-C. Pilgrim 1 , F. Barocchi 2 , A Cunsolo 3,4 , F. Formisano 3,4 , T. Gahl 6 , E.
Guarini 2 , A. Orecchini 3,4 , C. Petrillo 5 , F. Sacchetti 5 , J.-B. Suck 7
1 Institute of Physical Chemistry, Philipps-University of Marburg, Germany – 2 INFM-
Unità di Ricerca di Firenze, Italy – 3 INFM-OGG Grenoble, France – 4 Institut Laue-
Langevin, Grenoble, France – 5 INFM-Unità di Ricerca di Perugia, Italy – 6 Paul Scherrer
Institut, Villigen, Switzerland – 7 Technical University Chemnitz, Germany
BRISP is an Italian-German thermal neutron BRIllouin SPectrometer project, financed
by INFM (Italy) and BMBF (Germany). This TOF spectrometer is designed for inelastic
scattering experiments where wide energy ranges at small momentum transfer
are desired. The extension of the Q-ω-plane allows to address a number of longstanding
questions which were yet hampered due to kinematic restrictions of conventional
neutron spectrometers. The new possibilities range from detailed investigations of
magnetic dynamics in condensed matter to a study of fluid dynamics in systems close
to their liquid-vapour critical points. Collective density excitations at low Q can be
measured in glasses and fluids where the sound velocity reaches values up to 4000 m/s.
The instrument components are now completely installed at the HFR at the ILL in
Grenoble and the 1x2 m 2 two-dimensional position-sensitive detector and related electronics
[1] have meanwhile been completed. First experiments were carried out (see
Fig. 1) demonstrating the capability of this new instrument and confirming the calculated
predictions [2] for the energy resolution. Results [3] will be presented. BRISP
will be available in autumn 2006.
[1] P. van Esch, T. Gahl, B. Guerard, Nucl. Instr. Methods A 526/3 (2004) 493
[2] D. Aisa et al., Nucl. Instr. Meth. A 544/3 (2005) 620
[3] F. Sacchetti et al. Physica B: Condensed Matter (accepted)
Fig. 1: S(Q,ω)-spectra of liquid Pb, measured
with an incoming energy of 79.9
meV. Measured energy resolution is also
shown (2.7 meV, dashed line).