E0043

Neutron Time-of-Flight Diffractometer HIPPO. S. Vogel¹, D. Williams¹, H.-R. Wenk², R. B. Von Dreele¹, Y. Zhao¹, ¹LANSCE, MS H805, LANL, Los Alamos, NM 87545 ²Dept. Earth and Planetary Science, U.C. Berkeley CA 94720.

A consortium, consisting of University of California faculty and National Laboratory researchers have build a new TOF neutron diffractometer to study properties of polycrystalline and amorphous materials. The instrument HIPPO (for HIgh Pressure Preferred Orientation) became available for a user program in summer 2002.

A major limitation of neutrons has been long count times. With the new diffractometer HIPPO this problem has been reduced, taking advantage of the improved source at LANSCE, a short flight path and a novel three-dimensional arrangement of detector banks with 1360 ³He-tubes on five conical rings with diffraction angles of 10° to 150°. The usual data collection time is reduced to minutes, enabling us to study time-dependent processes in bulk samples with anisotropic properties. Count time for a typical single phase texture measurement is few minutes per orientation with 4 to 8 orientations needed; for a typical powder in a 3/8 inch V-can it is about 2 hours. A 75 cm diameter sample chamber can accommodate ancillary equipment such as goniometer, furnace (up to 2000K), cryostats (10K), load frame (up to 50 kN), high-pressure cells (up to 30 GPa, 2000K), and user provided equipment. An automated sample changer allows unattended measurements of up to 100 samples for powder and texture investigations.

The instrument is intended to make neutron diffraction not only a method for a few dedicated specialists but also a viable resource for chemistry, physics, materials and earth science communities.