Front-end optics enclosure showing the major components for beam conditioning
and delivery. Foreground: High-heat-load slits and double-crystal monochromator
(water-cooled diamond 111) feeding x-rays to the mainline stations (ID-C,D,E).
Background, left: Long vessel containing a 2.65m long rail on which the second
crystal (Si 220) of the branching-monochromator travels. This monochromator
delivers x-rays to ID-B, the side-station. HPCAT is the only beamline in the
world with such a wavelength-tunable instrument which allows two stations to run
Geophysical Laboratory researchers Eugene Gregoryanz and Olga Degtreyava with
HPCAT beamline scientist Maddury Somayazulu (right) during their recent
high-pressure experiments on sulfur, mercury and nitrogen. Station ID-B uses a
pair of state-of-the-art bimorph mirrors, unique in the USA, which focus a 0.5mm
x 0.5mm x-ray beam into a 5μm x 7μm spot at the sample within the diamond anvil
cell thereby delivering diffraction data untainted by the gasket material that
contains the sample at Mbar pressures. ID-B is equipped with both a CCD-based
detector and an Image-Plate reader to give scientists this world-unique
flexibility of either fast data acquisition (CCD) or a large dynamic range (IP).
Every photon counts in the revolutionary and challenging inelastic scattering
experiments at high pressures. The two large ultra-high vacuum vessels shown in
the photograph contain two meter-long mirrors which collect and focus the whole
x-ray beam into a 16μm x 60μm spot in the next station, ID-D, where a broad
range of x-ray spectroscopy techniques are used.
HPCAT director David Mao (front left), beamline scientists Yue Meng (front
right) and Michael Hu (back right), and lead technician Eric Rod, preparing an
x-ray emission spectroscopy experiment. The focused monochromatic x-ray beam
impinges on the sample and the scattered photons are analyzed by a bank of
crystals (in front of Eric) which re-focus the diverging photons onto a detector
in the back-scattered geometry for the highest resolution. In this experiment
David Mao and his team follow the low energy collective excitation of the
electron gas in sodium metal as a function of pressure.
HPCAT project manager Daniel Häusermann completing the assembly of the 0.9m long
horizontal focusing mirror before installation in ID-C. This custom-designed
water-cooled silicon mirror achieves minimal mechanical and thermal strain
operation and hence guarantees optimum performance in the highly challenging
spectroscopy experiments. [ID-E is a large end station constructed for
very-high-resolution phonon measurements, a future development of the HPCAT
project. It is currently used as a clean-room for assembly of critical
Beam-conditioning enclosure of the bending magnet beamline. In this station two
sections of the 6mrad-wide x-ray fan from an APS bending magnet (BM) are
selected and independently delivered to stations BM-B and BM-C/D. This gives the
HPCAT BM line the unique capability of running two experiments in parallel.
16BM-B: Beamline control scientist Arun Bommannavar conducting final software tests on the high-energy diffractometer (left). The Perspex helium enclosure in front of Arun contains a two-mirror micro-focusing system for polychromatic radiation. Soon to be completed, the BM line will give HPCAT a unique capability for alternating polychromatic and monochromatic micro-diffraction from micron-size crystallites in ultr-high-pressure pow