PHOTON SCIENCE

Large Volume Press – X-ray Probe for Research in Extreme Synthesis and planetary Studies

Anticipated for start of 2033.

Beamline concept

Motivation:

The high-pressure scientific communities both in Europe (DMG, EHPRG) and abroad (AIRAPT/COMPRES/ISRD, see appendix) will benefit tremendously from the LVP-XPRESS beamline at the new PETRA IV source. For decades, DESY has continued to serve as a historic hub for high-pressure in situ LVP experiments for users since 1991-2012 at DORIS (MAX80 at F2.1 & MAX200x at W2/HARWI II), and since 2019 at PETRA III (Aster-15 at P61B). New opportunities in disciplines such as phase relations, crystallography and rock deformation studies in the LVP are anticipated at PETRA IV, benefitting from faster acquisition times and complete XRD datasets e.g. by radial diffraction.

Description of LVP-XPRESS:

LVP-XPRESS proposes to addresses the growing demand for in situ studies of millimetre-scale materials under extreme pressures and temperatures, advancing geosciences, materials research, and chemistry with increasing industrial relevance. Utilizing state-of-the-art Large Volume Presses (Aster-15 and Paris-Edinburgh) and PETRA IV’s high-brilliance X-rays, it aims to enable unprecedented precision in exploring planetary interiors, novel material synthesis, and complex chemical reactions. Focused µ-beams for high-resolution X-ray diffraction and large beams for whole-sample imaging and tomography, promise breakthroughs in research and applications, including opportunities for industry.

Primary Scientific Fields:

• Geosciences
• Materials Sciences
• High-Pressure Chemistry

Proposed X-ray Techniques at HPHT in LVPs:

• Powder/Multi-grain Diffraction on crystalline solids
• Pair-Distribution Function (PDF) diffraction on melts and amorphous materials
• Absorption & Phase Contrast Imaging
• Diffraction/Scattering Computed Tomography (DSCT) & Imaging Tomography (uCT)

Proposed beamline layout

The P61B LVP station at PETRA III is transformed into a full beamline in the same sector of the North Hall (46g) at PETRA IV - a Phase-I beamline. A second Optics Hutch is converted into an in-line Experimental Hutch (EH1) for portable (smaller) LVPs such as a PE tomography press, and the existing Aster-15 LVP remains installed in the same location (EH2). The light source for the new in situ LVP beamline is changed. The original array of 10 Damping Wigglers of the PETRA III straight section will be removed and replaced by an RF section in the PETRA IV lattice. Behind this, a new CPMU-18 (cryo-cooled, super-conducting) undulator will be installed for the new beamline. It will have a (max) gap of 18 mm for high flux at high energies (40-120 keV). The proposed layout is shown in Figure 1 showing new optical elements such as a bent-Laue Double-Crystal-Monochromator (BL-DCM), Compound Refractive Lenses (CRLs) in transfocators for (pre-)focusing and defocusing. Other components include the heat-load filters, (fast) shutters and (rotating) slit systems. Beam focusing down to 1 um² (e.g. for DSCT), and beam expansion up to 3 x 3 mm² (e.g. for imaging) are considered for a range of discrete energies. Data acquisition schemes are described next.

Fig. 1. Schematic layout of the proposed beamline. Note: adj. SLT = adjustable (power) slits, adj. ROT SLT = adjustable rotatable slits. The double arrows indicate this beamline component can be (remotely) moved in and out of the beam. EH2 is accessible (for offline LVP experiments) when beam is delivered to EH1.

Modes of operation

The upgraded beamline supports multiple LVPs, including any transported to the beamline by users. While EH2 will largely remain dedicated to the existing Aster-15 LVP, EH1 will be compatible with typicaly Paris-Edinburgh-type presses or other small devices (including, possibly diamond-anvil cells). The type of experiments are, for example, visualised in Figure 2.

Fig. 2. Proposed AD-XRD and stress measurements in the Aster-15 LVP, as well as HPHT tomography in the PE-LVP.

[EH2] Operation of Aster-15 LVP (beam allocation: 70%)

Experiment type	Beam requirements for...		Scripted operation
	Diffraction	Imaging
Routine & Deformation (same energy)	Unfocused monochromatic beam (40 - 120 keV, 60 keV typical)	Large defocused beam for imaging	Rapid (< 1 s) CRL insertion and retraction in the defocussing transfocator, combined with incident slit adjustment to crop a region of homogeneous intensity
Special UHP/T generation (same energy)	Pre-focused beam (40 - 90 keV, 60 keV typical)	Unfocused beam for imaging (small sample/anvil gap)	Rapid (< 1 s) CRL insertion and retraction in the (pre)focusing transfocator, combined with incident slit adjustment to crop a region of homogeneous intensity
LVP experiments (different energies)	Unfocused monochromatic beams (40 - 120 keV)	Unfocused beams for imaging	No use of a transfocator, but 2 (or more) beam energies & their positions should be calibrated at the start of beam time. Then scripted operation of the monochromator to switch beam energy.
Other (?)

[EH1] Operation of PE-tomography LVPs (beam allocation: 30%)

Experiment type	Beam requirements for...		Scripted operation
	Diffraction	Imaging
PDF measurements (melts/glasses) (same energy)	Unfocused monochromatic beam (40 - 120 keV, 60 keV typical)	Large defocused beam for imaging	Rapid (< 1 s) CRL insertion and retraction in the defocusing transfocator, combined with incident slit adjustment to crop a region of homogeneous intensity
µCT absorption-contrast tomography (same energy)	n/a	Large defocused beam for imaging	Insertion of defocusing transfocator CRLs. No scripted BL component operations
Diff/Scattering Computed Tomography (DSCT) (same energy)	µ-focused beam monochromatic beam (40 - 120 keV)	Unfocused beams for locating sample	Insertion of pre- and focusing transfocator CRLs and alignment. No scripted BL component operations
Other (?)

Detectors

Absorption vs phase-contrast imaging

It is well known that for typical absorption-contrast imaging (radiography), the scintillator-based imaging optics is required to be typically at close distance to the sample (inside the LVP), whereas phase contrast is better resolved at large distances (3-4 m). In EH2, it may be practical to have two imaging systems for these applications rather than repositioning the image system in front (or behind) the area detector(s) for AD-XRD, also requiring flexible positioning at suitable distances to the sample. In EH1, the available space is limited and phase-contrast imaging will be less optimal.

X-ray diffraction acquisition