Accelerating Data Acquisition, Reduction, and Analysis at the Spallation Neutron Source

Abstract

ORNL operates the world's brightest neutron source, the Spallation Neutron Source (SNS). Funded by the US DOE Office of Basic Energy Science, this national user facility hosts hundreds of scientists from around the world, providing a platform to enable break-through research in materials science, sustainable energy, and basic science. While the SNS provides scientists with advanced experimental instruments, the deluge of data generated from these instruments represents both a big data challenge and a big data opportunity. For example, instruments at the SNS can now generate multiple millions of neutron events per second providing unprecedented experiment fidelity but leaving the user with a dataset that cannot be processed and analyzed in a timely fashion using legacy techniques. To address this big data challenge, ORNL has developed a near real-time streaming data reduction and analysis infrastructure. The Accelerating Data Acquisition, Reduction, and Analysis (ADARA) system provides a live streaming data infrastructure based on a high-performance publish subscribe system, in situ data reduction, visualization, and analysis tools, and integration with a high-performance computing and data storage infrastructure. ADARA allows users of the SNS instruments to analyze their experiment as it is run and make changes to the experiment in real-time and visualize the results of these changes. In this paper we describe ADARA, provide a high-level architectural overview of the system, and present a set of use-cases and real-world demonstrations of the technology.

Recent progress on HYSPEC, and its polarization analysis capabilities

“…HYSPEC also leverages the neutron event stream via Accelerating Data Acquisition, Reduction and Analysis (ADARA) [3], which adds into the neutron event stream values for motors, chopper settings and sample environments, as well as chopper phase information and neutron monitor events, and multiplexes the combined event stream. The multiplexed event stream feeds into immediate translation for NeXus files, a live viewing of reduced data using the Mantid [4] Live Listener, and remote system monitoring and alert tools.…”

“…Other aspects of HYSPEC distinguish it from TAX's. During alignment, it is common to attenuate the incident beam using thin B-10 loaded aluminium, in order to reduce the count rate on a single detector to at most ∼200 c/s saturation on the detectors when measuring Bragg peaks (the 3 He detector tubes saturate at such a low time-averaged count rate due to the pulsed nature of the elastically scattered neutrons). HYSPEC's momentumenergy resolution function differs from that of a TAX, since the Fermi chopper frequency sets E i resolution and the final energy is measured via Time of Flight.…”

“…The first involves a wide-angle quartz 3 He cell with inner radius ≈75 mm, to be placed in the uniform magnetic field electromagnet system shown in Fig. 7.…”

“…7. The ≈10 Gauss magnetic field is generated via an aberration-corrected 03017-p.5 vertical axis Helmholtz electromagnet, centered at the 3 He cell instead of the sample. To maximize the lifetime of the 3 He nuclei polarization the electromagnet is designed to achieve a spatial uniformity of 2.5 × 10 −5 cm −1 .…”

“…HYSPEC employs 3 He linear position sensitive tube detectors that are assembled into 20 sets of 8-packs. The 8-packs are arrayed in a cylindrical geometry around the sample position at a ≈ 4.5 m radius, with the axis of the cylinder oriented vertically.…”