General X-Ray Diffraction at BL14B1 SSRF

Andy Tan
Mar 16, 2019
3 min read

Updated: Feb 26, 2020

The Introduction

When I was a junior in high school, I participated in the Particle Physics Masterclass that my physics teacher arranged as a 3 day program. The first day would be spent learning the theory behind particle colliders and synchrotrons. Prior to the next meeting, students would analyze actual particle collision data recorded at CERN and identify particles based on their trajectory, momentum and energy within the collision data. The second day would be spent analyzing a histogram of all the results and includes a trip to the local Shanghai Synchrotron Radiation Facility, and the third day would be spent on a conference call with schools worldwide performing the same data analysis, along with some scientists working at CERN.

It was on the day trips to the Shanghai Synchrotron Radiation Facility that I met Dr. Wen Wen twice. I first met him as a junior in high school, and another time when I acted as a teaching assistant for the particle physics masterclass, in 2018.

Fig. 1 BL14B1 General X-Ray Diffraction Beamline within the SSRF

The Shanghai Synchrotron Radiation Facility

The Shanghai Synchrotron Radiation Facility (SSRF), at the time of its opening in May 2009 for user experiments, was the single most expensive scientific facility in the entire People's Republic of China. With a 3.5 GeV storage ring, it remains one of the most brilliant synchrotron light sources in the world. Under the newly renamed Shanghai Advanced Research Institute (formerly the Shanghai Institute of Applied Physics), the beamlines of SSRF continue to provide free beamline time for user experiments from research groups all over the world. Current efforts to upgrade the SSRF include more beamlines for specialized research (a quick example would be the recent addition of an ultra-hard x-ray beamline), and the construction of a free electron laser, which provides more flexibility in experimental techniques.

Fig 2. Prototype Battery Cell Experiment

My Internship

I had two winter internships at the Shanghai Synchrotron Radiation Facility under Professor Wen Wen, both times at the BL14B1 General X-Ray Diffraction Beamline. I learned to operate the Huber 6021 6 Circle Diffractometer, to switch out different rigs for different experiments, to secure the experimental hutch and activate the beamline to measure data, and to analyze the data from the various detectors and CCD cameras in order to get intensity vs. 2 theta plots as the result.

There were different kinds of user experiments almost every day, requiring different setups and tuning of the various geometries so that the x-ray beam will hit the experimental samples at exactly the right location and angle. I was able to learn different techniques used for analyzing different samples.

Fig. 3 Heated Rotation Experiment for studying Material Phase Changes

For example, a soil sample brought in by a research group in order to analyze the presence of specific elements and compounds within the sample had grain sizes that were far too large to be considered a homogeneous sample, so a rotation rig was used with a borosilicate glass tube to rotate the sample while the beamline emits x-rays. Another sample that was analyzed had peaks that corresponded to some of the "noise peaks" generated by x-ray diffraction and scattering off of the borosilicate glass tube, which would confound the data by altering the peaks of the plot. In that specific experiment, a tube of a different element had to be used in order to analyze the sample.

Many other rigs and devices are used at BL14B1, including a heated rotation rigs for analyzing phase changes in materials, but the most useful tools were still the 6 circles of rotation offered by the diffractometer. By manipulating the angles on these rotation circles, it is possible to accommodate for a wide variety of experimental setups, making it easier to obtain the data the users needed to further their research.