From the proceedings of the 2006 conference on SAXS, held in Kyoto, comes this article entitled “Small-angle X-ray scattering investigation of water droplets in mist” by Y. F. Yano et al..

The article itself is found lacking in many places, on which I’ll touch briefly at the end, but the topic itself is rather unique. They have attempted to recreate mist, fog, using an ultrasonic bath, and have attempted to measure its small-angle X-ray scattering pattern at Spring-8. In terms of the application of the technique to real-life systems everyone understands, you cannot get much closer.

However, I think there is quite some room for improvement on their research. First of all, they took a WAXS set-up to measure a SAXS pattern, which might not be the most ideal set-up in terms of minimising air-scattering. Their method for creating man-made mist might also require some more testing in order to ensure it accurately resembles actual natural mist. Finally, their analysis of their data is quite limited (if not inapplicable). I think they could have done much more with the data they obtained.

Nevertheless, the idea of measuring mist is a nice human interest topic that could, perhaps, be used to get more young people interested in the field.

A fancy new detector is being developed by the Swiss Light Source. This Pilatus detector would be of special interest in pushbutton machines, for its range in count rate would allow the use of this detector in a beamstop-less system.

Imagine a SAXS machine without a beamstop, and how convenient it would be, and it quickly becomes apparent that this would much simplify the operation and measurement requirements for samples. The advantages I can quickly think of are:
– no more beamstop alignment, 1 less set of x,y motor stages
– immediate determination of the beam center
– two-step determination of the primary and secondary beam intensity, greatly simplifying the required procedure for determining the sample attenuation/transmission factor, as well as the primary beam intensity in absolute units.

If it works as advertised, this detector could thus greatly simplify the SAXS technique.
Soon I’ll post a simple drawing of an example pushbutton machine.

Back on the topic of pushbutton machinery.

The ideal pushbutton machine could provide, for the beginning user, a control system that would not “challenge” them with a command-line interface, such as provided by TASCOM and SPEC. One option would be point-and-click interfaces on a computer screen. Another would involve a more hardware-oriented approach using midi-devices.

The first option is a no-brainer, and is probably already widespread in commercial systems. The disadvantage is that such an interface (a gui to TASCOM or SPEC), would require constant maintenance due to over-enthousiastic managers (e.g. “Ooh, wouldn’t it be cool to integrate xxx into the GUI”), and other gui-related issues.

The second option would be a nicer one, in my opinion. Recently, we’ve seen the uptake of button boxes for NMR machines, to simplify the controls of the software on the computer. Electron microscope machines have never much stepped away from dedicated controls, and for good reason. Dedicated controls provide the occasional user with a feeling of control, when button “A” is pressed, the machine performs a single specific task. Instead, pressing “A” on a keyboard could do anything, and thus requires some more warm-up time, alienating the user from the machine.

So how would we go about this? Well, the motor controls, where needed, could be controlled by an inexpensive device like the Behringer BCR2000. This midi control interface can then provide visual feedback on the approximate motor position, and provide rotary controls to change the position accordingly. The push-buttons could then initiate scripts that would control the vacuum (i.e. it could start sample_changing procedures), the generator, and the detector system (i.e. start measurements). The options are nigh endless.

I think such a control box would make the system a little more user-friendly, and thus lower the barrier to SAXS.

Next up in this series: automated processing of data.