Part 4: Simplify Beam Focusing with the Transparent X-ray Camera – Time-Saving In-Situ Collection of Beam Profile, Position, and Flux

Part 1 of this series on Sydor’s x-ray beam monitors provided an overview of diamond-based detectors.

Part 2 highlighted the capabilities of Sydor’s single-channel devices for use as intensity and timing monitors.

Part 3 explored the benefits of Sydor’s position monitors, designed to ensure beam alignment throughout the entirety of one’s beam time.

This 4th part of the series reviews existing beam profile monitoring methods, provides an introduction to the Transparent X-ray Camera (TXC), and highlights the performance advantages of using the TXC for beam focusing – this in contrast with another widely used monitoring method – an ion chamber.


INTRODUCTION TO THE TXC

32×32 pixel array of the TXC
Sydor TXC

The Transparent X-ray Camera is a beam profilometer that is manufactured using the same single-crystal electronic-grade diamonds as Sydor’s other diamond-based monitors. As discussed in the previous entry of this series, these diamonds have low x-ray absorption (>90% transmission for x-ray energies greater than 5 keV) for minimal beam and experiment disruption.

Sydor’s TXC in use

The TXC images beam in-situ across a 32 x 32 pixel array in order to track beam shape and position in real time. Each pixel is 60 x 60 μm in size. The TXC offers a solution to spatially resolve x-ray beams with linearity over a wide range of beam flux. This was tested and verified at a synchrotron beamline using a pink beam with 107 to 1016 photons/s flux.

The TXC is an exciting addition to Sydor’s diamond-based monitor suite. It allows for quick identification of beam deviation through imaging and quantifiable flux measurements to make troubleshooting and experiment alignment more efficient. One application that the TXC is particularly useful for is beam focusing using toroidal mirrors.

TOROIDAL MIRROR FOCUSING

Beamlines using toroidal mirrors manipulate the x-ray beam through time-consuming bending, rotation, and manipulation with x-ray optics. This process is used to generate various beam shapes for different experiments, with optimization requiring lengthy, iterative adjustments. As discussed in Part 3, in the world of light sources, beam time is a valuable resource, and time should be spent performing experiments, not assessing the beam.

Shown here is an example of the focusing process being done with a proof-of-concept device in line with a burn paper measurement. This demonstrates the improved imaging precision achieved using a diamond-based monitor vs. that of burn paper. Burn paper also requires movement and replacement of the paper after each measurement. This replacement requires the user to open the x-ray hutch doors and make the replacement which can take up valuable time and adds a frustrating step to the setup of a new experiment.

Example precision of a proof-of-concept TXC taken at Brookhaven National Laboratory

Using a TXC, its controller, with a PID loop, the beam is able to correct for beam drift, ensuring beam stability in real time. This process occurs automatically without the need for manual adjustment- reducing the time required for setup prior to an experiment.

Below is a sequence of frames taken from a video acquired using the TXC prototype at Brookhaven National Laboratory (BNL) at 6 frames per second using the live video option. In TXC Viewer software, users can immediately see the result of focusing a beam with toroidal mirrors.

Figure 5 Example of TXC being used to focus an x-ray beam at BNL.
Example of TXC being used to focus an x-ray beam at BNL. Click here to watch the video

EVALUATION AT NSLS-II COMPARING TXC PERFORMANCE WITH AN ION CHAMBER

Figure 6 TXC in use at NSLS-II's XFP beamline
TXC in use at NSLS-II’s XFP beamline

In 2022, scientists from Sydor, Stony Brook University, and the X-ray Footprinting (XFP) beamline evaluated the performance of the TXC. In this setup, the XFP pink beam was monitored using an existing ion chamber, with the TXC installed immediately downstream during testing. Measurements were taken with varying beam attenuation and positioning on the TXC. This was performed to evaluate the diamond-based beam profilometer’s dynamic range and compare the quality of the data with that of an ion chamber as a representative of a common beam monitoring solution.

The TXC has three gain stages capable of reading currents ranging from pA to mA per pixel. Aluminum and copper sheets of known thickness were used to attenuate the beam (peak ~1016 photons/s at ~7 keV). Some key findings included:

1.	Figure 7 Demonstration of linearity of the TXC vs. a ion chamber's response
Demonstration of linearity of the TXC vs. a ion chamber’s response
  • The signal observed by the TXC did not saturate within the measured current ranges; ion chamber signal saturated around 0.1 mA
  • The TXC resolved 0.78 nA of current at high gain with 1.57 mm Cu attenuating the beam to reduce the signal
  • The highest sustained total power absorbed by the TXC was over 0.1 W (16 mA) at low gain without any attenuation of the pink beam
  • The imaging area of the TXC varies in responsivity by less than 2%

The 16 mA measurement was made with the beam focused in 10% of the detector area and sustained over a 5 minute time period with no sensor degradation and no active cooling.

Figure 8 Response uniformity of the TXC
Response uniformity of the TXC

This performance is partly due to the high thermal conductivity of diamond, making it an ideal sensor material as discussed in Part 3.

To observe variation in intensity over the pixel array, the beam was reduced to <100 μm in size using a pinhole.  The team was able to generate sensitivity maps of the detector at 18 nA (high gain) and 17 μA (medium gain). The currents were observed using different Cu attenuation thicknesses. Using a voltage output on the electronics proportional to current measured by the TXC, software plotted the response uniformity over the full sensor active area. All results showed an extremely uniform response over the diamond’s active area, with an example shown here. In the 17 μA scans, the variation across the entire 32 x 32 sensor array was less than 2%.

The evaluation at NSLS-II demonstrated the robustness of the TXC’s use with high currents over extended time. The unit showed very uniform response and out-performed the linear range of an ion chamber.

AVAILABLE NOW THROUGH SYDOR TECHNOLOGIES

The Transparent X-ray Camera is now commercially available and fully supported by Sydor Technologies.

TXC monitor alongside the TXC Controller
All units are provided with the TXC Viewer software

Resources:

For technical information on the TXC, please see this informative poster.

For a more in-depth look at the TXC, read the paper from the Journal of Physics: Conference Series


In case you missed it, please take a look back at the first three parts of this series, accessible here:

For additional product information, please visit https://sydortechnologies.com/transparent-x-ray-camera/ or email info@sydortechnologies.com for a technical consultation with one of our technology experts.