Biography & Net Worth: New concept of high performance detector

New concept of high performance detector

SLAC’s Chris Kenney has a 16-module, 2.2-megapixel ePix 10k X-ray camera. credit: Jacqueline Ramser Aurel / SLAC National Accelerator Laboratory

When the Department of Energy’s SLAC National Accelerator Laboratory commissioned the world’s first hard X-ray free electron laser in 2009, it heralded a new era of science. The researchers were able to directly observe the superluminal motion of atoms in real time. Then we study how those motions affect the properties of chemical and biological materials and basic processes.

But the new machine Linac Coherent Light Source (LCLS) We also needed a new type of detector that could handle the powerful radiation of X-ray lasers and be fast, stable and flexible enough to support a large number of newly developed experiments.

Idea was the time when ePix was born. This is a new product of a very versatile detector that will be the flagship product for ultrafast X-ray experiments at LCLS.

“We chose to either develop multiple detectors, each designed for a particular experiment, or create a new one. Detector Angelo Dragon, program director at SLAC’s Detector R&D and Applied Microelectronics, said:

Today, its building block approach is at the heart of SLAC’s vision for the next generation of detectors that can meet more demanding experiments in the laboratory, especially with the LCLS upgrade, launching 10,000 times faster and 8,000 times faster. Will be done. Ancestor. This year, the ePix X-ray detector was also selected as a finalist for the prestigious R&D 100 awards.

“It’s an appreciation of all the effort the team has put in over the years,” Dragon said. “EPIX technology is a holistic design philosophy and a new concept for manufacturing high performance detectors that can be adapted to multiple applications. It is rewarding to see this approach pay off.”

Modular detector design for new astrophysical X-ray sources

Essentially, all ePix detectors are X-ray sensors, application-specific integrated circuits (ASICs) that define detector functions, electronics for reading signals, software for collecting data, cooling systems, and machines. ASICs consist of a shared set of building blocks such as housing. .. These common components have a standardized interface and can be grouped into different detector tiles with different characteristics. You can add more of these tiles to make a bigger detector.

Unlike earlier X-ray detectors that scientists have had, the ePix detector is fast enough for the fast sequence of ultrashort pulses in the LCLS and captures both the single photon and the full intensity of the X-ray beam. It is sensitive enough to be stable enough to function well for long periods of time. Temporary.

SLAC’s Angelo Dragon shows a silicon wafer containing approximately 50 ePix HR cores for application specific integrated circuits (ASICs). These are first-generation high-speed readout chips for the detector of the laboratory’s next-generation X-ray laser, the LCLS-II. credit: Jacqueline Ramser Aurel / SLAC National Accelerator Laboratory

“The important thing here is that the components speak the same language, so it’s very easy to connect them in multiple ways,” says SLAC, which has partnered with Dragon to drive ePix development in the lab since its inception. Senior staff scientist Chris Kenney said. “But the different detectors share a common architecture, but they are tailored to the specific experimental needs that are used.”

Enables prestigious X-ray science at SLAC and elsewhere

Currently, about 85% of LCLS experiments rely on ePix detectors. Last year, the LCLS contained more than petabytes, or 1 trillion bytes of user data—about half of them recorded using the ePix detector.

“These detectors are a very powerful technology platform that is absolutely critical to our success,” said Bob Schönlen, deputy director of science at LCLS. “When it was first introduced it was a huge step forward, and since then we have been at the forefront of science. The movement has influenced important processes in the world around us. Growth.”

The first detector was the ePix100. It has ultra-low noise detection for weak signals and a small pixel size of 50 µm for high resolution X-ray images. Over the years, Detector developers have added several other ePix variants. Recently, detector designers have introduced the ePix10k. It can take about 10x X-ray images per second of the previous generation, is 3x more sensitive, and can use up to 2 megapixels. Another variant, the ePix S, is particularly suitable for spectroscopic applications that analyze X-ray light with very small wavelength differences, or “colours”.

Researchers from DOE’s Argonne National Laboratory and the Advanced Photon Source at the European XFEL in Germany are also using this technique, which could be followed by other X-ray facilities around the world. Rayonics, which developed X-ray detectors for research, has started commercializing this technology. This would make it more widely available.

Preparing for the future of X-ray science

Meanwhile, the SLAC team is already focusing on the next challenge: Next year, the lab will be commissioning LCLS-II. It emits 1 million X-ray pulses per second, producing a beam that is 10,000 times brighter than the first pulse. -Generation X-ray laser.

“LCLS-II produces data so rapidly that it would not be possible to physically read and store all the information from the detector,” Dragon said. Therefore, he and his colleagues are developing an ePix version that processes the data differently.

New concept of high performance detector

Four ePix 10k cameras used for X-ray science at SLAC’s Linac Coherent Light Source (LCLS) and facilities around the world. ePix Technology was a 100 finalist of the prestigious R&D 2021 Awards. credit: Christopher Kenny / SLAC National Accelerator Laboratory

One way forward is a very fine line of detectors. High rate of raw data called ePixHR. The advanced LCLS-II data acquisition system compresses the data from these detectors without affecting the quality of subsequent analyses. It’s like generating a high quality JPEG from a raw image that contains a lot of data. The team has already built a prototype that can process 5,000 images per second, and plans to increase that number to 25,000 and eventually 100,000 images per second in future versions.

Another approach, called SparkPix, allows researchers to take images as fast as the LCLS-II X-ray flash. It takes advantage of the fact that not all data collected by the detector is equally important. In many cases, only a few frames of a series of images contain the actual X-ray signal, and some techniques use only a few pixels of a larger image for data analysis, so you don’t always have to read and save everything. . SparkPix processes such data inside the detector and extracts only the information it needs.

“These new developments allow us to advance the most ambitious scientific goals of LCLS-II,” says Schönlein. “But that’s not all. These detectors also create unexpected features that encourage scientists to think about entirely new types of experiments that use them.”

Overall Strategy for Lab Data Challenges

The very high data rates available from LCLS-II are one of the data challenges facing SLAC scientists in the coming years. Future research in particle physics, such as space and time legacy research at Rubin Observatory, next-generation analysis of the cosmic microwave background, and high brightness gradation at CERN’s Large Hadron Collider, is enormous. will create things. The amount of data that requires a new approach to how the data is recorded, analyzed and managed.

Traditionally, SLAC researchers and engineers in one area have designed and built most detectors, even when their partners are working in other areas. But recently, several designers have gathered in the lab’s Department of Innovation (TID) to create scientific instruments of the future.

“The challenges we face are very similar to those in the lab, so it’s most useful for science to team up and choose an integrated approach for data acquisition, computing, and detector development. You can,” Dragon says.

For example, X-ray and elementary particle detectors look for different signals, but often use the same set of components and require similar specifications such as faster times, smaller pixels, and higher resolution. Having a common strategy for detector development can optimize R&D in both areas, and technological advances in one area can lead to solutions in another.

With dozens of people from different SLAC boards and departments over the past decade, the ePix Detector program is a good example of a successful strategic collaboration. The state-of-the-art X-ray light source has become a model for TID to develop versatile detectors for other mission areas in the laboratory. ,


ATLAS Detector for a new era of physics


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