Research: Research Infrastructure to Meet Tomorrow’s Challenges
Solar cells, glasses, mobile technology, medical treatments – there is an endless list of inventions for which ion-beam based research has been decisive. The Tandem Laboratory conducts advanced analysis using accelerators in order to meet a wide range of future demands within electronics, materials research and energy production.
The walls of the Ångström Laboratory conceal a wealth of infrastructure that plays a crucial role in research across a range of the University’s subject areas. Buildings 4 and 5 contain one such establishment, the Tandem Laboratory, which houses four accelerators and eleven beamlines that are available for everything from non-destructive materials analysis to irradiation and fusion research. In terms of size and capacity, there is nothing comparable in the Nordics, while laboratory director Daniel Primetzhofer is only aware of two similar or larger laboratories within Europe.
“Now that the Svedberg Laboratory has closed down, our largest accelerator is the largest machine operating anywhere at Uppsala University. And our basic infrastructure is so modern that we can keep it operational for another 25 years.”
A recent announcement will further benefit the laboratory’s successful operations over the coming years; in September, the Swedish Research Council renewed the Tandem Laboratory’s grant as research infrastructure of national interest for the period 2021-2024. The total grant of SEK 16 million will primarily be used to develop the organisation.
“This will take place within the framework of a major collaborative project named the Accelerator-based Ion Technology Consortium, in which KTH and Linköping University are partners,” explains Daniel Primetzhofer. “The consortium will ensure that methodological development in the laboratory is in line with future needs in a wide range of different fields.”
High-quality services for external and internal users
The Tandem Laboratory currently has 12 local employees, most of them technicians; however, the central role in the organisation is held by the almost 300 users who use the infrastructure’s services every year. The majority of researchers come from Sweden and other Nordic countries, although in total the laboratory has users in some 20 countries. Customers also include industrial companies, public authorities and private citizens; however, according to Daniel Primetzhofer, research assignments always have priority:
“That said, we rarely encounter any unresolvable conflicts. The machines also operate outside office hours, normally for between 2,000 and 3,500 hours a year. Should analytical needs clash, it is generally possible to rearrange the times.”
A significant proportion of the lab’s operations involve radiocarbon dating, measurements that the Tandem Laboratory conducts over 4,000 times a year – more than any other Swedish facility. Although most carbon-14 dating is conducted in the fields of archaeology and cultural heritage, the technique is also used in areas such as forensic sciences.
“We have been known to cooperate with the police on criminal investigations. This may be happening sometimes in connection with the illegal trade in ivory or bird eggs; however, the police may also turn up with human bones to discover if they belong to a murder victim for whom they may have been searching for 25 years,” says Daniel Primetzhofer.
The Tandem Laboratory has also established an extensive collaboration with Karolinska Institutet on biomedical matters, as the lab is able to date extremely small amounts of biological material from the early 60’s onwards, accurate to up to one year. As part of this collaborative project, laboratory staff have performed tests such as determining the age of brain and other tissue after a stroke or heart attack to see which cell types regenerate and under what conditions.
“The developments we have made in accelerator mass spectrometry allow us to date minute amounts of DNA, which among other things gives us the rate of development for new neurons in various parts of the human brain, something that was previously impossible to determine.”
During radiocarbon dating, carbon atoms in samples are accelerated to speeds approaching 10 million kilometres per hour. The particles are transmitted through magnetic and electrical fields where, depending on their mass, they are steered in different directions in the accelerator. The individual atoms are counted by detectors placed at various locations, making it possible to determine the age of the material from the ratio of the different carbon isotopes.
Ion beams for tomorrow’s technology
Another of the Tandem Laboratory’s fields of activity is ion beam analysis of ultrathin coatings, for instance those on optics or electronics. These layers can make surfaces more visually attractive and harder, as well as less prone to friction. The lab’s latest accelerator application, Time-of-Flight Low Energy Ion Scattering (ToF-LEIS), allows researchers to study and characterise the composition and structure of the outermost atomic layer of a sample. The depth and properties of the material can then be altered and customised down to sub-nanometre scale.
“The lab is sometimes engaged to conduct this kind of analysis on products such as solar cells and new types of lithium battery; however, ion beam analysis can be applied to almost any type of thin film technology and the method has contributed greatly, and in many different ways, to the development of modern electronics,” says Daniel Primetzhofer.
“Aside from being crucial to the development of new electronics, there are no circuits in your or my mobile phone that have not been subject to ion irradiation in the form of ion beam implantation. This is quite simply a stage of manufacture. All large companies have their own ion irradiation facility. But, of course, we work with research groups engaged in developing the next generation of electronics, as well as startups that can’t afford to buy their own accelerators for irradiation within their own small-scale production. So, they come to us,” says Daniel Primetzhofer.
“People sometimes have slightly erroneous ideas about how objects like mobile phones have emerged. The fundamental research that led to many of the products we now see on the market is now 30 or 40 years old. And the research being conducted now in this building and in other Swedish higher education institutions will be crucial to how our personal electronics will look and work many years from now. So, our methods are necessary to develop the next generation of electronics.”
Increasing demand for low-energy ions
According to Daniel Primetzhofer, accelerators can outperform other advanced instruments such as electron microscopes, both in identifying chemical elements and revealing their distribution and absolute concentrations in material on a nanometre scale.
He describes how the laboratory’s unique methods can be used to characterise entirely unknown samples; for example, any random stone from the street. When the stone is placed in the accelerator, the user can obtain precise information on the elements it contains, from hydrogen to uranium, and how these are distributed in depth. In addition, this type of analysis requires minimal sample preparation and does not destroy the sample. The disadvantage of the accelerator is that it requires a good deal of space, something that is fortunately available at the Tandem Laboratory.
“The Pelletron accelerator is almost 50 metres from one end to the other and it occupies a 750 m2 hall.”
Word about the Tandem Laboratory’s capacity and expertise has spread and Daniel Primetzhofer feels that there has been a steady increase in the number of users over recent years. The announcement of the renewed appropriation from the Swedish Research Council raises the hope of much-needed new investment.
“The grant will benefit the development of the organisation greatly,” says Daniel Primetzhofer. “We would like to procure another accelerator for material analysis focused on lower energies, as there is a conflict between supply and demand. In terms of particles, higher energies are about both simpler physics and greater length scales; however, today when everything in technology is getting smaller and thinner, we need to use lower energies in order to study materials more closely down to sub-nanometre levels. Irradiation at lower energies is becoming increasingly common and a new instrument is to be constructed at the laboratory. We can develop along this entire front in order to meet future needs and the new grant gives us the opportunity to do just that.”