A vital network for particle accelerators

The development of new particle accelerators with unprecedented beam characteristics has driven the need for intense research and development programs in diagnostic techniques in recent years. Carsten Welsch has initiated a project that will collate knowledge from institutions around Europe in order to improve the development of these instruments and the training of those involved.

The physicist first had the idea for this project back in 2007. “I had the impression back then,” he explains “that there were a lack of links between European institutions involved in this field, particularly between universities, research centres and the industry sector. There was some training in the field of beam instrumentation, but nothing which could be called a ‘joined-up’ approach towards a structured training program.”

This led Welsch to set up the project known as DITANET, which is essentially a training and research network, from a consortium of presently 28 partners from all over the world.

Each of these partners are in some way involved in the development of instrumentation that monitors the characteristics of the charged particle beams used in particle accelerators, which include for example the beam current, beam position and the transverse and longitudinal beam profile.

“This network initially consisted of 23 institutions, but is now open to essentially any institution from around the world that is active in this research area,” says Welsch. “The partners share their ideas about ideal training schedules for PhD candidates and early stage Postdocs, and discuss how joint training methods such as topical workshop series and schools on specific research areas can be formed.”

As well as instigating new training techniques into the field of beam instrumentation, DITANET focuses on developing ‘beyond-state-of-the-art’ instrumentation for particle accelerators, ranging from working with the very low energy accelerators all the way up to the Large Hadron Collider (LHC) at CERN, the world’s largest and highest-energy particle accelerator.

“At the LHC, one of the trainees has developed a specific instrument called a longitudinal density monitor,” explains Welsch. “This monitor is able to detect the longitudinal beam profile of the LHC beam with a time resolution of 50 ps and a dynamic range of better than 104. What was originally intended as a prototype has now become avaluable tool for the operators to optimise the machine.”

“Another interesting facet of this monitor is that this measurement is carried out by using synchrotron radiation,” continues Welsch. “Synchrotron radiation is usually associated with electrons, which even at comparably low energies emit radiation in a circular accelerator due to them being so light. However, you would generally not be able to measure synchrotron light in an ion beam due to the comparative difference in mass between the ions and electrons. In the LHC, because the energy of the beam is so high, it has been possible to measure this synchrotron light even with lead ions and use these readings for the experiments taking place.” Another example are high intensity ion beams, which are now utilized in many accelerator facilities. These beams are then used, for example, for the production of neutrons, at neutrinos factories or in nuclear physics research. The transverse distribution of these beams needs to be accurately known to avoid any unwanted interaction with the vacuum chamber walls and to properly interact with the target.

A research team from the Commissariat à l’énergie Atomique et aux Energies Alternatives (CEA) in France have been developing a beam profile monitor based on light emission from excited rest gas atoms. In addition, tomography algorithms are being studied to reconstruct the 2D transverse beam profile observed along different directions. These measurements will then be used to collect information on specific ion beams, and this information can be applied for fine-tuning of the accelerator.

Developments have also been made in the instrumentation used in low energy beams of anti-particles. Some of the most exciting new discoveries in physics in the last few years have been concerning anti-hydrogen and anti-protons, which it has only been possible to study at CERN using very low energy beams of anti-particles. The DITANET projects at the Cockcroft Institute/University of Liverpool, UK have been integral in paving the way for a next generation antimatter research facility, such as the proposed FLAIR facility in Germany, by creating the unique set of instruments required for these exotic beams, which must monitor, for example, the beam position and beam profile in a non-destructive manner.

Although the cutting edge instruments that have been produced through the DITANET programme are quite an achievement, Welsch believes that it is the network of training programmes that will have more of an impact on the diagnostic field as a whole.

“Since the network was set up, we have organised a number of international schools on beam diagnostics involving each time between 70-100 participants, which for our community is very large,” explains Welsch. “We also run topical workshops that have brought instrumentation experts and early stage researchers together from all over the world and trained them in topical areas, such as low energy and low intensity beams. They typically involve bringing around 30 experts, both from within and external to the network, together, and consist of presentations, discussions on future directions to be taken and a general coming together of minds.”

The network will also organise an international conference later this year in Seville, Spain which will attract around 100 people. This will be an opportunity for people from the project to present the research they have been carrying out within the network, which the network partners hope can act as an enabler for their careers.

Looking further into the future, other project ideas have now been initiated based on the training ideas and research links within DITANET. “These projects will profit enormously from the experiences we have gained through DITANET,” says Welsch. “In terms of defining new training standards, there were many lessons learned regarding how one should structure the training of PhD students and early stage Postdocs. Whilst many of our ideas worked, some were not so successful, allowing for reflection and ongoing improvements to be made. Indeed, many of the new projects we have developed since would not have come into place were it not for the experience gained through DITANET.”

Within the DITANET network, the majority of particle accelerator based research infrastructure in Europe is involved in some way or another. This is complemented by partner institutions in the USA and, most recently, also Japan. It is this original and comprehensive approach that has made this project so successful, and hopefully it will continue to bear dividends for the particle accelerator community for years to come.

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Published: Wednesday, 4th January 2012