CERN Accelerating science

IPAC 18: Vancouver welcomes the world of accelerator physics!

The IPAC series of conferences offer the opportunity to member of the accelerator community to come together and consider the progress in their field as well as present the state of the art technologies emerging from ongoing R&D for future accelerators.

The 9th International Particle Accelerator Conference (IPAC'18) took place from 29 April to 4 May in Vancouver, Canada. The conference was hosted by TRIUMF and jointly sponsored by IEEE Nuclear & Plasma Society and the APS Division of Particle Beams. IPAC18 brought together more than 1200 participants from 31 countries and industry delegates reflecting the importance of strong partnerships to boost further the field of particle accelerators.

The Scientific Program included 63 invited talks and 62 contributed orals organized into opening and closing plenaries and three parallel sessions. Given the recent prominence of ring- and linac-based light sources, the program was adjusted to emphasize these machines. It is worth noticing also the geographical balance with 24% of the contributions coming from Asia, 41% from Europe, and 35% from America. This remarkable response ensures that IPAC’18 is truly international.

In addition to the Scientific Program, there was an Industry Panel discussion on successful models for technology transfer; an entertainment talk on the future of the kilogram which is destined this year to become defined by a combination of fundamental constants; the Women In Science and Engineering reception which focused on best practices for their retention and promotion; the Louis Costrel session at which IEEE and APS awards is 2018 prizes; and two special American Physical Society events: 125th Anniversary of Physical Review Celebration, and APS Referee and Author Tutorial.

The North American IPAC is committed to welcoming young researchers in our field, has heavily discounted fees for all students and worked with Asian and European counterparts to provide 107 student grants. A new feature of IPAC, introduced on a trial basis, is light peer review of a subset of papers; 190 papers were received and refereed. Nevertheless, the imperative to publish high quality papers in Physical Review Accelerators and Beams continues unabated. The JACoW proceedings continues unaffected.

The conference opened with welcome addresses from Kate Young, the Parliamentary Secretary for Science; and the Member of Parliament for London West (Ontario), the Hon. Bruce Ralston B.C.’s Minister of Jobs, Trade and Technology, and the conference chair Shane Koscielniak (TRIUMF).

The scientific programme was organized around eight main themes. The following selection of programme highlights  are the highly personal choices of the conference chair and the programme chair, Tor Raubenheimer (SALC). Their selection is in no way intended to diminish the significance of the other talks.

The 10th IPAC will take place in Melbourne, Australia, on 19-24 May 2019.

L Marco Zanetti (INFN), Frank Zimmermann (CERN)
Discussing a future strategy for muon colliders
8 Oct 2018

Discussing a future strategy for muon colliders

Discussing status and ongoing efforts in light of the upcoming European Strategy update.

Mohammed Shahzad (University of Strathclyde)
Laser-wakefield accelerators for High-energy coherent Terahertz radiation
26 Jun 2018

Laser-wakefield accelerators for High-energy coherent Terahertz radiation

Paper just published in New Journal of Physics describes a promising pathway to more efficient radiation sources

Lucio Rossi (CERN)
ARIES consortium produces world-class HTS tapes
24 Mar 2020

ARIES consortium produces world-class HTS tapes

REBCO conductor tapes reached a world-record critical current at 20T, strengthening the possibilities for a demonstrator of high-level accelerator magnets. Lucio Rossi, leader of the HL-LHC project, explains.

Laser-wakefield accelerators for High-energy coherent Terahertz radiation

High-power lasers can drive compact and cost-effective particle accelerators as a result of the large accelerating gradients achievable when using a plasma as the acceleration medium. A growing number of universities and research centers around the world routinely produce electron beams with energies from 10s of MeV to several GeV by focusing ultrashort laser pulses with power of tens or hundreds of terawatt into millimetre-scale gas or plasma targets. Laser-driven electron beams have an intrinsically short bunch duration, of the order of femtoseconds (10-15 s), and picocoulomb-level charge. During acceleration electrons can oscillate transversally in the plasma cavity, making laser-plasma accelerators also compact sources of X-ray radiation with 1-100 keV energy.

Electrons ejected at wide angles from the accelerating cavities trailing an intense laser pulse propagating in a plasma.

The same process leading to the formation of the accelerating cavity in a plasma also causes the emission of a high-charge electron beam in a large forward cone centred along the laser-propagation axis. Electrons are accelerated in lengths of about 10 µm by electric fields as large as 10-100 MV/m, resulting in the emission of a wide-angle beam with energy of about 1-2 MeV, nanocoulomb-level charge and sub-picosecond bunch duration. These high-charge, low-energy electron beams can be useful for applications such as non-destructive-testing, ultra-fast studies in condensed matter, radiolysis and radiotherapy. They can also be source of unwanted bremsstrahlung radiation if not properly dumped.


Measured spatial profile of the wide-angle electron beam.

In a paper that has just been published in New Journal of Physics, X. Yang and co-authors present the results from simulation studies they have performed. These suggest that wide-angle electron beams can produce high-energy coherent terahertz (THz) radiation if passed through an interface between two media of different dielectric properties, such as a thin metallic foil or at the plasma-vacuum boundary of the accelerator.

Radiation in the THz band, which lies between the mid-infrared and microwaves, is of great interested because of the wide range of possible applications in areas such as imaging, spectroscopy, microscopy and communication. THz radiation is typically produced using optical rectification in electro-optic crystals or acceleration of photocarriers in semiconductor antennas, but these methods are limited by the damage threshold of optical materials, which typically restricts the maximum energy to sub-µJ levels.

Electrons passed through a perfectly conducting interface emit transition radiation in a forward hollow cone, as well as in the backward specular direction. Because of the sub-picosecond bunch duration, transition radiation produced by wide-angle electron beams is coherent in the 0.1-5 THz frequency range, and has energy from 10s of µJ to mJ levels, depending on the radiator size and position. Laser-plasma accelerators are currently limited by the laser repetition rate, which is typically 1-10 Hz. Commercial lasers with 100 Hz-1 kHz repetition rate are however expected to become available soon, making possible to produce THz radiation with an average power of 1 W, which is comparable with a far-infrared free-electron-laser.


Mike Barnes (CERN)
First workshop on Pulse Power for Kicker Systems held at CERN
28 Jun 2018

First workshop on Pulse Power for Kicker Systems held at CERN

The PULPOKS 2018 workshop brought more than 40 participants to discuss the latest developments in the field of pulsed power for particle accelerators

Ricardo Torres (University of Liverpool)
Optimization of medical accelerators through international collaboration
2 Oct 2019

Optimization of medical accelerators through international collaboration

EU-funded OMA project has successfully developed technologies and techniques that help improve proton and ion beam cancer therapy.

Paul Wynne (International Irradiation Association)
The importance of knowledge transfer in the development and application of ionizing radiation
15 Jul 2020

The importance of knowledge transfer in the development and application of ionizing radiation

Companies provided the means by which ionizing radiation could be utilised in the development of products and services.

Daresbury security linac achieves 3.5 MeV

A small scale particle accelerator designed, and commissioned at STFC Daresbury Laboratory and the Cockcroft Institute has successfully accelerated an electron beam to 3.5 MeV. The linac, designed by Lancaster University and STFC Accelerator Science and Technology Centre (ASTeC) and Technology Departments, is optimised for X-ray screening of aviation cargo which is typically much smaller than shipping containers, i.e. 1 m3, and hence lower energies are required.

The Compact aviation cargo scanning linac commissioning team. (Pictures courtesy of STFC)

The new linac can vary its energy between 1-3.5 MeV and has a smaller footprint than other similar linacs. The beam can produce a peak current of 100 mA, and is pulsed at 200 Hz with 5 microsecond pulses. The linac operates at S-band and utilises a 17 keV thermionic electron gun and an S-band magnetron from Teledyne e2v. The RF linac structure utilises a pi mode, rather than the standard side-coupled design, to reduce the physical transverse dimensions thereby minimising the diameter of the shielding required. X-rays are produced by firing the beam onto a tungsten target to produce bremsstrahlung radiation. An important part of the project is to make a linac with simple controls and feedback, such that the energy and beam dose can be varied by operators at the airport without the need of accelerator scientists, and work in the next few months will be focussed on implementing techniques to accomplish this mode of operation.

Varying the beam energy and dose is important to ensure good contrast can be achieved, regardless of whether the cargo is filled with low attenuating or high attenuating materials. The linac is attached to a diagnostics beamline so that the beam can be fully characterised, or can be steered to the target. Cargo scanning typically operates with a vertical 1D array of detectors which is used to provide a 2D image by moving the cargo or the gantry horizontally. The facility therefore also includes a conveyor to move the cargo and a detector array to allow in-situ imaging. This follows on from a previous project that developed a highly compact X-band cargo scanning linac which was commissioned to operate at 1.5 MeV for a mobile cargo scanning applications.

The 3.5 MeV accelerating structure and electron gun (Pictures courtesy of STFC)

Dr Graeme Burt from Lancaster University and the Cockcroft Institute who led the linac design said “R&D into small industrial and security accelerators is vital to making progress in the field of accelerator engineering and ensuring new research in HEP machines is properly exploited in other areas”.

After completion, the prototype will be turned into a user facility for industrial and university users to access small industrial type electron beams for research into industrial, security, medical and environmental applications of accelerators run by STFC at Daresbury Laboratory. This facility perfectly complements the existing suite of accelerators at Daresbury including the existing 5 MeV VELA beam at Daresbury which delivers high quality, short-pulse, low emittance beams for industrial and academic exploitation purposes. Prof Peter McIntosh, Deputy Director of STFC ASTeC that enabled development and construction of the linac facility at Daresbury and will support its ongoing operation said, “translating the highly effective linac development capabilities we have within STFC and the Cockcroft Institute here at Daresbury, into industrial security applications such as this, is critically important and I’m excited at the prospect of now having a dedicated facility which can be utilised for furthering industrial application capabilities more extensively in the future”.

The facility development was funded by the STFC challenge led applied systems programme.

Anyone wishing to utilise the facility should contact Dr Donna Pittaway (

Ch. Bracco, D. Carbajo Perez and A. Perillo Marcone
Ensuring safer operation at higher luminosities
12 Mar 2018

Ensuring safer operation at higher luminosities

The higher bunch intensities and smaller beam emittances expected in HL-LHC call for a novel design of the Target Dump Injection (TDI)

Panagiotis Charitos
FCC collaboration publishes its Conceptual Design Report
28 Mar 2019

FCC collaboration publishes its Conceptual Design Report

FCC study publishes a conceptual design report demonstrating the feasibility of the different options explored for post-LHC circular colliders.

Daniela Antonio (CERN)
Power converters specially designed for CERN can now be used by the wider accelerator community
11 Dec 2019

Power converters specially designed for CERN can now be used by the wider accelerator community

CERN has developed new software layers to allow the wider particle accelerator community to use the CERN-specific power converters controls.