Scientific Highlights from the Department "Large Research Facilities" (GFA)

Scientific Highlights

1 April 2018

psi structures gradient.jpg

Outstanding high gradient performances of two test structures produced at PSI for the CLIC project

X-band (12 GHz) radio-frequency (RF) accelerating structures are under consideration for future free electron lasers, medical linacs and linear colliders. Two such structures, built by PSI in the framework of a CERN/PSI collaboration, are currently being tested at high power at CERN. They are reported to have reached an accelerating gradient in excess of 115 MV/m (CERN Courier, April 2018,, making them among the best X-band structures to have been tested by the CERN Linear Collider project group. The structures have benefitted from the fabrication protocols used for the SwissFEL C-band structures. The gradient continues to improve with further “conditioning” at CERN. For structure “aficionados” a recent conditioning curve (courtesy of CERN) shows structure T24PSI1 approaching 120 MV/m. The structures were financed by an SNF FLARE* grant 20FL20_147463.
* Funding for LArge international REsearch projects.

30 September 2017


Best publication

A team of GFA and CPT physicists has worked out a novel achromatic beam optics concept for a proton therapy gantry. The article on the concept in the journal Zeitschrift für Medizinische Physik has been awarded a prize for the best publication in 2016. The jury states: „The paper of Alexander Gerbershagen et al. entitled „A novel beam optics concept in a particle therapy gantry utilizing the advantages of superconducting magnets” describes a new concept of a first order design of the beam optics of a superconducting proton therapy gantry beam.

8 November 2016


X-band prototype structure

Radio-frequency structures at X-band frequencies (~ 12 GHZ) are being considered for applications in compact Free Electron Lasers, medical linacs, a future linear collider (CLIC project) and as a diagnostic for measuring ultra-short (femtosecond) electron pulses in FELs. A first prototype of such a structure has been built at PSI employing the realization procedures that have been developed for the C-Band (6 GHz) structures of the SwissFEL linac.

24 August 2016


First Electron Beam in the SwissFEL Facility

On August, 24th 2016, the electron gun accelerated the first photo-electrons in SwissFEL up to the energy of 7 MeV, initiating the beam commissioning phase of the new SwissFEL facility. After several days of RF conditioning, the gun reached the nominal acceleration gradient of 100MV/m at an input power of 17MW with a pulse-width of 1 micro second at an operating frequency of at 2998.8 MHz. This gun has previously already been commissioned in the SwissFEL Test Facility from June until October 2014 and then relocated to the new SwissFEL facility in the forest of Würenlingen.

11 September 2016


21st International Conference on Cyclotrons and their Applications

The 21st conference in this series takes place from September 12 to 16, 2016 at the Federal Institute of Technology in Zürich. The cyclotron is a simple and efficient particle accelerator and its invention for the purpose of performing fundamental research dates back to 1929. Ernest Lawrence received the Nobel Prize for his idea in 1939. Today cyclotrons are used in a broad range of applications from large and complex facilities for basic research to highly optimized and cost effective solutions for industrial and medical applications.

5 February 2016


Proton Accelerator Operation Statistics 2015

For the first time in the history of the High Intensity Proton Accelerator the availability of the facility reached an outstanding value of 95% in 2015 with a record value of 99.3% in week 44. In comparison to the two previous years this corresponds to a reduction of the downtime by 50%. The user operation in 2015 was started as scheduled and already in the first week the machine was available 97% of the scheduled beam time. In addition to the smooth operation of the facility, high intensity beam experiments could regularly be performed with currents of up to 2.4 mA.

29 January 2016


GFA delivers the SwissFEL magnets on schedule

The Paul Scherrer Institut is building an X-ray free electron laser (SwissFEL) providing a source of intense, ultra-short pulses of coherent radiation in the wavelength range of 0.1 nm to 0.7nm. For the hard X-ray beam line, the magnet section in GFA/ATK has the responsibility for the design, the procurement and the magnetic qualification of 267 electro-magnets of 22 different types. Several design studies were performed in an attempt to meet the required magnet specifications while optimizing construction and operation cost. Various types of dipole magnets (26 units in total) are used to bend the electron beam either horizontaly or vertically, whereas quadrupoles of 45 mm, 22 mm and 12 mm aperture (173 units), solenoids (10 units) and sextupoles (14 units) provide linear and non-linear focusing. Separate dipole correctors (44 units) complete the production. The majority of the magnets were manufactured in industry according to detailed magnet section specifications.

17 April 2015


ETH-Medal 2015 for outstanding MSc thesis

The detailed understanding of particle motion in the outer region (halo) of a bunched beam is of utmost importance for all existing and future high intensity hadron accelerators in view of minimizing particle losses and machine activation. Particle-core models separate the motion of halo particles from the core and treat them as test-particles. Therefore these reduced-order models are computationally inexpensive compared to full particle-in-cell simulations and can, to some extent, be derived analytically, thus giving insights into the non-linear mechanism of halo formation.

6 June 2014


First beam from the SwissFEL electron gun

The new 3 GHz photocathode gun will provide the electron bunches for SwissFEL and has recently been installed in the SwissFEL injector test facility. There, it replaced the CTF2-gun 5, borrowed from CERN. The new gun is capable now of operation with 100Hz repetition frequency and a higher field on cathode and improved field symmetry. After RF conditioning of about 4 days, the gun reached the nominal acceleration gradient of 100 MV/m at an input power of about 17 MW and pulse-width of 1 microsecond.

11 June 2013


RF Pulse compressor for the SwissFEL

The SwissFEL C-band (5.712 GHz) linac consists of 26 RF modules. Each module is composed of a single 50 MW klystron feeding a pulse compressor and four two meter long accelerating structures. The pulse compressor is a passive device that compresses in time the 3 μs pulse from klystron into a 330 ns pulse. The compressed power is then guided to the four accelerating structures. The pulse compressor is based on a single Barrel Open Cavity (BOC).

24 May 2013


MEGAPIE samples delivered to partners for post irradiation investigation

The MEGAWatt Pilot Experiment was operated for neutron generation with the PSI high intensity proton beam in 2006. The experiment utilized liquid target material, a lead bismuth eutectic. This marked a major milestone towards Accelerator Driven Systems (ADS), which are intended to be used for the incineration of nuclear waste. Now, after a 5 year long campaign at PSI and in ZWILAG, unique material samples from the irradiated target have been produced and distributed amongst the partners of this international initiative.

18 June 2012


ETH Zurich, IBM and Paul Scherrer Institut Researchers receive 2012 PRACE Award

HAMBURG: At the International Supercomputing Conference (ISC12) researchers from ETH Zurich, the renown science and technology university; IBM Research - Zurich and the Paul Scherrer Institute (PSI), Switzerland’s largest research centre for natural and engineering sciences, received the 2012 PRACE Award.

The PRACE Awards recognizes the best scientific paper in one of the following areas: a breakthrough in science achieved with high performance computing resources, algorithms or implementations that achieve significant improvements in scalability, or novel approaches to performance evaluation on massively parallel architectures.

21 December 2011


Vertical Emittance of the SLS Storage Ring

On the 6th of December 2011 the vertical emittance of the SLS storage ring could be reduced to a world record low value of 1pm rad. The vertical beam size in the short straight sections of the SLS is then only 3 micron (rms). This was achieved through vertical re-alignment of the magnet girders with 400mA stored beam and fast orbit feedback running, as well as through application of several different methods of coupling suppression using 36 skew quadrupoles. High resolution profile monitor utilizing vertically polarized component of synchrotron radiation allowed precise determination of the beam size.

23 June 2011


PSI sets world record with 1.4 MW proton beam

The highest average power proton beam in the world was produced on 20th of June in the 580 MeV cyclotron at Paul Scherrer Institut. Extremely low beam losses achieved in this 35 years old veteran cyclotron allowed PSI team of accelerator scientists and engineers to put 1.4 MW beam of protons onto the muon and neutron spallation targets. This beam is used to produce the brightest beam of muons in the world, as well as supply neutrons for the spallation source SINQ.