6 | Introduction Introduction | 7
Furthermore, DESY is not only a significant driver of scien-
tific progress, but it also has an economic impact as an
employer and through the commissioning of commercial
companies.
Delivering high-quality electron beams at high availability is
key to the success of our accelerator facilities. When
PETRA III went into operation at DESY in 2010, it was the
world’s most powerful X-ray source at the time. Since then,
it has been generating unique scientific findings and fur-
nishing essential data for innovative developments. More
than 3500 researchers carry out their experiments here
every year, somewhat more than half of them from Ger-
many. Converting the facility into PETRA IV will ensure that
it continues to meet the constantly increasing require-
ments and growing demand for non-destructive nanoscale
analyses in the future. Once completed, PETRA IV will be an
anchor facility for the Science City Hamburg Bahrenfeld
and the world’s most powerful X-ray source. This upgrade
is essential for Germany and Europe as a centre for science
and innovation in order to be internationally competitive in
a wide range of technologies.
Important developments pursued on both the accelerator
and the free-electron laser (FEL) sources of the European
XFEL have yielded record FEL photon energies and inten-
sities. One highlight in 2023 was the demonstration of
single-spike lasing with high intensities at the SASE2 undu-
lator by shaping the electron beam through self-fields and
detuning of the deflection arc optics. Preparations are
under way to upgrade the accelerator to continuous-wave
or high-duty-cycle operation, with a conceptual design
expected by 2027. DESY is developing an all-supercon-
ducting photoinjector for this purpose. In 2023, a break-
through test demonstrated successful high-gradient
operation with a copper cathode, advancing this effort.
After the first phase of the FLASH2020+ upgrade and the
replacement of the two oldest accelerator modules with
two freshly refurbished modules, the FLASH FEL facility
was routinely operated in 2023 with an energy gain of
I have now been working at DESY for more than five years
as Director of the Accelerator Division. DESY’s accelerators
are important instruments for science in the service of
society, and outstanding specialists with the highest level
of expertise work here. DESY has always been a pioneer in
accelerator research and development, courageously set-
ting new standards and enabling cutting-edge research.
Reflecting on 2023, I am reminded of the many challenges
we have already faced and overcome together. The resil-
ience and adaptability of the DESY staff members have
been remarkable, ensuring that DESY remains a beacon of
scientific excellence. It is this collective spirit and shared
dedication that make working at DESY so rewarding.
With the impact of our user facilities and our fundamental
research, we at DESY are part of the solution to the major
challenges facing society. We should take the lessons
learned from the pandemic to accelerate the health
research of tomorrow. When Federal Minister of Health
Karl Lauterbach visited DESY in June 2023, he praised the
interdisciplinary work at DESY as an outstanding example
of cutting-edge research in Germany.
In 2023, DESY achieved significant milestones, reinforcing
its status as a global leader in accelerator science and
research. The progress in the PETRA IV upgrade project
and the ongoing developments at our user facilities and at
the European XFEL X-ray laser have been particularly
inspiring. With the federal Budget Committee’s decision to
fund a pre-project for the fourth-generation synchrotron
radiation source PETRA IV, with co-financing by the City of
Hamburg, preparatory measures can now begin, in particu-
lar for the construction and prototype of an innovative,
energy-saving plasma injector and for the conversion of
the business model.
A study carried out by the Fraunhofer Institute for Systems
and Innovation Research in 2023 showed that DESY’s light
source PETRA III has created 2.25 billion euros in added
value. The PETRA IV upgrade could add a further 7.35 bil-
lion euros in value – possibly even considerably more.
450 MeV, bringing the electron beam energy to over
1.35 GeV and pushing the photon wavelength down
beyond 3.5 nm. A major milestone on the way to a seeded
FLASH1 user facility, which is described in this report, was
the successful demonstration of external seeding using
echo-enabled harmonic generation with parallel self-ampli-
fied spontaneous emission operation in the FLASH2 beam-
line. The impressive results leave us excited about the
future performance of the seeded FLASH1 user facility.
Accelerator R&D at DESY has always been at the forefront
of scientific innovation. Coming from an engineering back-
ground myself, it fills me with great pride that the 2023
Bjørn H. Wiik Prize – DESY’s most important science award
– went to an engineer, Julien Branlard, in recognition of his
outstanding contributions to developing the low-level radio
frequency systems for the stable, reliable and extremely
precise operation of the linear accelerators driving the
European XFEL and FLASH. In 2023, we have also deep-
ened our understanding of the physics behind the tuning
and optimisation of laser plasma acceleration. This further
lays the foundation for applying this technology in the
years to come.
Another highlight of my tenure during the past five years
has been witnessing the focus and successful implementa-
tion of our comprehensive sustainability strategy. This ini-
tiative is not just about reducing our environmental foot-
print but also about innovating in ways that make our
research infrastructure more efficient and resilient. Utilis-
ing the waste heat from our accelerators to heat the cam-
pus is a testament to our commitment to sustainability and
operational excellence, and I am delighted that the Helm-
holtz Association has approved funds of around 8 million
Wim Leemans
Director of the Accelerator Division
Accelerators at DESY
Introduction
Figure 1
During his visit, Federal Minister of
Health Karl Lauterbach commended
the interdisciplinary work at DESY as
an outstanding example of cutting-
edge research in Germany – and of
how this research directly benefits
people’s healthcare.
euros for the project implementation in 2023. Furthermore,
our technical groups have also explored options to run our
facilities in modes that reduce energy consumption, and
they have successfully implemented measures that are
having a significant impact.
Last but not least, the DESY management and staff would
like to thank Robert Feidenhans’l for his exemplary leader-
ship as Chairman of the Management Board at European
XFEL until the end of 2023, for his unwavering commitment
to excellence and the strong partnership with DESY, in par-
ticular with the Accelerator Division. We wish him all the
best and every success in his future endeavours. At the
same time, we warmly welcome Thomas Feurer, who has
taken over as the new Chairman of the Management Board
at European XFEL at the beginning of 2024, and we look
forward to continuing the great collaboration with our
partner institute.
As we look to the future, I am excited about the possibili-
ties that lie ahead. DESY’s commitment to innovation, sus-
tainability and scientific leadership is unwavering. I am con-
fident that we will continue to achieve great things, driven
by our shared passion for discovery and excellence. Thank
you to everyone who has contributed to our successes this
year. Your hard work and dedication are what makes DESY
a truly exceptional place to work.
Accelerators Highlights Annual Report