FAQ – About MAX 4U

MAX 4^U brings back our fourth-generation storage ring to the forefront: the best medium-energy (i.e., below 4 GeV) lightsource in Europe and the world.
MAX 4^U fulfills our ambitions to strengthen our beamline capabilities on our 3 GeV fourth-generation lightsource to secure the excellence, leadership, resilience and relevance of Swedish research and innovation with X-rays for the next decades.

MAX 4^U is MAX IV Laboratory’s proposal to upgrade its 3 GeV storage ring (R3), the world’s first fourth-generation storage ring, inaugurated in 2016.
The name captures the idea of taking MAX IV to the next level — for the user community and for science.
The vision driving MAX 4^U is to ensure the excellence, relevance, and leadership of Swedish academic and industrial research with X-rays for the next decades.

The MAX 4^U project has two components:

• An X-ray science & instrumentation component to strengthen our capabilities across our beamline portfolio on this storage ring. This comprehensive beamline readiness programme spans most of our existing undulator beamlines to ensure they can optimally benefit from the superior performance of the source and will add one (1) new beamline.
• A source upgrade with an accelerator upgrade to reduce the electron beam emittance

When MAX IV opened in 2016, it set the global benchmark for fourth-generation light sources, with performance 3 to 20 times better than that of any other synchrotron at the time. Since then, three comparable facilities — ESRF-EBS in France, Sirius in Brazil, SLS2.0 in Switzerland, and APS-U in the USA — have been upgraded to fourth-generation status, and many more are planned globally over the next decade.
The broader accelerator community has also made rapid advances in Multi-Bend Achromat (MBA) lattice design, the technology underpinning fourth-generation performance. This has also led to advances in optimized beamline design and instrumentation to fully exploit such sources.

Without action, MAX IV risks losing the competitive edge that has made it the X-ray lightsource of choice for researchers in Sweden, across Europe, and beyond. MAX 4^U is our strategic response: it returns MAX IV to the forefront of X-ray science, securing Swedish and European research leadership for the coming decades. As Sweden’s national synchrotron facility, maintaining this leadership is critical.

MAX 4^U will be the first upgrade of a fourth-generation lightsource. Conventional third-to-fourth-generation upgrades essentially strip away and rebuild the entire storage ring, often requiring beamline relocations and significant recommissioning, major civil engineering, and extended shutdowns.
MAX 4^U is different in several important ways:

• MAX 4^U is a more “surgical” intervention on the accelerator that achieves a major performance boost through minimal changes to existing hardware, reducing cost and disruption to our User Science programme.
• MAX 4^U does not involve relocating or realigning beamlines.
• MAX 4^U capitalizes on ten years of unique operational experience on a fourth-generation source.

No.
MAX 4^U will be the first upgrade of a fourth-generation lightsource.
It will bring back MAX IV to the forefront of fourth-generation medium-energy (i.e., below 4 GeV) synchrotron facilities.
This is an important distinction from what is happening at other facilities across the world, which are either transitioning from third- to fourth-generation or being built as fourth-generation synchrotron sources.
MAX IV is the only facility already operating at fourth-generation level since 2016 that is now planning to go further.