Proton Improvement Plan-II

Research program

PIP-II will open paths to discovery in particle physics, providing answers to some of the deepest questions concerning the nature of our universe.

By powering the world’s most intense beam of high-energy neutrinos, PIP-II will help scientists at DUNE meet its science goals, each of which depends on observing neutrinos.

PIP-II will enable the exploration of new physics by accelerating intense particle beams for several experiments, each of which provides new windows to the subatomic world.

The upgraded accelerator complex will provide unprecedented numbers of particles to help uncover theoretically predicted – but as yet unobserved — phenomena that are calculated to be either incredibly rare or incredibly difficult to detect. The sheer numbers of particles will help draw out the subtle behaviors that would otherwise stay under wraps.

It will also pave the way for future advances in accelerator technology.

Questions in need of answers

  1. What is the origin of matter? Are neutrinos the reason matter exists?
  2. What unknown properties of these particles and forces drive the evolution of the universe from the big bang to its present state, with its complex structures that support life — including us?
  3. What are the forces that enable these elementary constituents to form all that is visible?

These are the questions that particle physics seeks to answer.

Answering these questions requires powerful particle beams, which are possible only with the most advanced accelerator technology. The PIP-II accelerator complex, positioned at the forefront of accelerator technology R&D, will help solve these mysteries.


High-energy neutrino beams of unprecedented intensity for DUNE

PIP-II will be the “first gear” of the Fermilab accelerator complex and power the world’s most intense beam of high-energy neutrinos. From Batavia, Illinois, a beam of neutrinos will travel through 1,300 kilometers (800 miles) of earth to the Deep Underground Neutrino Experiment in South Dakota. There, scientists will use the neutrinos to solve some of the universe’s biggest mysteries.

But what are neutrinos? And why are Fermilab scientists working to create so many of them? Neutrinos are famous for being able to fly through everything — rock, lead, even us — without leaving a trace. The ghostly behavior of these neutral particles makes them exceedingly difficult to capture and thus difficult to observe. The PIP-II accelerator will enable generating a significantly higher neutrino intensity than previously available at Fermilab — in fact, the highest in the world, giving scientists more opportunities to study these maverick particles. The more neutrinos that are generated, the closer scientists get to answer big questions about the universe.

Particle physics and the Standard Model

Particle physics has been very successful in creating a major synthesis of elementary particles and forces, the Standard Model. At successive generations of particle accelerators in the United States, Europe and Asia, physicists have used high-energy collisions to discover many new particles. Studying these particles, they have uncovered both new principles of nature and many unsuspected features of the universe, resulting in a detailed and comprehensive picture of the workings of the universe.

Recently, however, revolutionary discoveries have shown that the Standard Model — while it represents a good approximation at the energies of existing accelerators — is incomplete. There is mounting evidence that new physics discoveries beyond the Standard Model await us.


PIP-II means more opportunities to observe rare process: muons converting to electrons 

Muon-based experiments include the search for an unimaginably rare process: the direct conversion of a muon, the electron’s heavier cousin, into an electron. The PIP-II accelerator complex would give scientists a staggering number of muons to search for the rare muon-to-electron conversion phenomenon.

The transformation of a muon into an electron and two neutrinos has been observed, but there’s nothing in the laws of physics that says that neutrinos must always accompany the electron.

If muon-to-electron conversion were observed in the Mu2e experiment, it would be evidence of the violation of one of nature’s conservation laws — physics beyond the expected Standard Model.

Accelerator technology advances

Greater demands are being placed on accelerator performance, and PIP-II will help advance the next generation of accelerator technology. In building PIP-II, scientists, engineers and technicians will provide a platform for cutting-edge accelerator developments.

Superconducting radio-frequency accelerating cavities, which efficiently generate high-energy particle beams, are one of the technologies at the forefront for future accelerators.

In addition, PIP-II is the highest-energy and highest-power continuous-wave proton accelerator ever built.

The capability and flexibility of PIP-II’s design will allow for customized beams (for instance, in various patterns, such as pulsing) and for those beams to be delivered to different experiments simultaneously.

Other technologies are being developed for future accelerator concepts, which require higher performance and lower cost. For instance, PIP-II will use the transformative potential of artificial intelligence and machine learning to deliver flexible beam patterns to users quickly, reliably and with minimal operational effort.

In building PIP-II, scientists, engineers and technicians will provide a platform for cutting-edge accelerator developments.