The Project

NEMESIS:
Exploring the Frontiers of Particle Physics with Muons and Neutrons

Overview

NEMESIS is an international research project that aims to uncover new physics beyond the Standard Model by combining two powerful approaches in particle physics: the high-intensity frontier of muons and the high-precision frontier of ultracold neutrons and polarized muons.

NEMESIS focuses on precision measurements and rare processes, where even the smallest deviation from theory could reveal entirely new physical laws. To reach this ambitious goal, the project develops cutting-edge technologies, including high-intensity particle beams, state-of-the-art detectors, innovative data acquisition systems, and advanced analysis tools. The collaboration unites leading researchers from Europe, Switzerland, and the United States, working across three major international laboratories: Fermilab (FNAL) and Brookhaven National Laboratory (BNL) in the USA, and the Paul Scherrer Institute (PSI) in Switzerland.

Searching for the Unseen: Charged Lepton Flavour Violation

A key goal of NEMESIS is the search for Charged Lepton Flavour Violation (cLFV) — processes that are forbidden in the Standard Model but could appear in the presence of new physics. These searches are conducted using the world’s most intense muon beams at Mu2e (FNAL), MEG II, and Mu3e (PSI). Muons are ideal probes for such studies thanks to their clean experimental signatures and rapidly advancing detector technologies. By joining forces, these experiments can increase sensitivity by up to four orders of magnitude beyond current limits, probing mass scales up to 10⁴ TeV — far beyond what current or planned colliders can reach.

Precision Measurements: Probing the Foundations of the Universe

At PSI, NEMESIS contributes to world-leading experiments using ultracold neutrons and polarized muon beams to perform high-precision measurements. Among these are the n2EDM and muEDM experiments, which aim to detect an Electric Dipole Moment (EDM) for the neutron and muon, respectively. A non-zero EDM would be a revolutionary discovery, providing direct evidence of new physics and offering clues about the origin of the matter–antimatter asymmetry in the Universe.

NEMESIS researchers also play leading roles in improving measurements of the neutron lifetime and in developing advanced detector technologies to enhance precision and control systematic effects.

Developing Next-Generation Technologies

Because of its reliance on high-intensity beams and sophisticated detectors, NEMESIS also serves as a platform for technological innovation. The project is advancing new generations of silicon and gas detectors, beam monitoring systems, and beam control techniques such as polarization and cooling.

These developments will not only push the boundaries of particle physics but also find applications in other fields, including:

  • Material science, through the characterization of advanced target materials for high-power beams
  • Medical physics, with detectors for Boron Neutron Capture Therapy
  • Homeland security, using novel technologies for detecting hazardous or illicit materials

A Global Scientific Effort

NEMESIS strengthens the collaboration between European, Swiss, and US research communities and builds a bridge between high-intensity and high-energy physics programs. By combining expertise, resources, and infrastructure, the project aims to make decisive progress in our understanding of the Universe and to develop technologies that will benefit both fundamental science and society.