Mu2e

Mu2e, or the Muon-to-Electron Conversion Experiment, is a particle physics experiment at Fermilab in the US. The goal of the experiment is to identify physics beyond the Standard Model, namely, the conversion of muons to electrons without the emission of neutrinos, which occurs in a number of theoretical models. Project co-spokesperson Jim Miller likens this process to neutrino oscillation, but for charged leptons. Observing this process will help to narrow the range of plausible theories. The experiment will be 10,000 times more sensitive than previous muon to electron conversion experiments, and probe energy scales up to 10,000 TeV. Mu2e, or the Muon-to-Electron Conversion Experiment, is a particle physics experiment at Fermilab in the US. The goal of the experiment is to identify physics beyond the Standard Model, namely, the conversion of muons to electrons without the emission of neutrinos, which occurs in a number of theoretical models. Project co-spokesperson Jim Miller likens this process to neutrino oscillation, but for charged leptons. Observing this process will help to narrow the range of plausible theories. The experiment will be 10,000 times more sensitive than previous muon to electron conversion experiments, and probe energy scales up to 10,000 TeV. Physicists have been searching for flavor violation since the 1940s. Flavor violation among neutrinos was proven in 1998 at the Super-Kamiokande experiment in Japan. In 1989, Russian physicists Vladimir Lobashev and Rashid Djilkibaev proposed an experiment to search for lepton flavor violation. The experiment, called MELC, operated from 1992 to 1995 at the Moscow Meson Factory at the Institute for Nuclear Research in Russia, before being shut down due to the political and economic crises of the time. In 1997, American physicist William Molzon proposed a similar experiment at Brookhaven National Laboratory. Research and development on the MECO experiment began in 2001, but funding was pulled in 2005. Mu2e is based on the MECO experiment proposed at Brookhaven, and the earlier MELC experiment at Russia's Institute for Nuclear Research. Research and development for the Mu2e experiment began in 2009, with the conceptual design complete in mid-2011. In July 2012, Mu2e received Critical Decision 1 approval (the second of five critical decision levels) from the Department of Energy, about one month after initial review. Project Manager Ron Ray asserted, 'I know of no other project that has received sign-off that quickly after review.' Funding of the Mu2e experiment was recommended by the Department of Energy's Particle Physics Project Prioritization Panel, in its 2014 report. Groundbreaking on the detector hall took place on April 18, 2015, with the hall expected to be complete in late 2016. Commissioning of the experiment is anticipated in 2019, and preliminary results are possible by around 2020. The experiment is anticipated to run for three years. Later improvements to the detector may increase the sensitivity of the experiment by one to two orders of magnitude, allowing a more in-depth study of any charged lepton conversion that may be discovered in the initial run. The Mu2e apparatus will be 92 feet (28 m) in length, and will consist of three sections. The total cost of the experiment is $271 million. Repurposed elements from the Tevatron collider will be used to generate and deliver an 8 GeV proton beam. These protons will collide with a tungsten production target in the production solenoid, producing a cascade of particles including pions, which decay into muons. Mu2e will produce between 200 and 500 quadrillion (2×1017 to 5×1017) muons per year. For every 300 protons hitting the production target, about one muon will enter the transport solenoid.