Design Mu2e

1 design

1.1 muon production
1.2 transport
1.3 detection

1.3.1 sensitivity

design

the mu2e apparatus 92 feet (28 m) in length, , consist of 3 sections. total cost of experiment $271 million.

muon production

repurposed elements tevatron collider used generate , deliver 8 gev proton beam. these protons collide tungsten production target in production solenoid, producing cascade of particles including pions, decay muons. mu2e produce between 200 , 500 quadrillion (2×10 5×10) muons per year. every 300 protons hitting production target, 1 muon enter transport solenoid.

transport

the 4.5-tesla magnetic field of production solenoid direct of particles produced s-shaped 2-tesla evacuated transport solenoid, consisting of 50 separate superconducting electromagnets, select muons charge , momentum, , carry desired slow muons detector after time delay.

detection

on entering detector solenoid, muons stop in aluminum target thick ten layers of aluminum foil, entering orbitals around nuclei within target. muons convert electrons without emitting neutrinos escape these orbitals , enter detector characteristic energy of around 105 mev.

the detector consists of 2 components: straw tracker measure momentum of outgoing particles; , electromagnetic calorimeter identify particle interactions record further study, identify type of particle passed through tracker, , confirm measurements of tracker. electron energy of around 105 mev indicate electron originated in neutrinoless muon conversion.

in order disturb path of electrons little possible, tracker uses little material possible. wire chamber tracker consists of panels of 15-micron-thick straws of metalized mylar filled argon , carbon dioxide, thinnest such straws ever used in particle physics experiment. electronics @ each end of straws record signal produced when electrons interact gas in straw, allowing trajectory of electrons reconstructed.

sensitivity

the rate of neutrinoless conversion of muons electrons constrained meg experiment less 2.4×10, , further constrained 7×10 sindrum ii experiment @ paul scherrer institute in switzerland. mu2e has expected sensitivity of 5×10, 4 orders of magnitude beyond sindrum ii, meaning see signal if few 1 in 100 quadrillion muons transforms electron.