The Mu2e Experiment at Fermilab STEVEN BOI, UNIVERSITY OF VIRGINIA - PowerPoint PPT Presentation

FERMILAB-SLIDES-18-789-E The Mu2e Experiment at Fermilab STEVEN BOI, UNIVERSITY OF VIRGINIA ON BEHALF OF THE MU2E COLLABORATION NUFACT 2018 This document was prepared by Mu2e collaboration using the resources of the Fermi National Accelerator Laboratory (Fermilab), a U.S. Department of Energy, Office of Science, HEP User Facility. Fermilab is managed by Fermi Research Alliance, LLC (FRA), acting under Contract No. DE-AC02-07CH11359. 1 8/13/2018 THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018

Charged Lepton Flavor Violation and the SM In an extension of the standard model, one which includes neutrino oscillations, lepton flavor is only approximately conserved, with some charged lepton flavor violation (CLFV) occurring due to neutrino oscillations. Such a process is exceedingly rare, a rate too small to be observed. Bonus : since we will never observe this, it is not a background to CLFV searches. THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018 2 8/13/2018 STEVEN BOI

CLFV beyond the SM Flavor physics effects for the most interesting observables in a While CLFV within the SM is selection of SUSY and non-SUSY models. effectively unobservable, the rate of 𝜈 + 𝑂 → 𝑓 + 𝑂 is uniquely sensitive to a host of BSM physics. ◦ Observation of 𝜈 → 𝑓 conversion is an unambiguous sign of new physics. ◦ Easy to produce high intensity muon beams. ◦ BSM models predict effects that would be measurable by next- generation experiments. ~ ★★★ Large effects ★★ SUSY Small effects ★ No effects A. de Gouvêa , et al THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018 3 8/13/2018 STEVEN BOI

Historical CLFV Searches Since the 1940s, searches for CLFV have been made, but so far only tighter constraints have been placed. Next-generation experiments will explore unconstrained phase space favored by many BSM models. 10 −4 Mu2e intends to improve the sensitivity by four orders of magnitude over the present limit. THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018 4 8/13/2018 STEVEN BOI

𝜈 + 𝑂 → 𝑓 + 𝑂 A simplified CLFV Lagrangian: 𝑛 𝜈 𝜆 𝜈 𝑆 𝜏 𝜈𝜉 𝑓 𝑀 𝐺 𝜈𝜉 + ℒ 𝐷𝑀𝐺𝑊 = 1 + 𝜆 Λ 2 ҧ 1 + 𝜆 Λ 2 ҧ 𝜈 𝑀 𝛿 𝜈 𝑓 𝑀 ෍ 𝑟 𝑀 𝛿 𝜈 𝑟 𝑀 ത 𝑟=𝑣,𝑒 A. de Gouvêa, R. Bernstein, et al Magnetic Moment Type Operator Λ : Mass Scale Sensitive to: 𝜈 → 𝑓𝛿 Mu2e Indirect probing 𝜈 → 𝑓 of mass scales up to 10 4 TeV. Λ (𝑈𝑓𝑊) 𝜆 : relative Contact Term Operator strength of magnetic moment MEG Sensitive to: type and contact 𝜈 → 𝑓 terms κ THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018 5 8/13/2018 STEVEN BOI

Flavor physics of leptons and dipole moments, arXiv:0801.1826 𝜈 + 𝑂 → 𝑓 + 𝑂 Marciano, Mori, and Roney, Ann. Rev. Nucl. Sci. 58, doi:10.1146/annurev.nucl.58.110707.171126 de Gouvea and Vogel, arXiv:1303.4097v2 A simplified CLFV Lagrangian: 𝑛 𝜈 𝜆 𝜈 𝑆 𝜏 𝜈𝜉 𝑓 𝑀 𝐺 𝜈𝜉 + ℒ 𝐷𝑀𝐺𝑊 = 1 + 𝜆 Λ 2 ҧ 1 + 𝜆 Λ 2 ҧ 𝜈 𝑀 𝛿 𝜈 𝑓 𝑀 ෍ 𝑟 𝑀 𝛿 𝜈 𝑟 𝑀 ത 𝑟=𝑣,𝑒 MAGNETIC MOMENT TYPE OPERATOR CONTACT TERM OPERATOR Supersymmetry Compositeness 𝑆 𝜈𝑓 ~10 −15 Λ 𝑑 ~3000 𝑈𝑓𝑊 Heavy Neutrinos Leptoquarks 1 𝑉 𝜈𝑂 𝑉 𝑓𝑂 ~8 × 10 −13 2 𝑁 𝑀𝑅 = 3000 𝜇 𝜈𝑒 𝜇 𝑓𝑒 Heavy 𝑎’ Two Higgs Doublet 𝑁 𝑎 ′ = 3000 𝑈𝑓𝑊/𝑑 2 𝑕 𝐼 𝜈𝑓 ~10 −4 𝑕 𝐼 𝜈𝜈 THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018 6 8/13/2018 STEVEN BOI

𝜈 + 𝑂 → 𝑓 + 𝑂 & Mu2e Mu2e will search for the coherent, neutrino-less 𝜈 → 𝑓 conversion in the presence of an aluminum nucleus. 𝜈 − + (𝐵, 𝑎) → 𝑓 − + 𝐵, 𝑎 The signal is a monoenergetic electron: ◦ 𝐹 𝑓 ≈ 𝑛 𝜈 − 𝐹 𝑐 − 𝐹 𝑠𝑓𝑑𝑝𝑗𝑚 ≈ 104.97 𝑁𝑓𝑊 ◦ Signal can be distinguished from background The ratio of 𝜈 + 𝑂 → 𝑓 + 𝑂 conversions to the number of muon captures by the aluminum nuclei will be measured: Γ 𝜈 − + 𝐵, 𝑎 → 𝑓 − + 𝐵, 𝑎 R 𝜈𝑓 = Γ 𝜈 − + 𝐵, 𝑎 → 𝜉 𝜈 + 𝐵, 𝑎 − 1 Mu2e intends to surpass the current limit in sensitivity by 4 orders of magnitude. ◦ Indirect probing of mass scales ℴ (10 4 TeV) A single event sensitivity (SES) of 3 × 10 -17 is required. THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018 7 8/13/2018 STEVEN BOI

𝜈 + 𝑂 → 𝑓 + 𝑂 & Mu2e Energy spectrum of electron emitted by muon decay in orbit 𝜈𝑂 → 𝑓𝜉 ҧ 𝜉𝑂 THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018 8 8/13/2018 STEVEN BOI

𝜈 + 𝑂 → 𝑓 + 𝑂 & Mu2e Energy spectrum of electron emitted by muon decay in orbit For: 3.6x10 20 POT 6.7x10 17 μ - stops assuming: R μ e = 1x10 -16 Signal yield = 3.5 evt DIO yield = 0.20 evt THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018 9 8/13/2018 STEVEN BOI

𝜈 + 𝑂 → 𝑓 + 𝑂 & Mu2e Intent: ◦ Four order of magnitude improvement in sensitivity over the current limit ◦ Set by SINDRUM II for 𝜈 + 𝑂 → 𝑓 + 𝑂 ◦ Probing of mass scales up to 10 4 TeV Achievements: ◦ World’s highest intensity muon beam ◦ Graded magnetic fields for greater muon collection ◦ Sub-event level management of backgrounds ◦ Pulsed beam structure ◦ High-efficiency Cosmic Ray Veto detector ◦ Tracker blind to >99% muon decay in orbit spectrum ◦ Fast timing Calorimeter with good energy resolution THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018 10 8/13/2018 STEVEN BOI

The Mu2e Experiment ( AT FERMILAB ) THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018 11 8/13/2018 STEVEN BOI

Mu2e Collaboration Comprised of 229 members from 37 Institutions. THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018 12 8/13/2018 STEVEN BOI

Mu2e at Fermilab THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018 13 8/13/2018 STEVEN BOI

Mu2e Beamline Using the existing accelerator Muon Campus Protons infrastructure, Mu2e will be the second building in the “Muon Campus” at Mu2e Fermilab. Delivery Ring Booster provides 8 GeV protons to the Booster Recycler. Recycler stacks protons into 4 bunches. Delivery Ring takes 1 out of every 4 bunches from the Recycler. Recycler Mu2e slow-extracts Protons every 1695ns. Runs with minimal impact on NO ν A. THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018 14 8/13/2018 STEVEN BOI

Mu2e Apparatus The Mu2e Apparatus is divided into three major solenoids: ◦ Production Solenoid ◦ Transport Solenoid ◦ Detector Solenoid ~25𝑛 THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018 15 8/13/2018 STEVEN BOI

Mu2e Apparatus The Mu2e Apparatus is divided into three major solenoids: ◦ Production Solenoid ◦ Transport Solenoid ◦ Detector Solenoid ~25𝑛 THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018 16 8/13/2018 STEVEN BOI

Mu2e Apparatus The Mu2e Apparatus is divided into three major solenoids: ◦ Production Solenoid ◦ Transport Solenoid ◦ Detector Solenoid ~25𝑛 THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018 17 8/13/2018 STEVEN BOI

Mu2e Apparatus The Mu2e Apparatus is divided into three major solenoids: ◦ Production Solenoid ◦ Transport Solenoid ◦ Detector Solenoid ~25𝑛 THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018 18 8/13/2018 STEVEN BOI

Mu2e Apparatus Graded magnetic fields sweep particles into the detector solenoid, creating the highest intensity muon beam to date. 1.0T 2.5T 4.5T 2.0T THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018 19 8/13/2018 STEVEN BOI

Mu2e Apparatus Production Solenoid A proton beam incident on a tungsten production target produces 𝜌 − . ◦ 8 GeV beam with 1695ns between pulses, well timed to 𝜐 𝐵𝑚 = 864ns ◦ 6 × 10 12 protons/second → 10 10 stopped 𝜈 − /second ◦ 𝜌 − move toward the transport solenoid, decaying into 𝜈 − . Proton Beam THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018 20 8/13/2018 STEVEN BOI

Mu2e Apparatus Transport Solenoid 𝜌 − and 𝜈 − beam propagate through the transport solenoid (TS) to the detector solenoid. ◦ Momentum selection ◦ Sign selecting collimator in the middle of the TS. 𝜈 − Sign Selection Collimator 𝜈 + THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018 21 8/13/2018 STEVEN BOI

Mu2e Apparatus Detector Solenoid 𝜈 − stop in an Aluminum target comprised of 37 thin 100 μm foils. ◦ With a rate of 6 × 10 12 protons/second incident on the production target, 1.1 × 10 10 𝜈 − /second reach the stopping target. ◦ The momentum and energy of 𝑓 − coming out of the stopping target is measured by the tracker and calorimeter. Calorimeter Tracker THE MU2E EXPERIMENT AT FERMILAB: NUFACT 2018 22 8/13/2018 STEVEN BOI