The Mu2e Solenoids • Physics Goals and Why it’s important to Fermilab and HEP • How the Experiment Works • Baseline Solenoid Design • SRF involvement in Mu2e Solenoids • Schedule Michael Lamm SRF Department for the Mu2e Collaboration January 14, 2013 1
What is Mu2e and why do it? Look for Charged Lepton Flavor Violation • Measure the Rare Process: - + N e- + N • relative to garden variety - + N nuclear capture → It will be world class experiment in the “Intensity Frontier” Single particle sensitivity goal of 10 -17 : 4 orders of magnitude improvement • Judged by P5 Committee to be a high priority for Fermilab and US HEP • → …either with or without a signal…. WITH: Indicate new physics beyond the “standard model” • WITHOUT: Put severe limits on theories beyond the standard model • It will compliment LHC Direct Observation Experiments • → Timing is right to do it….(Experiment will run ~2020) After the Tevatron is shut off….before Project X • Required accelerator resources compliment other Intensity Frontier experiments • It has a future: Knowledge learned will go into Project X era experiment • → Technically Challenging but very do-able Very interesting project for scientists and engineers • 1/14/2013 2 Mu2e Solenoids
Direct vs. Indirect Measurement – Indirect Measurement – Infer mass or existence of a particle by measuring reactions – Involves connection to theory – Example Beta decay of Neutron Process involves exchange of virtual W- W is involved in the process even though mass is x100 larger than P or n 1/14/2013 3 Mu2e Solenoids
Direct vs. Indirect Measurement – Example II – The ratio of the W/Z mass can be inferred by measuring the relative rate +N +X vs. +N +X because the former involves a virtual W with the other by a virtual Z Through the standard model, R exp related in a straight-forward way to M Z /M W : Rnc/Rcc~ ½- ½sin2( w), M Z /M W = 1/cos( w) 1/14/2013 4 Mu2e Solenoids
Mu2e:Indirect measurement experiment • Because of neutrino oscillations, we know that lepton flavor can be violated for neutral leptons charged leptons flavor violation is possible • Possible ways to observe this: Virtual mixing If is real : e e If is virtual: +P e P Draw all possible “legal” W Feynman diagrams using standard model virtual particles (W, , e ..) After calculate conclude: rate is very very small O(-50) can be real or virtual NEVER SEE IT 1/14/2013 5 Mu2e Solenoids
Theorists step in…. • There are numerous theories which predict the existence of: excited higher mass W, Z states, lepto-quarks, composite particles...etc • One can calculate a probability of this to occur…. ? e ? ? ? N N • The more channels increased probably of occurring • Essentially all models in play predict interactions within the range of Mu2e experiment reach • Some of these ? particles may be beyond the reach of LHC 1/14/2013 6 Mu2e Solenoids
Lepton Flavor Violating Experiments Goal:4 orders of magnitude more sensitivity than best present experiment • MEG II 2012 • Mu2e ~ 2020 1/14/2013 7 Mu2e Solenoids
Mu2e Strategy ( +P e P) – Start with high intensity, 100ns wide pulse of 8 GeV protons – Create a beam of high intensity, low momentum “in time” muons – Beam is full of “ in time” junk (pions, muons and electrons….) – Stop muons in aluminum target: form muonic atom - can be captured in a nucleus just like an electron – – Take advantage of muon life in atom to reduce background – Turn off the experiment to allow other particles in the muon beam (including a lot of background electrons…) to blow past detector – Turn experiment on, detect the electrons from target Note: experiment cannot tolerate out of time particles • Protons in between bunches 105 MeV e - • Muons that get lost in the transport 1/14/2013 8 Mu2e Solenoids
Mu2e Strategy (II) – Once muon is captured in nucleus…most of the time either decays in orbit or normal muon capture Our reaction - + N e- + N is kinematically constrained to produce – mono-energetic electrons of ~105 MeV (distinct signal from backgrounds) Computer Simulation in Detector 1/14/2013 9 Mu2e Solenoids
Dominant Signal Background Decay in orbit followed by nuclear recoil Background X20 e e N • Rate approaches conversion (endpoint) energy as (E s -E) 5 • If detector meets resolution specs, we should be able to see a signal at the 10 -16 level 1/14/2013 Mu2e Solenoids 10
Three Solenoids for Mu2e •Sign/momentum Selection •Negative Axial Gradient in straight sections to suppress trapped particles 8 GeV P • Transport Solenoid (TSu,TSd) • Detector Solenoid (DS) 8 meters • Production Solenoid (PS) • 8 GeV P hit target. Reflect and focus / ’s into muon transport • Strong Axial Gradient Solenoid Field •Graded field to collect conv. e - 24 meters •Uniform field for e - Spectrometer
Solenoids and Supportin g Infrastructure Production Solenoid (PS) • Transport Solenoid (TSu,TSd) • Detector Solenoid (DS) • Cryogenic Distribution • Field Mapping • Ancillary Equipment • Power Supply/Quench Protection • Installation and commissioning • Cryoplant (off project) • 1/14/2013 12 Mu2e Solenoids
Procurement Strategy • PS and DS will be built in industry – Final engineering design done by industry based on detailed requirements and specifications and reference design – We have already completed RFI with industry based on our preliminary specifications and reference design reports • Cost and schedules are consistent with our independent estimates • TS will be designed/built “in house” – Cryostat, mechanical supports built by outside vendors – Coils wound in-house or industry – Final assemble and test at Fermilab • Cryo Distribution similar to TS – Near final design in house – Feed box frames and components built in industry, final assembly in House • Recycle TeV HTS leads, Satellite Refrigerators • Power converters, quench protection electronics etc. purchased from industry whenever possible 1/14/2013 13 Mu2e Solenoids
Production Solenoid Concept 4.6T 2.5 T Axial Gradient Features: – 1.6 m aperture, 4 m long – 3 coils “3-2-2” layers – High strength aluminum stabilized NbTi conductor (similar to ATLAS Central Solenoid) – Aluminum outer support shells – Thermal Siphon Cooling – Mechanically supports Heat and Radiation Shield (HRS) Mu2e Solenoids 1/14/2013 14
Transport Solenoid • TS1,TS3,TS5: Straight sections with axial gradient TS2 • TS2/TS4: approximate toroidal field • Accomplished by 55 solenoid rings of different amp-turns TS1 • Two cryostats: TSU, TSD • TS3: TS3U, TS3D. Rotatable Collimator, Wider coils to TS3 P-bar window compensate for gap • Coil fabrication similar to MRI coils TS4 TS5 1/14/2013 Mu2e Solenoids 15
Detector Solenoid Concept Spectrometer Gradient Section Section – 1.8 m aperture , 10 m long, operating current ~6kA – 11 coils in total • Axial spacers in Gradient Section • Spectrometer section made in 3 sections to simplify fabrication and reduce cost – Coil fabrication similar to PS • Aluminum Stabilizer NbTi • Outer aluminum support structure for each coil sized for expected hoop stress Mu2e Solenoids 16 1/14/2013
Areas where SRF is contributing • Most of the Solenoid development work is taking place in the Technical Division – 25 FTE’s in FY2013, over 70 people working spend some fraction of time on this project! • Important work involving SRF Department staff – Cryogenic Distribution – Cryostat design – Test facility support – Mechanical Integration 1/14/2013 17 Mu2e Solenoids
Cryogenic Distribution • Tom Peterson is L3 manager for Cryo distribution – Jeff Brandt, Nandhini Dhanaraj…. – Feedbox design – SC distribution lines – Cryogenics interface to cryoplant 1/14/2013 18 Mu2e Solenoids
Thermosiphon Studies for Transport Solenoid Nandhini Dhanaraj Helium Gas Return Pipe Siphon Tubes Inlet pipe – liquid PS End helium Goal: - Compare Thermal siphon to Forced flow -Determine pipe sizes and locations -Refine estimate of cryogen usage Still to come: Apply similar analysis to PS and DS 1/14/2013 19 Mu2e Solenoids
Cryostat Design for the large solenoids Primary responsibility for production solenoid cryostat and cryostat support Part of collaboration with Bob Wand and Dan Evbota on the transport solenoid cryostat and mechanical supports Transport Production Solenoid Solenoid T. Nicol 1/14/2013 20
Mechanical Design of Mu2e Test Coil Test coil from Toshiba comes without V. Poloubotko cooling system. Square shape cooling channels Ongoing work to Clamp plank design practical coiling channel layout and mechanical support 1/14/2013 21 Mu2e Solenoids
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