MUON COLLIDER R&D Steve Geer Accelerator Physics Center Fermi National Accelerator Laboratory Accelerator Seminar SLAC., March 24, 2011   Muon Accelerator Program - MAP

PHYSICS LANDSCAPE STEVE GEERAccelerator Seminar SLAC 24 March, 20112

DECISION TREE STEVE GEERAccelerator Seminar SLAC 24 March, Pierre Oddone

MUON COLLIDER MOTIVATION STEVE GEERAccelerator Seminar SLAC 24 March, COST PHYSICS  If we can build a muon collider, it is an attractive multi-TeV lepton collider option because muons don’t radiate as readily as electrons (m  / m e ~ 207): - COMPACT Fits on laboratory site - MULTI-PASS ACCELERATION Cost Effective operation & construction - MULTIPASS COLLISIONS IN A RING (~1000 turns) Relaxed emittance requirements & hence relaxed tolerances - NARROW ENERGY SPREAD Precision scans, kinematic constraints - TWO DETECTORS (2 IPs) -  T bunch ~ 10  s … (e.g. 4 TeV collider) Lots of time for readout Backgrounds don’t pile up - (m  /m e ) 2 = ~40000 Enhanced s-channel rates for Higgs-like particles A 4 TeV Muon Collider would fit on the Fermilab Site

ENERGY SPREAD STEVE GEERAccelerator Seminar SLAC 24 March, Beamstrahlung in any e+e- collider  E/E   2

l + l - → Z’ →    - STEVE GEERAccelerator Seminar SLAC 24 March, ENERGY SCAN     with ISR+BStr (Eichten) e + e - with ISR e + e - with ISR+BStr Z’ Line shape EVENT RATE √s (GeV)

CHALLENGES Muons are produced as tertiary particles. To make enough of them we must start with a MW scale proton source & target facility. Muons decay  everything must be done fast and we must deal with the decay electrons (& neutrinos for CM energies above ~3 TeV). Muons are born within a large 6D phase-space. For a MC we must cool them by O(10 6 ) before they decay  New cooling technique (ionization cooling) must be demonstrated, and it requires components with demanding performance (NCRF in magnetic channel, high field solenoids.) After cooling, beams still have relatively large emittance. STEVE GEERAccelerator Seminar SLAC 24 March, 20117

MUON COLLIDER SCHEMATIC STEVE GEERAccelerator Seminar SLAC 24 March, Proton source: Example: upgraded PROJECT X (4 MW, 2±1 ns long bunches) muons per year that fit within the acceptance of an accelerator:   N =6000  m  //N =25 mm √s = 3 TeV Circumference = 4.5km L = 3×10 34 cm -2 s -1  /bunch = 2x10 12  (p)/p = 0.1%   N = 25  m,  //N =70 mm  * = 5mm Rep Rate = 12Hz

Muon Collider cf. Neutrino Factory STEVE GEERAccelerator Seminar SLAC 24 March, NEUTRINO FACTORY MUON COLLIDER In present MC baseline design, Front End is same as for NF

A DECADE OF PROGRESS NF Feasibility Studies STEVE GEERAccelerator Seminar SLAC 24 March, Successful completion of NF feasibility studies 1, 2, 2a, & International Scoping Study; launching of the ongoing International Design Study for a NF (IDS-NF) – Solid basis for planning the MC Design Feasibility Study (DFS) – Real progress on understanding how to make enough muons, capture them into bunches, reduce their energy spread, and begin to reduce their transverse phase space (ionization cooling). IDS-NF community plans to produce a Reference Design Report (RDR) in ~ 2 years. – Interim Design Report (IDR) has just been finalized, and is to be reviewed by an ECFA sub-panel May 5-6, 2011

STEVE GEERAccelerator Seminar SLAC 24 March, A DECADE OF PROGRESS Front-End Design ParameterDriftBuncherRotatorCooler Length (m) Focusing (T) (ASOL) RF f (MHz)360   RF G (MV/m)0  Total RF (V) ± → ± →  Front-end uses NCRF in a lattice of solenoids

STEVE GEERAccelerator Seminar SLAC 24 March, A DECADE OF PROGRESS Front-End Simulations With a 4MW proton source, this will enable O(10 21 ) muons/year to be produced, bunched, cooled & fit within the acceptance of an accelerator. Neuffer

STEVE GEERAccelerator Seminar SLAC 24 March, Proof-of-principle demonstration of a liquid Hg jet target in high-field solenoid ran at CERN PS in Fall Successfully demonstrated a 20m/s liquid Hg jet injected into a 15 T solenoid, & hit with a suitably intense beam (115 KJ / pulse !). Results suggest this technology OK for beam powers up to 8 MW with rep. rate of 70Hz ! Hg jet in a 15 T solenoid Measured disruption length = 28 cm 1 cm A DECADE OF PROGRESS Successful completion of MERIT

STEVE GEERAccelerator Seminar SLAC 24 March, A DECADE OF PROGRESS Ionization Cooling  TRANSVERSE COOLING: Muons lose energy by in material (dE/dx). Re- accelerate in longitudinal direction  reduce transverse emittance. Coulomb scattering heats beam  low Z absorber. Hydrogen is best, but LiH also OK for the early part of the cooling channel.  6D COOLING: Mix transverse & longitudinal degrees of freedom during cooling. Can be done in helical solenoids.  FINAL COOLING: To get the smallest achievable transverse emittance, over- cool the longitudinal emittance, and then work only on the transverse emittance letting the longitudinal phase space grow. ε t,, N (m) Liq. H 2 RF High Field (HTS) Solenoids

STEVE GEERAccelerator Seminar SLAC 24 March, Development of a cooling channel design to reduce the 6D phase space by a factor of O(10 6 ) → luminosity O(10 34 ) cm -2 s -1 Palmer Some components beyond state-of-art: o Very high field HTS solenoids & High gradient RF cavities operating in few Tesla fields Challenging are the solenoids in the last stages of cooling: o Original design needed 50 T solenoids. Recent improvements suggest 30 T sufficient. A DECADE OF PROGRESS Ionization cooling concepts & simulations HTS 30T

STEVE GEERAccelerator Seminar SLAC 24 March, PROGRESS THIS YEAR Ionization cooling concepts & simulations

A DECADE OF PROGRESS MuCool Test Area STEVE GEERAccelerator Seminar SLAC 24 March, MTA built at end of FNAL Linac for ionization cooling component testing 5 T magnet, RF power at 805 MHz & 201 MHz, clean room, LH 2 handling capability, 400 MeV beam from linac. Liq. H 2 absorber (KEK) 201 MHz cavities (LBNL et al.) 42 cm  Be RF window (LBNL) High Pressure RF Cavity (FNAL & Muons Inc.) FIRST BEAM IN MTA 28 FEBRUARY 2011 !

STEVE GEERAccelerator Seminar SLAC 24 March, Muon Beam Spectro- meter Cooling section Spectro- meter Multi-stage experiment at RAL to be completed ~2014 MICE – upstream beamline - Tests short cooling section, in muon beam, measuring the muons before & after the cooling section. one at a time. - Learn about cost, complexity, & engineering issues associated with cooling channels. -Vary RF, solenoid & absorber param- eters & demonstrate ability to simulate response of muons A DECADE OF PROGRESS Muon Ionization Cooling Experiment ( MICE)

STEVE GEERAccelerator Seminar SLAC 24 March, A DECADE OF PROGRESS Muon Ionization Cooling Experiment ( MICE) Spectrometer Solenoid MICE HALL Liq. H 2 Absorber Tracker in cosmic ray test stand RF Cavity

A DECADE OF PROGRESS Collider Ring STEVE GEERAccelerator Seminar SLAC 24 March, Emittances are large, but the muons circulate for only ~1000 turns before they decay. - First lattice designs exist. Need high field dipoles & quadrupoles that operate in large muon decay backgrounds Have studied open mid- plane magnet design (radiation & heat loads, field non-uniformity & affect on lattice performance) → looks OK. - More engineering studies needed. MARS energy deposition map for a 1.5 TeV collider dipole √s=1.5 TeV

A DECADE OF PROGRESS Detector Backgrounds STEVE GEERAccelerator Seminar SLAC 24 March,  Muon Collider detector backgrounds studied ~10 yrs ago ( ). Most detailed work done for a  s=4 TeV Collider.  The electron decay angles from  → e are O(10)  radians. Electrons typically stay inside beampipe for ~6m. Hence decay electrons born within a few meters of the IP are benign.  Shielding strategy: sweep the electrons born further than ~6m from the IP into ~6m of shielding.  MARS & GEANT studies gave consistent results. After optimization of shielding, for  s=4 TeV, particle densities in inner detectors similar to cm -2 s -1.

A DECADE OF PROGRESS New Detector Studies STEVE GEERAccelerator Seminar SLAC 24 March, New detector studies under way – initially for √ s=1.5 TeV. -Initial shielding configuration exists -Reliable MARS simulations exist (NEW: can now simulate decays from muons with ~ weight 1 “events” !) -Initial detector studies beginning -Much needs to be understood & optimized ILC – like detector with Muon Collider shielding cones MARS map of background particle densities in detector

THE BIRTH OF MAP STEVE GEERAccelerator Seminar SLAC 24 March, Oct 1, 2009 letter from Denis Kovar to FNAL Director: “Our office believes that it is timely to mount a concerted national R&D program that addresses the technical challenges and feasibility issues relevant to the capabilities needed for future Neutrino Factory and multi-TeV Muon Collider facilities....” Letter requested a new organization for a national Muon Collider & Neutrino Factory R&D program, hosted at FNAL. Muon Accelerator Program organization is now in place & functioning: >200 participants from 15 institutions: – ANL, BNL, FNAL, JLab, LBNL, ORNL, SLAC, Cornell, IIT, Princeton, UCB, UCLA, UCR, U-Miss, U. Chicago – MAP R&D proposal reviewed August 2010 … committee concluded that the “proposed work was very important to the field of high energy physics.”

MAP MISSION STATEMENT STEVE GEERAccelerator Seminar SLAC 24 March, The mission of the Muon Accelerator Program (MAP) is to develop and demonstrate the concepts and critical technologies required to produce, capture, condition, accelerate, and store intense beams of muons for Muon Colliders and Neutrino Factories. The goal of MAP is to deliver results that will permit the high-energy physics community to make an informed choice of the optimal path to a high-energy lepton collider and/or a next-generation neutrino beam facility. Coordination with the parallel Muon Collider Physics and Detector Study and with the International Design Study of a Neutrino Factory will ensure MAP responsiveness to physics requirements.

MAP ORGANIZATION STEVE GEERAccelerator Seminar SLAC 24 March, “” Level 0” “Level 1”

ORGANIZATION: L1 & L2 STEVE GEERAccelerator Seminar SLAC 24 March, L2 assignments - FNAL; 4½ people - Other Labs: 3 people - Universities: 3½ people - SBIR Companies: 1 person “Level 1”

PROPOSED MAP PLAN / DELIVERABLES STEVE GEERAccelerator Seminar SLAC 24 March, Deliver on our commitments to making MICE and the IDS- NF studies a success. Deliver a Design Study to enable the community to judge the feasibility of a multi-TeV Muon Collider (~FY16): (i) an end-to-end simulation of a MC complex based on technologies in- hand or that can be developed with a specified R&D program. (ii) hardware R&D and experimental tests to guide & validate the design work. (iii) Rough cost range. (iv) R&D plan for longer term activities (e.g. 6D cooling expt)

TECHNICAL CHALLENGES STEVE GEERAccelerator Seminar SLAC 24 March, There has been much progress over the last decade, but there remains many technically challenging issues that must be addressed before a Muon Collider can be built: – High field solenoids operating close to the target (4MW beam) – RF operation in magnetic fields – The last few stages of the cooling channel – Cost effective acceleration – Background mitigation & understanding detector performance

TECHNICAL CHALLENGES Target Solenoids STEVE GEERAccelerator Seminar SLAC 24 March, For a MW-class proton beams – How radiation hard can we make the solenoids? – What thermal loads can we manage? Need R&D to establish the limitations & build confidence in our target station designs 20T Target Solenoid – Conductor radiation tests – Radiation damage simulations & verification – Target station radiation simulations (MARS) – Thermal management studies? – Model magnet radiation tests

TECHNICAL CHALLENGES NCRF in Magnetic Fields STEVE GEERAccelerator Seminar SLAC 24 March, Significant degradation in maximum stable operating gradient for NCRF copper cavities in few Tesla coaxial field Ongoing R&D program to maximize gradient in B field: (i) high pressure gas filled cavities, (ii) Be cavities, (iii) ALD, (iv) magnetic insulation Mucool Test Area 805 MHz

TECHNICAL CHALLENGES High Field Solenoids STEVE GEERAccelerator Seminar SLAC 24 March, FNAL TD test cable. Test degradation of J c in cabling process  At the end of cooling channel want very high field (~30T) solenoids  On going national R&D to develop very high field HTS solenoids.  Great promise but many challenges: -Conductor performance -Quench protection -stresses PBL (SBIR) 35T design NHMFL YBCO Test Coil (27T –  B = 7T)

IMPACT OF MUON COLLIDER DESIGN FEASIBILITY STUDY STEVE GEERAccelerator Seminar SLAC 24 March, Based on NASA Technology Readiness Levels NOW PROPOSED MC-DFS Target & Dump Bunch / Phase Initial Cooling 6D Cooling Final Cooling Pre-Acceleration Acceleration Ring MUON COLLIDER PROPOSAL 7. System Prototype 6. Sub-System Beam Tests 5. Semi-realistic sub-systems 4. Early sub-system Bench Tests 3. Component R&D 2. Technical Concept 1. Basic Idea

PAST-PRESENT-FUTURE STEVE GEERAccelerator Seminar SLAC 24 March, NFMCC + MCTF Interim MAP FY07 – FY09 FY10 ≥FY11 ~4 M$~9 M$~10 M$~15 M$ (requested) First ~10 years MAP NOW

STEVE GEERAccelerator Seminar SLAC 24 March, INFORMING THE COMMUNITY

FINAL REMARKS STEVE GEERAccelerator Seminar SLAC 24 March, MAP is up and running: – MAP Management plan signed by DOE-OHEP – MAP Director search is under way ( ) There is a real chance to show, within ~6 years, that a multi-TeV Muon Collider is feasible with an estimated cost range, and to specify the remaining R&D needed. – The proposed plan requires ~15M$/yr (FY10 dollars) – Many challenges, but we believe we can succeed

A VISION STEVE GEERAccelerator Seminar SLAC 24 March, MW at ~3 GeV flexible time structure and pulse intensities 2 MW ( GeV) 1300 km START WITH PROJECT X Neutrinos Muons Kaons Nuclei “simultaneously”

A VISION STEVE GEERAccelerator Seminar SLAC 24 March, ADD NEUTRINO FACTORY Enhanced Neutrinos Enhanced Muons Muon Collider test bed Kaons Nuclei “simultaneously” 4MW protons 5 GeV muons 1300 km

A VISION STEVE GEERAccelerator Seminar SLAC 24 March, ADD MUON COLLIDER ++ -- 4 TeV Collider