The R&D effort towards a neutrino factory

1. M. Bonesini Sezione INFN Milano Bicocca Dipartimento di Fisica G. Occhialini The R&D effort towards a neutrino factory

2. MICE/ MERIT CNGS JHF ? Off-Axis  ? Factory MiniBooNE KamLand Roadmap HARP K2K-II  disappearance m212,12 at 2% LSND? 2005 • appearance NC/CC NuMI ISS  down to 1o 2010 F R&D 2015-20 CP violation Yellow Report CERN-2004-002, ECFA/04/230 Further informations: http://muonstoragerings.cern.ch 2030

3.  beams: conventional and nufact beams WANF (conventional) • Problem in conventional beams: a lot of minority components (beam understanding) • Following muon collider studies, accelerated muons are ALSO an intense source of “high energy”  • Crucial features • high intensity (x 100 conventional beams) • known beam composition (50%  50% e ) • Possibility to have an intense e beam • Essential detector capabilities: detect  and determine their sign Nufact NOW 2006 - Otranto

4. 1016p/s + e++  +e Oscillate + 0.9 1021 yr  3 1020 eyr 3 1020 yr Wrong Sign muons IEEE 2004 - Roma

5. X 5 present limit from the CHOOZ experiment 0.75 MW JHF to super Kamiokande with an off-axis narrow-band beam, Superbeam: 4 MW CERN-SPL to a 400 kt water Cerenkov@ Fréjus (J-PARC phase II similar) Neutrino Factory with 40 kton large magnetic detector. Sensitivity of Nufact 0.10 130 2.50 50 10 M. Mezzetto IEEE 2004 - Roma

6. Towards a Neutrino Factory: the challenges • Target and collection (HARP/MERIT) • Maximize + and - production • Sustain high power (MW driver) • Optimize pion capture INTENSE PROTON SOURCE (MW); GOOD COLLECTION SCHEME • Muon cooling (MICE) • Reduce +/- phase space to capture as many muons as possible in an accelerator • Muon acceleration • Has to be fast, because muons are short-lived ! (RLA, FFAG, … not covered in this talk) NOW 2006 - Otranto

7. US Study II Neutrino Factory studies and R&D USA, Europe, Japan have each their scheme. Only one has been costed, US study II: + detector: MINOS * 10 = about 300 M€ or M$ Neutrino Factory CAN be done…..but it is too expensive as is. Aim: ascertain challenges can be met + cut cost in half. IEEE 2004 - Roma

8. HARP at CERN PS • Study to optimize target : HARP experiment at CERN • ~420 Mtriggers collected on different targets 1.5-15 GeV/c • 4p detector (TPC+forward) • First results for NUFACT target optimization (see G. Catanesi talk) Tof Cerenkov Tpc A Layout of the Harp experiment IEEE 2004 - Roma spectrometer

9. First results for NUFACT targetry optimizatio From S. Borghi talk at NUFACT06

10. MERIT (MERcury Intense Target) • Proof of principle demonstration of Hg-jet target for a 4MW proton beam, contained in a 15-T solenoid for maximal collection of soft secondary pions • 24 GeV proton beam from CERN PS • Start Spring 2007 (nTOF area) 15-T solenoid during tests at MIT Hg delivery and containment system under construction at ORNL. Integration tests scheduled this Fall at MIT.

11. Accelerator acceptance R  10 cm, x’  0.05 rad rescaled @ 200 MeV Accelerato The big problem: reduction of emittance The muon beam emittance must be reduced for injection into the acceleration system • Energy spread ► phase rotation • Transverse emittance ► cooling andafter focalization IEEE 2004 - Roma

12. Stochastic cooling is too slow. A novel method for + and- is needed: ionization cooling Muon ionization cooling principle reality (simplified) reduce pt and pl heating A delicate technology and integration problem Need to build a realistic prototype and verify that it works (i.e. cools a beam) increase pl Difficulty:affordable prototype of cooling section only cools beam by 10%, while standard emittance measurements barely achieve this precision. Solution: measure the beam particle-by-particle NOW 2006 - Otranto

13. Muon Ionization Cooling Experiment • Build a section of cooling channel long enough to provide measurable cooling (10% ) and short enough to be affordable and flexible • Wish to measure this change to 1% • Requires measurement of emittance of beams into and out of cooling channel to 0.1% ! • Cannot be done with conventional beam monitoring device • Instead perform a single particle experiment: • High precision measurement of each track (x,y,z,px,py,pz,t,E) • Build up a virtual bunch offline • Analyse effect of cooling channel on many different bunches • Study cooling channels parameters over a range of initial beam momenta and emittances • Experiment approved in 2003 y CLRC and scheduled for first run in October 2007 IEEE 2004 - Roma

14. MICE setup: cooling + diagnostics

15. RF cavities Restore lost pL • 8 MV/m accelerator gradient • 4 T axial magnetic field Be window to minimize thickness MICE cooling channel R&D LH2 absorbers reduce muons momenta • Large ionization energy loss rate • Low scattering First cavity has been assembled The challenge: Thin windows + safety regulations NOW 2006 - Otranto

16. 3 Liquid Hydrogen absorbers • 8 cavities 201MHz RFs, 8MV/m • 5T SC solenoids MICE cooling channel Minimize heating term: • Absorber with large X0 • SC solenoid focusing for small T • High gradient reacceleration • 10% reduction of muon emittance for 200 MeV muons requires ~20MV RF • Challenge: integration of these elements in the most compact and economic way NOW 2006 - Otranto

17. cooling effect at nominal input emittance ~10% equilibrium emittance = 2.5 mm.radian Quantities to be measured in a cooling exp Difficulty: standard emittance measurement barely reach the required 0.1 % precision Solution: Single particle measurement • The advantages: • Separate measurement of transmittance and emittance variation • A precision on (Tin-Tout) <10-3 can be achieved • The challenge: The measurement should not affect the cooling Acceptance: beam of 5cm and 120 mrad rms curves for 23 MV, 3 full absorbers, particles on crest NOW 2006 - Otranto

18. Muon Emittance measurement G4MICE simulation of Muon traversing MICE Each spectrometer measures 6 parameters per particle x y t x’ = dx/dz = Px/Pz y’ = dy/dz = Py/Pz t’ =dt/dz =E/Pz Determines, for an ensemble (sample) of N particles, the moments: Averages <x> <y> etc… Second moments: variance(x) x2 = < x2 - <x>2 > etc… covariance(x) xy = < x.y - <x><y> > Covariance matrix M = Getting at e.g. x’t’ is essentially impossible with multiparticle bunch measurements Compare in with out Evaluate emittance with:

19. Spectrometer system requirements must be sure particles considered are muons throughout a) reject incoming e, p,  => TOF 2 stations 10 m flight with 70 ps resolution b) reject outgoing e => Cerenkov + Calorimeter 2. measure 6 particle parameters i.e. x,y,t, px/pz , py/pz ,E/pz 3. measure widths and correlations … resolution in all parameters must be better than 10% of width at equilibrium emittance (correction less than 1%) meas = true+ res = true [ 1+ (res/ true)2 ] (n.b. these are r.m.s.!) 4. robust against noise from RF cavities => Statistical precision 105 muons out/ in )= 10-3 in ~ 1 hour Systematics!!!! NOW 2006 - Otranto

20. Mice: tracker Must measure muon momenta & positions B Baseline tracker 5 planes of scintillating fiber tracker with 3 double layers. passive detector + fast • good for RF noise Very small fibers needed to reduce MS Little light  VLPC readout (D0 experience) NOW 2006 - Otranto

21. DATA MC KEK TB Data: Residual Distribution KEK TB Tracker 1T BESS Magnet

22. Apparatus: PID overview ISIS Beam Iron Shield TOF0 TOF1 Diffuser Iron Shield TOF2 EMCal Proton Absorber Ckov1 • In the cooling channel muons can be contaminated by • Pions in the incoming beam (muons parents) • Electrons in the outgoing beam (muon decay products) PID

23. TOF2 Cal MICE: Particle ID • Upstream: • TOF0/1 hodoscopes with 10m path, ~60 ps resolution • Cherenkov • / separation at better than 1% at 300 MeV/c • Downstream: • 0.5% of s decay in flight: need electron rejection at 10-3 to avoid bias on emittance reduction measurement • TOF2 hodoscope • Calorimeter for MIP vs E.M. Shower Frascati TB – TOF & CAL EMCAL TOF station NOW 2006 - Otranto

24. Emittance measurement from Geant-4 simulations

25. -  STEP I PHASE 1 (funded): start October 2007 • Characterize beam • Calibrate spectr I PID + Tracker STEP II +Solenoid STEP III ~ 2008 2008 -> STEP IV STEP V 2009? STEP VI IEEE 2004 - Roma

26. MICE at RAL Hall has been emptied and preparation to host the experiment begun NOW 2006 - Otranto

27. MANX (Muon collider And Neutrino factory eXperiment) • Proposed follow-up of MICE to obtain large cooling factors (~0.5) in few meters, using graded B fields to mach decreasing pm • Optimization under study, proposal submitted to FNAL (May 2006)

28. Summary and outlook “ Neutrino Oscillations provide us with exciting experimentally driven science. We might be in for big surprises.Neutrino Factories offer a new type of neutrino beam with impressivestatistical and systematic precision, and flexibility. If 13 is smaller than O(0.01) they will offer a way forward … but only if we invest in the R&D so that the option exists when the time comes. “ • As an example, R&D on muon cooling is a critical point (MICE at RAL) • Enthusiastic R&D is ongoing, and a lot has already been accomplished NOW 2006 - Otranto