Neutrino Factories and Muon Ionization Cooling Channels

1. Neutrino Factories and Muon Ionization Cooling Channels D. Errede HETEP University of Illinois 17 March, 2003

2. Why build a Neutrino Factory? (Physics, of course) What does a Neutrino Factory look like? In particular, what is an ionization cooling channel? What has the University of Illinois been doing with respect to a cooling channel?

4. The Physics of Neutrinos • Neutrino masses (pattern of the all fermion masses) • Neutrino oscillation parameters (fill in the CKM matrix for leptons) • CP Violating processes in the Lepton Sector (origin of baryon-antibaryon asymmetry in our universe?) • GUTS: relating properties of quarks and leptons Is there a grand unified scheme?

6. The Physics of Neutrinos Standard form for Mixing Matrix connecting weak and mass eigenstates Q12, Q23, Q13, d are the 4 real parameters that describe the mixing… d 0 implies CP violation. (phase between 0 and 2p )

7. The Physics of Neutrinos • Connect two weak eigenstates with the evolution operator – involves Hamiltonian H0 • Use two assumptions: m1 < m2 << m3 and dM2 = dm2atm = dm232 ~ dm231 we get And something similar but more complicated for nm

8. The Physics of Neutrinos The sign ofdm2 : solar neutrinos Matter effects : MSW (Mikheev, Smirnov, Wolfenstein) ne interacts with electrons in matter through the charged current interaction. This adds a term to the evolution operator. There is a resonance in matter near a = 1 for typical values of sin22q(10-3 - 10-2) “a” depends on Ne, GF, En, dm2 . q=q12 , q13

9. The Physics of Neutrinos The resonance applies to neutrinos for positive dm2 and antineutrinos for negativedm2. Thus we can get the mass hierarchy. -----m3 -----------m2 -----------m1 OR -----------m2 -----------m1 -----m3

10. The Physics of Neutrinos 3 Plausible Sets of Values 1 2 3 J - Jarlskog factor a measure of CP violatioin

11. The Physics of Neutrinos : CP VIOLATION … J = c12 c132 c23 s12 s13 s23sind Jarlskog J-factor a measure of CP violation CP Operation: C(neL) = neL P(neL) = neR CP Violating Process: For example: in vacuum

12. The Physics of Neutrinos CP Violating Processesin the Lepton Sector Why is this interesting/fun/exciting? A possible explanation for Baryogenesis. (So far CP violating processes in the b quark sector are insufficient to explain baryogenesis) A SCENARIO Heavy Neutral Leptons: Majorana neutrinos through see-saw mechanism produces a light neutrino pair and a heavy neutrino pair. N e- H+ or e+ H- (both massless particles because this is occuring before EW symmetry breaking).

13. N e- H+ or e+ H- The Physics of Neutrinos CP Violating processes provides excess of e+,m+,t+ over e-,m-,t- before EW phase transition. Andrei Sakharov says we also need non-equilibrium conditions so that these processes are not driven to equalize the numbers. Standard Model nonperturbative processes violate B, L, but conserve B-L. Churns lepton+’s into baryon material. Thank you Boris Kayser

14. The Physics of Neutrinos CP Violation in the Lepton Sector What would this have to do with CP violating processes in the low mass neutrino sector? We don’t know, but certainly CP violation in leptons at low mass makes CP violation in leptonic interactions at high mass scales more plausible. GUTs: one can also imagine unifying quarks and lepton such that their CKM matrices are also related. We won’t understand this until all the parameters are measured.

15. Neutrino Factory • High intensity beam on target to produce particles (p’s) for a secondary beam. - Proton Driver + Target • Collects p’s, allow them to decay into muons, spread bunch (large DE) and then perform phase rotation – Drifts + Induction Linacs • Reduce energy (and emittance) between induction linacs – Minicooling • Adiabatically change from one lattice to the next lattice – Matching Sections • Divide long bunch (~100 m) into short bunches that cooling section can handle - Buncher

16. Neutrino Factory 6. Reduce beam emittance – Cooling Channels 7. Accelerate to energy and emittance size that the next recirculating accelerators can handle - Linac • Accelerate from 2.8 GeV to 20 GeV – Recirculating Linear Accelerators (RLA’s) • Circulate muons and let some decay on production straight – Muon Storage Ring • Make measurements on neutrino interactions – Near and Far Detectors

18. Neutrino Factory: Proton Driver • Based on Feasibility Study 2 version of a neutrino factory…hence set at Brookhaven Natl Lab • AGS proton driver uses existing ring, bypasses existing booster and introduces 3 new superconducting linacs.

19. Neutrino Factory: AGS Proton Driver Parameters

20. High Intensity Source plus RFQ To target station 116 MeV Drift Tube Linac (first sections of 200 MeV Linac) Booster 400 MeV Superconducting Linacs AGS 1.2 GeV 24 GeV 0.4 s cycle time (2.5 Hz) 6 bunches 800 MeV 1.2 GeV AGS Proton Driver Layout

21. Cryo-Modules Insertion at room temp cavity C D A B Topology of a Period A B cavity D C Neutrino Factory: Superconducting Linacs Period Configuration of the cavities within the cryo-modules

22. AGS Injection Parameters

23. AGS : Harmonic 24 18 bunches AGS Proton Driver Bunch pattern for using harmonic 24 to create 6 bunches

24. Neutrino Factory : Target Energy on target 24 GeV, baseline beam power 1 MW, Pion momentum distribution peaks at 250 MeV, <pT> = 150 MeV  large angles coming off target…. Capture with 20 Tesla solenoid (r = 7.5cm, pTmax= 225 MeV). Actually a horn which “tapers” to 1.25 T (r= 30cm, pTmax= 67.5 MeV) (A horn converts transverse momentum into longitudinal momentum.) Target: High Z  maximize yield of p/p Goal of 2 1020 muon per year (107 seconds) decaying in detector direction, 50 kT, 1800 km away.

25. Neutrino Factory : Target Z

26. Neutrino Factory : Target • Liquid Hg jet target chosen for maximum yield. • Need to handle 1 – 4 MW beams. • Want vjet= 30m/s to resupply Hg. Tests achieved 2.5 m/s to date. ( 30m/s only resupplies mercury before next bunch on average – 6 x 2.5 Hz = 15/sec )

27. Target R&D for MW-Scale Proton Beams 27 • Carbon Target tested at AGS (24 GeV, 5E12 ppp, 100ns) • Probably OK for 1.5 MW beam … limitation: target evaporation • Target ideas for 4 MW: Water cooled Ta Spheres (P. Sievers), rotating band (B. King), conducting target, Front-runner = Hg jet • CERN/Grenoble Liquid Hg jet tests in 13 T solenoid • Field damps surface tension waves • BNL E951: Hg Jet in AGS beam • Jet (2.5 m/s) quickly re-establishes itself. Will test in 20T solenoid in future. 0 Tesla 13 Tesla t = 0 0.75 ms 2 ms 7 ms 18 ms

28. Neutrino Factory : Drifts and Induction Linacs • Beam has large energy spread. • Drift allows beam to spread out to a long bunch length. • Induction linacs accerlate late muons (lower energy) and decelerate early muons (higher energy).

29. Neutrino Factory : Drifts and Induction Linacs

30. Neutrino Factory : Drifts and Induction Linacs

31. Neutrino Factory : Drifts and Induction Linacs

32. Neutrino Factory : Drifts and Induction Linacs

34. Neutrino Factory : Drifts and Induction Linacs

35. Neutrino Factory : Minicooling inDrifts and Induction Linacs

36. Neutrino Factory : Buncher and Cooling Channel In order to fit muon beam into cooling lattice the Buncher separates the ~100m long trail of muons into rf buckets. The cooling channel (Pnominal = 200 MeV) then reduces the transverse emittance to a level acceptable for acceleration to 20 GeV.

37. Momentum-time distributions through the buncher

38. Neutrino Factory : Buncher and Cooling Channel

39. Momentum-time distributions through the buncher

41. Neutrino Factory : Cooling Channel Lattice Cell

42. Neutrino Factory : Cooling Channel

43. Neutrino Factory : Cooling Channel

44. Neutrino Factory : Cooling Channel

45. Neutrino Factory : Cooling Channel

46. Neutrino Factory : Cooling Channel

47. Neutrino Factory : Cooling Channel

48. Neutrino Factory : Cooling Channel

49. Absorber : Forced Flow Design

50. Approximate Equation Transverse Emittance in a step ds along the particle’s orbit: First term is the Ionization Energy Loss (Cooling) Term Second term is the Multiple Scattering (Heating) term