Futuri progetti agli acceleratori IFAE Lecce 24/4/2003 Prospettive sulle oscillazioni di neutrino Fasci convenzionali di neutrino Nuovi fasci di neutrino: beta beams, superbeams, neutrino factories R&D verso una neutrino factory Conclusioni M. Bonesini Sezione INFN Milano 1
1. 3-Generation Neutrino Oscillation Formalism For 3-generations: ν e, ν µ, and ν τ (and maybe even more... the sterile neutrino ν s s ) νe ν µ ντ = s 12 s s 12 23 c c 23 12 c c c 12 13 c 12 23 s 23 13 iδ 13e s s c 12 c c 12 23 s 23 s 12 s c 12 s 13 s 12 23 c s 23 13 s e 13 iδ e iδ s 13 s c e 23 23 iδ c c 13 13 ν1 ν 2 ν 3 CKM-like Mixing Matrix for Leptons Present limit from CHOOZ : sin 2 2θ 13 < 0.1. Both solar and atmospheric results are compatible with θ 13 =0. Solar + atmospheric neutrinos favour a near bi-maximal mixing matrix (very different from CKM matrix). Θ 13 drives ν µ > ν e subleading transitions -> the necessary milestone for CP violation search,... M Bonesini - INFN Milano 2
A Crystal Ball View Near-term long-baseline experiments focused on dominant ν µ ν τ channel Expect ~few percent measurements Possible direct observation of ν τ appearance Limited sensitivity to sin 2 2θ 13 Mini-BOONE will test LSND Precision mixing measurements imperative if confirmed M Bonesini - INFN Milano 3
Next Generation Goals Precision measurement of dominant oscillation ν µ ν τ channel Determine sign of m 23 2 Sensitivity to sub-dominant ν µ ν e channel at 1 level Sensitivity to δ CP Probably a phase 2 goal, after θ 13 M Bonesini - INFN Milano 4
NOW K2K-II νµ disappearance HARP KamLand MiniBooNE Roadmap 2005 2010 JHFν Θ13 down to 1 o MICE νf R&D CNGS NuMI? Off-Axis Θ13 m 2 12,θ 12 at 2% τ appearance NC/CC LSND? 2015? νfactory CP violation From L. Ludovici with some editing 2020 M Bonesini - INFN Milano 5
2. Conventional ν µ beams (from π decay) Primary protons hit target π + produced at 1 to 100 milli-radian angles magnetic horn to focus π + π + decay to µ + ν in long decay pipe left-over hadrons shower in hadron absorber rock shield ranges out µ + ν beam travels through earth to experiment p Target π + Decay Pipe Hadron Absorb. µ + Rock ν Exp. Horns M Bonesini - INFN Milano 6
ν beams: conventional and nufact beams Wanf Nufact Problem in conventional beams: a lot of minority components Following the studies for the muon collider, accelerated muons are ALSO an intense source of high energy neutrinos (µ + > e + ν e ν µ, µ >eν e ν µ ). Crucial features high intensity (x 100 conventional beams known beam composition (50% ν µ 50% ν e ) Possibility to have an intense ν e beam Essential detector capabilities: detect muons and determine their sign 7
Big problem in conventional ν beams experiments: beam understanding Use standard MC simulation : Geant, Fluka, Mars to full simulate target production +beamline (SLOW) Use dedicated parametrizations for secondary production in target ( Sanford-Wang, Malensek, BMPT... based on available data (Na56/SPY,...) + simulation of beamline (FAST) Minority components -> needs better knowledge of secondary production in target. More data needed on hadroproduction M Bonesini - INFN Milano 8
3. Neutrino Factories The ultimate tool for probing neutrino oscillation, based on muon decays (NOT π DECAY!!!) Enormous luminosity Exceptional purity Perfect knowledge of spectrum Flavor of initial neutrino tagged by charge Caveats: Technical challenges to muon acceleration Cost Proton drivers Targetry Particle production measurements RF manipulation Cooling Muon acceleration M Bonesini - INFN Milano 9
10 16 p/s µ + e + + ν µ +ν e 0.9 10 21 µ/yr 3 10 20 ν e /yr 3 10 20 ν µ /yr ν µ µ + Oscillate ν µ µ Wrong Sign muons M Bonesini - INFN Milano 10
Advantages of Muon Storage Ring Both ν e and ν µ species in beam: A way to get well understood, highintensity source of ν e s ν e ν τ or ν e ν µ High intensity allows: Probe small mixing angles Long distances Start to see earth matter effects for oscillations involving ν e s Reach solar neutrino region with acc beams 11
Comparison with Conventional ν Beam M Bonesini - INFN Milano 12
ν - Factory Beam and Detector Parameters High Rate Beam: 10 20-10 21 muon decays /yr ν rates higher than conventional beams for E storage > ~20 GeV Rate in detector E 3 High storage ring energy ~ 50 GeV Detector: Large: 10 kton Need at least µ ± id. (with beam flavor constraints). Better to also have e ± and τ ± identification ν events/gev for various µ beam energies 20 GeV 35 GeV 50 GeV M Bonesini - INFN Milano 13
Sensitivity of Nufact M Bonesini - INFN Milano 14
4. Conventional superbeams Exploit extremely intense proton sources to produce beam from π-decay Intermediate step to neutrino factory π beam necessary for µ beam Sensitivity intermediate between near-term experiments and neutrino factory Cost also intermediate Technical hill less steep to climb Proton drivers essentially designed (or existing) Radiation damage near target station may be important M Bonesini - INFN Milano 15
Possible Future Proton Drivers Source Place Proton Energy (GeV) Power (MW) Upgr. Booster FNAL 16 1? Upgr. NUMI FNAL 120 1.6 50 GeV PS JHF 50 0.77 ( 4) SPL CERN 2.2 4 M Bonesini - INFN Milano 16
CERN/SPL Proposed: Recycle LEP RF cavities into proton linac Proton kinetic energy: 2.2 GeV Power: 4 MW Protons/s=10 16 Outlook: Feasibility study M Bonesini - INFN Milano 17
SPL Neutrino Beam Liquid Hg jet target 20 m decay tunnel Kaon production negligible Few ν e content E ν ~ 250 MeV M Bonesini - INFN Milano 18
JHF 50 GeV PS at Jaeri Approved: 50 GeV PS -0.77 MW Proposed: Neutrino beamline to Kamioka (off-axis 295 km) Upgrade to 4 MW Outlook: Completion of PS in 2006/2007 M Bonesini - INFN Milano 19
JHF Neutrino Beams Wide-band beam Horn-focusing only Long high-energy tail Narrow-band beam Pions momentumselected with dipole Lower intensity Off-axis beam Intense, narrow Less tail than WBB 0.2% ν e around peak energy M Bonesini - INFN Milano 20
5. A roadmap to the neutrino factory Study to optimize target : HARP experiment at CERN Study to demonstrate the operation of a full size section of a cooling section: MICE experiment at RAL NUFACT ECFA WG to study neutrino factory and superbeam physics +. Cerenkov Tof Tpc A Layout of the Harp experiment spectrometer 21
Targetry Many difficulties: enormous power density pion capture Replace target between bunches: Liquid mercury jet or rotating solid target Stationary target: Proposed rotating tantalum target ring Sievers Densham 22
Harp at the Cern PS 2-24 GeV/c incident p beam on nuclear targets (Be, C,Al, Cu, Sn, Ta, Pb,... + Miniboone & K2K replica) Full solid angle acceptance PID for π/p separation Aims: cross sections at a 2% precision Data taking 2001-2002 about 71 * 10 6 triggers M Bonesini - INFN Milano 23
Harp experiment aims HARP (Hadron Production Experiment at the PS) designed to measure with few % accuracy cross sections for hadron production of protons (2 to 15 GeV/c) on various elements necessary to calibrate Monte Carlo simulations for: the design of a nu-factory the mastering of existing nu-beams the interpretation of atmospheric nu-oscillation experiments HARP was designed, built and assembled in 17 months! M Bonesini - INFN Milano 24
HARP schematic layout Tof with RPC HARP consists of a barrel spectrometer (TPC) and of a forward spectrometer (NDC) to cover the full solid angle, complemented by particle-id detectors Ckov ToF e-id Ckov beam TPC Forward spectrometer Tof MWPC Target M Bonesini - INFN Milano 25
Cooling: the problem (transverse phase space) Problem: µ Beam pipe radius of storage ring P or x and x reduction needed: COOLING Accelerator acceptance R 10 cm, x 0.05 rad Accelerato rescaled @ 200 MeV π and µ after focusing M Bonesini - INFN Milano 26
Ionization Cooling : the principle Liquid H 2 : de/dx sol IN Beam H 2 sol rf RF restores only P // : E constant OUT M Bonesini - INFN Milano 27
MICE: Muon Ionisation Cooling Experiment Proposal submitted to RAL SC Solenoids; Spectrometer, focus pair, compensation coil Liquid H2 absorbers or LiH? T.O.F. I & II Pion /muon ID precise timing 201 MHz RF cavities Tracking devices: He filled TPC-GEM (similar to TESLA R&D) T.O.F. III and/or sci-fi Precise timing Measurement of momentum, angles and position Electron ID Eliminate muons that decay M Bonesini - INFN Milano 28
Possible locations around Europe for FAR detector 3500 km 732 km 3500 km M Bonesini - INFN Milano 29
Detector (one option) Magnetized iron calorimeter Charge discrimination B = 1 T R = 10 m, L = 20 m Fiducial mass = 40 kt Baseline 732 Km 3.5 x 10 7 3500 Km ν µ CC ν e CC ν µ signal 1.2 x 10 6 2.4 x 10 6 1.0 x 10 5 5.9 x 107 1.1 x 105 Events for 1 year M Bonesini - INFN Milano 30
A Simple Neutrino Factory Detector (another option US MUCOL collab) Iron sampling calorimeter ~50 kton (10X the fiducial mass of MINOS), with extruded scintillator (R&D effort at Fermilab). This implies R&D on scintillators, that is a detector technology of general interest (calorimetry, TOF, fiber tracker, ). It can be applied also outside the realm of v physics, not the case with Lar TPC or water Cerenkov Suited to θ 13 exploration at large L and E, and sign( m 2 23) M Bonesini - INFN Milano 31
6. The BETA-BEAM 1. Produce a radioactive ion with a short beta-decay lifetime 2. Accelerate the ion in a conventional way (PS) to high energy 3. Store the ion in a decay ring with straight sections. 4. By its β decay, ν e (ν e ) will be produced. Muons: γ~500 E cms ~34 MeV QF~15 - SINGLE flavour (ν e ) - Known spectrum/intensity - Focussed (1/γ) - Low energy (E ν = 580 Mev) 6 He Beta-: γ~150 E cms ~1.9 MeV QF~79 18 Ne Beta+: γ~250 E cms ~1.86 MeV QF~135 The quality factor QF=γ/E cms (N int α γ/ E cms ) is bigger than in a conventional neutrino factory. In addition, ion production and collection is easier. Then, 500000X more time to accelerate. M Bonesini - INFN Milano 32
CERN baseline scenario Decay ring SPL Bρ = 1500 Tm B = 5 T L ss = 2500 m ISOL target SPS Decay Ring ACCUMULATOR PS Studies are made on EXISTING CERN machines. Why? Much more detailed knowledge exists, the best way to identify possible problems and limitations. M Bonesini - INFN Milano 33
Possible β - emitters (ν e ) Isotope Z A A/Z T 1/2 Q β (gs>gs) Q β eff. E β av. E ν av. <E_LAB> ( MeV) s MeV MeV MeV MeV (@ 450 GeV/p) 6He 2 6 3.0 0.807 3.5 3.5 1.57 1.94 582 8He 2 8 4.0 0.119 10.7 9.1 4.35 4.80 1079 8Li 3 8 2.7 0.838 16.0 13.0 6.24 6.72 2268 9Li 3 9 3.0 0.178 13.6 11.9 5.73 6.20 1860 11Be 4 11 2.8 13.81 11.5 9.8 4.65 5.11 1671 15C 6 15 2.5 2.449 9.8 6.4 2.87 3.55 1279 16C 6 16 2.7 0.747 8.0 4.5 2.05 2.46 830 16N 7 16 2.3 7.13 10.4 5.9 4.59 1.33 525 17N 7 17 2.4 4.173 8.7 3.8 1.71 2.10 779 18N 7 18 2.6 0.624 13.9 8.0 5.33 2.67 933 23Ne 10 23 2.3 37.24 4.4 4.2 1.90 2.31 904 25Ne 10 25 2.5 0.602 7.3 6.9 3.18 3.73 1344 25Na 11 25 2.3 59.1 3.8 3.4 1.51 1.90 750 26Na 11 26 2.4 1.072 9.3 7.2 3.34 3.81 1450 M Bonesini - INFN Milano 34
Anti-Neutrino Source Consider 6 He ++ 6 Li +++ ν e e - E 0 3.5078 MeV T/2 0.8067 s 1. The ion is spinless, and therefore decays at rest are isotropic. 2. It can be produced at high rates, i.e. 5E13 6 He/s 3. The neutrino spectrum is known on the basis of the electron spectrum. DATA and theory: <Ekine>=1.578 MeV <Eν>=1.937 MeV RMS/<Eν>=37% B.M. Rustand and S.L. Ruby, Phys.Rev. 97 (1955) 991 B.W. Ridley Nucl.Phys. 25 (1961) 483 M Bonesini - INFN Milano 35
Some experimental considerations The neutrino energy is controlled by the Lorentz boost γ of the parent ion Only possible backgrounds are: Detector backgrounds: single pions from NC and electrons misid as µ Atmospheric neutrinos M Bonesini - INFN Milano 36
Physics reach of beta beams etc (M. Mezzetto, NNN02) δ = 90 deg 99%C.L. Curves M Bonesini - INFN Milano 37
Nu2002 comparison chart F. Dydak 0.2-2 GeV ~10-4 ~1 YesYes Let s Fill the BB column! M Bonesini - INFN Milano 38
Conclusioni La fisica delle oscillazioni di ν e l item di punta di HEP, oltre alla ricerca dell Higgs ai collider adronici I futuri sviluppi in questo campo sono dominati dallo sviluppo di nuovi fasci di neutrino (nu-fact, superbeams,...) per cui si ha un attivo programma di R&D in Europa, negli US ed in Giappone M Bonesini - INFN Milano 39