SPL, Beta beams and the Neutrino Factory. Leslie Camilleri NuSAG 20th May 2006

What’s needed next?  Determine  13. Plans for several experiments using reactors, accelerators, etc…  Determine the mass hierarchy. Some of these experiments, specially if extended through the use of upgraded accelerators, would address this.  Any CP violation in the neutrino sector? A new neutrino facility (a neutrino factory or a beta-beam complex) would be the only sure way to address this problem.

Acknowledgments Beta Beams: Mats Lindroos, Mauro Mezzetto, J-E. Campagne. Neutrino Factories. Alain Blondel, Talks based on April 2006 International Scoping Study meeting at RAL. Presentations by:  Bob Palmer on machine  Paul Soler on Detectors  Yori Nagashima on Physics Roland Garoby and his team

European efforts on Future Neutrino Facilities  Superconducting Proton Linac (SPL).  Beta-beams. Conceptual design for a Nuclear Physics facility (ISOLDE type): Eurisol financed by European Union. Includes beta-beam studies. Synergy with beta-beams (radioactive ions): Proton driver, high power targets, beam cleaning ionization and bunching First stage acceleration, radiation issues. Will it be at CERN ? Decision in  Neutrino Factory The ultimate. Study under way through the International Scoping Study.  R&D on targets (MERIT) and muon cooling (MICE).

PSB SPL’ RCPSB SPS SPS+ Linac4 SPL PS LHC DLHC Output energy 160 MeV 1.4 GeV ~ 5 GeV 26 GeV 40 – 60 GeV 450 GeV 1 TeV 7 TeV ~ 14 TeV Linac2 50 MeV SPL: Superconducting Proton Linac (~ 5 GeV) SPL’: RCPSB injector (0.16 to GeV) RCPSB: Rapid Cycling PSB (0.4-1 to ~ 5 GeV) PS2: High Energy PS (~ 5 to 50 GeV – 0.3 Hz) PS2+: Superconducting PS (~ 5 to 50 GeV – 0.3 Hz) SPS+: Superconducting SPS (50 to1000 GeV) DLHC: “Double energy” LHC (1 to ~14 TeV) Proton flux / Beam power Evolution of the CERN accelerator complex: - Proposed combinations PS2 (PS2+) Priorities will be driven by LHC upgrade: *1,*2,*3,*4 *1 *2 *3 *4

Superconducting Proton Linac  Power : 4 MW  Kin. Ener. : Up to 5 GeV. More  ’s.  Repetition Rate: 50 Hz  Accumulator to shorten pulse length. (Reduce atmospheric ’s contam.)  Target: Liquid Mercury Jet to cope with stress due to high flux.  Focusing: Horn and Reflector optimized for 600 MeV/c particles  Detector: New lab in Frejus tunnel  (Safety gallery approved April 2006: opportunity)  Distance: 130km  Neutrino energy to be at oscillation maximum for  m 23 2 = 2.5 x eV MeV  350 MeV more sensitive  Detector mass: 440 kton fiducial.  Type: Water Cerenkov (Super-K)

MEMPHYS at Fréjus Up to 5 shafts possible Each 57m diam., 57m high For most studies assumed 3 x 145 ktons. Water Cerenkov Per shaft: 81,000 12” PMT’s  80 M€ including electronics (65M$ KL 62M$ ) +80 M€ for civil engineering. (65M$ KL 29M$ ) Depth: 4800 m.w.e FOR 100 ktons)

Advantage of mixing neutrino and antineutrino running 3.5 and 4.5 GeV proton beam 260 and 350 MeV options 5 years of running. 2 years of running and 8 years of running The curves flatten.  about

Beta beams Idea introduced by Piero Zucchelli. Accelerate radioactive ions decaying via  + or  -. Because of Lorentz boost, the decay electron neutrinos or antineutrinos will be focused forward into a beam. Look for: Appearance of  or  Advantages: “Clean” beams with no intrinsic  component. No need for magnet. Precisely calculable energy spectra. Energy of beam tunable through acceleration of ions.  Accelerate protons in SPL  Impinge on appropriate source  Bunch resulting ions(atmospheric ’s !)  Accelerate ions in PS and SPS.  Store in decay ring. 8 bunches.  6 He 6 Li + e - + e 18 Ne 18 F + e + + e Half lives: 0.8 sec and 0.64 sec. Stored together if  ( 18 Ne) = 1.67  ( 6 He) E  eV) x  200 – 500 MeV Detector: Same as for SPL (Frejus) Very attractive because:  Eurisol radioactive beam project for nuclear physics possibly at CERN..  PS and SPS exist.

6 He production by 9 Be(n,  ) need 100μA at 2.0 GeV for needed beta-beam flux Converter technology: J. Nolen et al., NPA 701 (2002) 312c. For 18 Ne: Proton beam into Magnesium oxide: Produce 18 Ne directly by spallation Source must be hot for 18 Ne to diffuse out. Cannot cool it. Limits beam and rate.

Production ring with ionization cooling Production Major challenge for 18 Ne But new production method: C. Rubbia et al. D2D2  D 2 gas jet in storage ring.  Inject ions ( 19 F) and store  Go through jet repeatedly increases probability to form radioactive ions  Regain energy loss with RF  High energy ions have smaller dE/dx than low energy ones. But will gain same amount from RF  even more energy  To compensate shape jet (fan) such that high energy ions (larger radius) traverse more material.   Longitudinal cooling. High E Low E

 sensitivity for  = 60,100 Statistics limited CP violation Asymmetry decreases with increasing    2% Syst. Unc. 2.9 x He ions and 1.2 x Ne ions per year decaying in straight sections M. Mezzetto SPSC Villars Down to 30 o E = (3 MeV) x  = 200 – 500 MeV

Optimization of  J. Burguet-Castell, hep/ph/ and M. Mezetto. Not necessary to store the 2 ion types simultaneously: 4 bunches each. Store 8 bunches of given type at a time and run each type half as long as in joint run. Frees from  ( 18 Ne) = 1.67  ( 6 He) constraint. Different schemes tried, all leading to higher energies. This is profitable because:  Higher event rates because of larger cross sections.  Better directionality: lower atmospheric background.  Signal events are in a region of lower atmospheric rate.  Fermi motion relatively less of a problem: better correlation between reconstructed and actual neutrino energy.  Can analyze energy dependence of appearance events instead of just counting them.

Fix baseline at Frejus 99% CL on  improves from > 30 o to > 15 o for a symmetric  scheme. The  13 sensitivity improves a little.  60,100 scheme 30 o 15 0  = 100  13 = 8 o  = 90 o  

Fix  at maximum SPS value: 150. For this  the optimum distance is 300 km The 99% CL  reach can be improved from 15 o to 10 o. and the  13 sensitivity can also be improved substantially But no existing laboratory at this distance! 300 km       60, km 150, km  sin 2 2  13 L(L( L(km)

Optimize for Gran Sasso  Optimize  for the a detector at the Gran Sasso (730km).     Needs new SPS. Frejus Standard 300 km Gran Sasso 350, km

SPL, Beta-beam (  =100), T2HK comparisons Mass: Each detector: 440 ktons, Running time: SPL and T2HK: 2 yrs + 8 yrs . Beta-beam: 5 yrs + 5 yrs. Systematics: 2% - 5%. 3  discovery potential on sin 2 2  13 3  discovery potential on CP viol. (Excluding  2% 5% J-E. Campagne et al hep/ph v1

Invoking CPT P( e   ) = P(   e ) Replace beta beam e by SPL  Run simultaneously for A total of 5 yrs only. Comparable to T2HK 10 yrs.  discovery

Mass Hierarchy Use atmospheric neutrinos (ATM) observed in MEMPHYS, in conjunction with SPL, beta and T2HK beams. Makes up for small matter effects due to short baseline With ATM

Systematic uncertainties Must be kept at the 2% level Most important ones:  Target mass difference between near and far detectors.  Uncertainty on  and cross sections (will be measured by near detector ?)

Uncertainty on cross-sections. Targets: free nucleons and water ??? Below 250 MeV: Very uncertain At 250 MeV: Double ratio ~ 0.9 Nuclear effects ~ 5% How well do we know these?

New idea: Electron capture in 150 Dy Partly stripped ions: The loss due to stripping smaller than 5% per minute in the decay ring Possible to produce Dy atoms/second (1+) with 50 microAmps proton beam with existing technology (TRIUMF). Problem: long lived 7 minutes. An annual rate of decays along one straight section seems a challenging target value for a design study Beyond EURISOL Design Study: Who will do the design? Is 150 Dy the best isotope? Atomic electron captured by proton in nucleus (A,Z) + e -  (A,Z-1) + e For instance: Dysprosium. Advantage: monochromatic e  beam J. Bernabeu et al hep-ph/

Potential of electron capture beams CP dependence of   e oscillation probability Run 5 years each at  =90 and  = ktons at Fréjus 5 test points  90  0  MeV

A possible schedule for a European Lab. at Frejus Year Safety tunnel Excavation Lab cavity Excavation P.S Study detector PM R&DPMT production Det.preparation InstallationOutside lab. Non-acc.physics P-decay, SN Superbeam Construction Superbeam betabeam Beta beam Construction decision for cavity digging decision for SPL construction decision for EURISOL site 

Mandate of the International Scoping Study The International  Scoping Study of a future accelerator neutrino complex will be carried by the international community between NuFact05, Frascati, June 2005, and NuFact06, August The physics case for the facility will be evaluated and options for the accelerator complex and neutrino detection systems will be studied. Its reach and feasibility will be compared to the Beta-beam and SPL options. The principal objective of the study will be to lay the foundations for a full conceptual-design study of the facility. Neutrino Factory Being studied in the context of the International Scoping Study

WHO ? International effort:  The ECFA/BENE network in Europe.  The Japanese NuFact-J collaboration.  The US Muon Collider and Neutrino Factory Collaboration.  The UK Neutrino Factory collaboration. CCLRC's Rutherford Appleton Laboratory will be the 'host laboratory' for the Study. (The effort was initiated by the UK).

Simplified Neutrino Factory Proton accelerator Muon accelerator Muon-to-neutrino decay ring Earth’s interior Detector Ion source Pion production target Pion to muon decay and beam cooling   p  s  s =  yr 9 x  yr    e + e   3 x e  yr 3 x   yr per straight section

Principle of detection    e +   e oscillates e     interacts giving    WRONG SIGN MUON interacts giving   Need to measure  charge  Magnetic detector Look for e     oscillations using e from  decay (Golden channel) 2 baselines or 2 energies to resolve ambiguities Other channels:  Platinum channel:    e  T violation   Silver channel: e   Resolve ambiguities.

Triangle or Race-track? Or else too many decays In 3 rd “useless” leg. Minimum length of 3 rd leg for given angle is when ring is vertical ~ 400m. Limited by geology If two far sites needed

Decisions taken at April ISS meeting Allows simultaneous collection of  + and  -. instead of horn instead of solid (  + +  - ) decays per year Half per straight section

Knowledge of Matter density along path 2500 km Lithosphere: solid,heterogeneous asthenosphere: Viscous, homogeneous Oceans: simpler, more accurate. Continents: more complicated, less accurate. “Best” 2  errors 1.5-3% Avoid: Alps, Central Europe Favour:Western Europe to US Atlantic Islands

Usefulness of the silver channel: e   S. Rigolin, hep-ph/ D. Autiero et al. hep-ph/ km and 730km e      and  e      Clones at 2 baselines are at different positions Clones for 2 reactions are also at different positions. Fine grained detector for  secondary vertex or kink: OPERA technology Alternative to 2 baselines? e      and  e      channels have “opposite” sign CP violation.

Detectors  Magnetized iron/scintillator.  Fully active scintillator + External magnetic field.  Water Cerenkov  Liquid argon in solenoidal field.  Hybrid emulsion detector in a magnetic field (Electron charge).  Near Detectors.

A Strawman Concept for a Nufact Iron Tracker Detector 1 cm Iron sheets Planes of triangular 4cm x 6 cm PVC tubes. Filled with liquid scintillator Read by looped WLS fibres Connected to APD’s. 60kA-turn central coil –0.5m x 0.5m –Average field of 1.5T –Extrapolation of MINOS –Structure based on NOvA using MINERvA-like shapes –Based on 175M$ for 90kt

 turns 10 solenoids next to each other. Horizontal field perpendicular to beam Each: 750 turns, 4500 amps, 0.2 Tesla. 42 MJoules. 5Meuros. Total: 420 MJoules (CMS: 2700 MJoules) Coil: Aluminium (Alain: LN2 cooled). Problem: Periodic coil material every 15m: Increase length of solenoid along beam?  How thick? NO A divided longitudinally into 10 sections Each section surrounded by low field solenoid. Fully active detector (NO A) with external magnetic field

Giant Liquid Argon Charge Imaging Experiment A. Rubbia Impression was that magnet limited detector mass to 15 ktons. US-Europe Synergy ?

Pb Emulsion layers  1 mm Stainless steel or Lead Film Air Gap DONUT/OPERA type target + Emulsion spectrometer B ~ 3Xo ~10Xo Can measure momentum of muons and of some fraction of electrons  dentify  using  topology Must be placed in a magnet

Comparison of beta-beam and factory Beta-beam advantages.  Synergy with Eurisol (if at CERN) + existing PS,SPS  Cost ?  Clean e and e beams: no need for magnet.  Negligible matter effects. (But hierarchy?)  Does not need 4 MW of power. (But if SPL is needed for better sensitivity…?) Beta-beam disadvantages  Low energy: Cross sections not so well known, muon mass effect Fermi motion Atmospheric neutrinos background  Silver channel energetically impossible  Need of SPL: Improve sensitivity Measure cross-sections

Comparison of beta-beam and factory II Advantages of Neutrino Factory  Ultimate reach  Smaller systematic errors  Presence of both  and e in beam allows measurement of cross-sections in near detector  Higher energies: better measured cross sections. Disadvantages of Neutrino Factory.  Technically more challenging  Cost  Deeper tunnel limits sites.  Matter effects must be well understood. Baselines carefully chosen.  Need for a magnetic detector to separate signal from background

Reach of beta-beams and  Factory About the same for other 4 quadrants of CP phase. Beta-beams and beta-beams + SPL Are better for sin 2 2  13 > (needs confirmation: cuts used in analysis E  > 5 GeV) Below this value factory is more sensitive.

MERIT: Hg jet target tests at CERN PS Test performed in magnetic field (15T) To simulate actual conditions:  collection solenoid Proton intensity: 2 x protons/pulse at 24 GeV 1cm diameter jet at small angle(40 mrad) to beam to maximize overlap: 2 inter. lengths. Aims: Proof of principle. Jet dispersal. Effect of field on jet flow and dispersal. Scheduled to run in Spring 2007

MICE: Muon cooling experiment at RAL Prove the feasibility of ionization cooling. Strong synergy with MUCOOL.

MICE: planning

Problems: a personal view. CERN: The priority will be given to a) Consolidation of existing machines. b) LHC luminosity upgrades, including whatever replacement machines it takes, including Nb 3 Sn IR quads. c) Possibly an energy upgrade of LHC. Nb 3 Sn dipoles ? d) Ongoing CLIC R&D. Internationally: a) ILC schedule, cost and site. b) Difficult to conceive the next big  project going ahead without having already measured  13. When will this be?

Time line 2010: A critical year in many ways. Possible ILC decision. CLIC possibilities. LHC results. Decision on LHC upgrade. Eurisol siting. CERN ? Possible first measurement of  13 : MINOS, Double CHOOZ

    l l-l- l+l+  Muons of both signs circulate in opposite directions in the same ring. The two straight sections point to the same far detector(s). OK Storing of both charges at once Discriminate events On the basis of timing (  ) Detector

Some decisions taken at April ISS meeting

Sign of  m 23 2 resolution with  beams At Frejus baseline there is NO sensitivity to the sign of the mass hierarchy. At 300 km there is some. But, clearly, the longer baseline (Gran Sasso) would be needed to make a significant statement.  m 23 2 > 0  m 23 2 