Neutrino Physics & the ISS Peter Dornan Imperial College London

16 March 2006P Dornan - MUTAC Why do Neutrino Physics? Least understood particle Beyond the Standard Model  A trivial Addition?  The Window on the Fundamental Theory? Ultimate theory must relate quarks & leptons  Cannot do this without a full understanding of the neutrino sector  Cannot do this with LHC or ILC

16 March 2006P Dornan - MUTAC Neutrinos are BSM In the SM  Neutrinos are massless  Lepton Flavour is Conserved  Neutrino & antineutrino distinguished on the basis of helicity Neutrino Oscillation shows  Neutrinos have mass  Lepton Flavour is not Conserved  Helicity cannot distinguish neutrinos from antineutrinos

16 March 2006P Dornan - MUTAC A Minor Extension of the SM? Neutrinos are Dirac Particles Right handed Neutrinos exist  With no known interactions Or very very weak ones Lepton Flavour is not respected But overall lepton number is conserved So Distinguish Neutrino and Antineutrino on the basis of Lepton Number  - whatever it is Masses, Mixing Parameters - and CP Violation  - just yet more parameters to feed into the theory

16 March 2006P Dornan - MUTAC A Window on a Higher Theory? now we can speculate Neutrinos are Majorana States  Neutrino and anti neutrino are not distinct  Right handed neutrinos exist at very high masses - ~ unification scale Mixing angles - and probably masses – could be related to those in the quark sector More forms of CP violation in the lepton area than the MNS phase  And this will solve the matter-antimatter mystery

16 March 2006P Dornan - MUTAC Why Neutrino Physics? These are the “Elevator” Answers  For the Ultimate Theory of Particles and Forces  For our Understanding of the Universe But Improving our Knowledge demands Complex & Challenging Experimentation. The basic tool is neutrino oscillation From Hitoshi Murayama When you meet your favourite senator And want a $1B But also to explain to immigration at O’Hare why you are coming to Fermilab

16 March 2006P Dornan - MUTAC Neutrino Oscillation  Neutrinos are produced - and detected - as lepton flavour - electron, muon, tau - eigenstates  Oscillations – neutrinos produced with one flavour change to another as they pass through space In the SM lepton flavour is conserved  - no oscillations For oscillation must have two sets of eigenstates – flavour e-states and mass e-states

16 March 2006P Dornan - MUTAC `atmospheric’`solar’ `cross/reactor’ Oscillation defined by 3 mixing angles,        phase  Oscillation Parametrisation

16 March 2006P Dornan - MUTAC Oscillation Probability For just two state system Depends upon Mixing Angle, Mass Squared Difference, L/E More Complex for a three state system and additional complications if neutrinos pass through matter

16 March 2006P Dornan - MUTAC Oscillation Signals - Disappearance  The early evidence Super-K Atmospheric results  disappearance having travelled through the earth SSM Prediction GalliumChlorine Deficits in Solar Neutrino Flux

16 March 2006P Dornan - MUTAC Appearance Signals - Atmospheric Super-K - L/E Analysis K2K First Long Baseline SK-I + SK+II Preliminary L/E (km/GeV) Data/prediction Oscillation No oscillation 1R-  spectrum E rec (GeV) 1234 Number of events

16 March 2006P Dornan - MUTAC Appearance Signals - Solar The SNO Result  Total Neutrino Flux as Expected Verifies Standard Solar Model  e Detected Flux Low Electron Neutrinos have oscillated to mu or tau neutrinos SSM Prediction Neutral Currents - Detects all Neutrinos Charged Current - Detects Electron Neutrinos

16 March 2006P Dornan - MUTAC Appearance Signals - Solar Kamland Reactor Experiment

16 March 2006P Dornan - MUTAC The Third Angle,  13 Small - only an upper limit from the Chooz Reactor Experiment Determining just how small  13 is the next pressing problem for neutrino oscillation physics

16 March 2006P Dornan - MUTAC Where are we? from: Maltoni, Schwetz, Tortola, Valle (’04) Also know m 2 > m 1 from matter effects in the sun

16 March 2006P Dornan - MUTAC How to Proceed? What Questions remain to be answered  Many! What must we measure?  Everything we can What can we measure?  Quite a lot With the right ingenuity - and investment

16 March 2006P Dornan - MUTAC Unanswered – Non Oscillation Expts Are Neutrinos Dirac or Majorana?  Neutrinoless double-beta decay What is the Absolute Mass?  Tritium Decay Spectrum  Neutrinoless double-beta decay  Cosmological data

16 March 2006P Dornan - MUTAC Unanswered – Oscillation Expts Is  23 maximal? How small is  13 ? CP Violation in the lepton sector? Mass hierarchy?  m 3 m 2 Is the MNS approach correct? CPT violation? The ultimate accuracy on the mixing angles and the mass differences  What accuracy is needed? (LSND? Sterile neutrino(s)? )

16 March 2006P Dornan - MUTAC Mass Hierarchy? Normal Inverted Require matter interactions to distinguish. Long Baseline No a > T2K Leads to degeneracies in superbeam expts. Critical for Neutrinoless double beta decay

16 March 2006P Dornan - MUTAC CP Violation  Vitally important for our understanding of nature and the universe  Arises from phases which flip sign on the change particle  antiparticle In SM Non-zero phase in the CKM quark mixing matrix  Describes observed CP violating effects  Does not explain the matter antimatter asymmetry  Standard MNS matrix has one phase, , (like CKM)  BUT, if neutrinos are Majorana additional phases and potential for substantial CP violation

16 March 2006P Dornan - MUTAC e Appearance in a  Beam - SuperBeam e Disappearance in a e Beam - Reactor  13 and  - Leptonic CP Violation  leads to CP Violation No  term

16 March 2006P Dornan - MUTAC The Imminent Future Two long base line experiments using a  beam MINOS  Numi Beam from FNAL to Soudan 735 km Two Detectors – near and far – magnetized Fe-scintillator Look for  disappearance   23,  m 2 23 e Appearance   13 (~factor 2 better than Chooz) OPERA  CNGS Beam from CERN to Gran Sasso 732 km One Far Detector – Emulsion Look for  Appearance

16 March 2006P Dornan - MUTAC In 3 – 10 Years -  13 Main aim is  13 - but will also improve other parameters Two off-axis Superbeam Experiments  T2K  No a One or more Reactor Experiments  Double Chooz and maybe Braidwood, Daya Bay, Angra dos Deis ……

16 March 2006P Dornan - MUTAC Possible Reactor Experiments ExperimentWhere Baseline (km) Overburden (m.w.e.) Detector size (t) sin 2 (2  13 ) Sensitivity (90% C.L.) NearFarNearFarNearFar Angra dos ReisBrazil < ~0.01 BraidwoodUS x2 <~0.01 Double ChoozFrance < ~0.03 Daya BayChina < ~0.01 Diablo CanyonUS < ~0.01 KASKAJapan < ~0.02 Kr2Det (Krasnoyarsk) Russia < ~0.03

16 March 2006P Dornan - MUTAC “near detector” “far detector Reactor Measurements of  13 No Dependence on , No matter effects

16 March 2006P Dornan - MUTAC MeV Linac 3GeV PS 50GeV PS (0.75MW) FD Neutrino Beam Line To SK Long baseline neutrino oscillation experiment from Tokai to Kamioka （ T2K ） J-PARC (50 GeV PS)  Construction: 2001~2007  Operation:2008~ T2K (Approved in Dec-03)  Construction:2004~2008  Experiment: 2009 ~ (60km N.E. of KEK) (~100xK2K) Super-K 50kton Phase 2  4MW, Mton, CPV Phase 1 (0.75MW + SK)    x disappearance  Precise  m 2, sin 2 2     e appearance  Finite  13 ?

16 March 2006P Dornan - MUTAC T2K prediction 90%C.L. sensitivities sin 2 2  13 CHOOZ excluded Off axis 2.5deg, 40GeV 5yr x 20  m 2 (eV 2 )  (  m 2 23 ) < 1×10 -4 eV 2  (sin 2 2  23 ) ~ 0.01 For 5yr running

16 March 2006P Dornan - MUTAC No a Upgrade of FNAL NuMi program. Off-axis configuration, and larger proton intensity (6.5x1020 proton/year). Very Long Baseline (810km) and sizeable matter effects Complementary to T2K program (mass hierarchy). ~ 2.22GeV 30Kton “fully” active detector. Liquid scintillator.

16 March 2006P Dornan - MUTAC No a Sensitivity similar to T2K. – improve with antineutrino run. ● Sensitivity to mass hierarchy. ● Synergies with T2K & reactor experiments: different matter effects and different degeneracies.

16 March 2006P Dornan - MUTAC The Precision Era - after T2K and Nova Around We shall have good measurements of   12,  23,  m 2 12,  m 2 23 Probably have a measurement of  13 Possibly know the mass hierarchy So can now plan for the ultimate neutrino measurements  Refine all parameters  Check consistency  Measure CP Violation This is the aim of the ISS

16 March 2006P Dornan - MUTAC CP Violation

16 March 2006P Dornan - MUTAC Neutrino source – options: Second generation super-beam  CERN, FNAL, BNL, J-PARC II Beta-beam Neutrino Factory

16 March 2006P Dornan - MUTAC The International Scoping Study  International scoping study of a future Neutrino Factory and super-beam facility Motivation Organisation Status  Physics Group  Accelerator Group  Detector Group ISS: next steps

16 March 2006P Dornan - MUTAC ISS: motivation Neutrino Factory – prior to launch of ISS  Several studies at the turn of the century US Studies I, II, IIa ECFA/CERN Study NuFact-J Study established feasibility & R&D programme  MUCOOL, MICE, MERIT…. But there have been advances since then Also appreciation of the need for an integrated accelerator-detector-physics approach  and an international approach

16 March 2006P Dornan - MUTAC ISS: motivation Goal: timely completion of conceptual design  Significant international effort taking several years Requires successful bids to provide the resources Preparation for design study  Review physics case  Critical comparison of options  Review options for accelerator complex: Prepare concept-development and hardware-R&D roadmaps for design-study phase  Review options for neutrino-detection systems Emphasis: identify concept-development and hardware-R&D roadmaps for design-study phase  Establish the Cost Drivers & Optimize Physics/$ - where there are alternatives Absolute scientific value - where only one method

16 March 2006P Dornan - MUTAC ISS: organisation

16 March 2006P Dornan - MUTAC Meetings Plenary meetings to date:  CERN: 22 – 24 September 2005 Attendance: 92 Americas: 15Asia: 12Europe 65  KEK: 23 – 26 January 2006 Attendance: 67 Americas: 11Asia: 28Europe 28 Working groups:  Physics: Workshops:Imperial: 14 – 21 November 2005 Boston 6 – 10 March 2006 Phone meetings  Accelerator: Workshops:BNL:07 – 12 December 2005 Phone meetings  Detector: Phone meetings Detector/Physics parallel at Physics workshops

16 March 2006P Dornan - MUTAC Acknowledgments This will be a very brief review of the activity in the ISS From the meetings - very many people have contributed so - it is hard to acknowledge everyone - so I apologise for failing to mention many of the contributors All plots and contributors can be found on the web

16 March 2006P Dornan - MUTAC Physics Group Theory subgroup :  What is the new physics  Need to distinguish between alternative theories  Establish the case for high-precision, high-sensitivity neutrino- oscillation programme Phenomenological subgroup  Review models of neutrino oscillations  Identify measurables that distinguish them and assess the precision required Experimental subgroup:  Use realistic assumptions on the performance of accelerator and detector to: Evaluate performance of the super-beam, beta-beam and Neutrino Factory alone or in combination  Make meaningful comparisons Muon physics subgroup:  Lepton-flavour violating processes – clear synergy with neutrino oscillations – possibly the next major discovery

16 March 2006P Dornan - MUTAC Some Theoretical Ideas Flavour symmetry:  Quarks and charged leptons do not carry the same hidden quantum numbers  All neutrinos carry the same hidden quantum numbers Allows differences in mass hierarchies and mixing matrices to be explained through symmetry breaking Random sampling of many such models indicates that large θ 13 is favoured

16 March 2006P Dornan - MUTAC Some Theoretical Ideas Quark-lepton complementarity  Intriguing Relations Coincidence fundamental  GUTs motivate relationships between the quark and lepton mixing matrices  Measurable relations  Need Precision

16 March 2006P Dornan - MUTAC

16 March 2006P Dornan - MUTAC

16 March 2006P Dornan - MUTAC A Possible Neutrino Sum Rule

16 March 2006P Dornan - MUTAC T owards a performance comparison A Major Goal of the ISS  Now many options  Must be reduced if there is to be a realistic design for a ‘precision era’ neutrino facility Requires justifiable assumptions:  Accelerator: flux, energy spectrum  Detector: E thresh, E Res (background, x-sect. uncertainty…) and optimised facility (accelerator, baseline, & detectors) Already a very substantial amount of work

16 March 2006P Dornan - MUTAC Cases under Consideration  Off axis super-beam: T2HK taken as example  Plan to explore different options (essentially vary E and L)  Beta beam: Low  :  = 100 and L = 130 km  High flux (~10 18 decays per year) and high flux (10 19 dpy) High  :  = 350 and L = 700 km  High flux (~10 18 decays per year) and high flux (10 19 dpy)  Also Beta beam abd superbeam combination  Neutrino Factory Performance studied as a function of:  E and L  E thresh and E Res

16 March 2006P Dornan - MUTAC Sample - CP sensitivity v. sin 2 2  13 Work in progress But highlights the importance of  13 in defining a strategy Huber, Lindner, Rolinec, Winter

16 March 2006P Dornan - MUTAC CPT & the MNS Theory In the Quark sector the CP violation parameters are determined in many ways Can we do the same in the neutrino sector? With 3 flavours and CPT  CP violation related in e ->   ->  e ->  Needs tau modes Murayama

16 March 2006P Dornan - MUTAC B eta beam, super beam comparison High θ 13 :  Beta beam & super beam alone:  sensitivity good Poor sign(  m 23 2 ) sensitivity Preliminary! Need to include better treatment of background and sys. err. Couce

16 March 2006P Dornan - MUTAC Neutrino Factory: optimisation Study performance as a function of muon energy and baseline Detector:  100 kton, magnetised iron  Importance of threshold sensitivity Can trade muon energy against detector threshold and resolution

16 March 2006P Dornan - MUTAC ISS status: Accelerator Group Subsystems & subgroups  Proton driver  Target and capture  Front end Bunching and phase rotation Cooling  Acceleration  Decay ring

16 March 2006P Dornan - MUTAC Accelerator Group – mission Two phase approach:  Phase 1: Study alternative configurations; arrive at baseline specifications Develop tools required for end-to-end simulations ‘Top-down’ cost evaluation required to guide choices  Phase 2: Focus on selected option(s)  Begin to consider engineering issues Through initial engineering studies, identify R&D required in ‘International Design Study’ phase Presently working through Phase 1  Highlights 

16 March 2006P Dornan - MUTAC Proton driver: Key issues for Neutrino Factory proton driver:  Beam current limitations  Creation of short bunches  Repetition rate limitations  Space charge limitations  Tolerances Largely driven by downstream constraints Survey carried out:

16 March 2006P Dornan - MUTAC RAL 4 MW FFAG Proton Driver RAL design 5 bunches per pulse 50 Hz repetition rate 10 GeV Isochronous FFAG with insertions RF system naturally gives 2 ns rms pulse need to add 6 th harmonic to get 1 ns rms Issue: Bunch length at injection

16 March 2006P Dornan - MUTAC Target and capture Issues for target and capture system:  Optimum proton-driver energy  Optimum target material  Constraints on target operation at 4 MW Proton bunch intensity Proton bunch length Repetition rate Possible materials  Liquid mercury preferred for high-power operation  Solid tantalum may be an option  Carbon probably OK up to 1 MW

16 March 2006P Dornan - MUTAC Target and capture: proton energy Different simulations disagree  MARS  Geant4 Preliminary conclusion:  Proton driver energy in range 5 – 15 GeV

16 March 2006P Dornan - MUTAC Target and capture MERIT experiment at CERN  High-power liquid-mercury jet target engineering demonstration

16 March 2006P Dornan - MUTAC Front-end Review and compare performance of existing schemes (CERN, KEK, US)  Conclusions will require cost model to be developed Evaluate trade-offs between degree of cooling and downstream acceptance  Figure of merit (muons per proton)  Need to define options for acceptance downstream of cooling channel Small, medium, and large?  Optimisations: Minimise RF required Optimum choice of materials for absorber in cooling channel  Evaluate cost optimum

16 March 2006P Dornan - MUTAC Front end: new configurations

16 March 2006P Dornan - MUTAC Cooling: hardware R&D programme Complementary programmes:  MuCool: Design, prototype, and test – using an intense proton beam – cooling channel components  MICE: Design, construct, commission, and operate – in a muon beam – a section of cooling channel and measure its performance in a variety of modes Both programmes well advanced

16 March 2006P Dornan - MUTAC Acceleration: FFAG development Increasing effort on scaling and non- scaling FFAG PRISM: Phase rotated intense muon source  Under construction in Osaka Commissioning 2007  Proof of principle ‘non-scaling’ FFAGDecay ring EMMA :Electron model of muon acceleration

16 March 2006P Dornan - MUTAC Decay ring Issues:  Racetrack or triangle geometry  20 GeV or 50 GeV or 20 GeV-upgradable  How to handle both muon charges (1 ring or 2)  Length of µ bunch train (constrains circumference)  RF to maintain bunch structure  Beam loading (~MW µ beams)  Shielding from µ decays

16 March 2006P Dornan - MUTAC Decay Ring - Options Isosceles Triangle (G Rees)  Circumference = 1170 m  length of each production straight = 301 m (2 x 0.26 efficiency)  5 bunch trains per cycle  angles of triangle depend on ring and target sites designed for apex angle = 22.4 o 27, 34.5, 45, 52 also possible (±1 o ) Racetrack geometry (C Johnstone),  C = 1371 m  both 20 GeV and 50 GeV use same lattice  production straight 496 m long (36% production efficiency) quad focusing - maximum beta = 155 m, 167 m

16 March 2006P Dornan - MUTAC ISS status: Detector Group Detector options and subgroups  Large water Cherenkov ISS activity focuses on consideration of R&D required:  Photo tubes  Front-end electronics  Liquid argon  Emulsion  Magnetic sampling calorimeter  Near detector Further instrumentation issues:  Flux, muon-polarisation measurement

16 March 2006P Dornan - MUTAC Detector technology: summary Magnetised liquid argon:  Golden, platinum, and silver channels accessible Magnetised sampling calorimeter:  Golden channel accessible Sampling fraction:  Can totally active ‘get’ some silver or platinum sensitivity Hybrid detector system?

16 March 2006P Dornan - MUTAC Liquid argon Detector concepts Various configurations being studied in ISS:  Glacier  T2K-LAr (near det.)  NuMI LArTPC

16 March 2006P Dornan - MUTAC Emulsion detector – MECC

16 March 2006P Dornan - MUTAC Magnetic sampling calorimeter Concept:  Magnetised iron? Sampling fraction?  Air toroid  Cost ~ $300M Electron Muon

16 March 2006P Dornan - MUTAC Near detector

16 March 2006P Dornan - MUTAC Timescales: the challenge

16 March 2006P Dornan - MUTAC ISS – Summary The ISS was launched at NuFact05 and is now half way through its one year programme  Conclude at NuFact06 and a report early fall It has demonstrated a strong desire to have an internationally coordinated effort for future neutrino research (c.f linear collider)  New ideas  Many clarifications It has brought together accelerator & detector scientists with their experimental and theoretical physics colleagues in a very productive way It has built up a momentum which must be used as a springboard for the next phase

16 March 2006P Dornan - MUTAC ISS – Immediate Future Next Plenary Meeting RAL, UK, April 24 – 29 Preceded by an Accelerator Group Workshop Final Meeting Irvine, Aug 21 – 22 Just before NuFact06 Still much to be done – more help always welcome Visit the website   Transparencies from all the meetings etc.  Join the mailing lists  Help to establish the best way forward