 and the US Neutrino Programme Leslie Camilleri CERN, PH GDR Neutrino IPNO Orsay, 4 octobre 2006

Plan of Talk  Where do we stand and what do we still need to measure?  NO A  The detector  Its performance  The NUMI beam  Its present and future performance  Its current user: MINOS. Present and expected performance.  NO A sensitivity  NO A status and schedule.  The US programme  Accelerators  Double  decay  Reactors

3-family oscillation matrix S = sine c = cosine   CP violation phase.    drives SOLAR oscillations: sin 2  12 = (+- 16%)   23 drives ATMOSPHERIC oscillations: sin 2  23 = (+44% -22%)   13 the MISSING link ! sin 2  13 < 0.03  Set by a reactor experiment: CHOOZ.

Mass hierarchy Sign of  m 2 23 m2m1m2m1 m3m3 m2m1m2m1 m3m3  m 23 2 = 2.7 x eV 2  m 23 2 = 2.7 x eV 2  m 12 2 = 7.9 x eV 2 > 0.05 eV 2 Normal Hierarchy Inverted Hierarchy Oscillations only tell us about DIFFERENCES in masses Not the ABSOLUTE mass scale: Direct measurements or Double  decay Upper limit: Tritium  decay: mass ( e ) < 2.2 eV Lower limit: (2.7 x ) 1/2  > 0.05 eV  m 12 2 = 7.9 x eV 2 e  

What’s needed next?  Determine  13.  Determine the mass hierarchy.  Any CP violation in the neutrino sector?

NO A The NOνA Collaboration consists of 142 physicists and engineers from 28 institutions: Argonne, Athens, Caltech, College de France, Fermilab, Harvard, Indiana, ITEP, Michigan State, Minnesota-Twin Cities, Minnesota-Duluth, Northern Illinois, Ohio, Ohio State, Oxford, Rutherford, Rio de Janeiro, South Carolina, SMU, Stanford, Texas, Texas A&M, Tufts, UCLA, Virginia, Washington, William and Mary Five Italian universities with about 20 senior physicists are actively discussing joining NOνA. Its main physics goal will be the study of ν μ →ν e oscillations at the atmospheric oscillation  m 2.

Correlations in Oscillation Probability From M. Lindner: Measuring P (  ~ e ) does NOT yield a UNIQUE value of  13. Because of correlations between  13,  CP and the mass hierarchy (sign of  m 2 31 ) CP violation: Difference between Neutrino and Antineutrino Oscillations Mass hierarchy accessible through Matter effects.

Energy dependence of matter effects In vacuum and without CP violation: P(   e ) vac = sin 2  23 sin 2 2   sin 2  atm with  atm = 1.27  m 2 32 (L/E) To be at maximum oscillation at L = 800km E must be 1.64 GeV, and at L = 295km E = 0.6 GeV Introducing matter effects, at the first oscillation maximum: P(   e ) mat = [1 +- (2E/E R )] P(   e ) vac with E R = [12 GeV][  m 2 32 /(2.7x10 -3 )][2.8 gm.cm -3 /  ]~ 12 GeV +- depends on the mass hierarchy. Matter effects grow with energy and therefore with distance. 3 times larger (27%) at NO A (1.64 GeV) than at T2K (0.6 GeV)

NO A Detector Given relatively high energy of NUMI beam, decided to optimize NO A  for resolution of the mass hierarchy. Go as high in energy as possible To keep L/E constant at 2.7 x eV 2 Go as far as possible, but remain in US. At Ash River near Canadian border (L = 810km) : New site. Above ground.  Detector placed 14 mrad (12 km) Off-axis of the Fermilab NUMI beam (MINOS).

NO A Detector Fully active detector consisting of alternating planes of horizontal and vertical 15.7m long plastic PVC tubes filled with liquid scintillator (BC 517L): Total mass 25ktons. Each tube viewed by a looped WLS fibre both ends of which are read by a single avalanche photodiode (APD) cells TiO 2 Coated PVC tubes Tubes are wide enough (6 cm) to allow large bending radius and no damage to fibre  The loop is a “perfect” mirror

Avalanche Photodiode  Hamamatsu 32 APD arrays  Pixel size 1.8mm x 1.05mm (Fibre 0.8mm diameter)  Operating voltage 400 Volts  Gain 100  Operating temperature: -15 o C (reduces noise) Photon Asic for APD’s: 2.5 pe noise

Why APD’s ? The quantum efficiency of APD’s is much higher than a pm’s: ~80%. Especially at the higher wave lengths surviving after traversing the fibre.

Fibre/Scintillator cosmic ray test Inserted looped 15.7m long fibre in 60 cm long PVC tube filled with liquid scintillator. Exposed to cosmic rays. Measured 20 p.e. for a mip signal at the far end. Asic for APD’s: 2.5 pe noise  S/N ~ pe

Half Block Prototype Being Built at Argonne

Location Surface detector with about 3m overburden to reduce the em component of cosmic rays.

  e discrimination e CC  CC Electrons shower: many hits/plane. Muons do not: just one hit/plane.  CC background rejection: 7.1 x 10 -4

Neutral Current background:  N   p  o Look like electrons and e CC, if two photons are not recognized.  NC background rejection: 1.3 x 10 -3

The MINOS/NO A Neutrino beam: NUMI. Move horn and target to change energy of Beam

OFF-AXIS Technique Neutrino Energy Spectrum is narrow know where to expect e appearance Can choose the off-axis angle and select the mean energy of the beam. ( Optimizes the oscillation probability)  Target Horns Decay Pipe Detector Most decay pions give similar neutrino energies at the detector:

The Neutrino Beam components Signal Sin 2 2  13 = 0.04 Beam e ~ 0.5% Major background    Will have a NEAR detector to measure this e spectrum

MINOS detector Study of atmospheric mass region through  disappearance

Far detector results Suppression of events at low energy Expected unoscillated

New MINOS measurements ( Experiment ended) Compatible with and comparable to SK More precise than K2K. K2K

The MINOS future MINOS baseline 3.4 x pots / year Improvement by about a factor of 3 in 3 years

The Proton Beam as of today 2.8 x p’s per spill (2.2 secs) For a Fermilab year of 2 x 10 7 secs 2.4 x pots/year. (Achieved 1.27 x10 20 in first turn-on year) MINOS baseline 3.4 x pots/year. ~280 kW

The  beam after the collider shuts down (2009)  No antiproton production batches in Main Injector  No downtime for preparing collider shot. No time for antiproton transfer from accumulator to recycler.  Transfer time of 12 booster batches to Main Injector (0.8 sec). Instead transfer them to recycler during Main Injector cycle, and then transfer in one go  New RF in main injector  Upgrade of NUMI target. This should bring the Main Injector to a 1MW level Cost: M$.  PROTONS: 6.5 x protons on target per year. A gain of a factor of > 2 in numbers of protons delivered.

Beam assumptions  2010: Full shutdown to convert MI to 1 MW machine.  2011: 44 weeks running at 400 to 700 kW (Partial (5kT)detector)  2012: 38 weeks running at 700kW to 1 MW.  2013 and beyond: 44 weeks at 1 MW. Degradation factors assumed:  Accelerator uptime: 85%.  Average to peak intensity: 90%.  NO A uptime: 90%. Running time:  Start running as soon as 5kT installed.  2 years to build up to full detector.  Run for 6 years from end of construction. Total: 60.3 x pots

Signal and background I 6% electron shower energy resolution 3.5% muon energy resolution Maximum likelihood applied to events to separate e events from background. Yields 23% efficiency for e signal events including fiducial inefficiency Background suppression: –7.1E-4  CC –1.3E-3 Neutral Current Optimized Figure of Merit –#Signal / sqrt(#bkd) = 32 ~140 signal events for 60 x pot for sin 2 2  13 = background events. (12 intrinsic beam e and 7 neutral currents)

Signal and Background II Statistical Power: why this is hard and we need protons For sin 2 2  13 = 0.1: : S=142.1, B=19.5 : S= 71.8, B=

3  sensitivity to  13 = 0 The correlations are much reduced by running BOTH and. Discovery limit is better than 0.02 for ALL  ’s  and BOTH mass hierarchies. only 60.3 x pot 30.2 x pot each and . (removes some correlation)

Comparison to T2K and a Reactor Experiment T2K Reactor Braidwood Double Chooz T2K may not be latest Not very different Comparable to a Very sensitive reactor experiment

95% CL Resolution of the θ 23 Ambiguity Combining accelerator experiments (sensitive to sin 2 (θ 23 )sin 2 (2θ 13 )) with reactor experiments (sensitive to sin 2 (2θ 13 ))

95% CL Resolution of the Mass Ordering Important to establish hierarchy:  Per se  If inverted next generation of double beta decay experiments can determine if the neutrino is its own antiparticle.  To measure CP violation need to remove hierarchy uncertainty because it contributes an apparent CP violation. Will depend on value of  13 !!

Combining NOνA and T2K Δm 2 = eV 2 Some improvement at high values of  13.

δ vs. sin 2 (2θ 13 ) Contours for Test points: Normal Mass ordering Normal Mass Ordering Some limited sensitivity at 1 

Cost and schedule  Total cost (Far and near detectors, building, admin etc…) 226 M$ (including 57 M$ contingency) Status  Approved by Fermilab Program Advisory Committee: Stage 1 Approval, (April 2005).  Prioritized by NuSAG.  Recommended by P5 for construction start in Fiscal Year 2008 (October 2007).  Critical Decision Zero (CD0) granted. Mission need.  Obtained CD1 approval: Range of Schedules and costs.  CD2 next end 2006(?): Final cost, schedule and TDR.  Granted $10M in R&D for generic oscillation experiment.  Proton Driver CD0 shelved at this stage. But R&D can continue. Alternative plans for Main Injector upgrade to 1 MW, maybe 1.2 MW. Schedule  Assumption: Approval early  Building ready: June (Agreement with U. of Minnesota).  Five kilotons: Early  Completion: 2012.

The US programme: Accelerators I. MINOS. MiniBooNE    e search at the Fermilab booster: Results on the LSND observation this year. High energy data already presented. SciBooNE: K2K SciBar detector In MiniBooNE beam: low energy cross sections MINERVA.  cross sections at low energy in the near hall of NUMI beam. Going through approval process

The US programme: Accelerators II. T2K 280m: Participation in 280m near detector supported.  0 detector inside the UA1/NOMAD magnet for the near detector and work on beam. T2K 2Km: Participation in Water Cerenkov, civil engineering and liquid argon (150 tons). Only at later stage if possible. Liquid argon R&D: to determine whether scalable to tens of kilotons.

The US programme: Double –  decay. NuSAG recommendations: Recommended the first three EXO:Potential for reducing the background by extracting and identifyng resulting Barium atom as a second stage

The US programme: Reactors.  NuSAG recommended a US experiment to get down to a sensitivity of sin 2 2  13 of ~0.01. Both Daya Bay and Braidwood had this potential.  The DOE has stopped Braidwood and encouraged Daya Bay.  NuSAG encouraged participation in Double Chooz but with lower scientific priority because of its lower reach.  The DOE does not go along with this but possibly the NSF will.

Very Long baseline: New NuSAG charge. Assume a MW accelerator. Discuss baselines: Compare 800km (NO A), to km baselines: Fermilab or Brookhaven to new Underground site at Henderson or Homestake. Types of detectors: Liquid Argon or Water Cerenkov? Broad band: covering several oscillation maxima at once or narrow band. Sensitivity and physics programme. Joint BNL/FNAL study currently being carried out on these issues. Report: Oct. 2006

Extra Slides

Cost breakdown ContingencyTotal Cost M$ Far Detector Active detector30% 79.5 Electronics and DAQ55% 13.4 Shipping21% 7.0 Installation43% 13.5 Near Detector44% 3.1 Building and outfitting58% 29.3 Project management25% 4.7 Additional contingency 14.1 Total50%164.7

Far detector PVC modules +assembly $28.782M Liquid Scintillator +handling $30.309M Wave-length shifting fibres$17.430M Electronics, Trigger,DAQ$13.412M

Near Detector in MINOS Surface Building 45,000   CC events2,200 e CC events 6.5 x pot in 75 mrad off-axis beam Kaon peak

Confirmed by KAMLAND: Reactor antineutrinos to detector at Kamioka Solar Experiments KAMLAND KamLAND + Solar Completely consistent

New MINOS measurements ( Experiment ended)

Why are neutrino masses so low???? Other particles Fascinating !!!!! Also Lower limit: (2.4 x 10-3) 1/2 > 0.05 eV

APD response Measured with light equivalent to one and two mip’s Noise Signal well separated from noise pe

Summary of backgrounds BackgroundEvents% ErrorError Beam e 11.97%0.8   CC 0.515%0.08 NC7.15%0.4 Total19.55%0.9 Efficiency for e signal: 24%

8-fold degeneracies   13 -  ambiguity.  Mass hierarchy two-fold degeneracy   23 degeneracy: For a value of sin2 2  23, say 0.92,  23 can be 33.5 o or 56.5 A measure of P  e can yield a whole range of values of  13 Measuring with ’s as well reduces the correlations NO A will most probably run first 3 years with and then 3 more with This will also improve the complementarity with T2K if they run only.

The road ahead

Particle Physics Projects Prioritization Panel (P5) June 2006 October > October 2008

Initial Tests Using Extrusions from Existing Die (Smaller) 48 ft Measured light yields N = 80 exp(-L/4.6)+10 exp(-L/5000) 4.2 cm 2.2 cm Geometry gives factor of pe goes to 23 pe Reflectivity gives factor of pe goes to 27 pe 3.87cm 6cm Final Design Titanium dioxide 13 p.e. at 15.7m

Far Detector Assembly Detector has 64 (31-plane) blocks Can fill with scintillator and run during construction Half-Size planes built & tested at Argonne 31-plane block 1-cm expan- sion gap 31-plane block

Near Detector to understand the beam 262 T 145 T totally active 20.4 T fiducial (central 2.5 x 3.25 m) 8-plane block 10.6 T full 1.6 T empty Muon catcher 1 m iron Target region Veto region 9.6 m 5 m 3.5 m Shower containment region

  e separation Electrons (shower) Electrons (shower) Muons Low energyHigh energy  CC background rejection: 7.1 x 10 -4

Near detector locations Site 1.5 Far  beam