Neutrino physics: experiments and infrastructure Anselmo Cervera Villanueva Université de Genève Orsay, 31/01/06

2Overview Measuring oscillation parameters Current status and objectives Ongoing experiments and near future Looking for CP violation: Facilities Detectors Strategies Open questions Conclusions

3 Measuring osc. parameters   295 Km E ~0.7 GeV detector source e e e 99.6% 0.4% 96% 4% oscillation Parameter Current knowledge ChannelExperiments  m 2 23 |,   20% error  disappearance Atmospheric + K2K  m 2 12,   10% error e or e disapp. Solar + Kamnland   <10 o e disapp Chooz (reactor) Sign of  m 2 23 unknown  CP unknown atmosphericsolar  CP e →  or  → e |  m 2 23 |,  23    disapp Sign of  m 2 23 e →  or  → e ( matter effects )    → e or e →  T2K  13 =8 0

4 Strategies oscillations without e oscillations with e science fiction atmospheric solarinterference current beams Conventional beams Super-beams current beams Conventional beams Super-beams future beams Beta-beams Neutrino factory future beams Neutrino factory future beams Neutrino factory Also CP violation

5 The sun and the atmosphere cannot tell us much more We need hand made neutrinos: We can chose the right L and the right E. L/E is not the relevant quantity anymore because of matter effects with near detectors To know the beam composition and energy: with near detectors  reduce systematic errors neutrino source Look at the right channel: appropriate neutrino source Build large detectors (the statistics is essential) Chose the right technology for the channel to detect: Muons Muons: segmented calorimeters, water cherenkov, liquid argon Electrons Electrons: low Z calorimeters, water cherenkov, liquid argon Taus Taus: emulsions And very important: A good knowledge of neutrino cross sections is crucial near detectors

6 In 5 years from now Conventional neutrino beams: long baseline experiments NUMI beam: MINOS(2005) CNGS beam: OPERA (2006) Nuclear reactor experiments Measure precisely the atmospheric parameters Demonstrate Explore  13 down to 5 0 sin 2 (2  13 )~0.03 Double-Chooz (2007) Magnetised iron calorimeter Emulsions

7 Super-beams ( ) Off-axes technique: narrow band beam Improve beam purity Increase beam power Adjust L/E to the oscillation maximum go down to  13 ~3 0 or sin 2 (2  13 )~0.01 Upgraded NuMi beam ~14mrad off-axis 6.5  POT/year (25  with Proton Driver) 30kton liquid scintill. detector 24% effic. for e detection Approved by FNAL PAC in April, NuMi off axes: NOvA (2010) JPARC beam: T2K (2009) Farther improve atmospheric parameters

8 In the next 10 years  13 could be measured However these experiments cannot address CP violation

9 CP violation asymmetry is a few % and requires excellent flux normalization (neutrino fact., beta beam or off axis beam with not-too-near near detector) atmospheric solarinterference NOTES: 1.sensitivity is more or less independent of  13 down to max. asymmetry point 2.This is at first maximum! Sensitivity at low values of  13 is better for short baselines, sensitivity at large values of  13 is better for longer baselines (2d max or 3d max.) 3.sign of asymmetry changes with max. number. for sin  = 1  -beam example

10 We need to produce and measure neutrinos and antineutrinos Either produce e and detect  or vice versa Problems: The asymmetry is small Systematic errors need to be very well controlled: super-beams Beam composition: for super-beams low energy beams Neutrino cross sections: mostly for low energy beams Detection efficiencies Correlation with other parameters:  13 and sign(  m 2 23 ) through matter effects. Degeneracies: Ambiguities related with lack of knowledge on: Sign(  m 2 23 )  23  or  23 

11 Improved Super-beams T2HK: 4 MW power, MT detector SPL to Frejus TRE CERN SPL LSM-Fréjus Near detector 130km New optimisation: 4 MW; Energy: 2.2  3.5 GeV Particle production 440 kTon

12 Beta-beams Pure e or e beam no beam systematics Low energy beam cross section systematics Use same detectors as super-beams !!! Could use existing facilities at CERN neutrinos of E max =~600MeV

13 Neutrino factory 50%   50% e  no beam systematics High energy beam no cross section systematics Complicated and expensive: a lot of R&D needed HARP, MICE, etc India CERN layout

14 Detectors I 3D active detector: Imaging Calorimetry Cherenkov Interesting option: very challenging A lot of ongoing R&D Well known technique: Super-K Interesting for e/  separation in low energy beams Liquid Argon TPC Water Cherenkov

15 Detectors II Full active with liquid scintillator: Super-NOvA Or Sampling Iron Calorimeter The measurement of the muon charge is essential Interesting for neutrino factory: Golden channel Tracking Magnetised Calorimeters Interesting to solve degeneracies in a neutrino factory: The CP term has opposite sign Silver channel Hybrid emulsion detectors

16 Strategies 1.Both (  B+SPL) and NUFACT outperform e.g. T2HK on most cases. 2.Combination of  B+SPL is really powerful. 3.For sin 2 2  13 below 0.01 NUFACT as such outperforms anyone 4.For large values of  13 systematic errors dominate.

17 Systematics and degeneracies At large values of  13 systematic errors dominate: Matter effects in neutrino factory Neutrino cross sections in  -beams Neutrino cross sections and beam flux normalization in super-beams Same channel 2 baselines (750, 3500) 2 channels: golden and silver Same baseline Degeneracies can be solved combining different channels or baselines

18 Some open questions Can we control systematic errors ? Measurements in a near station should be addressed The neutrino factory studies are not optimised for large  13 since low energy neutrinos (second oscillation maximum) are not detected One should aim to see the second maximum by lowering the muon detection threshold (from 5 to 1.5 GeV) Reduce the density of the detector A magnetised NOvA would do the job Is it possible to achieve wrong sign electron detection ? The performances of the different detectors are not know at the same level. Full simulations with input from existing detectors should be carried out for all of them The measurement of the different parameters requires different optimizations for each facility. That means that probably one needs a combination of facilities All these questions are being addressed at the moment by ISS/BENE

19 Outlook IF CP violation exists in neutrinos it should be observable It is possible to conceive a major neutrino infrastructure for Europe with outstanding performance (e.g. the CP violating phase would be observed over most of the phase space) The detailed choice should be based on reasonable cost estimate and performance evaluation, and the range in  13. effort is now targeted at: for NUFACT: improving matter effects determination and the detectors concepts for the low energy option: understanding the sources of systematic errors when dealing with low energy events Some encouraging progress has already been made but a detector design study with extensive prototyping will be needed to be in a position to make serious proposals by the end of this decade. Nowadays the neutrino is the less known of the elementary particles and a clear gate to new physics Priority must be for neutrino facilities