Neutrino physics: experiments and infrastructure

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

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

3. atmospheric solar Measuring osc. parameters En~0.7 GeV T2K q13=80 nt 99.6% 96% nm ne oscillation detector 4% source ne ne 0.4% 0.4% 295 Km |Dm223|, q23nmdisapp q13 nm→ ne or ne→nm Sign of Dm223 ne→nm or nm→ ne(matter effects) dCP ne→nm or nm→ ne

4. Conventional beams Super-beams current beams future beams Neutrino factory Conventional beams Super-beams current beams future beams Neutrino factory Beta-beams Neutrino factory future beams Strategies atmospheric solar interference oscillations withoutne science fiction oscillations withne Also CP violation science fiction

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 • To know the beam composition and energy: with near detectors •  reduce systematic errors • 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: segmented calorimeters, water cherenkov, liquid argon • Electrons: low Z calorimeters, water cherenkov, liquid argon • 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) Magnetised iron calorimeter Emulsions Measure precisely the atmospheric parameters Demonstrate Nuclear reactor experiments Double-Chooz (2007) Explore q13 down to50 sin2(2q13)~0.03

7. Super-beams (2009-2015) JPARC beam: T2K (2009) • Off-axes technique: • narrow band beam • Improve beam purity • Increase beam power • Adjust L/E to the oscillation maximum Farther improve atmospheric parameters NuMi off axes: NOvA (2010) Approved by FNAL PAC in April, 2005. go down to q13~30 or sin2(2q13)~0.01 • Upgraded NuMi beam • ~14mrad off-axis • 6.51020 POT/year (251020 with Proton Driver) • 30kton liquid scintill. detector 24% effic. for ne detection

8. In the next 10 years q13 could be measured • However these experiments cannot address CP violation 100 50 30

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 solar interference • NOTES: • sensitivity is more or less independent of q13 down to max. asymmetry point • This is at first maximum! Sensitivity at low values of q13 is better for short baselines, sensitivity at large values of q13 is better for longer baselines (2d max or 3d max.) • sign of asymmetry changes with max. number. for sin  = 1 b-beam example

10. We need to produce and measure neutrinos and antineutrinos • Either produce ne and detect nm or vice versa • Problems: • The asymmetry is small • Systematic errors need to be very well controlled: • Beam composition: for super-beams • Neutrino cross sections: mostly for low energy beams • Detection efficiencies • Correlation with other parameters: • q13 and sign(Dm223) through matter effects. • Degeneracies: Ambiguities related with lack of knowledge on: • Sign(Dm223) • q23>p/4 or q23<p/4

11. TRE Improved Super-beams • T2HK: 4 MW power, MT detector • SPL to Frejus 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 ne or ne beam no beam systematics • Low energy beam cross section systematics • Use same detectors as super-beams !!! • Could use existing facilities at CERN neutrinos of Emax=~600MeV

13. Neutrino factory • 50% nm50% neno beam systematics • High energy beam no cross section systematics • Complicated and expensive: a lot of R&D needed • HARP, MICE, etc CERN layout India

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

15. Detectors II Tracking Magnetised Calorimeters • 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 Hybrid emulsion detectors • Interesting to solve degeneracies in a neutrino factory: • The CP term has opposite sign • Silver channel

16. Strategies • Both (bB+SPL) and NUFACT outperform e.g. T2HK on most cases. • Combination of bB+SPL is really powerful. • For sin22q13 below 0.01 NUFACT as such outperforms anyone • For large values of q13 systematic errors dominate.

17. Systematics and degeneracies • At large values of q13 systematic errors dominate: • Matter effects in neutrino factory • Neutrino cross sections in b-beams • Neutrino cross sections and beam flux normalization in super-beams Degeneracies can be solved combining different channels or baselines Same channel 2 baselines (750, 3500) 2 channels: golden and silver Same baseline

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 q13 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 q13. • 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