n e Appearance Experiment with Off-axis Detector in a NuMI Beam

1. ne Appearance Experiment with Off-axis Detector in a NuMI Beam • Physics • Off-axis NuMI Beam • Detector Issues • Off-axis Experiments: evolution of the accelerator and detectors • Scenarios February 15, 2003 Adam Para

2. Neutrinos vs Standard Model Whereas • There is a major effort to complete the Standard Model (Higgs search) • There is a broad front of experiments looking for possible deviations from the Standard Model (SUSY searches, B-physics experiments, g-2, EDM, …) The first evidence for physics beyond the standard model is here: • Neutrino mass and oscillations Where does it lead us? • Just an extension (additional 9? 7? Parameters) ? • First glimpse at physics at the unification scale ? (see-saw??) • Extra dimensions? • Unexpected? (CPT violation ???)

3. The outstanding questions in neutrino physics, AD2003 • Neutrino mass pattern: This ? Or that? • Electron component of n3(sin22q13) • Complex phase of s  CP violation in a neutrino sector  (?) baryon number of the universe • mixing angle q23 : sin22q23 = 1 – eNew symmetry? Broken?

4. The key: nm ne oscillation experiment 3 unknown, 2 parameters under control, neutrino/antineutrino

5. Anatomy of Bi-probability ellipses d Minakata and Nunokawa, hep-ph/0108085 ~cosd • Observables are: • P • P • Interpretation in terms of sin22q13, d and sign of Dm223 depends on the value of these parameters and on the conditions of the experiment: L and E ~sind sin22q13 Rates differ by factor of 4 for the same sin22q13

6. Mass Textures and q13 Predictions, Examples Altarelli,Feruglio, hep-ph/0206077

7. Off-axis NuMI Beams: unavoidable byproduct • Beam energy defined by the detector position (off-axis, Beavis et al) • Narrow energy range (minimize NC-induced background) • Simultaneous operation (with MINOS and/or other detectors) • ~ 2 GeV energy : • Below tau threshold • Relatively high rates per proton, especially for antineutrinos • Matter effects to amplify to differentiate mass hierarchies • Baselines 700 – 1000 km

8. Oscillation probability vs physics parameters Parameter correlation: even very precise determination of Pn leads to a large allowed range of sin22q23  antineutrino beam is more important than improved statistics

9. ne Appearance Counting Experiment: a Primer This determines sensitivity of the experiment • Systematics: • Know your expected flux • Know the beam contamination • Know the NC background*rejection power (Note: need to beat it down below the level of ne component of the beam only) • Know the electron ID efficiency

10. Sources of the ne background At low energies the dominant background is from m+e++ne+nm decay, hence • K production spectrum is not a major source of systematics • ne background directly related to the nmspectrum at the near detector ne/nm ~0.5% All K decays

11. NuMI Off-axis Detector Low Z imaging calorimeter: • Glass RPC or • Drift tubes or • Liquid or solid scintillator Electron ID efficiency ~ 40% while keeping NC background below intrinsic ne level Well known and understood detector technologies Primarily the engineering challenge of (cheaply) constructing a very massive detector How massive?? 50 kton detector, 5 years run => • 10% measurement if sin22q13 at the CHOOZ limit, or • 3s evidence if sin22q13 factor 10 below the CHOOZ limit (normal hierarchy, d=0), or • Factor 20 improvement of the limit

12. Signal and background Clean track = muon (pion) Fuzzy track = electron

13. Background examples nm CC - with p0 - muon NC - p0 - 2 tracks

14. Beam-Detector Interactions • Optimizing beam can improve signal • Optimizing beam can reduce NC backgrounds • Optimizing beam can reduce intrinsic ne background • Easier experimental challenge, simpler detectors • # of events ~ proton intensity x detector mass • Allocate the re$ources to maximize the product, rather than individual components

15. A Quest for NuMI Proton Intensity NuMI Intensity Working Group, D. Michael/P. Martin Nominal “NuMI year”

16. Two phase program Phase I (~ $100-200 M, running 2007 – 2014) • 50 kton (fiducial) detector with e~35-40% • 4x1020 protons per year • 1.5 years neutrino (6000 nm CC, 70-80% ‘oscillated’) • 5 years antineutrino (6500 nm CC, 70-80% ‘oscillated’) Phase II ( running 2014-2020) (D. Harris) • 200 kton (fiducial) detector with e~35-40% • 20x1020 protons per year (new proton source?) • 1.5 years neutrino (120000 nm CC, 70-80% ‘oscillated’) • 5 years antineutrino (130000 nm CC, 70-80% ‘oscillated’)

17. Conclusions • Neutrino Physics is an exciting field for many years to come • Most likely several experiments with different running conditions will be required to unravel the underlying physics • Fermilab/NuMI beam is uniquely matched to this physics in terms of beam intensity, flexibility, beam energy, and potential source-to-detector distances that could be available • Important element of the HEP program in the US for the next 20 years

18. Project Evolution (so far) • May 2002: Workshop ot Fermilab, 140 people • June 2002: LOI submitted • September 2002: All about NuMI – UCL London, 27 participants • Now: Argonne- Athens - Berkeley - Boston - Caltech - Chicago - College de France - Fermilab -Harvard - ITEP - Lebedev - UC-London - LSU - MIT - MSU – Minnesota-Crookstone - Minnesota-Duluth -Minnesota-Minneapolis - TUM-Munchen - NIU - Ohio-Athens - Oxford - Pittsburgh - Princeton - Rochester - Rutherford - Sao Paulo - Stanford - Stony Brook - Sussex- Texas-Austin - TMU-Tokyo - Tufts - UCLA - Virginia Tech - York-Toronto(115 physicists) (red – joined since LOI submission) • Expression of interest from several more institutions • January 2003 : Detector Workshop at SLAC ~65 people, narrow technologies to sampling calorimeters • April 2003: Detector Workshop at Argonne, compare gas/scintillator detector designs

19. What size collaboration is needed to construct and do physics with the detector? Do the collaborators have other, overlapping obligations ? The detector is huge but simple. The size of the technical/engineering staff is the most critical for for the timely design/construction/installation of the experiment. At present there are some 45 institutions, 140 physicists involved. More groups are expressing their interest. While most people have, to a varying degree, other obligations at this time, the strength of the collaboration already now is sufficient to ensure a success of the experiment. We expect a significant influx of interested parties once the project becomes more real.

20. What is the timeline/schedule for the Off-Axis beam and detector? NuMI beam: start operation spring 2005 (Reminder: a major investment of US High Energy Physics) Detector construction: schedule driven by external factors. An optimistic scenario: • Oct 03 – proposal • fall 03 - spring 04 initial reviews, cost and design validation • summer 04 - approval • 04 - 05 construction of a near detector, preparation of infrastructure for mass production • 05 site selection, start site preparation • 06 start construction • 07 start data taking with adiabatically growing detector • 08 complete construction

21. What is the estimated project cost including the beam and detector? Please give the basis for the cost estimate. Beam exists. Three-fold intensity upgrades is estimated to cost $45M.Based of on the work of the joint Beams Division/NuMI/MINOS working group. A committee dedicated to the review, validation and specific recommendation is being formed. Detector costs are based on the existing experience of MINOS and other experiments, like BELLE, using the same technology. An estimated detector cost is in the range of 1-3 M$ per kton. Large cost savings can be accomplished by optimization of the longitudinal sampling. The current cost estimates assume 1/3 radiation length sampling which provides a very comfortable background rejection. [Need a complete validated design to have a credible cost estimate]

22. How does the Off-Axis Detector fit into the evolving world picture, especially the JHF-SuperK experiment, in terms of adding an important new contribution to ourunderstanding of particle physics? Determination of the neutrino mixing matrix, mass hierarchy, possible studies of CP violation will require multiple precise measurements taken under different conditions (distance, energy, matter effects). In principle, the NuMI beam provides enough flexibility to complete the entire program, given a sufficienty large number of massive detectors located at different positions. This would be a very long, and very expensive program. Parallel measurements at JHF, with no matter effects, will help to extract the interesting physics parameters in a shorter (still probably very long) time scale. A possible new reactor experiment measuring/further limiting q13 would be a great help in reducing the correlations between the parameters of interest.

23. Determination of mass hierarchy: complementarity of JHF and NuMI Combination of different baselines: NuMI + JHF extends the range of hierarchy discrimination to much lower angles mixing angles Minakata,Nunokawa, Parke

24. Two body decay kinematics At this angle, 15 mrad, energy of produced neutrinos is 1.5-2 GeV for all pion energies  very intense, narrow band beam ‘On axis’: En=0.43Ep