Neutrino Oscillation Experiments. Kevin McFarland University of Rochester. Workshop on Nuclear and Particle Physics at JHF GeV PS KEK 10 December 2001

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1 Neutrino Oscillation Experiments Kevin McFarland University of Rochester orkshop on Nuclear and Particle Physics at JF GeV PS KEK 10 December A Roadmap for Neutrino Oscillations 2. Neutrino Oscillation Phenomenology 3. The Experimental Situation The Imminent Future 4. Experimental Ideas for Progress 5. The Roadmap Revisited

Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 2 Roadmaps In Scientific Research The recent US EPAP sub-panel charged with charting a 20-year future of high energy physics

2 Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 2 Roadmaps In Scientific Research The recent US EPAP sub-panel charged with charting a 20-year future of high energy physics in the US drew heavily upon the concept of a Roadmap A roadmap is an extended look at the future of a chosen field of inquiry composed from the collective knowledge and imagine of the brightest drivers of change in that field Robert Galvin Former CEO, Motorola hy a roadmap? map : because we have a broad sense of the goals of our exploration road : because we can conceive of promising routes to reach our goals

Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 3 Goals of the US Particle Physics Roadmap Very Rare Processes Ultimate Unification Neutrinos iggs idden Dimensions

3 Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 3 Goals of the US Particle Physics Roadmap Very Rare Processes Ultimate Unification Neutrinos iggs idden Dimensions Supersymmetry Cosmic Connections Extra Space Dimensions Dark Matter and Energy Anti Matter Particle Astrophysics Studies of neutrino oscillations play a key role in at least two of these concepts Ultimate Unification: attempting to find a unified description of fundmental forces and particles Cosmic Connections: using our description of fundamental particles and fields to draw inferences about the present, past and future of the Universe

Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 4 Neutrinos and Unification Particle periodic table Common structure of weak interactions in quark and lepton sector No

4 Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 4 Neutrinos and Unification Particle periodic table Common structure of weak interactions in quark and lepton sector No contact between quark and lepton sector No explanation for generations An underlying cause for these patterns? Neutrino oscillation probes leptonic mixing Neutrino mass hierarchy can be tested Tests for Predictive Grand Unified Theories (extended gauge groups)

$#"%$ owever, bright baryonic matter is only a small fraction Neutrinos may account for a fraction of the dark matter & ' ( )+*, '.$

5 Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 5 Neutrinos and the Cosmos Dark Matter igh- Supernovae, cosmic microwave background measurements suggest a universe with!#"%$ owever, bright baryonic matter is only a small fraction Neutrinos may account for a fraction of the dark matter & ' ( )+*, '.-0/2143 ev5 Matter-Antimatter Asymmetry The Universe appears to be overwhelmingly constructed of matter with little anti-matter CP violation in the early Universe can lead to such assymetries 6 But known CP violation (quark system) is insufficient Leptogenesis from lepton sector CP violation? 6 7 are the probe of this CP violation!

6 Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 6 Neutrino Mixing ν ν µ ν τ + µ + τ + = 8 9 :<; ν= ν> ν? Neutrino Flavor Neutrino Mass 8 9 :<; = Maki-Nakagawa-Sakata Mixing Matrix

7 T 5 w Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 7 Two Generation h A 8 I J Akjml n A 5 K CDistance *X MMMMLNOQPSRUT *` V RZY\[ T ] V_^ RZYa[ T ObPSRcT Fpo RZY\[ q F RZY\[ rssstvusw ox y F 1 dfeeee g F z 1 { 1 km5 GeV5 Akj Log(L/E)

8 ( n y J D y ^ y ^ Ÿ Ÿ Ÿ Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 19 Three Generation Mixing T DkF T F. T D 8 I J MMMMMLN ƒ ƒˆ Š Œ ƒ Œ Ž ƒ ƒ Š Ž ƒ ƒ Ž ƒ ƒ ƒ Ž % ƒ ƒ Ž % ƒ ƒ { / z y F F. y F DkF š '. œ 'ž Ÿ F. ª «š ª ± ³²µ š ' ' `Ÿ ª F. 0 š ¹ ±.²µ š ' œ ' Ÿ š ' œ ' Ÿ š ' œ ' Ÿ š ' Uœ ' Ÿ «¹ 0 F. 0 º» š ª ±.²µ dfeeeee g Standard Scenario F o RZY\[ T F. ¼ D ² & ½ F. ½ (atmospheric) F o RZY\[ T DkF & ½ DkF ½ (solar) T D small (COOZ)

9 Á y F Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 20 CP Violation in Neutrino Oscillation CP Violation requires: Appearance measurements h 1 CPT conservation ià At least two 5 K h 5 (two interfering amplitudes required) y Non-zero 8 I J phase, Observable is «K h 5 ] h 5 h h

10 Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 21 CP Violation Scenarios ' œ ' Çœ Çœ Çœ Standard Scenario for 0 º F. One amplitude with, ª F. Other amplitude with, Be a sunny optimist and assume LMA solar solution (Super-K) F. If ÉÈ š ' Uœ ' Ÿ F. If ÉÌ š ' œ ' Ÿ F. ÉÍ If Â ª Ê Ë, big and small 0 ª Â, ÊBË small and may be big! ª... 'ž cœ ' Revenge of LSND, e.g. Two mass scales are now ÎÐÏÒÑ»Ó, CP violation at much shorter baselines! Ô¹Õ Ö_ØÚÙ!

11 ø n ü ü 2 2 ùúû ö þ 2 2 ÿ ρ ÿ ρ 2 2 Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 22 - e ν e ) P(ν µ Matter Effects Oscillation νû e- νû e- + - ' νû - e νû 0 º F..Ý šßþ Ÿ F. 0 º F³ áà šãâ Þ ^ äæå Ý n ç è F. éà šãâ Þ Fëê F ì í î Þ n áï š ' cœ '.ðñÿ nl š 'ò cœ 'òðóÿ Ìô D õžõžõ Largest in, sign of ', 'ž propagation Ü Oscillations F. Ÿ ^ äæå F. Ÿ km (Mocioiu and Shrock hep-ph/ ) neutrino vacuum anti neutrino L=730km sin 2θ 13 = sin 2θ 23 = ö 1000 ö E[GeV]/ m 2 [ev 2 ] ν e ) P(ν µ µ ν e ) P(anti ν ý 3 ý 4 10 E[GeV]/ m 2 [ev 2 ] L=7330km full function const. ρ approx. L=7330km sin (2θ 23 )=.9 sin (2θ 13 )=.1 full function const. ρ approx. sin (2θ 23 )=.9 sin (2θ 13 )= ý ý ý 4 10 E[GeV]/ m 2 [ev 2 ] 5 10 ý

12 b ` a c Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 23 Matter Effects and CP at Long Baselines o prqis tauwvyxytzs { }q~s { ƒ} pri ~ŝ ƒ "!$# %'&)(+*,.-0/ ;:=<?>A@ BDCFEGJIKGML N OQPSR PUTDVJXY0UZ\[+]_^ fqgihj ŠŒ Ž J r ˆ ˆ M J S š œužjÿ? kqlimn de (Barger, Geer, Raja, hisnant)

13 Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 32 So, hat ill e Know? K2K, MINOS, CERN-NGS will precisely probe atmospheric oscillations known to 30%, «ª ˆ M to 20% Small, but not zero chance, we will have discovered M± 0² (³µ ² ³ ) LSND will be confirmed/refuted (BooNE) If ¹ ºº»½¼ ¾rÀ confirmed, suggests light neutrinos ÇwÈD δμ (ν ο ). ν 2 ν 3 (νá=âãåäæ )»½ÉËÊÍÌÎÈDÀ ν 0 ν 1 δμ 2 1 δμ ill know oscillation parameters? Ï, Ðª ˆ M Ï to ÑÓÒ Ô or better SNO/KAMLAND will have determined solar oscillation parameters

14 Û Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 33 The Lingering Questions Is that all there is? ÕÖ Unitarity of 3-generation mixing matrix ÕÖ Sterile neutrinos: how many and mixings? Measurement of small mixing ( ÙØ ÚwÛÜ ) Confirmation of Matter Effects in accelerator beam? Mass hierarchy: how many light, how many heavy? CP violation? The likely key question for experiments: hat is the value of 2Ø ÚwÛˆ evá?) (or, can I see ÝˆÞ Ö Ý Ú at ßˆà áãâ äjåçæ è ³é ² ³ sets difficulty for measurements of mass hierarchy, CP violation è This assumes: solar large mixing angle, large ê ( LMA ), LSND has not observed oscillation

15 Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 34 Tools of the Future 1. Optimizing conventional (meson decay) neutrino beams igh power proton sources (megawatt) Improved beam designs at low ë ì Reducing detector backgrounds 2. Muon decays as a source of neutrinos Source of Ý Þ AND Ý Ú Beam backgrounds negligible Requires significant R&D 3. Megaton detectors ill serve as next generation proton decay detectors as well

16 Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 35 Progression of íïî ð ñ'í Sensitivity Ultimate Best Conventional superbeams based on high rate proton sources can make huge strides forward Ultimate is M protons, ò0ò kton-yr in Liquid Ar Much depends on controlling backgrounds But even first muon based neutrino sources do much better ÕÖ someday...

17 Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 36 Controlling Backgrounds ith the Beam! Most problematic backgrounds to Ý Ú are higher energy ÝˆÞ and Ýˆó in beam Off-axis from ô direction makes beam approximately monochromatic (first proposed for BNL-889 beam)

18 â â Û Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 37 hy Muon Sources? Conventional (ôqõ ) Beam Economics Production rates fall steeply with increasing ë ö (production cross-section, proton acceleration) ø ì ù ø ö ë ö (neutrino cross-section, divergence) ú Beam Economics Produce and capture at low energies (large cross-section, higher û power) Accelerate parent beam after cooling ø ì ù ø Þ ë Û Þ if only produce, capture, accelerate and cool were simple!

19 Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 38 Snowmass Neutrino Oscillation Summary here do neutrino physicists in the U.S. see the focus of the field in the future? The recent evidence for neutrino oscillations is a profound discovery. The US should strengthen its lepton flavor research program by expediting construction of a high-intensity conventional neutrino beam ( superbeam ) fed by a 1-4 M proton source. A superbeam will probe the neutrino mixing angles and mass hierarchy, and may discover leptonic CP violation. The full program will require neutrino beams at a number of energies, and massive detectors at a number of baselines. These facilities will also support a rich program of other important physics, including proton decay, particle astrophysics, and charged lepton CP- and flavorviolating processes. The ultimate laboratory for neutrino oscillation measurements is a neutrino factory, for which the superbeam facility serves as a strong foundation. The development of the additional needed technology for neutrino factories and muon colliders requires a ongoing vigorous R&D effort in which the US should be a leading partner.

20 Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 39 Might the US Upgrade NUMI? è GeV beam, ü Ò mr from FNAL to Soudan (NUMI) Axis è ý0ý Ò þ ÿ þ0òò km (US or Canada) Probability P(ν µ νe ) δ=0 δ=45 δ=90 δ=135 δ=180 δ=225 δ=270 δ=315 L= 911 km m 2 sol= 5.0e-5 ev 2 m 2 atm= 3.0e-3 ev 2 sin 2 (2Θ 12 )= 0.8 sin 2 (2Θ 23 )= 1.0 sin 2 (2Θ 13 )= 0.01 Asymmetry CP Asymmetry δ=0 δ=45 δ=90 δ=180 L= 911 km m 2 sol= 5.0e-5 ev 2 m 2 atm= 3.0e-3 ev 2 sin 2 (2Θ 12 )= 0.8 sin 2 (2Θ 23 )= 1.0 sin 2 (2Θ 13 )= At å å km, the matter effects are large compared to the CP-violating effects Determine mass hierarchy with coarse measurement U² from U± and ± beams? Requires, of course, a high power proton source E (GeV) E (GeV)

21 Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 40 Imitation is the Most Sincere Form of Flattery The rest of the Ý world thinks so much of the potential of the JF ˆå GeV PS... è Design studies at FNAL and CERN for high intensity proton sources that have serious costing and site layout è Interest is great because physics motivation is great

22 Kevin McFarland, University of Rochester, Neutrino Oscillation Experiments 41 Summary and Roadmap Neutrino physics is a rapidly expanding, exciting field In the short-term future we expect to learn much ÕÖ ÕÖ Resolution of solar, LSND Ý oscillations Precision for atmospheric transition e know our next goal ÕÖ ÕÖ A complete picture of mixing Three (or more) generations participating ³é ² ³ Sterile? And ultimately... ÕÖ Mass hierarchy, CP violation igh power proton sources and large detectors are key tools Neutrino Roadmap igh Rate Low Energy ν ν µ e ν Megaton Detectors Multiple Baselines mass hierarchy glimpse CP violation Develop Muon Based Beams study CP violation

The Physics of Neutrinos

AAAS Feb. 15, 2004 The Physics of Neutrinos Boris Kayser Neutrinos are Abundant We, and all the everyday objects around us here on earth, are made of electrons, protons, and neutrons. In the universe,