Neutrinos Worth The Wait Kevin Mc Farland University

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Neutrinos: Worth the Wait Kevin Mc. Farland University of Rochester Warwick University Physics Departmental Colloquium 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 30 November 2005

Neutrinos: Worth the Wait especially when snowed in… Kevin Mc. Farland University of Rochester “snowed in” Warwick University Physics Departmental Colloquium 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 30 November 2005

Neutrinos and Slowness… • Neutrino physics has historically been a slowly developing field – due to the properties of the neutrino, as we shall see • But neutrino physics is heating up into a very active field – driven by experimental results – and by new technologies • So first, some history and perspective… 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait A Typical February View of the George Eastman Theater at the University of Rochester 3

The Birth of the Neutrino Wolfgang Pauli 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 4

Translation, Please? 4 th December 1930 Dear Radioactive Ladies and Gentlemen, As the bearer of these lines, to whom I graciously ask you to listen, will explain to you in more detail, how because of the ”wrong” statistics of the N and 6 Li nuclei and the continuous beta spectrum, I have hit upon a desperate remedy to save the ”exchange theorem” of statistics and the law of conservation of energy. Namely, the possibility that there could exist in the nuclei electrically neutral particles, that I wish to call neutrons, which have spin and obey the exclusion principle and which further differ from light quanta in that they do not travel with the velocity of light. The mass of the neutrons should be of the same order of magnitude as the electron mass (and in any event not larger than 0. 01 proton masses). The continuous beta spectrum would then become understandable by the assumption that in beta decay a neutron is emitted in addition to the electron such that the sum of the energies of the neutron and the electron is constant. . . From now on, every solution to the issue must be discussed. Thus, dear radioactive people, look and judge. Unfortunately I will not be able to appear in Tübingen personally, because I am indispensable here due to a ball which will take place in Zürich during the night from December 6 to 7…. Your humble servant, W. Pauli 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 5

Translation, Please? • To save the law of conservation of energy? β-decay The Energy of the “β” • If the above picture is complete, conservation of energy says β has one energy, but we observe this instead – Pauli suggests “neutron” takes away energy! • The “exchange theorem of statistics”, by the way, refers to the fact that a spin½ neutron can’t decay to an spin½ proton + spin½ electron – he doesn’t call it the “Pauli exclusion principle”, to his credit… 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 6

Fundamental Forces • Of the four fundamental forces, three are important for the structure of matter around us Strong force Gravity – holds planets, galaxies, etc. together Electromagnetism – holds nucleus together – so strong that quarks are confined – holds atoms together – keeps matter from collapsing under the force of gravity 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 7

Theories of Forces • Modern force description is quantum field theory… – often illustrated w/ its lowest order perturbative expansion… • First theory of weak interactions (Fermi theory of beta decay, 1933) – also names the “neutrino” to distinguish from Chadwick’s neutron Enrico Fermi Neutron Beta Decay 30 November 2005 Neutrino-Neutron “Quasi Elastic” Scattering K. Mc. Farland, Neutrinos: Worth the Wait 8

How to Hunt a Neutrino • How do we see any fundamental particle? • Electromagnetic interactions kick electrons away from atoms • But neutrinos don’t have electric charge. They only interact weakly – so we only see by-products of their weak interactions 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 9

How Weak is Weak? • Weak is, in fact, weak. • A 3 Me. V neutrino produced in fusion from the sun will travel through water, on average, before interacting. – The 3 Me. V positron (anti-matter electron) produced in the same fusion process will travel 3 cm, on average. • Moral: to find neutrinos, you need a lot of neutrinos and a lot of detector! 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 10

Discovery of the Neutrino • Reines and Cowan (1955) – Nobel Prize 1995 – 1 ton detector – Neutrinos from a nuclear reactor Reines and Cowan at Savannah River 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 11

Solar Neutrino Hunting • Radiochemical Detector Ray Davis (Nobel prize, 2002) – ν+n p+e- (stimulated β-decay) – Use this to produce an unstable isotope, ν+37 Cl 37 Ar+e- , which has 35 day half-life – Put 615 tons of Perchloroethylene in a mine • expect one 37 Ar atom every 17 hours. 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 12

Solar Neutrino Hunting • Ran from 1969 -1998 • Confirmed that sun shines from fusion • But found 1/3 of ν ! 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 13

Modern Solar Neutrino Hunting • Kamiokande and Super-Kamiokande (Masatoshi Koshiba, Rochester Ph. D 1955, Nobel Laureate 2002) 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 14

Modern Neutrino Hunting • The Sun, imaged in neutrinos, by Super-Kamiokande sadly, not the same angular scale Existence of the sun confirmed by neutrinos! 30 November 2005 The Sun, optical image K. Mc. Farland, Neutrinos: Worth the Wait 15

Our Timescale So Far… • Pauli and Fermi (theory) 1930 • to Reines and Cowan (discovery) 1950 • to Davis (solar neutrinos) 1970 1990 • to Koshiba (supernova and oscillations) – progress continues to accelerate into the exciting neutrino programs of today… 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 16

Next Steps: The Broadest Goals • Understand mixing of neutrinos – a non-mixing? CP violation? • Understand neutrino mass – absolute scale and hierarchy • Understand interactions – new physics? new properties? n • Use neutrinos as probes – nucleon, earth, sun, supernovae 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait n 17

Qualitative Questions • The questions facing us now are fundamental, and not simply a matter of “measuring oscillations better” • Examples: – Are there more than three neutrinos? – What is the hierarchy of masses? – Can neutrinos contribute significantly to the mass of the universe? – Is there CP violation in neutrino mixings? 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 18

The Broadest Goals • Understand mixing of neutrinos – a non-mixing? CP violation? • Understand neutrino mass – absolute scale and hierarchy • Understand interactions – new physics? new properties? n • Use neutrinos as probes – nucleon, earth, etc. 30 November 2005 n K. Mc. Farland, Neutrinos: Worth the Wait 19

What We Hope to Learn From Neutrino Oscillations • Near future – validation of three generation picture • confirm or disprove LSND oscillations (>3 neutrinos) • precision tests of “atmospheric” mixing at accelerators • Farther Future – neutrino mass hierarchy, CP violation? • Precision at reactors • sub multi Mega. Watt sources • 10 1000 k. Ton detectors 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 20

Minimal Oscillation Formalism • If neutrino mass eigenstates: 1, 2, 3, etc. • … are not flavor eigenstates: e, , • … then one has, e. g. , take only two generations for now! different masses alter time evolution time 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 21

Oscillation Formalism (cont’d) • So, still for two generations… appropriate units give the usual numerical factor 1. 27 Ge. V/km-e. V 2 • Oscillations require mass differences • Oscillation parameters are mass-squared differences, dm 2, and mixing angles, q. • One correction to this is matter… changes q, L dep. Wolfenstein, PRD (1978) 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait e- density 22

Solar Neutrinos • There is a glorious history of solar neutrino physics – original goals: demonstrate fusion in the sun – first evidence of oscillations SAGE - The Russian-American Gallium Experiment 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 23

Culmination: SNO • D 2 O target uniquely observes: – charged-current – neutral-current • The former is only observed for e (lepton mass) • The latter for all types • Solar flux is consistent with models – but not all e at earth 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 24

KAMLAND • Sources are Japanese reactors – 150 -200 km for most of flux. Rate uncertainty ~6% • 1 k. Ton scint. detector in old Kamiokande cavern – overwhelming confirmation that neutrinos change flavor in the sun via matter effects 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 25

Solar Observations vs. KAMLAND + KAMLAND = • Solar neutrino observations are best measurement of the mixing angle • KAMLAND does better on dm 212 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 26

Atmospheric Neutrinos • Neutrino energy: few 100 Me. V – few Ge. V • Flavor ratio robustly predicted • Distance in flight: ~20 km (down) to 12700 km (up) 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 27

Super-Kamiokande • Super-K detector has excellent e/ separation 2004 Super -K analysis old, but good data! • Up / down difference! 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 28

Neutrino Beam from KEK to Super-K K 2 K figures courtesy T. Nakaya • Experiment has completed data-taking – confirms atmospheric neutrino oscillation parameters with controlled beam – constraint on dm 223 (limited statistics) 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 29

Enough For Three Generations figures courtesy B. Kayser dmsol 2 dm 122≈8 x 10 -5 e. V 2 dmatm 2 dm 232≈2. 5 x 10 -3 e. V 2 • Oscillations have told us the splittings in m 2, but nothing about the hierarchy • The electron neutrino potential (matter effects) can resolve this in oscillations, however. 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 30

Three Generation Mixing slide courtesy D. Harris • Note the new mixing in middle, and the phase, d 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 31

But CHOOZ… • Like KAMLAND, CHOOZ and Palo Verde expt’s looked at anti- e from a reactor – compare expected to observed rate, s~4% • If electron neutrinos don’t disappear, they don’t transform to 2 dm 23 muon neutrinos – limits -> e flavor transitions at and therefore |Ue 3| is “small” 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 32

Optimism has been Rewarded “We live in the best of all possible worlds” – Alvaro de. Rujula, Neutrino 2000 • By which he meant… had not Eatm /Rearth < dmatm 2 <Eatm /hatm and had not solar density profile and dmsol 2 been well-matched… • We might not be discussingn oscillations! 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 33

Are Two Paths Open to Us? • If “CHOOZ” mixing, q 13, is small, but not too small, there is an interesting possibility dm 232, q 13 e dm 122, q 12 • At atmospheric L/E, SMALL LARGE 30 November 2005 LARGE SMALL K. Mc. Farland, Neutrinos: Worth the Wait 34

Implication of two paths • Two amplitudes dm 232, q 13 e dm 122, q 12 • If both small, but not too small, both can contribute ~ equally • Relative phase, d, between them can lead to CP violation (neutrinos and anti-neutrinos differ) in oscillations! 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 35

Leptonic CP Violation in Oscillations • CP violation and matter effects lead to a complex mix… • CP violation gives ellipse Minakata & Nunokawa but matter effects shift JHEP 2001 the ellipse in a long-baseline accelerator experiment… • Stakes are high: – CP violation in leptons could, in fact, have seeded Universe’s matter-antimatter asymmetry 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 36

But LSND… figures courtesy S. Brice • LSND anti- e excess – 87. 9± 22. 4± 6. 0 events – statistically overwhelming; however… LSND dm 2 ~ 0. 1 -1. 0 e. V 2 Atmos. dm 2 ≈ 2. 5 x 10 -3 e. V 2 Solar 30 November 2005 dm 2 ≈ 8. 0 x 10 -5 e. V 2 K. Mc. Farland, Neutrinos: Worth the Wait cannot be accommodated with only three neutrinos 37

Mini. Boo. NE figures courtesy S. Brice • A very challenging experiment! • Have ~0. 6 E 21 protons on tape • First e appearance results in early 2006 (? ) 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait Signal Mis-ID Beam 38

Next Steps (Brazenly Assuming Three Neutrinos) • MINOS and CNGS • Reactors • T 2 K and NOv. A graphical wit courtesy A. de. Rujula • Mating Megatons and Superbeams • Beta ( e) beams and neutrino factories ( e and ) 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 39

Isn’t all of this overkill? • Disentangling the physics from the measurements is complicated • Different measurements have different sensitivity to matter effects, CP violation – Matter effects amplified for long L, large E – CP violation cannot be seen in disappearance (reactor) measurement e e Huber, Lindner, Rolinec, Schwetz, Winter 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait assumes sin 22 q 13 = 0. 1 40

Nu. MI-Based Long Baseline Experiments • 0. 25 MWatt 0. 4 MWatt proton source • Two generations: – MINOS (running) – NOv. A (future) 15 mrad Off Axis 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 41

MINOS Goal: precise disappearance measurement Gives dm 223 30 November 2005 735 km baseline 5. 4 kton Far Det. 1 kton Near Det. Running since early 2005 K. Mc. Farland, Neutrinos: Worth the Wait 42

CNGS Goal: appearance • 0. 15 MWatt source • high energy beam • 732 km baseline • handfuls of events/yr 1 mm e-, 9. 5 Ge. V, p. T=0. 47 Ge. V/c t n interaction, E =19 Ge. V 1. 8 k. Ton 3 kton fiugres courtesy A. Bueno 30 November 2005 Pb Emulsion layers figures courtesy D. Autiero K. Mc. Farland, Neutrinos: Worth the Wait 43

Back to Reactors • Recall that KAMLAND saw anti- e disappearance at solar L/E • Have not seen disappearance at atmospheric L/E 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 44

Why Reactors? • CHOOZ (reactor) has left us without evidence of anti- e disappearance indicating |Ue 3|>0 – reactors are still the most sensitive probe! • CHOOZ used a single detector – therefore, dead-reckoning used to estimate neutrino flux from the reactor – could improve with a near/far technique • KAMLAND has improved knowledge of how to reject backgrounds significantly (remember, their reactors are ~200 km away!) 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 45

How Reactors? • To get from ~4% uncertainties to ~1% uncertainties, need a near detector to monitor neutrino flux • For example, Double-CHOOZ proposes to add a second near detector and compare rates – new detectors with 10 ton mass – total error budget on rate ~2% – low statistics 10 t limit spectral distortion, 1 km baseline likely shorter than optimum not an engineering drawing • Optimization beyond Double-CHOOZ… – ~100 ton detector mass – optimize baseline for dm 223 – background reduction with active or passive shielding 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 46

Where Reactors? • A series of proposals with different technical choices • All challenging experiments to limit systematics 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 47

Megawatt Class Beams • J-PARC – initially 0. 7 MWatts 4 MWatts • FNAL Main Injector – current goal 0. 25 MWatts 0. 4 MWatts – future proton driver upgrades? • Others? 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 48

J-PARC Facility 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 49

A Digression: Off-axis • First Suggested by Brookhaven (BNL 889) • Take advantage of Lorentz Boost and 2 body kinematics • Concentrate flux at one energy • Backgrounds lower: – NC or other feed-down from high low energy – e (3 -body decays) 30 November 2005 figure courtesy D. Harris K. Mc. Farland, Neutrinos: Worth the Wait 50

T 2 K • Tunable off-axis beam from J-PARC to Super-K detector – beam and backgrounds are kept below 1% for e signal – ~2200 events/yr (w/o osc. ) d=0, no matter effects 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 51 figures courtesy T. Kobayashi

Nu. MI-Based Long Baseline Experiments • 0. 25 MWatt 0. 4 MWatt proton source • Two generations: – MINOS (running) – NOv. A (future) 15 mrad Off Axis 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 52

NO A figure courtesy M. Messier • Use Existing Nu. MI Goal: beamline e appearance • Build new 30 k. Ton In beam Scintillator Detector • 820 km baseline-compromise between reach in q 13 and matter Assuming Dm 2=2. 5 x 10 -3 e. V 2 effects figures courtesy J. Cooper 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait e+A→p + - e- 53

Future Steps after T 2 K, NOv. A • Beam upgrades (2 x – 5 x) • Megaton detectors (10 x – 20 x) • BUT, it’s hard to make such steps without encountering significant TECHNICAL DIFFICULTIES – hereafter “T. D. ” 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 54

TD: More Beam Power, Cap’n Example: Fermilab Proton Driver Neutrino “Super. Beams” NUMI SY-120 Fixed. Target Off. Axis 8 Ge. V neutrino 8 Ge. V Linac ~ 700 m Active Length Main Injector @2 MW 30 November figure courtesy 2005 G. W. Foster Parallel Physics and Machine Studies … main justification Is to serve as source for new Long baseline neutrino K. Mc. Farland, Neutrinos: Worth the Wait 55 experiments

TDs: Beamlines pictures courtesy D. Harris • Handling Many MWatts of proton power and Nu. MI Horn 2. turning it into neutrinos is not trivial! Note conductors Nu. MI tunnel boring machine. 3. 5 yr civil construction Nu. MI Target shielding. More mass than far detector! 30 November 2005 and alignment fixtures Nu. MI downstream absorber. Note elaborate cooling. “Cost more than Nu. Te. V beamline…” – R. Bernstein K. Mc. Farland, Neutrinos: Worth the Wait 56

TDs: Detector Volume • Scaling detector volume is not so trivial figure courtesy G. Rameika • At 30 kt NOv. A is about the same mass as Ba. Bar, CDF, Dzero, CMS and ATLAS combined… – want monolithic, manufacturabile structures – seek scaling as surface rather than volume if possible 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 57

For Perspective… • Consider the Temple of the Olympian Zeus… 17 m • 17 m tall, just like NOv. A! – a bit over ½ the length • It took 700 years to complete – delayed for lack of funding for a few hundred years • Fortunately construction technology has improved your speaker 30 November 2005 – has the funding situation? K. Mc. Farland, Neutrinos: Worth the Wait 58

TDs: Detector Volume (cont’d) Depth (below surface) • For megatons, housing a detector is difficult! Span figures courtesy C. -K. Jung 60 m UNO: 60 m span 1500 m depth UNO. ~1 Mton. (20 x Super-K) 40% photocathode 10% photocathode • Sensor R&D: focus on reducing cost – in case of UNO, large photocathode PMTs – goal: automated production, 1. 5 k$/unit 30 November 2005 60 m K. Mc. Farland, Neutrinos: Worth the Wait Field Map, Burle 20” PMT 59

TDs: Neutrino Interactions figures courtesy D. Casper, G. Zeller • At 1 -few Ge. V neutrino energy (of interest for osc. expt’s) – Experimental errors on total cross-sections are large • almost no data on A-dependence – Understanding of backgrounds needs differential cross-sections on target – Theoretically, this region is a mess… transition from elastic to DIS n –p 0 n n + 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 60

Futuristic Accelerator Beams • Conventional Beam figures courtesy D. Harris Detector Needs • Beta Beam • Neutrino Factory • Great experimental benefits to new beam technology, but beams are very challenging! And costly… 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 61

The Broadest Goals • Understand mixing of neutrinos – a non-mixing? CP violation? • Understand neutrino mass – absolute scale and hierarchy • Understand interactions – new physics? new properties? n • Use neutrinos as probes – nucleon, earth, etc. 30 November 2005 n K. Mc. Farland, Neutrinos: Worth the Wait 62

Neutrinoless Double-Beta Decay • Double beta decay is a rare, but observed process graphics courtesy Symmetry magazine • “Neutrinoless” implies that the neutrino is its own anti-particle (Majorana particle) calculable • The prize: 30 November 2005 evaluable w/ largish uncertainties (ai is a “Majorana phase”. Please look it up because I’m K. Mc. Farland, Neutrinos: Worth the Wait 63 not going there…)

Experimental Challenges • Observables: electron energy, final state nucleus (EXO) – Electron energy requires excellent resolution and low non bb backgrounds – Tagging the final state nucleus is “finding a needle in a haystack” 2 n 0 n sum electron energy / Q • Must have significant quantities of bb isotopes – not necessarily easy to purify. good detector material? – nuclear physics guidance limited on “best” isotopes 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 64

Current Results to Date • Results • To notice: – 76 Ge, 130 Te have large quantities, best limits so far – There is a claimed observation figure and table from APS n report: direct mass group • controversial • significant non-bb backgrounds (hard-to-predict Bi lines) 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 65

0 bb Future • If the Heidelberg-Moscow 76 Ge result is correct, should be confirmed “easily” • If not, want to push sensitivities to mbb 2 to at least level of dm 223 (maybe dm 212) – approximately two (maybe four) orders of magnitude lower than present situation • Experiments are very difficult want confirming signals in multiple isotopes – many exciting ideas for future experiments 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 66

0 bb Approaches: CUORE • Calorimetric (thermal) detector which is the bb source (Te. O 2) figures courtesy E. Fiorini heat bath – ~ke. V resolution at bb endpoint (2528 ke. V) Thermal sensor – Currently running “Cuoricino”, 40 kg – Full CUORE expects to have 750 kg, Te. O 2 reduced background levels crystal e- e. CUORE R&D (Hall C) CUORE (Hall A) 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait Cuoricino (Hall A) 67

Other 0 bb Approaches • COBRA: Semi-conductor Cd. Zn. Te detector – multiple bb isotopes! – room temperature, so no cryogenics (advantages for growing detector size, keeping contaminated materials away) • NEMO – Tracking/calorimetric detector external to source foils (10 kg of bb isotopes in prototype) – Geiger mode wire chambers, B=25 G – Scint/Low Rad. PMT calorimeter • Field is being driven by a multiplicity of prototypes 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 68

Other Mass Determinations? figures courtesy K. Eitel cosmology & structure formation astrophysics: SN To. F measurements D. N. Spergel et al: Sm < 0. 69 e. V (95%CL) powerful, but very indirect potential for ~few e. V sensitivity direct, but precision requires detailed knowledge of SN b decay kinematics: microcalorimeters magnetically adiabatic collimating electrostatic spectrometers 187 Re 3 H 30 November 2005 direct, but very challenging experiments K. Mc. Farland, Neutrinos: Worth the Wait 69

figures courtesy K. Eitel KATRIN phase space determines energy spectrum E 0 = Ee + E (+ recoil corrections) d. N/d. E (E 0 -Ee) × [ (E 0 -Ee)2 – mn 2 ]1/2 10 e. V theoretical b spectrum near endpoint retarding (variable) E-field allows only MAC-E spectrometers (Mainz, Troitsk) E>DEret. to pass m <2. 2 e. V(95%CL) (sensitivity limit) energy resolution: : DE/E=Bmin/Bmax = 6 T Bmin = 3× 10 -4 T so DE~1 e. V 30 November 2005 KATRIN sensitivity m <0. 2 e. V(90%CL) commissioning in 2008 K. Mc. Farland, Neutrinos: Worth the Wait 70

The Broadest Goals • Understand mixing of neutrinos – a non-mixing? CP violation? • Understand neutrino mass – absolute scale and hierarchy • Understand interactions – new physics? new properties? n • Use neutrinos as probes – nucleon, earth, etc. 30 November 2005 n K. Mc. Farland, Neutrinos: Worth the Wait 71

Neutrino Interactions • So broad a subject… so little time • • Precision EWK Neutrino magnetic moments Non-standard neutrino interactions Parity-violating probe 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 72

Neutral Currents in Neutrinos • Neutrino neutral current? – LEP invisible width, only 2 s – Nu. Te. V may be very large isospin violation • Future reactors? Conrad, Link, Shaevitz – if reactor experiments have precision for q 13, may also be able to measure neutral currents – opportunity for a purely leptonic probe 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 73

MINERv. A, for Oscillations • Noted that neutrino interactions are poorly known… • Backgrounds or signal rate uncertainties for next accelerator oscillation experiments could limit precision • Enter MINERv. A at Nu. MI beamline – newly approved cross-section experiment in Nu. MI near hall – construction start in late 2006; taking data by 2008 For example, MINERv. A helps MINOS know relationship νµp→νµpπ0 between visible Photon tracks! and true energy figures courtesy B. Ziemer, D. Harris, R. Flight 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 74

The Broadest Goals • Understand mixing of neutrinos – a non-mixing? CP violation? • Understand neutrino mass – absolute scale and hierarchy • Understand interactions – new physics? new properties? n • Use neutrinos as probes – nucleon, earth, etc. 30 November 2005 n K. Mc. Farland, Neutrinos: Worth the Wait 75

MINERv. A, Axial Form Factors • An experiment like MINERv. A can add to knowledge of nucleon structure! – Jefferson Lab for neutrinos • Example: axial structure of proton at high Q 2. – of interest because of puzzling behavior of vector form factors figures courtesy H. Budd, R. Flight 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 76

Journey to the Center of the (Spherical) Earth: Geoneutrinos • Another use of neutrinos as a probe figures courtesy G. Fiorentini • The journey in brief: – earth radiates 30 -45 TWatts in heat – the hypothesis: this is due to radioactivity of the earth – this radioactivity emits low energy anti-neutrinos from U and Th decays detectable via – one complication: much of U/Th is in crust 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 77

Geoneutrinos (cont’d) figures courtesy G. Fiorentini • Crust distribution is location dependent, but can be determined by geochemical surveys • Subtraction of the variable (local) part leaves the “global” U/Th Kamioka • At right, expected local and maximum “global” signal for U – “TNU” unit is 10 -32 ev/prot-yr 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 78

Geoneutrinos (cont’d) figures courtesy Nature • First measurement from Kam. LAND! – very challenging backgrounds! a reactors 2. 0 3. 0 Neutrino Energy (Me. V) • Rate of U+Th anti-neutrino reactions of (28± 14)x 10 -32/proton/yr – heat limit of <60 TW at 95% confidence 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 79

Breathless Conclusions • There is a lot going on in neutrino physics! • Nature has been kind to us so far, and answers to fundamental questions may be ripe for the picking • But, new experiments are getting more difficult… – Still, we’ve been historically patient in neutrino physics (e. g. , 30 years from Pauli to Reines and Cowan) – And it’s been worth the wait! 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 80

Acknowledgements input or source material supplied by (with or without their knowledge): A. de. Rujula, B. Kayser, D. Harris (also editorial help! thank you!), T. Nakaya, S. Parke, S. Brice, D. Autiero, T. . Kobayashi, M. Messier, J. Cooper, G. W. Foster, G. Rameika, C. -K. Jung, M. Bishai, H. Gallagher, B. Ziemer, H. Budd, E. Fiorini, G. Gratta, X. Sarazin, K. Eitel, R. Flight, D. Casper, H. Minakata, G. Zeller, G. Fiorentini, Nature, The Particle Adventure, Star Trek and Symmetry magazine 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 81

Supplementary Slides 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait

More to learn from the sky? • Sign-separated atmospheric neutrinos – MINOS detector is first with this capability Time vs Y Time vs Z – determine charge from bend y x z Y vs X Strip vs Plane ~1 yr MINOS figures courtesy M. Bishai, H. Gallagher Y vs Z • Why study neutrino vs. anti-neutrino oscillations? – possibility to test CPT violation scenarios if suggested by Mini. Boo. NE and LSND results 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 83

Observing Matter Effected Oscillations • We apparently have seen matter effects in the sun… can we verify it in the earth? • Best results from Super-K • Expect ~2% effect – Not there yet • Interesting for future solar experiments… 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 84

Who Cares About β-Decay? • Weak Nuclear Force – its exciting role is to, well, make β-decays – that sounds awfully anticlimactic… who cares? • actually, you do. A lot. – Fusion in the sun requires that a proton turn into a neutron. Inverse of β-decay! – Without β-decay, we are stuck where the sun don’t shine… 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 85

Slides for my Amusement 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait

Is there an easier way? • Why, yes! Leave it to Star Trek to point the way! • Apparently, according to several episodes, Lt. Jordy La. Forge’s VISOR can actually detect “neutrino field emissions” – and what do we do in science except emulate Star Trek? • Sadly, this technology is the sole purview of the Pentagon for use in spotting neutrino emissions from their political opponents… so we need other tools. 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 87

Is there no escape from Neutrinos? Cosmic Gall Neutrinos, they are very small. They have no charge and have no mass And do not interact at all. The earth is just a silly ball To them, through which they simply pass, Like dustmaids down a drafty hall Or photons through a sheet of glass. They snub the most exquisite gas, Ignore the most substantial wall, Cold-shoulder steel and sounding brass, Insult the stallion in his stall, And, scorning barriers of class, Infiltrate you and me! Like tall And painless guillotines, they fall Down through our heads into the grass. At night, they enter at Nepal And pierce the lover and his lass From underneath the bed - you call It wonderful; I call it crass. – John Updike 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 88

Solar Neutrino Hunting • Radiochemical Detector Ray Davis (Nobel prize, 2002) – ν+n p+e- (stimulated β-decay) – Use this to produce an unstable isotope, ν+37 Cl 37 Ar+e- , which has 35 day half-life – Put 615 tons of Perchloroethylene in a mine Physicist Ray Davis not to be confused with Ray “Stingray” Davis, bass vocalist for Parliament Funkadelic, seen below “Tearing the Roof Off the Sucka” in a rare Homestake Mine Concert appearance • expect one 37 Ar atom every 17 hours. 30 November 2005 K. Mc. Farland, Neutrinos: Worth the Wait 89