The Future of Neutrino Physics in a Post-MiniBooNE Era

H. RayLos Alamos National Laboratory

The Future of Neutrino Physics in a Post-

MiniBooNE Era

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Outline

Introduction to neutrino oscillationsLSND : The motivation for MiniBooNEMiniBooNE Overview & Current StatusThe Spallation Neutron Source

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Standard Model of Physics

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Standard Model of Physics

NeutrinoOscillationsObserved

Assume NeutrinosHave Mass

Introduce mass into SM via RH field (Sterile Neutrinos)

which mix w/ LH fields(SM )

Use Oscillations to find

Sterile Neutrinos

NeutrinoOscillationsObserved

Assume NeutrinosHave Mass

Introduce mass into SM via RH field (Sterile Neutrinos)

which mix w/ LH fields(SM )

Use Oscillations to find

Sterile Neutrinos

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Neutrino Oscillations

e =

Weak state Mass state

1

2

cos cos -sin sin

|(0)> = -sin |1> + cos |2>

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e =

Weak state Mass state

1

2

cos cos -sin sin

|(t)> = -sin |1> + cos |2>

e-iE1t e-iE2t

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Posc = |<e | (t)>|2

Posc =sin22 sin2 1.27 m2 L

E

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Posc =sin22 sin2 1.27 m2 L

E

Distance from point of creation of neutrino beam to detection point

Is the mixing angle

m2 is the mass squared difference between the two neutrino states

E is the energy of the neutrino beam

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LSND

800 MeV proton beam + H20 target, Copper beam stop

167 ton tank, liquid scintillator, 25% PMT coverage

E =20-52.8 MeVL =25-35 meters

e + p e+ + n n + p d + (2.2

MeV)

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The LSND Result

Different from other oscillation signals

Higher m2

Smaller mixing angle

Much smaller probability (very small signal) ~0.3%

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The LSND Problem

Posc =sin22 sin2 1.27 m2 L E

m2ab= ma

2 - mb2

Something must be wrong!Flux calculation Measurement in the detectorBothNeither Reminiscent of the great Ray Davis

Homestake missing solar neutrino problem!

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Confirming LSND

Posc =sin22 sin2 1.27 m2 L E

m2ab= ma

2 - mb2

Want the same L/EWant higher statisticsWant different sources of systematic errorsWant different signal signature and

backgrounds

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MiniBooNE

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MiniBooNE Neutrino Beam

Start with an 8 GeV beam of protons from the booster

Fermilab

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The proton beam enters the magnetic horn where it interacts with a Beryllium target

Focusing horn allows us to run in neutrino, anti-neutrino modeCollected ~6x1020 POT, ~600,000 eventsRunning in anti- mode now, collected ~1x1020 POT

Fermilab

World record for pulses pre-MB = 10M

MB = 100M+

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p + Be = stream of mesons (, K)Mesons decay into the neutrino beam

seen by the detectorK+ / + + +

+ e+ + + e

Fermilab

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An absorber is in place to stop muons and un-decayed mesons

Neutrino beam travels through 450 m of dirt absorber before arriving at the MiniBooNE detector

Fermilab

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MiniBooNE Detector

12.2 meter diameter spherePure mineral oil2 regions

Inner light-tight region, 1280 PMTs (10% coverage)

Optically isolated outer veto-region, 240 PMTs

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Observing Interactions

Don’t look directly for neutrinos

Look for products of neutrino interactions

Passage of charged particles through matter leaves a distinct markCerenkov effect / lightScintillation light

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Cerenkov and Scintillation Light

Charged particles deposit energy in the medium

Isotropic, delayed

Charged particles with a velocity greater than the speed of light * in the medium* produce an E-M shock wave v > c/nSimilar to a sonic boom

Prompt light signature

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Event Signature

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MiniBooNE

Lots of e in MiniBooNE

beam vs ~no e in LSND

beamComplicated and

degenerate light sourcesRequire excellent data to

MC agreement in MiniBooNE

MB : e

LSND : e Lots of e in MiniBooNE

beam vs ~no e in LSND

beamComplicated and

degenerate light sourcesRequire excellent data to

MC agreement in MiniBooNE

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The Monte Carlo

Cerenkov lightScintillation lightFluorescence from

Cerenkov light that is absorbed/re-emitted

Reflection Tank walls, PMT faces,

etc.

Scattering off of mineral oil Raman, Rayleigh

PMT Properties

Sources of Light Tank Effects

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Step 1 : External Measurements

Start with external desktop measurements

IU Cyclotron 200 MeV proton beamExtinction rate = 1 / Extinction Length

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Step 2 : Internal Samples

Identify internal samples which isolate various components of the OM

UVF, Scint are both isotropic, same wave-shifting/time constants

Low-E Neutral Current Elastic events below Cerenkov threshold

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Step 3 : Verify MC Evolution

Calibration Sample

Provide e Constraint

Background to CCQE Sample

Mean = 1.80, RMS = 1.47Mean = 1.19, RMS = 0.76

Mean = 20.83, RMS = 25.59Mean = 3.48, RMS = 3.17

Mean = 16.02, RMS = 25.90Mean = 3.24, RMS = 2.94

Examine cumulative 2/NDF distributions across many physics samples, many variables

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The Monte Carlo Chain

External Measurements and Laser Calibration

First Calibration with Michel Data

Calibration of Scintillation Light with NC Events

Final Calibration with Michel Data

Validation with Cosmic Muons, CCQE, e NuMI, etc.

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Quasi-Elastic Events

Constrain the intrinsic e flux - crucial to get right!

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Signal Region e Events

PRELIMINARY

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MiniBooNE Current Status

MiniBooNE is performing a blind analysis (closed box)Some of the info in all of the dataAll of the info in some of the dataAll of the info in all of the data

Public Announcement April 11th

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Final Outcomes

Confirm LSND Inconclusive Reject LSND

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Final Outcomes


Need to determine what causes oscillations

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Final Outcomes


Need to collect more data / perform

a new experiment

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Final Outcomes




a new experiment

SNS

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Final Outcomes


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Final Outcomes


SNS

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All Roads Lead to the SNS




a new experiment

SNS

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What is the SNS?

Accelerator based neutron source in Oak Ridge, TN

Spallation Neutron Source

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The Spallation Neutron Source

1 GeV protons Liquid Mercury target

First use of pure mercury as a proton beam target

60 bunches/secondPulses 695 ns wide

LAMPF = 600 s wide, FNAL = 1600 ns wide

Neutrons freed by the spallation process are collected and guided through beam lines to various experiments

Hg

Neutrinos come for

free!

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Target Area

- absorbed by target

+DAR Mono-Energetic!= 29.8 MeV

E range up to 52.8 MeV

(Liquid Mercury (Hg+) target)

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+ + + = 26 ns

+ e+ + + e = 2.2 s

Pulse timing, beam width, lifetime of particles = excellent separation of neutrino types

Simple cut on beam timing = 72% pure

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+ + + = 26 ns

+ e+ + + e = 2.2 s

Mono-energetic E = 29.8 MeV

, e = known distributions end-point E = 52.8 MeV

MiniBooNE

SNS

GeV

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Neutrino spectrum in range relevant to astrophysics / supernova predictions!

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Proposed Experiments

Osc-SNSSterile Neutrinos

-SNSSupernova Cross Sections

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-SNS Near Detectors

Homogeneous, Segmented Primary function = cross sections for astrophysics Most relevant for supernova neutrino detection =

2H, C, O, Fe, Pb

Full proposal submitted to DOE in August, 2005

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Osc-SNS Far Detector

MiniBooNE/LSND-type detector

Higher PMT coverage (25% vs 10%)

Mineral oil + scintillator (vs pure oil)

Faster electronics (200 MHz vs 10 MHz)

~60m upstream of the beam dump/targetRemoves DIF bgd

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Neutrino Interactions

Elastic ScatteringQuasi-Elastic ScatteringSingle Pion ProductionDeep Inelastic Scattering

MeV

GeV

SNS Allowed Interactions

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Neutrino Interactions @ SNS

All neutrino types may engage in NC interactions

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All neutrino types may engage in NC interactions

Muon mass = 105.7 MeV, Electron mass = 0.511 MeVMuon neutrinos do not have a high

enough energy at the SNS to engage in CC interactions!

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Appearance Osc. Searches2 oscillation searches at SNS can be

performed with CC interactions to look for flavor change

Appearance : e (ala LSND)e + p e+ + nn + p d + 2.2 MeV photon

Appearance : e

e + 12C e- + 12Ngs

12Ngs 12C + e+ (~8 MeV) + e

MiniBooNE uses e + n e- + p

lower E e

vs higher E e

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Appearance : e

e + 12C e- + 12N

12N 12C + e+ (~8 MeV) + e

Intrinsic e vs mono-energetic e

from

E of e- (MeV) E of e- (MeV)

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Why the SNS?

Beam Width

S:B Osc. Candidate

sLSND e

600 s 1:1 35(observed R >

10)

FNAL e

1600 ns

1:3 ~400

SNS e

695 ns 5:1 ~448/yearExpected for LSND best fit point of : sin22 =0.004 dm2 = 1

May be < 500 ns!

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Sterile NeutrinosSterile neutrinos = RH neutrinos, don’t

interact with other matter (LH = Weak)Use super-allowed NC interactions to search

for oscillations between flavor states and sterile neutrinos

Disappearance : e

+ C + C *C * C + 15.11 MeV photon

One detector : look for deficit in x events

Two detectors : compare overall x event rates

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Sterile Neutrinos

Near Detector only Near + Far Detector

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Sterile Neutrinos

“There are several indirect astrophysical hints in favor of sterile neutrinos at the keV scale. Such neutrinos can explain the observed velocities of pulsars, they can be dark matter, and they can play a role in star formation and reionization of the universe.” Kusenko, hep-ph/0609158

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Sterile Neutrinos

R-process nucleosynthesis Balantekin and Fuller, Astropart. Phys. 18, 433 (2003)

Pulsar kicks Kusenko, Int. J. Mod. Phys. D 13, 2065 (2004)

Dark matter Asaka, Blanchet, Shaposhnikov, Phys. Lett. B 631, 151 (2005)

Formation of supermassive black holes Munyaneza, Biermann, Astron and Astrophys., 436, 805 (2005)

Play impt. role in Big Bang nucleosynthesis Smith, Fuller, Kishimoto, Abazajian, astro-ph/0608377

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… but that’s not all! CP/CPT Violation

CPT violation (or CP + sterile neutrinos) allows different mixing for , anti-

Possible explanation for positive LSND, null MiniBooNE

Compare , anti- measured oscillation probabilities CP : e e

CPT : X X

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Mass Varying NeutrinosAll positive oscillation signals occur in matter

(K2K, KamLAND, LSND); no direct information on oscillation parameters in air/vacuum

Impose relationship between nus + dark E through scalar field

Scalar field couples to matter field = different osc parameters in vacuum & mediums

MaVaNus + 1 Sterile nu = LSND yes, MB no!Require a path to detector which can be

vacated/filled with dirt to test Barger, Marfalia, Whisnant. Phys. Rev. D 73, 013005 (2006) Schwetz, Winter. Phys. Lett. B633, 557-562 (2006)

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Why the SNS?


Looking fornew physics

Need much higher statistics

Need to perform analysis with anti-neutrinos to completely rule out LSND

Precise, well-defined neutrino/anti-neutrino beamwith very high statistics and low backgrounds

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Why the SNS?SNS : well known E spectrum to allow

precise measurementsSNS : simultaneous measurements in

neutrino, anti-neutrino modesSNS : different systematics to LSND, MB

Second cross check of LSNDSNS : can perform beyond the standard

model searches not open to MB Sterile neutrino search, CP/CPT, MaVaNus

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The Global Picture

The Neutrino MatrixAPS Multi-Divisional Neutrino Study, Nov 2004 www.aps.org/policy/reports/multidivisional/neutrino/upload/

main.pdf

Pg ii

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The Global Picture


main.pdf

Pg iii

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The Global Picture


main.pdf

Pg 27

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The Global Picture


main.pdf

Pg 27

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SummarySNS is about to become the best neutrino

based facility in the USDOE proposal for 2 near detectors

awaiting fundingLANL white paper produced for far

detectorWaiting on MiniBooNE result to go forward

with a proposalRegardless of the outcome of MiniBooNE,

the future of *precision* neutrino measurements in the US lies at the SNS!

Backup Slides

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A Brief History of Neutrinos

1930 : Postulated by Pauli1950-60 : First detection by Reines-

Cowan, inverse beta decay~1935 : First nu mass experiments

1972 Bergkvist, mass upper limit1980 - 85 : Soviet ITEP, mass up&low

limitInfamous 17 keV neutrino

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SNS Stats~17% of incident protons produce pions2.3 x 10-5 - decay before capture+ stopped <0.3 ns1.3 GeV protons produce :

0.098 +, 0.061 -

For 9.6 x 1015 protons/sec on target get 0.94 x 1015 of each flavor : , Anti-, e

Anti-e / Anti- < 3 x 10-4

Flux @ 50 m from target = 3 x 106 s-1 cm-

2

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Sterile Neutrinos

Near detector : ~2056 events/year (25 ton)Far detector : ~3702 events/year (500 ton)

+ C + C *

C * C + 15.11 MeV photon

Event rates only for

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Event Rates per Year

250 ton detector @ 60 m, 100% eff

e 12C e- 12Ngs 9378

e 12C e- 12N* 4294

Total e 12C e- X 13,672

12C

12C*15.11 3702

12C

12C*15.11 7504

e 12C e

12C*15.11 6186

Total 12C

12C*15.11

17,392

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Lorentz ViolationLSND, Atm, Solar oscillations explained by

small Lorentz violationSize of violation consistent with size of

effects emerging from underlying unified theory at Planck scale Kostelecky, Mewes. hep-ph/0406255 (2004)

Oscillations depend on direction of propagation

Don’t need to introduce neutrino mass!Look for sidereal variations in oscillation

probability

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Neutron Background

109 neutrons/day pass through near detectors

CC measurements = bgd freeneutron bgds greatly suppressed for t > ~1

s after start of beam spill production is governed by lifetime (~2.2

s )

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Near Detector Rates

Segmented (10 ton fiducial mass)Iron = 3200 CC/yearLead = 14,000Al = 3,100

HomogeneousCarbon = 1,000Oxygen = 450

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Minos

98.0ionNormalizat

syst) (stat 00.12sin

eV10syst) (stat 74.2m

13.0232

2344.026.0

232

=+=

×+=

−

−+−

120 GeV proton beamGraphite target2 movable horns1.27x1020 POTNext up : e osc search

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MINERAPlaced in NuMi beamline,

directly upstream of MinosSegmented solid

scintillator detector, use Minos as det

C, Fe, Pb targetsQuasi-Elastic Q2, CC

Coherent prod. at very high E (6, 20 GeV)

Construction complete by 2009

4 yr run plan

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NOA

Off-Axis detector Near & Far Detectors

Documents

The Future of Neutrino Physics in a Post-MiniBooNE Era