Neutrino Physics - Lecture 5 Steve Elliott LANL Staff Member UNM Adjunct Professor 505-665-0068,...

Neutrino Physics - Lecture 5

Steve Elliott

LANL Staff Member

UNM Adjunct Professor

505-665-0068, [email protected]

Spring 2007 Steve Elliott, UNM Seminar Series

2

Lecture 5 Outline

• Finish Solar Neutrinos

• Neutrinos from the AtmosphereThe neutrinos

Past experiments

What we know and what we want to learn


3

The hierarchy questionN

orm

al

Inve

rted


4

The “Dark Side” of solar neutrinos

€

νe (t)

ν μ+τ (t)

⎛

⎝ ⎜

⎞

⎠ ⎟=

cosθ sinθ

−sinθ cosθ

⎛

⎝ ⎜

⎞

⎠ ⎟ν 1(t)

ν 2 (t)

⎛

⎝ ⎜

⎞

⎠ ⎟

Two “flavors” are involved in solar neutrino oscillations. νe and a linear combination of ν and ν.

€

P(ν e → ν e ) = 1− sin2 2θ sin2 1.27δm2

ER

⎛

⎝ ⎜

⎞

⎠ ⎟


5

The “Dark Side” of solar neutrinos II

For </4, ν1 is mostly νe. But for ’ =/2 - /4, ν1 is mostly ν+. Thus, although oscillations in a vacuum cannot distinguish between and ’, matter oscillations can.

€

P(ν e → ν e ) = 1− sin2 2θ sin2 1.27δm2

ER

⎛

⎝ ⎜

⎞

⎠ ⎟

€

sin2 2θm =sin2 2θ

sin2 2θ + (LL0

− cos2θ )2That is cos2 changes sign.


6

Solar Neutrino Results

there is no dark side

Early fit to solar neutrino data. Note solution space for tan>1.

Ph

ys.L

ett.

B49

0 (2

000)

125


7

The addition of KamLAND


8


9

What’s left to do?

• Is our model of neutrino mixing and oscillation complete, or are there other mechanisms at work?– Without luminosity constraint, pp and 7Be fluxes poorly

known.– With constraint, 7Be is still poorly known.

• Is nuclear fusion the only source of the Sun’s energy and is it steady state?

• What is the correct hierarchial ordering of the neutrino masses?


10

Non-Standard Interactions and New Properties

• Do neutrinos have non-standard interactions?• Are there unexpected properties?• Non-standard interactions of neutrinos with

matter would lead to modifications of matter effects in oscillations.

• NSI on order of 10-30% of SM weak interaction are possible and compatible with accelerator and oscillation data.

• Such large effects would affect solar neutrino data. Since NSI must mimic SM behavior in the matter dominated region, but be small in the vacuum region, the transition region is a good place to look.


11

The Vacuum-matter transition

This classic LMA oscillation probability curve might be altered by NSI.

Vacuum Matter

Abo

ut2

MeV

hep

-ph

/030

5159


12

Future Solar Neutrino Experiments

Experiment Target Reaction Threshold

Borexino ~300 t liq. Scint. ES ~250 keV

KamLAND ~600 t liq scint. ES ~250 keV

LENS 60 t In load in scint

CC

HERON 68 m3 LHe ES ~45 keV

CLEAN 40 t liq. Ne ES ~35 keV

MOON Few t of 100Mo CC 168 keV


13

Future Experiments


14

Atmospheric NeutrinosUp vs. Down

atmosphere

Detector

Primary

Cosmic Ray

~20 km

~10000 km

€

+ → + +ν

↓

→ e+ + ν e + ν μ

€

Expect Rμ / e =ν μ + ν μ

ν e + ν e≈ 2

Meas.Rμ / edata

Rμ / e MC

≈ 0.6 − 0.7


15

IMB and Kamiokande• Previous large water Cherenkov detectors• Built to look for proton decay, atmospheric

neutrinos are a significant background: hence lots of study

• Kamiokande was able to lower threshold to see solar neutrinos

• Saw SN1987A, but not pdk• Statistically weak indication of atmospheric

neutrino oscillations• Led to plan for Very Large SuperK


16

SuperK

• 1000 m underground

• 50,000 tons of water

• 12,000 pmts


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Results


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L/E analysis (Ishitsuka: NOON 2004)


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L/E results


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Maximal mixing and the future

If sin213 is different than 0, Earth matter effects can resonantly enhance the subdominate transitions depending on the sign of m23

2.


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Future Experiments

Experiment Target Status

SuperK 50 kt water Continue on

SNO 1 kt heavy water Just completed

MINOS Iron magnetized calorimeter

Operating

INO 30-50kt magnetized tracking calorimeter

proposal

UNO/HyperK Mt class water proposal


22

SNO is “small” but deep

Neutrino Physics - Lecture 5 Steve Elliott LANL Staff Member UNM Adjunct Professor 505-665-0068,...

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