solar neutrinos: the puzzle, its resolution prof. tim chupp 03 july 1991: 10Å ca-k image source:...

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Solar Neutrinos: The Puzzle, its Resolution

Prof. Tim Chupp

03 July 1991: 10Å Ca-K Image

Source: National Solar Observatory (J. Harvey)

Fall 2004 Physics Phact Quiz

A. Along with protons, one of the components of the nucleus

B. The antiparticles of the electron

C. Neutral subatomic particles emitted in radioactive decay

D. Small fruit flavored candies

What are neutrinos?

A. Along with protons, one of the components of the nucleus

B. The antiparticles of the electron

C. Neutral subatomic particles emitted in radioactive decay

D. Small fruit flavored candies

What are neutrinos?

Fall 2004 Physics Phact Quiz

The Neutrino Postulate

By the 1920's, radioactivity was recognized as the emission ofparticles of several forms called alpha (), beta (), and gamma ().

Radium Source

Magnetic FieldInto Page

• 's are electrons emitted when a nucleus changes charge: e.g. 14C __> 14N + e-

6 7

• Energy conservation: [m(14C) - m(14N)]c2 = Q = KEe+KER

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

M. Curie


P. Curie


Becquerel

• Momentum conservation:

pepR

electronrecoil nucleus

pe ≈ ___ √ 1+2mc2/Q

Electron momentum fixed by Q

Qc

photos from www.nobel.se

counts

momentum

pe ≈ ___ √ 1+2mc2/Q

Electron momentum fixed by Q

Qc

To rescue momentum and energy conservation, a new particle was invented:

• neutral• undetectable

• negligible mass• spin 1/2

The NEUTRINOlittle neutral one


Enrico Fermi


Wolfg. Pauli

hypothesized worked it out

Address to Group on Radioactivity

Tubingen

Theory of Beta Decay

" photos from www.nobel.se

Neutrino InteractionsBeta decay: 14C __> 14N + e- + 14O __> 14N + e+ +

mc2

14N

14O14C

5730 y

70 s

Capture: + p __> n + e+ + 37Cl __> 37Ar + e-

(inverse beta-decay)

Electron capture: 203Pb + e- __> 203Tl +

Particle Decays: __> e± + __> e± + etc.

Neutrino Scattering : e-

p

Neutrino Detection:Thirty Years after the neutrino was postulated free neutrinos

were detected by Fred Reines and Clyde Cowan

+ p __> n + e+

They needed a source of neutrinos: nuclear explosion? reactor



Photo: Univ. California Irvine



Hanford, WaH2O + 108Cd

n+108Cd __> 109Cd + e++e- __> + (0.511 MeV)e.g. PET imaging

200 liter

1014 n/s

(one in 10-18; < 1/hour)

underground at Savannah River

There are six kinds of neutrino

14C __> 14N + e- + 14O __> 14N + e+ +

antineutrino neutrino comes with electron comes with positron

ee

__> ± + __> e± + Neutrinos produced by π-decay DO NOT interact with protons

e

Tau/ discovered by Marty Perl (Michigan Professor 1955-63)


Perl shared the1995 Nobel Prize

with ReinesQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

I.I. Rabi on the muon:"Who ordered that?"

photos from www.nobel.se

Flavor Conservation

e <__> e- e <__> e+

µ <__> µ- µ <__> µ+

<__> - <__> +

Charged currents

pnD Deuterium BreakupNeutral currents

Neutrinos:

• Produced in weak interactions (p <__> n)

• Hardly interact at all: 4x10-19/meter H2O

• Hard to detect

• Neutrino interactions conserve flavor (e, µ, )

• Very small mass (m = 0 ?)



The SunM = 1.99x1030 kg R = 6.96x108 m

Tsurface = 6420 K; Tcore = 15.5x106 K

L = 3.9x1026 Watts

Provided by Hydrogen Fusion

4(1H) _> 4He + 2(e+) + 2(e) + 26.72 MeV

L = 1.8 x1038 /sec

Intensity@Earth: 6.3x1014/m2/s

only 100x less than Reine's reactor flux



Standard Solar Model1. Spherical

2. stable hydrostatic equilibrium

3. Gas pressure (outward) balances gravity (inward)

dP(r)/dr = -[4πG(r)/r2] ∫(r') dr'

4. 4.6 B years old and evolving

5. Surface abundances (H, He, Li...) constant

6. Luminosity = fusion rate in core currently



Opacity

The sun is OPAQUE to photons produced in the core.

Photons make random walks from the sun's core to the surface

Rapidly "thermalize" and take thousands of Years to reach surface (convection)

Only Neutrinos can tell directly us what's happening NOW in the Sun's core

Hydrogen Fusion in the Sun

1H+1H __> 2H + e+ + e or 1H + e - __> 2H + e++ e

(E< 0.42 MeV) (E= 1.44 MeV)

1H+2H __> 3He

86% 3He + 3He __> 4He + 2 1H or14% 3He + 4He __> 7Be +

7Be + e- __> 7Li + e

(E= 0.38; 0.86 MeV)

or0.02% 1H + 7Be __> 8B +

7Li +1H __> 2 4He

__> 8Be + e+ + e

(E< 14 MeV)

4(1H) _> 4He + 2(e+) + 2(e) + 26.72 MeV

*

__> 2 4He

99.75%

Also some CNO-cycle (Hans Bethe)

0.25%

Solar neutrino spectrum

Detecting Solar Neutrinos + 37Cl __> 37Ar + e-

• Lots of chlorine (24% 37Cl)

• E > 0.81 MeV

mc2(37Ar) > mc2(37Cl)

• Deep underground 1500 meters (to reduce cosmic ray background)

• Remove and detect 37Ar (t1/2=35 days): 37Ar + e- __> 37Cl* +

• Expected rate: 0ne 37Ar every six days in 610 tons C2Cl4 (tertrachlorehtelyene)

Bruno Pontecorvo, Louis Alvarez, Ray Davis, John Bachall

Ray Davis

+ 37Cl __> 37Ar + e-

IMPOSSIBLE IS NOTHING

convinced Maurice Goldhaber,director of Brookhaven Nat. Labto support experiment:





installed 100,000 gallon C2Cl4 tank in Homestake Goldmine,Lead, SD: BR reduced from 10000 to 0.1 per day

≈ 5 37Ar atoms were extracted per MONTH: bubbling helium through tank

radioactive 37Ar detected with high efficiency



from Brookhaven National Lab

37Cl Solar Neutrino Results

"The Solar Neutrino Problem"

1 SNU = 1 capture/sec/1036 atoms

Puzzle

3 years to 1976

All data to 19802.2 ± 0.4 SNU

Current Theory7.5±1.5 SNU

Is Ray Davis wrong?

• argon atoms added before each extraction: 95% extraction efficiency in 24 hours

• added C2Cl4 with 36Cl to show argon is not trapped 36Cl __> 36Ar + e+ +

• added 500 37Ar atoms to detector and later extracted

• produced 37Ar in detector with a neutron source:37Cl+n __> 37S+p p+37Cl __> 37Ar + n

Extensive Calibrations:

Is the neutrino physics wrong?

e + 37Cl __> 37Ar + e+

• 37Ar __> 37Cl + e+ + e well studied

• BUT no direct calibration

in detector

in the sun

Hydrogen Fusion in the Sun

1H+1H __> 2H + e+ + e or 1H + e - __> 2H + e++ e

(E< 0.42 MeV) (E= 1.44 MeV)

1H+2H __> 3He

86% 3He + 3He __> 4He + 2 1H or14% 3He + 4He __> 7Be +

7Be + e- __> 7Li + e

(E= 0.38; 0.86 MeV)

or0.02% 1H + 7Be __> 8B +

7Li +1H __> 2 4He

__> 8Be + e+ + e

(E< 14 MeV)

4(1H) _> 4He + 2(e+) + 2(e) + 26.72 MeV

*

__> 2 4He

99.75% 0.25%

Every Few Years

The Solar Neutrino Problem Persisted

Is the Standard Solar Model Wrong?

Is 10,000 years all the time we've got?

Is the sun Cooling?

8B neutrino rate depends strongly on core temperature: T13

A 10,000 K temperature difference could do it.

This is too large to explain the current sun in equilibrium



John Bachall

Solar Physics results are very consistent

Solar Oscillations show speed of sound

Davis and Bachall stand bytheir respective results

Low Energy Neutrinos: Less Model Dependent71Ga + __> 71Ga + e-

Soviet-American Gallium Experiment"SAGE"

Gallex: Gran Sasso TunnelItaly

Deficit of Solar Neutrinos Confirmed: ≈2/3 expected

Directly calibrated with source

Cerenkov Detectors



http://www.aerospaceweb.org/question/aerodynamics/q0074.shtml

When v > ___ a "shock wave" results. cn

index of refraction (4/3 for water)

Hit

Hit

Rings of hits identify direction/energy

electron from neutrino interaction

Cerenkov Detectors

earlier

later Detectors

IMB - The very first



Designed to detectproton decay (p__>π0e+)



2.5 million gallons H2O

2048 phototubes

from University of Michigan: J.A. vanderVelde





SN1987a: 170,000 LY away

8 events detected by IMB

Set limit on me

e + p __> n + e+

from University of Michigan: J.A. vanderVelde

Cernekov Detectors: Energy and direction

e + e- __> e + e-



Kamiokande/Super-KQuickTime™ and aTIFF (Uncompressed) decompressor




Photo: Kamioka Observatory, ICRR (Institute for Cosmic Ray Research), The University of Tokyo

e + e- __> e + e-



SNO-Sudbury Neutrino Observatory




Photo courtesy of SNO

e

e

pn

D

Neutral Current Deuterium BreakupMeasures ALL neutrino types

Solar Neutrinos

e

x

e+D__> p+p+e-

x+D__> p+n+x

x + e-__> x + e-

SK

SNOSNO

SNO}

It's the neutrinos


are needed to see this picture. QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

for each e produced in the Sun.................0.5 e detected at the Earth

what happens in between?

Neutrino Oscillations

Bruno Pontecorvo

Neutrino Quantum MechanicsQuantum systems have DISCRETE STATES/QUANTUM LEVELS

Atom

1

2Nucleus

1

2

spin up

NMR

spin down

neutron

E=mc2

proton

e.g. two state systems

1

2




4Ehm2c

e = ___ (1 + 2)1

√2 e= ______ Probability of e oscillates

x = ___ (1 - 2)1

√2

1= _____hcE1

2= _____hcE2

Neutrino Waves

Diffraction

All points on edge are sources

Double Slit: Feynman's Favorite 2-state system



screen measures (E1+E2)2

E1+ E2

e

E1 E2




E1- E2

x

Interference due to path-lengthdifference

Matter - Enhanced Oscillations - MSW



E1 E2

E1+ E2




E1- E2

matter increases m

Mikheyev, Smirnov, Wolfenstein: enhanced neutrino oscillations

Reactor Searches

reactor

e detector

m2=5.5x10-5 eV2

Kamland collaboration

Accelerator Searches - what is x?

m2=5.5x10-5 eV2

e= ___ (1+2)

µ __>

e

1√2

m2 large!

e= sin 1+ cos 2

Atmospheric neutrinos show µ __> e

LSND collaboration

SummaryQuickTime™ and a

TIFF (Uncompressed) decompressorare needed to see this picture.

The standard solar model works exceedingly well.Our understanding of the sun is essential to all ofstellar evolution from star formation to supernovae

8B solar neutrino flux is consistent with SSM

e __> x oscillations: neutrino quantum mechanicsQu ic k T im e ™ a nd a

T IF F (Unc o m pre s s e d ) de c o m pre s s o ra re ne e de d to s e e th is p ic tu re .


e __> reactor neutrinos oscillate too

µ __> evidence: atmospheric 's; accelerator (large m2)


are needed to see this picture. They got it rightQuickTime™ and aTIFF (Uncompressed) decompressor


Davis Bachall

But there's a lot left to do...

What's Next?• What is x (what are 1, 2, 3)?

Accelerator oscillation experiments with long baselineMeasure e-µ; e-; µ-

• Measure m2 and sin2 better

• Precision solar neutrino spectroscopy

• Double beta decay (e __> e oscillations)

• Cosmic neutrino detectorsAMANDA: Cerenkov detector in Antarctic iceANTARES: Cerenkov detector deep underwater

• Particle Physics of neutrino mixing - Beyond the Standard Model

solar neutrinos: the puzzle, its resolution prof. tim chupp 03 july 1991: 10Å ca-k image source:...

Documents

n e n

n e n

n e n p

e n nneutrinos

flavor e

pb e

weak interactions p

cd ge e