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Gianni FiorentiniGianni Fiorentini

Solar NeutrinosSolar Neutrinos

• The previous millenium: e disappearance

• SNO: An appearance experimentAn appearance experiment • Solar neutrinos undergo flavor conversion e -> ( or

• Non e are the main component of the flux at E >5 MeV

• Main issue: mechanism of conversion?• What have we learnt on the Sun ?• What can we learn from neutrinos ?

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The 2002 Nobel prize:The 2002 Nobel prize:new ways of looking at the skynew ways of looking at the sky

Riccardo Giacconi“for pioneering contributions to astrophysics, which have led to the discovery of cosmic X-ray sources"

Ray Davis and Masatoshi KoshibaRay Davis and Masatoshi Koshiba

““for pioneering contributions to astrophysics, for pioneering contributions to astrophysics, in particular for the detection of cosmic in particular for the detection of cosmic neutrinos”neutrinos”

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Davis: a formidable Davis: a formidable

radiochemical experimentradiochemical experiment

•Since 1970 Davis has been looking for solar ee by means of the Pontecorvo reaction:

ee+ + 3737Cl -> Cl -> 3737Ar + eAr + e•Collect for one month Ar atoms, extract them and look for their decay: 3737Ar + e ->Ar + e ->ee+ + 3737ClCl•Expt. sensitive only to e, mainly from B,and to a smaller extent from Be.•The signal of neutrinos was observed, however: - Cl(exp)= 1/3 Cl (SSM)Cl(exp)= 1/3 Cl (SSM)- No directionality- No real time- (Signal possibly correlated with “11 years” solar cycle)

< pp >Be

< B >

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Neutrino telescopes:Neutrino telescopes:Kamiokande and Kamiokande and SuperkamiokandeSuperkamiokande

•Koshiba and his school have developed directionaldirectional and real timereal time -detectors:•Study of elastic collisions of with electrons in a huge water tank+ e(at rest) -> + e( moving)

•Electron direction is strongly correlated with that of neutrinos ((-telescope).-telescope).•Electrons are detected by means of the emitted Cerenkov light in water.•The energy spectrum of electrons can be measured.•Sensitive to e with E>6MeV (B only) • also detected (= = 1/6 e) but cannot be distinguished from e

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SuperkamiokandeSuperkamiokande(20,000m(20,000m33 water detector water detector with 10,000 phototubes)with 10,000 phototubes)

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The heart of Kam. The heart of Kam. and SuperKam.and SuperKam.

•It is in the =50 cm phototubes especially developed by Hamamatsu.

•MITI financed a joint R&D project betweenHamamatsu and the Metropolitan Tokyo University.

•As a return, Japan has a got a Nobel prize and the world leader for phototube production.

50 cm50 cm

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The results of Kamiokande The results of Kamiokande and SuperKamiokandeand SuperKamiokande

Sun ->

•Neutrinos do comedo come from the Sun•Neutrino disappearance is confirmed:•SK(exp)= 0.45 SK(SSM)SK(exp)= 0.45 SK(SSM)•The B-neutrino spectrum looks undistorted•Seasonal variations consistent with geometry•No day-night variation observed, at the % level•No apparent correlation with the solar cycle

•Why is the SK signal higher than Davis? •The two expts become consistent with each other and with SSM if some 2/3 of Borone-> or ) (Villante Lisi GF 98). •An experiment is needed which can distinguish ( or ) from e.

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The Gallium experimentsThe Gallium experiments•Gallex (now GNO) at LNGS and SAGE in Russia have shown that the Sun is powered by nuclear reactionspowered by nuclear reactions, measuring (mainly) the pp and Be neutrinos by means of:

e+ 71Ga-> e + 71Ge

•A radiochemical method is used.•Again a deficit with respect to SSM:•Ga(exp) =(0.59 +-0.06)Ga(SSM)• Important deficit since predictions Important deficit since predictions on pp and Be are much more robust.on pp and Be are much more robust.•Cannot separate the amount of (pp) and (Be).

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Disappearance vs. AppearanceDisappearance vs. Appearance

??

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SNO: SNO: the appearance experimentthe appearance experimentA 1000 tons heavyheavy water detector sensitive to B-neutrinos by means of:

•CC: CC: ee+d -> p + p + e+d -> p + p + esensitive to e only, provides agood measurement of e spectrum,weak directionality

•NC: NC: xx+d -> p + n + +d -> p + n + xx

Equal cross section for allall flavours.Measures total 8B flux from Sun.

•ES: ES: xx+e -> e + +e -> e + xx

Mainly sensitive to e, strong directionality

The important point is that SNO can determine both: (e) andand (e + + )

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SNO resultsSNO results

•Total measured B-flux is in excellent agreement with SSM

•2/3 of produced B-neutrinos transform into or .

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Implications for neutrinosImplications for neutrinos

Neutrino Energy (MeV)

< P ee

>

•From exp.tal rates one can deduce the energy dependence of the survival probability Pee:

•SNO&SK give Boron: PPeeee(E>5MeV) (E>5MeV) 1/ 31/ 3

•Cl- SNO&SK -> Be+CNO:PPeeee(0.8<E<5MeV) (0.8<E<5MeV) 0.2-0.50.2-0.5

• Ga-Cl- SNO&SK -> pp:PPeeee(0.2<E<0.4MeV) (0.2<E<0.4MeV) 3/43/4

•Energy dependence is found.•Be is worst determined (wait for Borexino)

•Complete analysis include all other observables (spectra, day/night, seasonal variations…),see e.g Fogli@Lisi, Smirnov, Bahcall...

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Neutrino oscillationsNeutrino oscillations•The total 81 data are well fitted within the simplest scheme of oscillations between two active neutrinos•The best fit is provided by the LMA solution, with:mm22= 6.2 10= 6.2 10-5-5 eV eV22

tantan22 = 0.4 = 0.4ffBB=1.06 =1.06

•The energy dependence (and large suppression) is related to matter effect in the Sun.•Other oscillation solutions (SMA, Just-So,LOW, sterile…) are presently disfavoured by data.

Warning: oscillations are sensitive to mass differencesdifferences, not to the absolute mass scalescale.

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Crucial predictions of the LMA solutionCrucial predictions of the LMA solution

Earth matter effect. So far 1 effect in SK and 2 in SNO.It needs time…..

NC/CCNC/CC Day/night asymmetry %Day/night asymmetry %

SNO will get significant improvement on NC in near future, by adding salts with large n-absorption x-section.

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Kamland: a crucial test Kamland: a crucial test of the LMA solutionof the LMA solution

•If LMA is the solution, the oscillation length of MeV (anti) neutrinos is L100 Km.•Kamland, an 800 ton scintillator detector, is measuring events from a dozen reactors, through:anti- + p ->e+ +n n+p->d+•In the absence of oscillation, some 400ev/yr are expected (above geo-)

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Oscillations or what else?Oscillations or what else?

•Kamland is a crucial test for the LMA solution, which predicts a large reduction of reactor events.

•Remind that other solutions are possible for the solar neutrinos, e.g:

•Spin-flavour transitions, induced by the solar magnetic field (Okun, Akhmedov. ..)

•Hypothetical flavour changing interactions, inside the sun (Wolfenstein)

•Both these explanations predict a null effect for Kamland

SFT

FCI

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Neutrons and neutrinosNeutrons and neutrinos

•In 1940 Pontecorvo applied the recent slow neutron studies of the Rome group to invent the neutron well logneutron well log, an instrument still used for oil (and water) prospection.

•Now that we have learnt enough on neutrinos, we have to learn from neutrinos

The Oil And Gas Journal, 1940, p.32

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Implications for the SunImplications for the Sun•Boron neutrinos are a probe of the deep solar core, their production being peaked at .05Ro.•Their flux depends on nuclear physics inputs (branches of ppI, ppII and ppIII) and on astrophysical inputs (Z/X, opacity, diffusion, luminosity).•These latter control the central central temperaturetemperature T :(B) =(B)SSM (T/TSSM)2020 (S/SSSM)•Due to high power dependence, (B) is a good thermometer for the solar interior, if nuclear physics (S=S33s34

-0.5 SS1717Se7-1) is well

determined.

•From present data:T=15.7(1+-1%)10T=15.7(1+-1%)1066KK

•Comparable errors arise from (B) and S17(after LUNA measurements at LNGS)•Observational accuracy comparable to that of SSM.•Information complementary to helioseismology, which determines u =T/.

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Bruno PontecorvoBruno Pontecorvo

Three great ideas:

i)The Sun as a neutrino source

ii) The Cl-Ar method

iii)Neutrino oscillations

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The success of SSM and helioseismologyThe success of SSM and helioseismology

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1BP2000

U/U

(Model-Sun)/Model

Model=BP2000

Sun=from inversionof helioseismic data

Error estimate: from Dziembowki et al. Astrop. Phys. 7 (1997) 77

Agreement to the level of few in 10-3.Systematic errors from the inversion procedure dominate accuracy (starting solar models, interpolation…)

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LUNA at LNGSLUNA at LNGS

Laboratory for Underground Nuclear Astrophysics at Gran Sasso.

LUNA-I has measured the 3He+3He->4He +2p at the solar Gamow peak, by using a 50 KV undergroundaccelerator at LNGD

LUNA-II is measuring the p+14N->15O + reaction, with a new200 KV accelerator

A new measurement of p-7Beis planned.

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(Anti)- neutrinos from Earth(Anti)- neutrinos from Earth

•What is the content of radioactive material (U, Th and K) inside Earth?•What is the radiogenic contribution to heat flow? •Detection of (anti) neutrinos neutrinos produced in the Earth interiorproduced in the Earth interior is the way for measuring Earth radioactivity, once we know the fate of neutrinos.

•This is becoming possible now...

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Expectations for Expectations for Kamland and Kamland and BorexinoBorexino

Signal energy [MeV]Signal energy [MeV]

•(anti)-+p-> n+e+

•e+ releases energy and annihilates:S.E.=E(e+) + 2me

•Delayed coincidence with 2MeV from p+n->d+.•Separation from reactor events.• -osc. give 1/2 reduction

24Detectors built for studying neutrinos from reactors and Sun,will also have the first signal of anti neutrinos from Earth..

From Sun to Earth:From Sun to Earth:Kamland (Jap) and Borexino (LNGS)Kamland (Jap) and Borexino (LNGS)

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A few references…*)A few references…*)•Recent Data:SNO: Ahmad et al nucl- ex/204009SK: Fukuda et al hep-ex/0205075

•Recent analysis :Fogli et al, hep-ph/0106247 + 0203138+ 0206162Barger et al hep-ph/0204253Bahcall et al hep=ph/024314Berezinsky and LisiDe Holanda and Smirnov hep-ph/0205241

•See also transparencies of Neutrino 2002, Munich athttp://neutrino2002.ph.tum.de

*)and a lot of apologies for missing references

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AppendixAppendix

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pp-chainpppp--chainchain

99,77%

p + p d+ e+ + eE 0,42 MeV

0,23%

p + e - + p d + eE = 1,44 MeV

3He + 3He + 2p

S(0)=(5,4 0,4) MeVb

3He + p + e+ + e

E 18 MeV

~210-5 %84,7%

13,8%

0,02%13,78%

3He + 4He 7Be + S(0)=(0,52 0,02) KeV b

7Be + e- 7Li + + e

E 0,86 MeV

7Be + p 8B +

d + p 3He +

7Li + p +

pppp I I pppp III III pppp II II hep hep

8B 8Be*+ e+ +e 2

E 14,06 MeV

S(0)=(4,000,068)10-22 KeV b

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AppendixAppendix

Neutrino Energy (MeV)

Neu

trin

o flu

x

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Uncertainties on B and Be productionUncertainties on B and Be production

Source 8B 7Be___________________________p-p 0.04 0.023He+3He 0.02 0.023He+4He 0.08 0.08p+7Be +0.14-0.07 0Comp. 0.08 0.03Opacity 0.05 0.03Diffusion 0.04 0.02Luminosity 0.03 0.01

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Energy dependence of different oscillationsEnergy dependence of different oscillations

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Summary of ocillation solutionsSummary of ocillation solutions

SolutionSolution mm22(eV)(eV)22 tan2tan22/d.o.f.

LMA 5.5E-5 0.42 71.3/79LOW 7.3E-8 0.67 79.7/79QVO 6.5E-10 1.33 74.9/79SMA 5.2E-6 1.1E-3 83.1/79

Fogli et al hep-ph0206162Fogli et al hep-ph0206162

LMA gives a good fit, LOW and VO survive at 3, SMA is excluded at 5

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Pull off diagramsPull off diagrams

P de Hollanda and SmirnovP de Hollanda and Smirnov

LMA gives a good fit, LOW and VO survive at 3, SMA is excluded at 5

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Spin flavor precession*Spin flavor precession*•Transitions Transitions ee-> anti- -> anti- mm could could be driven by solar magnetic field be driven by solar magnetic field if neutrino has a transition if neutrino has a transition magnetic moment magnetic moment ..

•Can reconcile strong Can reconcile strong suppression at intermediate suppression at intermediate energy (Be) with no distortion at energy (Be) with no distortion at high energy ( B)high energy ( B)

•Consistent with data provided:Consistent with data provided:-- = (0.3-1)10 = (0.3-1)10-11-11 BB

-B-Bmaxmax= 10= 1055 G G-Suitable B(r) profile-Suitable B(r) profile*)*)Lim, Marciano, Akhmedov, Valle, Miranda..Lim, Marciano, Akhmedov, Valle, Miranda..

RSF