1 Neutrino: a spy of the innermost solar interior Nuclear reactions in the Sun and solar neutrinos

2 The spy of nuclear reactions in the Sun The real proof of the occurrence of nuclear processes is in the detection of reaction products (holds for Sun & Earth)The real proof of the occurrence of nuclear processes is in the detection of reaction products (holds for Sun & Earth) For the Sun, only neutrinos can escape freely from the production region.For the Sun, only neutrinos can escape freely from the production region. By measuring solar neutrinos one can learn about the deep solar interior (and about neutrinos…)By measuring solar neutrinos one can learn about the deep solar interior (and about neutrinos…)

3 The luminosity constraint The total neutrino flux is immediately derived from the solar constant K o :The total neutrino flux is immediately derived from the solar constant K o : If one assumes that Sun is powered by transforming H into He (Q=26,73MeV):If one assumes that Sun is powered by transforming H into He (Q=26,73MeV): 4p+2e - -> 4He + ? Then one has 2 e for each Q of radiated energy, and the total neutrino produced flux is:Then one has 2 e for each Q of radiated energy, and the total neutrino produced flux is: if L and L e are conserved = if L and L e are conserved 2 e ?

4 Towards neutrino energy spectra To determine  tot we did not use anything about nuclear reactions and solar models.To determine  tot we did not use anything about nuclear reactions and solar models. In order to determine the components (  pp,  Be  B …)one has to know the relative efficiencies of nuclear reactions in the Sun (branches ppi/ppII/ppIII…)In order to determine the components (  pp,  Be  B …)one has to know the relative efficiencies of nuclear reactions in the Sun (branches ppi/ppII/ppIII…)

5 The pp-chain 99,77% p + p  d+ e + + e 0,23% p + e - + p  d + e 3 He+ 3 He  +2p 3 He+p  +e + + e ~2  %84,7% 13,8% 0,02%13,78% 3 He + 4 He  7 Be +  7 Be + e -  7 Li + e 7 Be + p  8 B +  d + p  3 He +  7 Li + p ->  +  pp I pp III pp II hep hep 8 B  8 Be*+ e + + e 2 

6 A group picture Neutrino Energy [Mev] Neutrino flux [cm -2 s -1 ]

7 Another group picture The production region of neutrinos

8 A 40 year long journey In 1963 J Bahcall and R Davis, based on ideas from Bruno Pontecorvo, started an exploration of the Sun by means of solar neutrinos.In 1963 J Bahcall and R Davis, based on ideas from Bruno Pontecorvo, started an exploration of the Sun by means of solar neutrinos. Their trip had a long detour, generating the “solar neutrino puzzle”Their trip had a long detour, generating the “solar neutrino puzzle” All experiments, performed at Homestake, Kamioka, Gran Sasso and Baksan exploring different portions of the solar spectrum, presented a deficit of e.All experiments, performed at Homestake, Kamioka, Gran Sasso and Baksan exploring different portions of the solar spectrum, presented a deficit of e. Were all experiments wrong?Were all experiments wrong? Was the SSM wrong?Was the SSM wrong? Was nuclear physics wrong?Was nuclear physics wrong? Or did something happen to neutrinos during their trip from Sun to Earth?Or did something happen to neutrinos during their trip from Sun to Earth?

9 Disappearance vs. Appearance ?

10 SNO: the appearance experiment A 1000 tons heavy water detector sensitive to B-neutrinos by means of: CC: e +d -> p + p + e CC: e +d -> p + p + e sensitive to e only, provides a good measurement of e spectrum with weak directionality NC: x +d -> p + n + x NC: x +d -> p + n + x all Equal cross section for all flavors. It measures the total 8 B flux from Sun. ES: x +e -> e + x ES: x +e -> e + x Mainly sensitive to e, strong directionality. The important point is that SNO can determine both:  ( e ) and  ( e +  +  )

11 SNO results The measured total B neutrino flux is in excellent agreement with the SSM prediction. Only 1/3 of the B-neutrinos survive as e 2/3 of the produced transform into  or  SSM & N.P are rightSSM & N.P are right All experiments are rightAll experiments are right Neutrinos are wrongNeutrinos are wrong

12 From Sun to Earth: The KamLAND confirmation anti- e from distant (  100 km) nuclear reactors are detected in 1Kton liquid scintillator where: Anti  e +p -> n + e + n + p -> d +  Obs./Expected= 54/ ( ) Oscillation of reactor anti- e proven -> Oscillation of reactor anti- e proven - > SNO is confirmed with man made (anti)neutrinos

13 The impact of SNO and KamLAND BeforeSNO AfterSNO-I AfterKamLAND AfterSNO-II

14 Bruno Pontecorvo The Cl-Ar method Neutrino sources (sun, reactors, accelerators) Neutrino oscillations Neutron Well LoggingA New Geological Method Based on Nuclear Physics Neutron Well Logging - A New Geological Method Based on Nuclear Physics, Oil and Gas Journal, 1941, vol.40, p An application of Rome celebrated study on slow neutrons, the neutron log is an instrument sensitive to water and hydrocarbons. It contains a (MeV) neutron source and a (thermal) neutron detector. As hydrogen atoms are by far the most effective in the slowing down of neutrons, the distribution of the neutrons at the time of detection is primarily determined by the hydrogen concentration, i.e. water and hydrocarbons.

15 From neutrons to neutrinos We have learnt a lot on neutrinos. Their survival/transmutation probabilities in matter are now understood. We have still a lot to learn for a precise description of the mass matrix (and other neutrino properties…) Now that we know the fate of neutrinos, we can learn a lot from neutrinos.Now that we know the fate of neutrinos, we can learn a lot from neutrinos.

16 What next? Neutrinos and Supernovae Neutrino contribution to DM Neutrinos and the Earth Neutrinos and the Sun

17 The measured boron flux The total active    ( e +  +   boron flux is now a measured quantity. By combining all observational data one has:   = 5.5 (1 ± 7%) 10 6 cm -2 s -1. The central value is in good agreement with the SSM calculation present   /   =7%Note the present 1  error is   /   =7% next few years   /    3%In the next few years one can expect to reach   /    3% BP2000 C FRANECGARSOM   [10 6 s -1 cm -2 ]

18 s 33 s 34 s 17 s e7 s pp Nuclear The Boron Flux, Nuclear Physics and Astrophysics nuclear physics   depends on nuclear physics and astrophysics inputs Scaling laws have been found numerically* and are physically understood s s s 17 1 s e7 -1 s pp -2.7   =   (SSM) · s s s 17 1 s e7 -1 s pp -2.7 com 1.4 opa 2.6 dif 0.34 lum 7.2 · com 1.4 opa 2.6 dif 0.34 lum 7.2 These give flux variation with respect to the SSM calculation when the input X is changed by x = X/X (SSM). Can learn astrophysics if nuclear physics is known well enough.  astro * Scaling laws derived from FRANEC models including diffusion. Coefficients closer to those of Bahcall are obtained if diffusion is neglected.

19 Uncertainties budget Nuclear physics uncertainties, particularly on S 34, dominate over the present observational accuracy   /   =7%. The foreseeable accuracy   /   =3% could illuminate about solar physics if a significant improvement on S 34 is obtained. For fully exploiting the physics potential of a   measurement with 3% accuracy one has to determine S 17 and S 34 at the level of 3% or better. Source  X/X (1   /   (1  S330.06*0.03 S S17**0.05 ? **0.05 Se70.02 Spp Com Opa Dif Lum *LUNA gift ** See later

20 Progress on S 17 S 17 (0) [eV b] Ref. Adel.-Review RMP 70,1265 (1998) Nacre-Review 21 ± 2 NP 656A, 3 (1999) Hammache et al 18.8 ± 1.7 PRL 86, 3985 (2001) Strieder et al 18.4 ± 1.6 NPA 696, 219 (2001) Hass et al 20.3 ± 1.2 PLB 462, 237 (1999). Junghans et al ± 0.6 PRL 88, (2002)+ nucl exp Baby et al ± 0.7 PRL. 90, (2003) Results of direct capture expts**. JNB and myself have long been using a conservative uncertainty, however recently high accuracy determinations of S 17 have appeared. Average from low-energy (<425KeV) data of 5 recent determinations yields: S 17 (0)= 21.4 ± 0.5 with    dof=1.2 A theoretical error of ± 0.5 has to be added.A theoretical error of ± 0.5 has to be added. However all other expts. give somehow smaller S17 than Junghans et al. **See also Gialanella et al EPJ A7, 303 (2001) Note that indirect methods also give somehow smaller values In conclusion, it looks that aIn conclusion, it looks that a 5% accuracy has been reached.

21 Remark on S 17 and S 34 For a long time S 17 was the main uncertainty. S 17 (0)= 20.5 ± 1 eVbIf S 17 (0)= 20.5 ± 1 eVb a 5% accuracy has been reached. The 9% error of S 34 is the main source of uncertainty for extracting physics from Boron flux. LUNA measurement of S 34 will be extremely important. Source  S/S (1   /   S330.06*0.03 S S17** Se70.02 Spp Com Opa Dif0.10***0.03 Lum

22 Sensitivity to the central temperature Boron neutrinos are mainly determined by the central temperature, almost in the way we vary it. (The same holds for pp and Be neutrinos) Bahcall and Ulmer. ‘96  i /  i SSM B Be pp T/T SSM Castellani et al. ‘97

23 The central solar temperature The various inputs to   can be grouped according to their effect on the solar temperature. All nuclear inputs (but S 11 ) only determine branches ppI/ppII/ppIII without changing solar structure. The effect of the others can (largely) be reabsorbed into a variation of the “central” solar temperature: 20.   =   (SSM) [T /T (SSM) ] 20.. S s s 17 s e7 -1 Source dlnT/dlnS  dln  B /dlnS   S S S1701 Se70 Spp Com Opa Dif Lum (  20)Boron neutrinos are excellent solar thermometers due to their high (  20) power dependence.

24 Present and future for measuring T with B-neutrinos   /   =7%  S nuc / S nuc =At present,   /   =7% and  S nuc / S nuc = 10% (cons.) translate into  T/T= 0.6 % the main error being due to S 17 and S 34.  S nuc /S nuc =0If nuclear physics were perfect (  S nuc /S nuc =0) already now we could have:  T/T= 0.3 %   /   =3%When   /   =3% one can hope to reach (for  S nuc /S nuc =0) :  T/T= 0.15 %

25 The central solar temperature and helioseismology For the innermost part, neutrinos are now (  T/T = 0.6%) almost as accurate as helioseismology They can become more accurate than helioseismology in the future. Helioseismology determines sound speed. The accuracy on its square is  u/u  0.15% inside the sun. Accuracy of the helioseismic method degrades to 1% near the centre. Boron neutrinos provide a complementary information, as they measure T.  u/u 1  3  present  T/T future

26 The Sun as a laboratory for astrophysics and fundamental physics A measurement of the solar temperature near the center with 0.15% accuracy can be relevant for many purposes –It provides a new challenge to SSM calculations –It allows a determination of the metal content in the solar interior, which has important consequences on the history of the solar system (and on exo-solar systems) One can find constraints (surprises, or discoveries) on: –Axion emission from the Sun –The physics of extra dimensions (through Kaluza-Klein axion emission) –Dark matter (if trapped in the Sun it could change the solar temperature very near the center) – … BP-2000FRANECGAR-SOM T6T

27 CNO neutrinos, LUNA and the solar interior The principal error source is S 1,14. The new measurement by LUNA is obviously welcome.The principal error source is S 1,14. The new measurement by LUNA is obviously welcome. A measurement of the CNO neutrino fluxes would provide a stringent test of the theory of stellar evolution and unique information about the solar interior. Source  X/X (1  )   /    O /  O S S S Se Spp S1, Com Opa Dif Lum Solar model predictions for CNO neutrino fluxes are not precise because the CNO fusion reactions are not as well studied as the pp reactions.Solar model predictions for CNO neutrino fluxes are not precise because the CNO fusion reactions are not as well studied as the pp reactions. Also, the Coulomb barrier is higher for the CNO reactions, implying a greater sensitivity to details of the solar model.Also, the Coulomb barrier is higher for the CNO reactions, implying a greater sensitivity to details of the solar model.

28 Solar neutrino experiments and CNO cycle Solar neutrino experiments set an upper limit (3  ) of 7.8% to the fraction of energy that the Sun produces via the CNO fusion cycle. An order of magnitude improvement upon the previous limit. New experiments are required to detect CNO neutrinos and to proof that some 1% of the solar luminosity is generated by the CNO cycle. Bahcall, Garcia & Pena-Garay Astro-ph

29 Is the Sun fully powered by nuclear reactions? Are there additional energy sources beyond 4H->He?: Are there additional energy losses, beyond photons and neutrinos?Are there additional energy losses, beyond photons and neutrinos? One can determine the “nuclear luminosity” from measured neutrino fluxes, K nuc =  tot Q/2, and compare with the observed luminosity K:One can determine the “nuclear luminosity” from measured neutrino fluxes, K nuc =  tot Q/2, and compare with the observed luminosity K: K nuc /K= 1.4 ( %) (1  ) This means that, within 25%, the Sun is actually powered by 4H->He fusion…This means that, within 25%, the Sun is actually powered by 4H->He fusion…

30 Summary Solar neutrinos are becoming an important tool for studying the solar interior and fundamental physics. Better determinations of S 34 and S 1,14 are needed for fully exploiting the physics potential of solar neutrinos. All this brings towards answering fundamental questions: Is the Sun fully powered by nuclear reactions?Is the Sun fully powered by nuclear reactions? Is the Sun emitting something else, beyond photons and neutrinos?Is the Sun emitting something else, beyond photons and neutrinos?