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Insights in stars, neutrino physics and in the Earth. Gemma Testera INFN Genoa ( Italy ) “Neutrino Physics: Present and Future” Erice 2013. G. Testera INFN Genoa (Italy) Erice 2013. Neutrinos from the Sun. The Sun a nd the H burning stars produce neutrinos. 4p.

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insights in stars neutrino physics and in the earth

Insights in stars, neutrino physics and in the Earth

Gemma Testera

INFN Genoa (Italy)

“Neutrino Physics: Present and Future”

Erice 2013

G. Testera INFN Genoa (Italy) Erice 2013


Neutrinos from the Sun

The Sunand the H burningstars produce neutrinos


4He+ 2 e+ + 2 ne+ 26.8 MeV

Meanenergy =0.53 MeV 2% of the totalenergyproduced

  • Tworeactioncycles:
  • ppchain
  • CNO chain

G. Testera INFN Genoa (Italy) 35th Erice School, 2013


The pp fusion chain

G. Testera INFN Genoa (Italy) 35th Erice School, 2013


The CNO chain



12C : catalyst

Very important for stars with mass higher than the SUN

Main CNO cycle

12C + p ®13N + g

13N ® 13C + e+ + ne

13C + p ®14N + g

14N + p ®15O + g

15O ®15N + e+ + ne

15N + p ®12C + 4He


G. Testera INFN Genoa (Italy) 35th Erice School, 2013


Solar Neutrino energy spectrum at Earth



A. Serenelli et al., Astroph. J. 7432 2011

G. Testera INFN Genoa (Italy) 35th Erice School, 2013


Why do wemeasure solar neutrinos ?

  • Solar n studies began to prove that Sun shines by nuclear fusion reaction: solar n are a
  • powerful probe allowing to understand the interior of the Sun
  • The Sun can be used to calibrate stellar models
  • The flux and specrum of nallows to discriminate between solar models
  • The Sun is a source of pure ne : good to studyoscillations
  • The baseline of 108 Km allows sensitivities to Dm2 up to 10-10 eV2
  • The Sunallowsprobingnpropagation in a high density medium 100g/cm3:
  • interaction of neutrinos with matterinfluences the oscillationphysics
  • Non standard ninteractions can produce a measurablesignal with solar n

Mixture of neutrino physics and astrophysics


Standard solar model

  • Stars are formed by a gravitationallyboundsystem of primordial gas
  • (roughlyHelium 25%, the restisHydrogen)
  • Energy loss by radiationcontractionheatinghydrogen fusion
  • Expansion and balance betweengravity and pressure force: hydrostaticequilibirum

Solar model hypothesis

  • Sunis in hydrostaticequilibrium
  • Sunissphericallysymmetric
  • The energy transport is induced by photons or convection.
  • The radiative energy transport is dominant in the solar core, while the convective energy transport becomes important near the solar surface
  • Energy production is due to nuclear reactions
  • Initialparameters
  • Xini : initial mass fraction of Hydrogen
  • Yini : initial mass fraction of Helium
  • Zini : initial mass fraction of allotherselements (calledmetals)
  • Characteristiclenght scale for convection
  • Others parameters: cross sections of nuclearreactions

Standard solar model

  • Evolution up to the solar age : 4.57 Gy
  • The model must reproduce
  • The measuredSunluminosity L
  • The Sunradius R
  • The ratio Z/X (metal/Hydrogen) at the Sunsurface (surfacemetallicity)
  • The input parameters are changeduntil the presentday data are reproduced
  • Output of the solar model
  • n production region and nfluxes and spectra
  • Depth of the convection zone RCZ
  • SurfaceHeliumabundanceYsurf
  • Profile of X(r) ,Y(r), Z(r),
  • Density and sound speedprofile vs r

High and lowmetallicity

How to measure the Z/X value ?

- Chemicalanalysis of primitive meteorites

- emission line from solar corona

- composition of the solar wind

New method (recentlydeveloped):

development of three-dimensionalradiation hydrodynamic (3D RHD) models of the solar athmosphere : revision of the solar composition determined from the solar spectrum.

Z/X from the 3D RHD model = 0.0178

Previousvalue of Z/X = 0.0245-0.0249

Twoflavours of Standard solar model

High metallicity(old Z/X) : older model, itdoesnot match the Z/X measured with

the new 3D RHD model

Lowmetallicity(new Z/X) : itreproduces the new measuredvalue of metallicity;

butthisdoesnot match the elioseismic data


High and lowmetallicity and elioseismology

  • Helioseismology: acusticoscillations of the Sunsurface
  • The study of the Suninternalstructureentered a new age with helioseismoogy
  • (about 20 years ago, before the formulation of the new models of the Sunathmosphere)
  • Millions of solar modes (frequencies) havebeendetected
  • From the measuredfrequenciesyouget : - sound velocity in the Sun’sinterior;
  • - constraintsabout radiative opacity;
  • - constraintsaboutchemicalcomposition;
  • elioseismology solar interior
  • High metallicity solar modelsreproduce the elioseismology data
  • Lowmetallicitymodels do notreproduceelioseismology data
  • Lowmetallicitymodelsreproduce the modernmeasurementsaboutsurface
  • metallicity
  • Reproduction of elioseismology: success of the Standard Solar model beforeevidence of neutrino oscillations.

Solar Neutrinos flux predictions

Present predictions

Present predictions:

High and Low metallicity


High metallicity

Low metallicity

Aldo M. Serenelli et al. 2011 ApJ743 24

G. Testera INFN Genoa (Italy) Erice 2013


The solar neutrino problem and its solution

G. Testera INFN Genoa (Italy) Erice 2013


Now we know that n oscillate: move the focus to low energy solar n spectroscopy

  • Evidence of n oscillations and massive neutrinos
  • Interaction of neutrinos with matter complicate the oscillation scenario
  • Important for solar (and supernova) neutrinos: MSW
  • Year 2002: SNO results with NC
  • Nobel Prize for R. Davis (chlorine exp.) and Koshiba
  • Kamland results

Solar n mainly influenced by

2 flavours:

Kamland +solar

PRL 94 081801 (2005)

arxiv 1303.4667v1 (2013) Kamland Coll.

  • Solar neutrino measurements now:
  • understand details of the oscillation model
  • provide input for solar models
  • Borexino : very low energy solar n spectroscopy


G. Testera INFN Genoa (Italy) Erice 2013


The lowestenergythreshold in a real time detector solar n detector: Borexino @G. Sasso Laboratory (Italy)

Stainless Steel Sphere:

R = 6.75 m

2212 PMTs


270 t PC+PPO (1.5 g/l)

in a 150 mm thick

inner nylon vessel (R = 4.25 m)

n detection:

elastic scattering on electrons

Buffer region:


4.25 m < R < 6.75 m

  • ≈500 phe/MeV (electron equivalent)
  • Energy resolution 4.5%
  • Space resolution 10 cm @1MeV
  • “wall less” Fiducial Volume
  • Pulse shape capability
  • Calibration in situ with radioactive sources
  • Accurate Monte Carlo modeling of the
  • energy and time response function
  • No signature except the spectral shape
  • Needed extremely low background

Outer nylon vessel:

R = 5.50 m

(222Rn barrier)

Water Tank:

g and n shield

m water Č detector

208 PMTs in water

The smallest radioactive background in the world:

9-10 orders of magnitude smaller than the every-day environment

G. Testera INFN Genoa (Italy) Erice 2013


7Be (0.862 MeV) solar flux from Borexino

  • ne flux reduction 0.62 +- 0.05
  • ne survival probability 0.51 +- 0.07 @0.862MeV

G. Bellini et al., Borexino Collaboration +C Pena Garay, Phys. Lett. B707 (2012) 22.

G. Bellini et al., Borexino Collaboration, Phys. Rev. Lett. 107 (2011) 141362.

G. Testera INFN Genoa (Italy) Erice 2013


pep (1.44 MeV) solar flux measurement and CNO limits

in Borexino



G. Bellini et al., Borexino Coll., Phys. Rev. Lett. 108 (2012) 051302

Best limit on CNO- not yet enough to select solar models….

G. Testera INFN Genoa (Italy) Erice 2013


Can we discrimininate between solar models ??

Borexino data

High met. (1s)

Low met. (1s)

G. Testera INFN Genoa (Italy) Erice 2013


8B solar neutrinos

SNO has provided the absolute 8B flux

Figure from PRC 84, 035804 (2011)

Kamland coll.

G. Testera INFN Genoa (Italy) Lepton Photon 2013


8B solar neutrinos

Kamland PRC 84, 035804 (2011)

Borexino (3MeV threshold)

G. Bellini et al. PRD 82 033006 (2010)


LMA prediction

SNO CC events

arxiv 1109.0763 SNO LETA 3.5 MeV threshold

Super K. Suzuki@Neutrino Telescopes Venice 2013

G. Testera INFN Genoa (Italy) Erice 2013


Solar 8B : the Up-turn???

LMA survival probability

  • lower the thereshold as much as possible
  • Hints for new physics??
  • Background issues
  • Statistics
  • SuperKamiokande can see the effect

arxiv 1012.5627v2 (2011)

G. Testera INFN Genoa (Italy) Erice 2013


Assuming the luminosity constraint

G. Testera INFN Genoa (Italy) Erice 2013


Electron neutrinos survivalprobablityPee

Vacuum regime

LMA prediction

Combined analysis


Matter regime

Pee as expected from n oscillation

+Matter effect (LMA-MSW)

G. Testera INFN Genoa (Italy) Erice 2013


Pee and not standard n interactions

arxiv 1305.5835v1 (2103)


What next on solar neutrinos???

  • Direct measurement of pp neutrino spectrum: test Sun luminosity
  • High precision pep: Non Standard Interactions (NSI), test LMA with accuracy
  • Measure CNO : solar and stellar models
  • 8B up-turn: reduce the threshold (non standard interactions, sterile neutrinos…)
  • Improve 7Be measurement (and calculation) (solar models)

What next ? Borexino Phase II

After the purification of the scintillator

Krypton: strongly reduced: consistent with zero cpd/100t from spectral fit

210Bi : from ~70 cpd/100tons to 20 cpd/100tons) ;

238U (from 214Bi-Po tagging) < 9.7 10‐19 g/g at 95% C.L.

232Th < 2.9 10-18 g/g at 95% C.L.


It may be possible to estimate the 210Bi content from 210Po evolution in time;

pp, higher precision pep and 7Be, toward CNO: are in the wish list of Borexino

G. Testera INFN Genoa (Italy) Erice 2013


What next ? SNO+

  • Fill SNO with liquid scintillator
  • 780 tonnes LAB+PPO
  • 9000 PMTS
  • Water shield by Ultra Pure Water
  • Wide physics program

Assuming the Borexino

background level

Reduced 11C background due to the depth


70 m/day@SNO+

…..The worse enemy is 210Bi

  • Begin scintillator filling: early 2014
  • Check Background
  • Priority is bb decay (add 130Te to scintillator)

G. Testera INFN Genoa (Italy) Erice 2013


What next : LENS Indium based liquid scintillator

R. Raghavan, Phys.. Rev. Lett. 37, 259 (1976)


Clean signature of ne events

(In pure LS the spectral shape is the

only signature)

Delayed t=4.6 ms

Q= 114 keV sensitivity to pp , 7Be, pep, CNO, 8B

Clean spectral measurement: En=e--114keV



Random coincidences of b decay of 115In (In activity ≈0.25 Bq/g)

Important only for pp

10 t In: 400 pp/year

8 1013 decays/year

3D segmentation of the detector: Lattice with teflon reflectors, PMTS at the end

Space and time cuts

G. Testera INFN Genoa (Italy) Erice 2013


What next ? LENS Indium based liquid scintillator

8% In can be loaded in LS

9000 g/MeV (about 75 % of clean LS)

Att . Lengh 8m

Time stability > year

Detector prototype under test in the Kimbalton mine (Virginia):

6X6X6 lattice

130 liters LS (microLens)

Simulated spectrum; 5 years,

10 tons of Indium loading in LS

LENS expected performances

C. Grieb et al.,PhysRevD 75 0903006 (2007)

G. Testera INFN Genoa (Italy) Erice 2013


What next:? Cryogenic Xenon, Neon (noble liquid) scintillators for low en. solar spectroscopy

  • First run performed
  • Detector upgrading
  • Resuming data taking in summer 2013
  • Current focus: Dark matter
  • Long term goal: solar neutrinos

K. Hiraide Moriond 2013

arxiv 1301.2815v1 (2013)


conceptual design

100t liquid neon

Small prototype running at SNOLAB

arxiv 1111:3260v2 (2012)

Astroparticle Physics 22 (2005) 355

M. Kinsey et al.,

G. Testera INFN Genoa (Italy) Erice 2013


What next: LENA

Liquid scintillator and PMT: scaling up (X 150) Borexino keeping its performances

(or doing even better)

G. Testera INFN Genoa (Italy) Erice 2013


SUPERNOVA neutrinos

  • About 20 events from SN1987A detected by KamiokandeII, IMB (water Cerenkov)+
  • Baksan, LSD (scintillators)
  • Supernova rate: few/100 years
  • Not negligible probability now
  • Present and planned neutrino detectors may see order of magnitude more events that for SN1987A
  • Many models
  • Stellar physics
  • MSW
  • Neutrino-neutrino interactions – collective flavour oscillations
  • Special signature in the emitted neutrino spectra
  • Complicated link between shape of the original n flux and oscillations
  • Signature in the shape of the spectra reaching the detectors
  • Light curves: time evolution of the detected neutrino signals
  • Earth matter effect

Effect sensitive to the

mass hierarchy

Be ready to measureall the flavours, time and energyspectra!

S. Choubey et al. arXiv:1008.0308 (2010) with many refences

Dighe, Smirov arXiv: 9907423v2 (1999)

G. Testera INFN Genoa (Italy) Erice 2013


SUPERNOVA neutrinos: example of time evolution of n luminosity

Prompt neburst



Fisher et al.,2010 [arxiv:0908.1871]

G. Testera INFN Genoa (Italy) Erice 2013


SUPERNOVA neutrinos: several differences in models

Adapted from H. Duan, JJ Cherry “Aspen Winter Workshop” Feb 2013

G. Testera INFN Genoa (Italy) Erice 2013


SUPERNOVA neutrinos: several channels in present and future detectors

1.8 MeV threshold, high cross section

Clean signature if n can be detected

(Liquid scint., Gd in water at Superk)

Largest cross section

En> 1.8 MeV

Inverse beta decay

  • “prompt signal”
  • e+: energy loss + annihilation
  • (2 g 511 KeV each)
  • “delayed signal”
  • n capture after thermalization (2.2 g in H)

All flavour, directionality, no energy threshold

Elastic scatt.

E threshold,

signature (daughter in excited states)

CC reactions on nuclei

Low recoil energy

Ok for scintillators (many free protons)

Sensitive to nx

np elastic scattering

Low recoil energy

Possible in cryogenic noble liquid scintillators

n Nucleus elastic scattering

G. Testera INFN Genoa (Italy) Erice 2013


SUPERNOVA neutrinos: expected number of events

Take this as example:

many variations from model to model

SuperK: mainly

Addition of Gd in water:

project well advanced!!

K. Scholberg arxiv 1205.6003v1 (2012)

G. Testera INFN Genoa (Italy) Erice 2013


SUPERNOVA neutrinos: n p elastic scattering in low background liquid scintillators

B. Dasgupta, J. Beacom arxiv 1103.2768 (2011)

J. Beacom et al., arxiv 0205220 (2002)

  • Superkamiokande will mainly measure anti-ne
  • ne : the best detector is probably liquid argon
  • n p scattering important for measuring the spectrum of nmnt and antinu (all nx)

Expected recoil spectrum including quenching (SNO+ taken as example)

True proton recoil spectrum

Sensitive to <Enx>!

<E>=8 MeV

<E>=5 MeV

<E>=3.5 MeV

200 KeV energy threshold

111 events @ SNO+

@ Borexino

@ Kamland


Low backgroun technologies developed for solar n

make detectors powerful for Supernova ….

G. Testera INFN Genoa (Italy) Erice 2013


RELIC supernova neutrinos



Atmospheric anti- ne

G. Testera INFN Genoa (Italy) Erice 2013


RELIC supernova neutrinos:upperlimits from SupeKamiokande (2012)

Event rate from DSNB

in 22.5 Kt water Cerenkov detector


Experimentalprogram to add

Gadolium in water is in progress;

Interestingperspectives for the DSNB

detection in SK


Antineutrinos from the Earth: geon

The crust and uppermantle

are reasonablyknown

Whatabout the lowermantle

and the core?

Geonallows to see the inner

part of the Earth

Ifenough data will be collected

thenitwill be possible to

discriminate betweenEarth’s model

Anti v emiited by U,Th,K: related to the radiogenicheat

CMB: Core MantleBoundary

G. Testera INFN Genoa (Italy) Erice 2013


Antineutrinos from the Earth: geon

  • Detected by Kamland and Borexino
  • G. Bellini et al., (Borexino Coll.) Phys. Lett. B 687 (2010) 299; Phys Lett B 722 4 (2013) 295 Borexino Coll.

T. Araki et al., (Kamland Coll.) Nature 436 (2005) 499;

A. Gando et al. (Kamland Coll.) Nature Geoscience 4 (2011) 57 ; arxiv 1303.4667v1 (2013) Kamland Coll.

See Neutrino Geoscience (Takayama) 2013

Energy spectrum of geon :

En>1.8 MeV

106 cm–2 s–1from Uand Thin the Earth

107 cm–2 s–1 from potassium,

Compare with

flux of 6 × 1010 cm–2 s–1 from the Sun

  • Low flux: 3 order of magnitude less than 7Be solar n!
  • Geon: they probe the U,Th content of the Earth (no K)
  • Multidisciplinary research: particlephysics&geophysics
  • Possiblebecauselow back detectors havebeendeveloped for solar and
  • reactorneutrinos

G. Testera INFN Genoa (Italy) Erice 2013


Heat balance

  • The temperature of the Earth increases with the depth : about 25° C/Km
  • Internalheat = residualheat from formation of the planet (about 20%) +
  • contribution from radioactivedecays of long life isotopes (U, Th, K)
  • T(core) = 6000-7000 K!
  • Below 80 -100 Km from the surface: meltedrocks
  • Heatflowstoward the surface
  • Heatloss from the Earth = 47 TW (4.7 × 1013 Watts) (or 30 TW?)
  • The present day heat source is by radioactive decays
  • Measuring the geov :
  • determine the amount of U and Th
  • and thusconstrain the radiogenicheat
  • From meteorites: U:Th = 3:9
  • The generation of the Earth’s magnetic field,
  • its mantle circulation, plate tectonics
  • and secular (i.e. long lasting) cooling are
  • processes that depend on terrestrial heat
  • production and distribution

G. Testera INFN Genoa (Italy) Erice 2013


Detection of geonand the reactor background

Simulation for Borexino

Simulation for Kamland



1MeV≈ 500 p.e.

  • Reactors antin are a source of background
  • Lower effect in Borexino ( there are not near reactors)
  • Borexino has also lower background (accidental, an…)
  • But larger target mass in Kamland 300t/1000t before the FV cuts

G. Testera INFN Genoa (Italy) Erice 2013


geonresults in 2103

G. Testera INFN Genoa (Italy) Erice 2013


Try to find the contribuion of U and Th



Chondritic U-Th ratio

Best fit

S(238 U) = 26.5 ± 19.5 TNU

S(232 Th) = 10.6 ± 12.7 TNU

Best fit

S(238 U)= 116 events

S(232 Th) = 8 events

G. Testera INFN Genoa (Italy) Lepton Photon 2013


Geon: implications about Earth models

TNU=1ev/ (y 1032 protons)

G. Testera INFN Genoa (Italy) Erice 2013



  • Solar neutrinos entered in the spectroscopy phase
  • Interest for solar models (CNO)
  • Verification of the oscillation physics (pep for Pee and NSI, Upturn of 8B)
  • Direct pp measurement expected
  • Geoneutrinos have been detected : more data are neceessary to constrain Earth models
  • Low background detectors developed for solar physisc have great potential for Supernova
  • Understanding details of supernova physics demands next generation detectors
  • (high statistics)
  • Supernova neutrinos are very rich of informations about astrophysics and neutrino properties

G. Testera INFN Genoa (Italy) Erice 2013