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

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

The Sun and the H burning stars produce neutrinos

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

Mean energy =0.53 MeV 2% of the total energy produced

Two reaction cycles:• pp chain• CNO chain

KTSun61015

Neutrinos from the Sun

The pp fusion chain


12C + p ® 13N + g

13N ® 13C + e+ + ne

13C + p ® 14N + g

14N + p ® 15O + g

15O ® 15N + e+ + ne

15N + p ® 12C + 4He

nB

nN

nO

12C : catalyst

Main CNO cycle

The CNO chain

Very important for stars with mass higher than the SUN


Solar Neutrino energy spectrum at Earth

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

CNO

Neutrinos/cm2/sec/MeV


Why do we measure 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 n allows to discriminate between solar models

• The Sun is a source of pure ne : good to study oscillations

• The baseline of 108 Km allows sensitivities to Dm2 up to 10-10 eV2

• The Sun allows probing n propagation in a high density medium 100g/cm3: interaction of neutrinos with matter influences the oscillation physics

• Non standard n interactions can produce a measurable signal with solar n

Mixture of neutrino physics and astrophysics

Standard solar model

• Stars are formed by a gravitationally bound system of primordial gas (roughly Helium 25%, the rest is Hydrogen)• Energy loss by radiation contraction heating hydrogen fusion• Expansion and balance between gravity and pressure force: hydrostatic equilibirum

• Sun is in hydrostatic equilibrium• Sun is spherically symmetric• 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

Initial parameters• Xini : initial mass fraction of Hydrogen• Yini : initial mass fraction of Helium• Zini : initial mass fraction of all others elements (called metals)• Characteristic lenght scale for convection

• Others parameters: cross sections of nuclear reactions

Solar model hypothesis

Evolution up to the solar age : 4.57 GyThe model must reproduce- The measured Sun luminosity L- The Sun radius R- The ratio Z/X (metal/Hydrogen) at the Sun surface (surface metallicity)

The input parameters are changed until the present day data are reproduced

Output of the solar model• n production region and n fluxes and spectra• Depth of the convection zone RCZ

• Surface Helium abundance Ysurf

• Profile of X(r) ,Y(r), Z(r),• Density and sound speed profile vs r

Standard solar model

How to measure the Z/X value ?- Chemical analysis of primitive meteorites- emission line from solar corona- composition of the solar wind

New method (recently developed):development of three-dimensional radiation 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 = 0.0178Previous value of Z/X = 0.0245-0.0249

Two flavours of Standard solar model1) High metallicity (old Z/X) : older model, it does not match the Z/X measured with the new 3D RHD model 2) Low metallicity (new Z/X) : it reproduces the new measured value of metallicity;

but this does not match the elioseismic data

High and low metallicity

• Helioseismology: acustic oscillations of the Sun surface

• The study of the Sun internal structure entered a new age with helioseismoogy(about 20 years ago, before the formulation of the new models of the Sun athmosphere)

• Millions of solar modes (frequencies) have been detected

• From the measured frequencies you get : - sound velocity in the Sun’s interior; - constraints about radiative opacity; - constraints about chemical composition; elioseismology solar interior

• High metallicity solar models reproduce the elioseismology data• Low metallicity models do not reproduce elioseismology data• Low metallicity models reproduce the modern measurements about surface metallicity• Reproduction of elioseismology: success of the Standard Solar model before

evidence of neutrino oscillations.

High and low metallicity and elioseismology

Solar Neutrinos flux predictions

Aldo M. Serenelli et al. 2011 ApJ 743 24

Present predictions

CNO

High metallicity Low metallicity


n Diff. %

pp 0.8

pep 2.17Be 8.8

8B 17.7

13N 26.7

15O 30.0

17F 38.4

Present predictions:High and Low metallicity

The solar neutrino problem and its solution

exp years reaction threshold Solar sensitivity method result

Chlorine 1968 -1994

ne+37Cl= e- +37Ar 0.814 MeV 8B , pep, 7Be radiochemical615 tons

R(exp/SSM)=0.34±0.03

Gallex-GN0 1991-2003 ne+71Ga= e- +71Ge 0.233 8B , pep, 7Be,pp Radiochemical30.3 t

R(exp/SSM)= 0.58±0.05

SAGE 1990- ne+71Ga= e- +71Ge 0.233 8B , pep, 7Be,pp radiochemical 50 t

0.59±0.06

Kamiokande (SuperKamiokande still running)

1987-1995 nx+e-= nx+e- 7.5…3.5

8B Cerenkov light 2.14 Kt water(22.4 Kt)

0.46±0.02

SNO 19992006(moving to SNO+)

ne+d=e-+p+p (CC)ne+d=nx+p+n (NC)ne+e-=nx+e- (ES)

53.5

8B 1Kt D20Cerenkov

8B flux consistent with SSM!!Solar neutrino problem solved

Kamland(reactor antinu)

2002 - Anti-ne+p= n+e- Liquid scintillator Reactor antinuL/E sensitive to solar region

Borexino 2007- nx+e-= nx+e- 0.2 8B , pep, 7Be,pp Liquid scintillator 7Be,pp,8B


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

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

22,112 mD

2 flavours: Kamland +solar PRL 94 081801 (2005)

LMA-MSW

arxiv 1303.4667v1 (2013) Kamland Coll.


Water Tank: g and n shield m water Č detector208 PMTs in water

Scintillator:270 t PC+PPO (1.5 g/l)in a 150 mm thick inner nylon vessel (R = 4.25 m)

Stainless Steel Sphere:

R = 6.75 m2212 PMTs

Outer nylon vessel:R = 5.50 m(222Rn barrier)

Buffer region:PC+DMP quencher 4.25 m < R < 6.75 m

The smallest radioactive background in the world: 9-10 orders of magnitude smaller than the every-day environment

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

-- ® ee xx nn

n detection: elastic scattering on electrons

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


7Be (0.862 MeV) solar flux from Borexino

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

tcpdR syststatBe

100/5.146 )(5.16.1)(7

- tcpdR noscillationo 100/2.574

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

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


pep (1.44 MeV) solar flux measurement and CNO limits in Borexino

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

n Interaction Rate (cpd/100t)

DATA/SSM(high metallicity)

Counts/(days 100 t) ratio

pep 3.1±0.6 (stat) ± 0.3(sys) 1.1±0.2

CNO <7.9 <1.5

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


pep

CNO

Can we discrimininate between solar models ??

.8

8

methighSSMBfluxB

.7

7

methighSSMBefluxBe

High met. (1s)

Low met. (1s)


Borexino data

Figure from PRC 84, 035804 (2011)Kamland coll.

SNO has provided the absolute 8B flux

8B solar neutrinos

G. Testera INFN Genoa (Italy) Lepton Photon 2013

Kamland PRC 84, 035804 (2011) Borexino (3MeV threshold)

arxiv 1109.0763 SNO LETA 3.5 MeV thresholdSuper K. Suzuki@Neutrino Telescopes Venice 2013

8B solar neutrinos

LMA prediction

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

SNO CC eventsSuperKamiokande


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)


)()(046.5 107.0123.0

159.0152.0 syststat

--

Assuming the luminosity constraint


Electron neutrinos survival probablity Pee

Combined analysisBorexino&solar

Pee as expected from n oscillation+Matter effect (LMA-MSW)

Vacuum regime

Matter regime


LMA prediction

arxiv 1305.5835v1 (2103)

Pee and not standard n interactions

•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 on solar neutrinos???

What next ? Borexino Phase II

After the purification of the scintillator1) Krypton: strongly reduced: consistent with zero cpd/100t from spectral fit2) 210Bi : from ~70 cpd/100tons to 20 cpd/100tons) ; 3) 238U (from 214Bi-Po tagging) < 9.7 10 19‐ g/g at 95% C.L.4) 232Th < 2.9 10-18 g/g at 95% C.L.5) 210Po6) It may be possible to estimate the 210Bi content from 210Po evolution in time;

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


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

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

Reduced 11C background due to the depth104 m/day@Borexino70 m/day@SNO+…..The worse enemy is 210Bi


What next : LENS Indium based liquid scintillator

R. Raghavan, Phys.. Rev. Lett. 37, 259 (1976)*115115 SneIne ® -n

)497()116(115*115 keVkeVSnSn gg ®

prompt

Delayed t=4.6 ms

Q= 114 keV sensitivity to pp , 7Be, pep, CNO, 8BClean spectral measurement: En=e--114keV

Signal Background

Random coincidences of b decay of 115In (In activity ≈0.25 Bq/g)Important only for pp10 t In: 400 pp/year8 1013 decays/year 3D segmentation of the detector: Lattice with teflon reflectors, PMTS at the end Space and time cuts

Clean signature of ne events(In pure LS the spectral shape is the only signature)


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

Simulated spectrum; 5 years, 10 tons of Indium loading in LS

What next ? LENS Indium based liquid scintillator

8% In can be loaded in LS9000 g/MeV (about 75 % of clean LS)Att . Lengh 8mTime stability > year

Detector prototype under test in the Kimbalton mine (Virginia):6X6X6 lattice130 liters LS (microLens)

LENS expected performances


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

K. Hiraide Moriond 2013

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

CLEAN conceptual design100t liquid neon

Astroparticle Physics 22 (2005) 355M. Kinsey et al.,

Small prototype running at SNOLABarxiv 1111:3260v2 (2012)

arxiv 1301.2815v1 (2013)


What next: LENA

Liquid scintillator and PMT: scaling up (X 150) Borexino keeping its performances (or doing even better)


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

S. Choubey et al. arXiv:1008.0308 (2010) with many refencesDighe, Smirov arXiv: 9907423v2 (1999)


Be ready to measure all the flavours, time and energy spectra!

Prompt ne burst Accretion Cooling

Fisher et al.,2010 [arxiv:0908.1871]

SUPERNOVA neutrinos: example of time evolution of n luminosity


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

SUPERNOVA neutrinos: several differences in models


® enpe 1.8 MeV threshold, high cross sectionClean signature if n can be detected(Liquid scint., Gd in water at Superk)Largest cross sectionEn> 1.8 MeV

-- ® ee xx All flavour, directionality, no energy threshold

Inverse beta decay

Elastic scatt.

--® eZNZNe )1,1(),(-® eZNZNe )1,1(),(CC reactions on nuclei

E threshold, signature (daughter in excited states)

np elastic scattering pp ® nn Low recoil energyOk for scintillators (many free protons)Sensitive to nx

SUPERNOVA neutrinos: several channels in present and future detectors

n Nucleus elastic scattering


Low recoil energy Possible in cryogenic noble liquid scintillators

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

K. Scholberg arxiv 1205.6003v1 (2012)

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!!


® enpe

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 nm nt and antinu (all nx)

<E>=8 MeV

<E>=5 MeV

<E>=3.5 MeV

True proton recoil spectrumSensitive to <Enx>!

200 KeV energy threshold

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

111 events @ SNO+27 @ Borexino66 @ Kamland>103@LENA

Low backgroun technologies developed for solar nmake detectors powerful for Supernova ….


Atmospheric anti- ne

reactor

solar

RELIC supernova neutrinos


RELIC supernova neutrinos:upper limits from SupeKamiokande (2012)

Event rate from DSNB in 22.5 Kt water Cerenkov detector (SuperKamiokande)

Experimental program to addGadolium in water is in progress;Interesting perspectives for the DSNBdetection in SK

Antineutrinos from the Earth: geon

The crust and upper mantleare reasonably known

What about the lower mantleand the core?

Geon allows to see the innerpart of the Earth

If enough data will be collected then it will be possible to discriminate between Earth’s model

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


CMB: Core Mantle Boundary

Energy spectrum of geon :

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: particle physics&geophysicsPossible because low back detectors have been developed for solar andreactor neutrinos

® enpen En>1.8 MeV

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


106 cm–2 s–1 from U and Th in the Earth 107 cm–2 s–1 from potassium, Compare with flux of 6 × 1010 cm–2 s–1 from the Sun

• The temperature of the Earth increases with the depth : about 25° C/Km• Internal heat = residual heat from formation of the planet (about 20%) + contribution from radioactive decays of long life isotopes (U, Th, K)• T(core) = 6000-7000 K!• Below 80 -100 Km from the surface: melted rocks

• Heat flows toward the surface• Heat loss 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 thus constrain the radiogenic heat

• 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 heatproduction and distribution

Heat balance


1MeV≈ 500 p.e.

Simulation for Borexino Simulation for Kamland

•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

Detection of geon and the reactor background

reactors

Geon


geon results in 2103


Chondritic U-Th ratio

Best fitS(238 U) = 26.5 ± 19.5 TNUS(232 Th) = 10.6 ± 12.7 TNU

Try to find the contribuion of U and Th

KamlandBorexino

Best fitS(238 U)= 116 eventsS(232 Th) = 8 events

G. Testera INFN Genoa (Italy) Lepton Photon 2013

Geon: implications about Earth models


TNU=1ev/ (y 1032 protons)

Conclusions

•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


Insights in stars, neutrino physics and in the Earth

Documents

solar n studies

solar neutrinos

solar athmosphere

solar age

solar core

solar composi

n fluxes

specrum of n