1. n Low energy neutrino scattering: from nuclear physics
to neutrino (astro)physics n
Cristina VOLPE
(Institut de Physique Nucléaire Orsay, France)

2. OUTLINE Neutrino physics : status and open questions
Core-collapse SN neutrinos
and neutrino scattering
OUTLINE
Low energy n-scattering:
General aspects
Future n-scattering experiments
Conclusions

3. IT REQUIRES THAT NEUTRINOS
The conjecture of neutrino oscillations
Pontecorvo, 1957
Neutrinos can modify their flavor while travelling.
This is the neutrino oscillation phenomenon.
SOURCE L
DETECTOR ne nm ne nm
The oscillation probability
Bruno Pontecorvo
(1913 – 1993)
oscillation
amplitude
The phenomenon depends
on oscillation paramaters.
oscillation
frequency
Dm2 = m22-m12
IT REQUIRES THAT NEUTRINOS
ARE MASSIVE.

4. Recent Advances in Neutrino Physics
1998 : Super-Kamiokande discovers neutrino oscillations.
2000 : SNO measures the total (ne, nm, nt ) solar neutrino flux.
2001 : K2K confirms Super-Kamiokande result.
2002 : KAMLAND determines the solar solution (LMA).
2006 : MINOS measures precisely the atmospheric Dm2.
2007 : Mini-BOONE does not confirm the LSND observation.
AN IMPRESSIVE PROGRESS
IN THE LAST DECADE in our
knowledge of its properties.
Ln/En ratio [km/GeV]
oscillation
decoherence
decay
1.6
1.4
1.2 1
0.8
0.6
0.4
0.2
data/expectation
Many puzzles have been
solved with an incredible
impact on various domains
of physics.

5. THEORETICAL DESCRIPTION?
n3=nt
mixing angle q ne nm n1 n2
ne cos q sin q n1 =
nm sin q cos q n2
Dm2 = m22-m12
flavour basis
mass basis
The time evolution is :

6. THE 3-flavours OSCILLATION PARAMETERS
In the case of three families, there are three mass eigenstates
(n1,n2,n3) and three flavour eigenstates (ne,nm,nt).
Only two Dm2 are independent.
Dm212
Dm322 n3 nm nt
q23
The two basis are related by
a unitary matrix, called the
Maki-Nakagawa-Sakata-
Pontecorvo (MNSP) matrix. n2 ne n1
q12
q13 ne n1 nm
q13 n2
q23
q12 nt n3
THE CP violating phase INTRODUCES A n-n ASYMMETRY.

7. THE PRESENT STATUS ? To reconstruct the MNSP mixing matrix :
3 mixing angles, 1 CP Dirac phase, 2 Majorana phases
(SNO, Kamland)
(Super-Kamiokande, K2K, MINOS, …OPERA) ?
( CHOOZ,...)
The Dirac and Majorana phases are unknown.
The Dirac phase influence neutrino oscillations, Majorana ones do not.
To reconstruct the mass pattern:
Experimentally only mass squared differences are known.

8. A wealth of experiments are under construction or at a R&D level.
THE key OPEN QUESTIONS
To reconstruct the MNSP mixing matrix
The third mixing angle q13
Double-CHOOZ, Daya-Bay, T2K,..
KATRIN, MARE,…
Gerda, Cuore, Super-Nemo,…
from beta-beams, super-beams,
neutrino factories, double-beta
decay experiments
supernovae, n-factories, double-beta,…
The Dirac and Majorana phases
(CP violation)
To reconstruct the mass pattern
The absolute mass scale
The mass hierarchy
Dm212
Dm213 m2 m1 m3
Mass scale?
Inverted
Normal
The neutrino nature
A wealth of experiments are under
construction or at a R&D level.
exciting discoveries might be close…

9. q13 – expected sensitivities
P. Huber, M. Lindner, T. Schwetz, W. Winter, arXiv:
Discovery potential (90% CL) for sin2 2q13
from reactors and accelerators
THE VALUE OF Q13 CRUCIAL FOR FUTURE CP SEARCHES.

10. Neutrinos in Nature Two diffuse neutrino backgrounds never observed :
10-12
10-8
10-4
100
104
108
1012
1016
1020
1024
Flux (cm-2 s-1 MeV-1)
10-6
10-3 1
103
106
109
1015
1018
meV meV eV keV MeV GeV TeV PeV EeV
Neutrino Energy (eV)
Cosmological neutrinos
Solar n
Supernova neutrinos
Geo-neutrinos
Reactor neutrinos
Athmospheric neutrinos
n from quasars
330 / cm3
65 milliards / cm2 / s
1058 en 10 s
Two diffuse neutrino backgrounds never observed :
from the Early Universe
and from supernovae

11. n-oscillations in astrophysics & cosmology
Neutrino oscillations are crucial to understand and predict neutrino
evolution in several contexts :
Neutrinos emitted from the Sun
A wealth of solar experiments.
Neutrino time and energy spectra from massive stars
(core-collapse supernovae) and accretion disk-black
hole (AD-BH) scenarios
Observatories existing (ex. SK, KamLAND, LVD)
or under study, as « megaton detectors »: MEMPHYS,
GLACIER, LENA -- LAGUNA Design Study in FP7 --
one of the 7 ASPERA (astroparticle in Europe) priorities
Neutrino evolution in the Early Universe
Just before Big-Bang Nucleosynthesis

12. Core-collapse supernovae (SN)
99 % of the energy is emitted
as neutrinos of all flavours in
a short burst of about 10 s. ne nt nm NS
Supernova 1987A
Totani et al., Astr.. J. 1998
t (s)
0.1 1. 10
collapse
accretion
cooling of the
neutron star
Neutrinos follow closely the explosion.
Bring CRUCIAL INFORMATION
ON THE EXPLOSION AND
unknown n-PROPERTIES.

13. IMPRESSIVE PROGRESS in the last years
Supernova simulations have reached a high degree of complexity
(2D-3D, convection, accurate nuclear networks, neutrino transport,
the SASI mode,…)
Mezzacappa et al, « Ascertaining the core-collapse supernova mechanism:
An emerging picture ? », AIP conf. Proc. 924(2007)234
The understanding of neutrino flavour conversion in these
explosive phenomna is undergoing a major progress (coupling
to matter, to the neutrino-neutrino interaction, shock wave
and turbulence effects).
Duan, Fuller and Qian,``Collective Neutrino Oscillations,'' arXiv: ;
Duan and Kneller,``Neutrino flavour transformation in supernovae,''
J. Phys. G 36, (2009) [arXiv:
Neutrino-nucleus interactions are important :
to understand the nucleosynthesis of heavy elements
(neutrino interactions on protons and neutrons «  kills » the
r-process in these sites).
to determine the response of supernovae observatories)

14. Future SN observations
Several detectors are running (ex. Borexino, Kamland, Super-K,…) .
Large-size detectors are under study (LAGUNA DS, FP7, ).
Future strategy
Ando,Beacom,Yuksel PRL95 (2005)
To measure the neutrino
luminosity curve from a future
(extra)galactic explosion
(ex. 105 events in MEMPHYS).
II. To measure the diffuse
supernova neutrino background
(sensitive to the star formation
rate as well).

15. ne detection: n-nucleus measurements
necessary to determine the supernovae observatories’s response
HALO, LENA, GLACIER, MEMPHYS
208Pb
12C
40Ar
16O

16. SN neutrinos and n-properties : q13
For a supernolva at 10 kpc,
Present limit : sin22q13< 0.1
(CHOOZ)
In a lead observatory the signal is:
(20 MeV)
(10 MeV)
Engel, McLaughlin,Volpe, PRD67(2003)
CC + 2n events depend on the ne
average energy and therefore
on the value of the third neutrino
mixing angle.
HALO PROJECT
Planned AT SNOLAB.

17. The search for the third n-mixing angle
First calculation including the n-n interaction and shock wave effects.
Gava, Kneller, Volpe, McLaughlin, Phys. Rev. Lett. 103 (2009), arXiv:
FLUXES
ON EARTH
adiabatic
non-adiabatic
ne + p n + e+
POSITRON TIME SIGNAL
29 MeV
15 MeV
The dip (bump) can be seen at 3.5 (1) sigma in
Super-Kamiokande if a supernova at 10 kpc explodes..
A SIGNATURE IN THE POSITRON TIME
SIGNAL IF sin22q13 > 10-5 OR sin2q13 < 10-5

18. The supernova neutrino background
Present limits :
1.08 ne cm-2s-1 from SK (Ene > 19.3 MeV) Malek et al, PRL 90 (2003) & 2009
ne cm-2 s-1 from LSD (25 < Ene < 50 MeV) Aglietta et al. A Phys 1 (1992)
The star formation rate is nowadays
constrained by various observations.
Uncertanties remains, especially at
small redshifts (a factor of 2 at z = 0).
The star formation rate
Yuksel, et al Astrophys. J.683, L5(2008).
C. Lunardini, Astr. Phys., 26, 190 (2006)
Theoretical predictions on the
relic neutrino fluxes are very
close to the present upper
limit.

19. DSNB event rates in -observatories
There is an energy window free
from backgrounds, where neutrinos
from past supernovae can be
discovered either with advanced
technologies or with large size
observatories.
Wurm et al,
PRD 75 (2007)
Argon detectors (100 kton).
after 10 years
Normal Hierarchy
Nevents
Detection window L S
MeV 66 58
MeV
106 96
S.Galais, J.Kneller, C.Volpe and J.Gava, to appear in PRD, arxiv:

20. ? n  n n = n The neutrino nature bb
The search for the nature
neutrinoless bb decay bb
76Ge
76As
76Se ?
Dirac particle
Majorana p.
due to Majorana neutrino
exchange, physics beyond
the Standard Model.
bb : 2n  2p + 2e-
Lepton-violating process
Experiments search
THE bb-DECAY observation : A MAJOR DISCOVERY.

21. The experimental challenge
A (debated) claim for evidence.
CUORE and GERDA will
confirm/refute it and
reach about 100 meV
sensitivity.
< mn> < 0.3 – 1.0 eV
The best present upper limit.
A large number of projects under study.

22. The theoretical challenge
bb(2n) m b ne
(3He, t)
(d, 2He)
76As bb
76Ge
76Se
Constraints on the calculations
come from related weak
measurements :
beta-decay,
muon-capture,
charge-exchange reactions,
double-beta decay process (2n).
The predictions on the half-lives
present significant uncertainties.
Reducing the uncertainties is a major open problem.

23. Double-beta decay and n-nucleus
2b(0n): 2n  2p + 2e-
The half-life calculations
involve many transition
matrix elements of high
multipolarity.
F. Simkovic et al,
PRC77 (2008)
Volpe, hep-ph/ , J. Phys.G.31(2005)
One can show that the states involved in neutrinoless double-beta decay due to the exchange a Majorana neutrino are the same states as those excited in neutrino-nucleus interactions.
n-NUCLEUS MEASUREMENTS TO GET INFORMATION on THE
HIGH MULTIPOLE MATRIX ELEMENTS AND THE VALUE OF gA…

24. n-physics
neutrino
scattering
Fermi Gas
astrophysics
nuclear
physics

25. Low-energy neutrino scattering
Nuclear Degrees
of Freedom
Nucleon Degrees
of Freedom
SUPERNOVA
ATMOSPHERE
SUN,REACTOR
ACCELERATORS 10 50
100
1000
(MeV)
500
n-Energy
EFT, Microscopic
Approaches (RPA,
Shell Model), EPT,…
Fermi Gas
Experimental data are very scarce (d and 56F, 12C).
Theoretical predictions are absolutely necessary.
Many calculations exist based on various models.

26. THEORETICAL ASPECTS ISOSPIN AND SPIN-ISOSPIN MODES are EXCITED. ne e
The effective V-A interaction Hamiltonian.
Using perturbation theory :
The nuclear transition probabilities are the key quantities :
exclusive
inclusive
ISOSPIN AND SPIN-ISOSPIN MODES are EXCITED.

27. An example of current uncertainties
Allowed approximation
(qr 0)
Comparison of different
theoretical predictions
for the neutrino-iron
cross section.
Bertulani and Samana,
PRC78 (2008)
arXiv:
NEED FOR NEW MEASUREMENTS !

28. INTENSE NEUTRINOS SOURCES
CONVENTIONAL SOURCES ne p+
m+ + nm m+
e + nm + ne
BETA-BEAMS PS
SPS E U R I S O L
storage
ring n
6Li ne
P. Zucchelli, Phys. Lett. B (2002)

29. PHYSICS STUDIED WITHIN THE EURISOL DS (FP6, 2005-2009)
C.Volpe, J Phys G 30 (2004).
LOW ENERGY BETA-BEAMS
A proposal to establish a facility for the production of
intense and pure low energy neutrino beams (100 MeV). PS
SPS E U R I S O L
storage
ring n
BASELINE
n-nucleus cross sections
(detector’s response,
r-process, 2b-decay)
fundamental interactions
studies (Weinberg angle,
CVC test, mn)
PHYSICS POTENTIAL
astrophysical applications
close
detector n
PHYSICS STUDIED WITHIN THE EURISOL DS (FP6, )

30. NEUTRINO-NUCLEUS MEASUREMENTS
Lazauskas and Volpe, NPA 2007
ne + 208Pb Bi + e- Pb Bi 0+ 1+ 1- 2+ 3-
IAS
No exp. info
A better knowledge
is needed
Gamow-Teller
Low energy beta-beams:
A TOOL TO STUDY
SPIN-ISOSPIN EXCITATIONS.

31. n-nucleus scattering measurements at v
n-nucleus scattering measurements at
future spallation facilities: SNS,JSNS,ESS?,SPL
R. Lazauskas and C. Volpe, in preparation.
EVENTS (3 107 s)
Predictions on the expected
number of events for a detector located at different distances from the source.
1470
384 63
12C
16O
998
261 43 ne /s
40Ar
1 ton cubic detector
8860
2310
380
56Fe
9100
2330
377
100Mo
17300
420
716
208Pb
34500
8820
1430
Distance(m) 10 20 50

32. Conclusions & Perspectives
Low energy neutrino scattering has timely
applications for key open issues in neutrino
physics and astrophysics.
Accurately predicting the cross sections
Is challenging.
Related or direct measurements are needed,
with future facilities - low energy beta-beams
or conventional sources.

33. Danke.
Thank you!
Andromeda (M31)
Grazie.
Merci.