Transcript n - CEA-Irfu

Low energy neutrino scattering:
from nuclear physics
to neutrino (astro)physics
n
Cristina VOLPE
(Institut de Physique Nucléaire Orsay, France)
Neutrino physics : status and
open questions
OUTLINE
Core-collapse SN neutrinos
and neutrino scattering
Low energy n-scattering:
General aspects
Future n-scattering experiments
Conclusions
The conjecture of neutrino oscillations
Pontecorvo, 1957
Neutrinos can modify their flavor while travelling.
This is the neutrino oscillation phenomenon.
L
SOURCE
ne nm
DETECTOR
ne
nm
The oscillation probability
Bruno Pontecorvo
(1913 – 1993)
oscillation
amplitude
The phenomenon depends
on oscillation paramaters.
IT REQUIRES THAT NEUTRINOS
ARE MASSIVE.
oscillation
frequency
Dm2 = m22-m12
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.
AN IMPRESSIVE PROGRESS
IN THE LAST DECADE in our
knowledge of its properties.
Many puzzles have been
solved with an incredible
impact on various domains
of physics.
oscillation
decoherence
decay
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
1
10
102
103
Ln/En ratio [km/GeV]
104
data/expectation
2007 : Mini-BOONE does not confirm the LSND observation.
THEORETICAL DESCRIPTION
?
n3=nt
ne
nm
n1 q
ne
n2
nm
cos q
=
flavour basis
The time evolution is :
sin q
-sin q
cos q
mixing angle
n1
n2
Dm2 = m22-m12
mass basis
n e t  = cosq  e iE t n 1  sin qe iE t v2
1
2
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).
Dm322
Dm212
n3
2
2
2
2
2
2
2
D
m
=
m

m

m

m

m

m
 i
2
1
3
2
1
3
nm
nt
i =1,3
q23
n1
q12
n2
ne
q13
0
0  c13
 nnee   1
  

nnm  =  0 c23 s23 q23 0
nn   0  s
  s ei
c
23
23 
13
 tt  
Only two Dm2 are independent.
The two basis are related by
a unitary matrix, called the
Maki-Nakagawa-SakataPontecorvo (MNSP) matrix.
cij = cosqij sij = sin qij
0 s13e  i  c12 s12

1
0 q   s12 c12
13
0
c13  0
0
0 nn1 
 
0 n 22 
q112nn 
 3 
THE CP violating phase INTRODUCES A n-n ASYMMETRY.
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.
THE key OPEN QUESTIONS
To reconstruct the MNSP mixing matrix
The third mixing angle q13
Double-CHOOZ, Daya-Bay, T2K,..
The Dirac and Majorana phases from beta-beams, super-beams,
neutrino factories, double-beta
(CP violation)
To reconstruct the mass pattern
The absolute mass scale
The mass hierarchy
KATRIN, MARE,…
supernovae, n-factories, double-beta,…
Dm212
Mass scale? Dm213
m2
m1
m3
Inverted
The neutrino nature
decay experiments
m3
m2
m1
Normal
Gerda, Cuore, Super-Nemo,…
A wealth of experiments are under
construction or at a R&D level.
exciting discoveries might be close…
q13 – expected sensitivities
P. Huber, M. Lindner, T. Schwetz, W. Winter, arXiv: 0907.1861
Discovery potential (90% CL) for sin2 2q13
from reactors and accelerators
THE VALUE OF Q13 CRUCIAL FOR FUTURE CP SEARCHES.
Neutrinos in Nature
1024
1020
Flux (cm-2 s-1 MeV-1)
Cosmological neutrinos
1016
1012
Solar n 65 milliards / cm2 / s
330 / cm3
108
Supernova neutrinos 1058 en 10 s
Geo-neutrinos
Reactor neutrinos
104
100
Athmospheric neutrinos
10-4
n from quasars
10-8
10-12
10-6
meV
10-3
meV
1
eV
103
keV
106
MeV
109
GeV
Neutrino Energy (eV)
1012
TeV
1015
PeV
1018
EeV
Two diffuse neutrino backgrounds never observed :
from the Early Universe and from supernovae
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
Core-collapse supernovae (SN)
nt
ne
99 % of the energy is emitted
as neutrinos of all flavours in
a short burst of about 10 s.
NS
Supernova 1987A
nm
collapse
accretion
cooling of the
neutron star
Totani et al., Astr.. J. 1998
0.1
1.
t (s)
10
Neutrinos follow closely the explosion.
Bring CRUCIAL INFORMATION
ON THE EXPLOSION AND
unknown n-PROPERTIES.
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,…)
A. 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:1001.2799;
Duan and Kneller,``Neutrino flavour transformation in supernovae,''
J. Phys. G 36, 113201 (2009) [arXiv:0904.0974.
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)
Future SN observations
Several detectors are running (ex. Borexino, Kamland, Super-K,…) .
Large-size detectors are under study (LAGUNA DS, FP7, 2008-2010).
Future strategy
I. 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).
Ando,Beacom,Yuksel PRL95 (2005)
ne detection: nnucleus measurements
necessary to determine the supernovae observatories’s response
HALO, LENA, GLACIER, MEMPHYS
208Pb
12C
40Ar
16O
SN neutrinos and n-properties :
For a supernolva at 10 kpc,
In a lead observatory the signal is:
Present limit : sin22q13< 0.1
(CHOOZ)
(20 MeV)
(10 MeV)
CC + 2n events depend on the ne
average energy and therefore
on the value of the third neutrino
mixing angle.
Engel, McLaughlin,Volpe, PRD67(2003)
HALO PROJECT
Planned AT SNOLAB.
q13
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:0902.0317
adiabatic
FLUXES
ON EARTH
non-adiabatic
ne + p
n + e+
29 MeV
15 MeV
POSITRON TIME SIGNAL
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
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
6.8 103 ne cm-2 s-1 from LSD (25 < Ene < 50 MeV) Aglietta et al. A Phys 1 (1992)
The star formation rate
The star formation rate is nowadays
constrained by various observations.
Uncertanties remains, especially at
small redshifts (a factor of 2 at z = 0).
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.
DSNB event rates in n-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
17.5-41.5 MeV
66
58
4.5-41.5 MeV
106
96
S.Galais, J.Kneller, C.Volpe and J.Gava, to appear in PRD, arxiv:0906.5294
nn
The neutrino nature
Dirac particle
n=n
?
Majorana p.
The search for the nature
neutrinoless bb decay
76As
76Ge
76Se
bb : 2n  2p + 2eExperiments search
Lepton-violating process
due to Majorana neutrino
exchange, physics beyond
the Standard Model.
THE bb-DECAY observation : A MAJOR DISCOVERY.
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.
The theoretical challenge
76As
b
m
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.
Double-beta decay and n-nucleus
2b0n: 2n  2p + 2eThe half-life calculations
involve many transition
matrix elements of high
multipolarity.
F. Simkovic et al,
PRC77 (2008)
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 neutrinonucleus interactions.
Volpe, hep-ph/0501233, J. Phys.G.31(2005)
n-NUCLEUS MEASUREMENTS TO GET INFORMATION on THE
HIGH MULTIPOLE MATRIX ELEMENTS AND THE VALUE OF gA…
Fermi Gas
Low-energy neutrino scattering
Nuclear Degrees
of Freedom
Nucleon Degrees
of Freedom
ATMOSPHERE
SUN,REACTOR
10
50
100
500
1000 (MeV)
n-Energy
SUPERNOVA
EFT, Microscopic
Approaches (RPA,
Shell Model), EPT,…
ACCELERATORS
Fermi Gas
Experimental data are very scarce (d and 56F, 12C).
Theoretical predictions are absolutely necessary.
Many calculations exist based on various models.
THEORETICAL ASPECTS
The effective V-A interaction Hamiltonian.
ne
C
N
e
Using perturbation theory :
The nuclear transition probabilities are the key quantities :
inclusive
exclusive
ISOSPIN AND SPIN-ISOSPIN MODES are EXCITED.
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:0802.1553
NEED FOR NEW MEASUREMENTS !
INTENSE NEUTRINOS SOURCES
CONVENTIONAL SOURCES
p
ne
m  nm
m
e  nm  ne
BETA-BEAMS
6Li
ne
P. Zucchelli, Phys. Lett. B (2002)
E
U
R
I
S
O
L
n
SPS
PS
storage
ring
LOW ENERGY BETA-BEAMS
C.Volpe, J Phys G 30 (2004).
A proposal to establish a facility for the production of
intense and pure low energy neutrino beams (100 MeV).
E
U
R
I
S
O
L
BASELINE
SPS
PS
n
n
storage
ring
close
detector
PHYSICS POTENTIAL
n-nucleus cross sections
(detector’s response,
r-process, 2bdecay)
fundamental interactions
studies (Weinberg angle,
CVC test, mn)
astrophysical applications
PHYSICS STUDIED WITHIN THE EURISOL DS (FP6, 2005-2009)
NEUTRINO-NUCLEUS MEASUREMENTS
Lazauskas and Volpe, NPA 2007
750
ne + 208Pb
=6
=10
=14
208Bi
ev
500
Pb 0+
250
Bi
+ e-
2+
1310+
1+
0
0
+
1
-
1
+
2
-
A better knowledge
is needed
2
+
3
-
3
+
4
No exp. info
Gamow-Teller
Low energy beta-beams:
A TOOL TO STUDY
SPIN-ISOSPIN EXCITATIONS.
=6
=10
=14
-
-5
4x10
DAR
-1 -1
IAS
-
 (MeV s )
0
-5
2x10
0
0
20
40
60
En (MeV)
80
100
n-nucleus scattering measurements at
future spallation facilities: SNS,JSNS,ESS?,SPL
R. Lazauskas and C. Volpe, in preparation.
Predictions on the expected
number of events for a detector
located at different distances
from the source.
1015 ne /s
1 ton cubic detector
EVENTS (3 107 s)
12C
1470
384
63
16O
998
261
43
v
40
Ar
8860
2310
380
56Fe
9100
2330
377
100Mo
17300
420
716
208Pb
34500 8820
Distance(m) 10
20
1430
50
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.
Danke.
Thank you!
Andromeda (M31)
Grazie.
Merci.