1. Institut de Physique Nucléaire Orsay, France
Physics
with a very first
Low-energy Beta-beam n
Cristina VOLPE
Institut de Physique Nucléaire Orsay, France

2. P L A N n-Nucleus Interactions: Low-energy Beta-beams Site
Nuclear Astrophysics
- Nuclear Structure Studies
- Neutrino Physics P L A N
Site
Status and Pespectives

3. n n n g The beta -beam concept 6He 6He Zucchelli, PLB 2002
Q 1/ n
6He
Lorentz boost
high g n
6He
-beam concept

4. Low-energy Beta-beams
C. Volpe, Journ. Phys. G. 30 (2004), hep-ph/
THE PROPOSAL
To exploit the beta-beam concept to produce
intense and pure low energy ( MeV) neutrino beams.
PHYSICS POTENTIAL
boost n
6He
Neutrino-nucleus interaction studies. n
6He
Neutrino properties,
like the n magnetic moment. …
A BETA-BEAM FACILITY FOR LOW ENERGY NEUTRINOS.

5. n-Nucleus studies: Motivation
Neutrino
experiments
STANDARD MODEL
and BEYOND
NUCLEAR
PHYSICS C N ne e
Supernovae,
Nucleosynthesis
ASTROPHYSICS
Neutrino-Nucleus Interactions
A topic of current great interest for
various domains of physics.

6. Understanding Nucleosynthesis
The site where the heavy
elements are synthetized
is not known.
Supernova type II explosions:
99 % of the energy is emitted as neutrinos.
Calculations of abundances.
neutrino
capture ! N
N+1
N-1 Z
Z+1
neutron
capture
b-decay
NEUTRONS
PROTONS
neutron-rich
(exotic) nuclei.
n-NUCLEUS INTERACTIONS ARE NEEDED.

7. Meyer, McLaughlin, Fuller, 1998.

8. NEUTRINOS AS a PROBE for NUCLEAR STRUCTURE STUDIES.
C. Volpe et al., Phys. Rev. C65, 2002.
ne + 208Pb Bi + e-
E X A M P L E
<Ene >=
15 MeV 2+ 1- 3- 1-
30 MeV 1+ 0+ Bi Pb
50 MeV
The contribution to
the total cross section
increases for increasing
impinging neutrino energy.
no experimental information
is available.

9. Neutrinoless Double-beta Decay
n  n
n Dirac
n Majorana
n = n
How do we search for
the n-nature? ?
76Ge
76As
76Se
bb(0n)
Klapdor et al., 2001
> y (90% C.L.)
< mn> < 0.3 – 1.0 eV
The present best limit.
Beyond the Standard Model
(e.g. exchange of massive
Majorana neutrinos)
2b(0n): 2n  2p + 2e-
Lepton-violating process

10. Theoretical Situation
G : phase space factor
M : nuclear matrix elements
<mn> : effective neutrino mass
G( ) M2 <mn>2 Q5 bb 1 =
Theoretical predictions (mainly performed within Shell Model
and QRPA) exhibit significant variations of the neutrinoless
double-beta decay half-lives for the same candidate emitter.
This has important implications, in particular it translates in
an uncertainty on the n-mass.
REDUCING THE UNCERTAINTIES: A MAJOR CHALLENGE.

11. 76Ge
Bobyk,Kaminski,Simkovic,PRC2001
76Se
76Ge
76As
bb(0n) m b
Several processes have been considered to constrain
the nuclear matrix elements, in particular beta-decay,
muon capture, 2b(2n), charge-exchange reactions.
C.Volpe, hep-ph/ , to appear in Journ. Phys. G.
One can show that the states involved in neutrinoless double
beta decay due to the exchange of a massive Majorana neutrino
are the same states as those excited in neutrino-nucleus
interactions.

12. n-Nucleus Interactions: Present status
Neutrinos probe nuclei over a wide energy range.
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 (deuteron and iron, carbon).
Theoretical predictions are absolutely necessary.
The interpolation between these two regimes as well as
the extrapolation from stable to exotic nuclei are needed.

13. Low-energy Beta-beams
C. Volpe, Journ. Phys. G. 30 (2004), hep-ph/
THE PROPOSAL
To exploit the beta-beam concept to produce
intense and pure low energy ( MeV) neutrino beams.
PHYSICS POTENTIAL
boost n
6He
Neutrino-nucleus interaction studies. n
6He
Neutrino properties,
like the n magnetic moment. …
A BETA-BEAM FACILITY FOR LOW ENERGY NEUTRINOS.

14. Neutrino-nucleus measurements
SITES
Neutrino-nucleus measurements
Two options studied :
Large ring
(standard b-beam)
Small Ring
(ex. GSI future ring)
Serreau and Volpe,
hep-ph/ ,
PRC70 (2004). PS
SPS E U R I S O L n
Beta-beam baseline at CERN
Storage
Ring
close
detector d
length of the
straight sections L
total length

15. SNS Proposal at OAK Ridge Laboratory
Y. Efremenko, 2004.
From the decay of
pions and muons
SCIENTIFIC OPPORTUNITIES (Journ. Phys. G29, 2003)
Neutrino-nucleus interaction studies
Neutrino-oscillation searches
Non-standard components of the weak interaction
We have taken similar detectors.

16. n-Nucleus Rates at low-energy b-beams
J. Serreau
and C. Volpe,
PRC70 (2004)
hep-ph/
Neutrino Fluxes g n
<En>~2gQb/2
Small Ring : Lss = 150 m, Ltot = 450m Large Ring :Lss = 2.5 km, Ltot =7.5 km
Small Ring
Large Ring
25779
82645
103707
7922
9453
1956
ne + 208Pb
ne + 16O
ne + D
Events
per year
for g=14
Mass (tons) 35
952
360
INTERESTING INTERACTION RATES CAN BE OBTAINED.
A SMALL DEVOTED STORAGE RING IS BETTER.

17. Low-energy Beta-beams
Feasibility Study within
EURISOL Design Study
Beta-beam baseline
at CERN E U R I S O L
Acceleration issues
SPS
M. Benedikt and
M. Lindroos, CERN
Storage
Ring PS
Storage Ring
Size
Space-charge effects
Duty cycle
Intensities n
close
detector n
J. Payet and
Chancé,
CEA Saclay, France
Detectors issues
(remember LSND and KARMEN)
THE FEASIBILITY STUDY just STARTED.

18. Conclusions and Perspectives
The study of neutrino-nucleus interactions at low
energy represents an interesting axis of research.
This is of interest for different domains of physics.
Low-energy beta-beams require a small storage
ring. The feasibility study has just started.
A detailed study of the detector issues, at least
for one typical example, is needed.
Low-energy beta-beams might
furnish the very first beta-beam.