1. Laboratory for Underground Nuclear Astrophysics
The LUNA experiment
Laboratory for Underground Nuclear Astrophysics
Reunion prospective: Univers et Rayons Cosmiques

2. Why studying nuclear fusion reaction cross sections?
- Stars are powered by nuclear reactions
They determine:
stellar evolution and dynamics
elements origin and abundances
neutrino production
Reunion prospective: Univers et Rayons Cosmiques 1

3. Heavy elements nucleosynthesis
LUNA MV
The scientific program:
12C(a,g)16O: Carbon/Oxygen in the universe
SN Type II, Type Ia…
13C(a,n)16O:
22Ne(a,n)25Mg:
3He(4He,g)7Be: Solar neutrinos
Heavy elements nucleosynthesis
Reunion prospective: Univers et Rayons Cosmiques 2

4. 12C(,)16O Holy Grail of Nuclear Astrophysics
Oxygen-16
12C(,)16O
Most important reaction in He-burning phase
Determines Carbon-Oxygen abundance in the universe
Influences late stellar evolution
nucleosynthesis of heavy elements
Carbon/Oxygen determines:
dynamics of SN type II
end of heavy stars (Black Hole, Neutron star)
peak-luminosity and shape of SN type Ia
(standard candles in measurements of cosmological distances)
Reunion prospective: Univers et Rayons Cosmiques 3

5. nucleosynthesis of heavy elements
Heavy elements are produced in neutron capture processes
13C(a,n)16O
neutron sources
22Ne(a,n)25Mg
Reunion prospective: Univers et Rayons Cosmiques 4

6. Neutrino production in the Sun
p + p  d + e+ + ne
d + p  3He + g
3He +3He  a + 2p
3He +4He  7Be + g
7Be+e- 7Li + g +ne
7Be + p  8B + g
7Li + p  a + a
8B 2a + e++ ne
84.7 %
13.8 %
13.78 %
0.02 %
pp chain
ONLY if the cross sections of the involved reactions are accurately known
Neutrino flux from the Sun can be used to study:
Solar interior composition
Neutrino properties
ONLY if the cross sections of the involved reactions are accurately known
Reunion prospective: Univers et Rayons Cosmiques 6

7. Why going in an underground laboratory?
Energy range in stars ~ kTstar ( ~ 10 keV for H-burning ; ~ 100 keV for He-burning)
Due to Coulomb barrier, cross section ~ pbarn-fbarn …even less!!
Extremely low measured reaction rate
12C(a,g)16O
It is mandatory to have very low background
Surface
Underground
Perform measurements in an underground laboratory
Reunion prospective: Univers et Rayons Cosmiques 7

8. Laboratory for Underground Nuclear Astrophysics
LUNA site
LNGS (1400 m rock shielding  4000 m w.e.)
LUNA MV
(2018->...)
3.5 MV
LUNA 1
( )
50 kV
LUNA 2
(2000…)
400 kV
Radiation
LNGS/surface
Muons
Neutrons
10-6
10-3 7

9. Key nuclear reactions studied with LUNA1, LUNA2
LUNA 1: 3He(3He,2p)4He ; first direct measurement at solar energies (neutrino problem)
LUNA 2: 14N(p,g)15O: determination of age of the globular clusters (age of the universe)
3He(4He,g)7Be: precise determination of 8B and 7Be neutrino flux
d(4He,g)7Li: Li –problem in BBN
LUNA 1 accelerator: 50 kV
LUNA 2 accelerator : 400 kV
At the moment unique accelerator facility underground
Reunion prospective: Univers et Rayons Cosmiques 9

10. Heavy elements nucleosynthesis
LUNA MV
The scientific program:
3He(4He,g)7Be: solar neutrinos
13C(a,n)16O:
22Ne(a,n)25Mg
12C(a,g)16O: C/O ratio in the universe
SN Type II, Type Ia…
Heavy elements nucleosynthesis
3.5 MV accelerator
LUNA-MV
LUNA-MV
existing meas.
existing meas.
Reunion prospective: Univers et Rayons Cosmiques 10

11. Experimental challenges
12C(a,g)16O : - extremely pure (10-7) and stable solid carbon target
- high efficiency, high resolution and bck-free gamma-detector
13C(a,n)16O, 22Ne(a,n)25Mg : - dense and pure 22Ne gas target
- high efficiency and bck-free neutron detector
(Possible) French contribution
Carbon target (CSNSM-Orsay)
Sidonie implanter at CSNSM:
consolidated expertise in high pure implanted targets
Neutron detector (CPPM)
Expertise in :
detector simulation and characterization
- low background environment
Proximity of neutron facility (Cadarache)
good occasion to develop new expertise (neutron detection)
Reunion prospective: Univers et Rayons Cosmiques 11

12. Status of the LUNA-MV project
February 2013 the “Starting up the LUNA MV Collaboration” workshop was organized at the LNGS
September 2013: different WG were formed
Neutron detector (F. Cassol)
Solid carbon targets (A. Formicola)
Gamma detector (R. Menegazzo)
LUNA-MV has been financed with a total of 5.3 Meuro by Italian Research Ministry:
Accelerator
Site preparation
Shieldings
Beam-lines
Reunion prospective: Univers et Rayons Cosmiques 12

13. Schedule
Site definition -Tender for the accelerator- Beam lines and detectors R&D
2016 beginning of Site preparation - Infrastructures
2017 Accelerator arrival at LNGS – Shielding – beam lines construction
2018 Calibration of the apparatus and first beam on target
Competitive project
A USA project (CASPAR) is aiming to install a 1 MV machine at the SURF lab (Homestake): time schedule similar to LUNA-MV
Collaboration has started with CASPAR project
Reunion prospective: Univers et Rayons Cosmiques 13

14. “ We are made of star-stuff”
Interested people at CPPM: J. Busto, F. Cassol, H. Costantini
preliminary work: Feb Dic. 2013
present status: frozen participation due to:
2 years delay of the project (change of location at LNGS)
at present no French critical mass (CPPM, CSNSM only)
Something to keep in mind for
LUNA-MV looks for collaborators
Connected to the Cosmology, Astrophysics and Particle physics
Small scale experiment: small investment for good quality physics
Short time needed for physics results
Ideal experiment for students (from experimental work to data analysis and astrophysical implications)
“ We are made of star-stuff”
(Carl Sagan 1973)