The LUNA experiment Laboratory for Underground Nuclear Astrophysics

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

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

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

Holy Grail of Nuclear Astrophysics 12 C( , )16 O Most important reaction in He-burning phase • Determines Carbon-Oxygen abundance in the universe Oxygen-16 • 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

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

Neutrino production in the Sun p + p d + e + + ne pp chain d + p 3 He + g 84. 7 % 3 He 13. 8 % +3 He a + 2 p 3 He +4 He 7 Be + g 0. 02 % 13. 78 % 7 Be+e- 7 Li + g +ne +p a+ a 7 Be + p 8 B + g 8 B 2 a + e++ ne 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 Reunion prospective: Univers et Rayons Cosmiques 6

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

Laboratory for Underground 8 Nuclear Astrophysics LUNAsite LNGS (1400 m rock shielding 4000 m w. e. ) LUNA MV (2018 ->. . . ) 3. 5 MV LUNA 1 (1992 -2001) 50 k. V LUNA 2 (2000 …) 400 k. V Radiation LNGS/surface Muons Neutrons 10 -6 10 -3 7

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

LUNA MV The scientific program: 3 He(4 He, )7 Be: 13 C( , n)16 O: 22 Ne( , n)25 Mg 12 C( , )16 O: solar neutrinos Heavy elements nucleosynthesis C/O ratio in the universe SN Type II, Type Ia… 3. 5 MV accelerator LUNA-MV existing meas. Reunion prospective: Univers et Rayons Cosmiques existing meas.

Experimental challenges 12 C( , )16 O : - extremely pure (10 -7) and stable solid carbon target - high efficiency, high resolution and bck-free gamma-detector 13 C( , n)16 O, 22 Ne( , n)25 Mg : - dense and pure 22 Ne 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

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

Schedule 2014 -2015 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

- Interested people at CPPM: J. Busto, F. Cassol, H. Costantini - preliminary work: Feb. 2013 -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 2015 -2020 - 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)