NuPECC - Milan 9 2012 Present and future of Laboratory Underground Nuclear Astrophysics Alba Formicola - Status of the D(, ) 6 Li measurement -Status of.

NuPECC - Milan 9 2012

Present and future ofLaboratoryUnderground

NuclearAstrophysics

Alba Formicola

-Status of the D(,)6Li measurement

-Status of the 17O(p,)18F measurement

-Status of the LUNA MV project and plans for the future

NuPECC - Milan 9 2012NuPECC - Milan 9 2012

BBN : Production of the lightest elements (D, 3He, 4He, 7Li, 6Li) in the first minutes after the Big Bang

The case of 6LiIt has the next-highest predicted primordial abundance after D, 3He, 4He

and 7LiIt has been found in non negligible quantities in very old low metallicity

halo stars unexpectedly high amount (2-3 orders of magnitude compared to available BBN network predictions - NACRE)

The primordial abundance is determined by the rate of two reactions:D(a,)6Li which produces practically all the 6Li

6Li(p,)3He which destroys 6Li sufficiently well known

Theoretical estimates in the region of interest differ by 1-2 orders of magnitude

NuPECC - Milan 9 2012NuPECC - Milan 9 2012

Experimental set-up to study the D()6Li reaction

D(α,α)D

Rutherford scattering

D(D,n)3He

reaction

also D(D,p)toccurs with similar

cross sectionmonitoring of

neutron production

Beam induced background

4He beam (I ~300A) on a windowless

D2 gas target (P=0.3mbar)

beam current measurement by calorimeter

HPGe detector for γ detection

(n,n’) reaction on the surrounding

materials (Pb, Ge, Cu).-ray background in the

D(a,)6Li RoI (~1.6 MeV)

Direct measurement of the D()6L cross section at astrophysical energies

The next beam time is scheduled for March and April 2012

measurement with an AmBe neutron source to compare with simulation results

further work to understand the background in the γ-detector

17O+p is of paramount importance for understanding hydrogen-burning in different stellar environments:

Red Giants Novae starsMassive StarsAsymptotic Giant Branch (AGB)

Astrophysical motivation to study the 17O(p,γ)18F reaction

Hot-CNO Cycle

Rolfs et al. Nuc. Phys. A217 29-70 (1973) –

Fox et al. Phys. Rev. C 71, 055801 (2005) –193 keV res. meas. : ωγ193= (1.2±0.2)×10-6 eV

Chafa et al. Phys. Rev. C 75, 033810 (2007) - Activation meas. : ωγ193= (2.2±0.4)×10-6 eV

Newton et al. Phys. Rev. C 81, 045801 (2010): cross section measurements

17O 18F

18O

(β+ν)

NuPECC - Milan 9 2012NuPECC - Milan 9 2012

Experimental setup to study the 17O(p,γ)18F reaction

Proton energy range covered : 193- 400 keV with an average current I~300 μA

Enriched 17O targets Activation and Prompt on Ta backings Gamma measurements

18O(p,γ)19F target profile

NuPECC - Milan 9 2012NuPECC - Milan 9 2012

On resonance spectra of the 17O(p,γ)18F reaction

18F

17O+p

Ep= 193 keV5789

1080

937

38393791

3358

3134

25232101

1041

Ex(keV)

R -> 3791R -> 2101

R -> 3133

R -> 1080R -> 937

937 1080

NuPECC- Milan 9 2102

In a very low background environment such as LNGS, it is mandatory not to increase the neutron flux above its average value

OnC 1613 ),(α beam intensity: 200 µATarget: 13C, 2 1017at/cm2

(99% 13C enriched)Beam energy(lab) ≤ 0.8

MeV

MgnNe 2522 ),(α beam intensity: 200 µATarget: 22Ne, 1 1018at/cm2

Beam energy(lab) ≤ 1.0 MeV

OC 1612 ),( OnC 1613 ),( from

α beam intensity: 200 µATarget: 13C, 1 1018at/cm2 (13C/12C =

10-5)Beam energy(lab) ≤ 3.5 MeV

• Maximum neutron production rate : 2000 n/s

• Maximum neutron energy (lab) : 5.6 MeV

The LUNA MV project

12C()16O the “Holy Grail” from Nobel Lecture 1993 by William Fowler

Higher energy machine 3.5 MV single ended positive ion accelerator

Next-generation underground laboratory for Nuclear Astrophysics:

…. call to the European Nuclear Astrophysics community for a wider collaboration in support of the next-generation underground laboratory. To state your interest to contribute to any of the Work Packages under International Collaboration

WP1: Accelerator + ion source

WP2: Gamma detectors

WP3: Neutron detectors

WP5: Solid targets

WP6: Gas target

WP7: Simulations

WP8: Stellar model calculations

Representatives: Aliotta Marialuisa, Luis Fraile, Zsolt Fulop, Alessandra Guglielmetti