nupecc - milan 9 2012 present and future of laboratory underground nuclear astrophysics alba...
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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