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Nuclear Burning in Stars (E star ) ( E ) = S(E) e –2 E -1 Reaction Rate(star) (E) (E) dE Gamow Peak Maxwell Boltzmann Extrap.Meas. LUNA results Men in.

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Presentation on theme: "Nuclear Burning in Stars (E star ) ( E ) = S(E) e –2 E -1 Reaction Rate(star) (E) (E) dE Gamow Peak Maxwell Boltzmann Extrap.Meas. LUNA results Men in."— Presentation transcript:

1 Nuclear Burning in Stars (E star ) ( E ) = S(E) e –2 E -1 Reaction Rate(star) (E) (E) dE Gamow Peak Maxwell Boltzmann Extrap.Meas. LUNA results Men in pits or wells sometimes see the stars…. Aristotle Carlo Broggini, INFN-Pd

2 INFN - Laboratori Nazionali del Gran Sasso D.Bemmerer,R.Bonetti,C.Broggini*,F. Confortola,P.Corvisiero,H.Costantini,Z.Elekes, A.Formicola, Z. Fülöp, G.Gervino,A.Guglielmetti, C.Gustavino, G. Gyurky, G. Imbriani, M.Junker, A.Lemut, B.Limata, V.Lozza,M.Marta,R.Menegazzo, P.Prati, V.Roca, C.Rolfs, M.Romano, C.RossiAlvarez, O.Straniero,F.Strieder, E.Somorjai,F.Terrasi,H.P.Trautvetter INFN : Genova, LNGS, Milano, Napoli, Padova, Torino Inst.Physik mit Ionenstrahlen, Ruhr- Universität Bochum (GE) Atomki Debrecen (Hungary) LUNA

3 luna Voltage Range : kV Output Current: 1 mA 400 kV) Absolute Energy error ±300 eV Beam energy spread: <100 eV Long term stability (1 h) : 5 eV Terminal Voltage ripple: 5 Vpp Ge detector F = 0.7 m -2 h -1 FnFn cm -2 s -1

4 p + p d + e + + e d + p 3 He + 3 He + 3 He +2p 3 He + 4 He 7 Be + 7 Be+e - 7 Li + + e 7 Be + p 8 B + 7 Li + p 8 B 2 + e + + e 84.7 %13.8 % % 0.02% pp chain

5 14 N(p, g ) 15 O Q=7.3 MeV N+p O 1/2 + 7/2 + 5/2 + 3/2 + 3/2 - 5/2 + 1/2 + 1/2 -

6 10 -7 mbar10 -6 mbar10 -4 mbar mbar Windowless gas-target Max 10 mbar Low energy: gas target + BGO

7 Reaction Rate = counts/day Background rate = counts/day t = daysQ = C beam energy: 80 keV

8 cno from the Sun Globular cluster age C yield in AGB stars S t (0)=1.61±0.08±0.16 keV b

9 3 He(, g ) 7 Be Solar Neutrinos: 7 Be, 8 B BBN 7 Li prompt gammaCross section from prompt gamma down to 90 keV (CM energy) using 4 He beam on 3 He target radioactive decayActivation via off-line radioactive decay measurements of the 7 Be atoms collected in the beam catcher All with a final error < 5 % Q=1.6 MeV

10 Summary of previous measurements = 0.51 ± 0.02 keV b = 0.57 ± 0.03 keV b 0.53 ± 0.05 keV b (9%) [Adelberger 98] 0.54 ± 0.09 keV b (16%) [NACRE 99] Recommended S 34 (0) values: R-matrix analysis: 0.51 ± 0.04 keV b (8%) [Descouvemont 2004]

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13 Activation measurement o 4 He 350 keV o ~ 230 µA oRecirculated mbar Bi 7 Be

14 SourceDeterminationRelative Uncertainty Detector efficiencyMeasured1.8 % Beam currentCalibrated calorimeter1.5 % Beam heating effectMeasured (typical correction: 5%) 1.3 % Target thicknessPressure and temperature measurements 0.6 % Backscattering lossMeasured and simulated (typical correction: 2.1%) 0.5 % 478 keV -ray branchingFrom literature0.4 % Incomplete 7 Be collectionMeasured and simulated (typical correction: 1.6%) 0.4% Effective energyMeasured % Parasitic 7 Be productionMeasured upper limit0.04 % Sputtering lossUpper limit from MC Simulation0.02 % Total3.0 % Systematic uncertainties and corrections

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17 Prompt -spectra o 4 He 400 keV o ~ 300 µA oIrradiation time: 4.4d o 4 He 220 keV o ~ 240 µA oIrradiation time: 24.4d

18 3 He(, g ) 7 Be: the Sun: 7 Be and 8 B neutrinos Big-Bang 7 Li 14 N(p, g ) 15 O: down to 70 keV (T=60 T 6 ) cno from the Sun reduced by 2 Globular cluster age increased by Gy Higher C yield in AGB stars LUNA has shown that it is possible to measure (E star ): 3 He ( 3 He,2p) 4 He, 2 H(p, g ) 3 He 3 He ( 3 He,2p) 4 He: down to 16 keV no resonance within the solar Gamow Peak

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20 S 14,1 /5 S 14,1 x5 Standard CF88

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22 25 Mg(p, g ) 26 Al Q=6.3 MeV Nucleosynthesis Mg-Al Astronomical interest of the from 26 Al decay Ge detectorsCross section at keV (CM energy) using Ge detectors (not underground) BGO summing crystalsCross section at lower energies using BGO summing crystals (underground)


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