LUNA beyond the Sun Carlo Broggini INFNPadova Men
LUNA beyond the Sun Carlo Broggini, INFN-Padova Men in pits or wells sometimes see the stars…. Aristotle Nuclear Burning in Stars s(Estar) s( E ) = S(E) e– 2 ph Reaction Rate(star) F(E) s(E) d. E Gamow Peak Maxwell Boltzmann s E-1 Extrap. Meas.
F = F 0. 7 m-2 h-1 n 3 10 -6 cm-2 s-1 luna
LUNA 1 ( 50 k. V) Voltage Range : 1 - 50 k. V Output Current: 1 m. A Beam energy spread: 20 e. V Long term stability (8 h): 10 -4 Terminal Voltage ripple: 5 10 -5 LUNA 2 (400 k. V) Voltage Range : 50 -400 k. V Output Current: 1 m. A (@ 400 k. V) Absolute Energy error ± 300 e. V Beam energy spread: <100 e. V Long term stability (1 h) : 5 e. V Terminal Voltage ripple: 5 Vpp Ge detector
pp chain p + p d + e + + e d + p 3 He + 84. 7 % 3 He 13. 8 % +3 He +2 p 3 He +4 He 7 Be + 0. 02% 13. 78 % 7 Be+e- 7 Li + + e +p + 7 Be + p 8 B + 8 B 2 + e++ e
278 7556 1/2 7/2 + 5/2 + -21 6859 6793 3/2 + - 504 6176 3/2 - 5241 5/2 + 5183 1/2 + 1/2 - 7297 14 N+p 7276 14 N(p, g)15 O + Q=7. 3 Me. V 15 O 0
25 Mg(p, g)26 Al 304 Ex (ke. V) 6598 190 6496 130 6436 4 - 92 6399 2 - ECM (ke. V) Novae explosive Burning (T 9>0. 1) AGB or W-R Stars (T 9~0. 05) No direct strength resonance data (level structure derived from the singe particle transfer reaction: 25 Mg(3 He, d)26 Al) Q = 6306 ke. V 25 Mg+p Astrophysical sites AGB stars; Novae; Massive stars. J 5+ 5+ Motivation 26 Alm 26 Al 0 228 0 Nucleosintesis of the elements 0+ 24<A<27 5+ Astronomical interest of 1809 ke. V 26 Mg line
What else can be done with LUNA II (400 k. V) ? reaction Q-value (Me. V) Gamow energy (ke. V) 12. 13 10 -300 130 50 17 O(p, )18 F 5. 6 35 -260 300 65 18 O(p, )19 F 8. 0 50 -200 143 89 23 Na(p, )24 Mg 11. 7 100 -200 240 138 22 Ne(p, )23 Na 8. 8 50 -300 250 68 1. 47 50 -300 700(direct) 50(indirect) 50 15 N(p, )16 O CNO Ne-Na BBN D( , )6 Li Lowest meas. Energy (ke. V) LUNA limit proposal submitted to INFN (2008 -2012)
2 H( , g)6 Li Q=1. 47 Me. V Burning energy: 50 -300 ke. V
12 C( , )16 O • MV-accelerator • 12 C-enriched targets • Beam intensity: 500 A • Detection efficiency: 50% total 2. 5% single segment (angular distributions) • Detection set-up: scintillator-crystal ball • We would have the possibility to measure angular distributions down to 600 ke. V and total S-factor down to 500 ke. V with 10% accuracy • Theoreticians ask for 10% uncertainty on Stot(300) Great step forward: so far, 10% accuracy only over 1. 5 Me. V
Reactions powering the astrophysical s-process Neutron source reactions: 13 C(a, n)16 O and 22 Ne(a, n)25 Mg - Important for nucleosynthesis of elements heavier than iron -Take place in helium- and carbon-burning reactions in massive and AGB stars -For 13 C(a, n)16 O data above 270 ke. V are available (Gamow peak ~170 ke. V, LUNA ~200 ke. V) - For 22 Ne(a, n)25 Mg data above 850 ke. V are available (Gamow peak ~470 -700 ke. V, LUNA ~630 ke. V) MV-accelerator
Accelerator requirements: MV electrostatic accelerator Option 1: HVEE + conventional RF ion source Option 2: NEC + ECR high charge state ion source Two possible layouts: letter of intent submitted to LNGS
COLLABORATION Germany BOCHUM, Inst. For Experimental Physics, Ruhr-Universitat: C. Rolfs, F. Strieder, H. P. Trautvetter DRESDEN, Inst. For Radiation Physics, Forschungszentrum Dresden-Rossendorf : D. Bemmerer, M. Marta Hungary DEBRECEN, ATOMKI: Z. Elekes, Zs. Fulop, Gy. Gyurky, E. Somorjai Italy GENOVA, Università degli Studi and INFN: F. Confortola, P. Corvisiero, H. Costantini, A. Lemut, P. Prati LNGS, Gran Sasso: A. Formicola, C. Gustavino, M. Junker MILANO, Università degli Studi, Ist. Di Fisica Generale Applicata and INFN: R. Bonetti, A. Guglielmetti, C. Mazzocchi NAPOLI, Università, Dip. Scienze Fisiche and INFN: G. Imbriani, A. Di Leva, B. Limata, E. Roca, M. Romano, O. Straniero NAPOLI, II Università, Dip. Scienze Ambientali and INFN: F. Terrasi PADOVA, Università degli Studi and INFN: C. Broggini, A. Caciolli, R. Menegazzo, C. Rossi Alvarez TORINO, Università, Dip. Fisica Sperimentale and INFN: G. Gervino
3 He( , g)7 Be Q=1. 6 Me. V Solar Neutrinos: 7 Be, 8 B BBN 7 Li • Cross section from prompt gamma down to 90 ke. V (CM energy) using 4 He beam on 3 He target • Activation via off-line radioactive decay measurements of the 7 Be atoms collected in the beam catcher • All with a final error < 5 %
Summary of previous measurements <S 34(0)> = 0. 51 ± 0. 02 ke. V b Recommended S 34(0) values: R-matrix analysis: <S 34(0)> = 0. 57 ± 0. 03 ke. V b 0. 53 ± 0. 05 ke. V b (9%) [Adelberger 98] 0. 54 ± 0. 09 ke. V b (16%) [NACRE 99] 0. 51 ± 0. 04 ke. V b (8%) [Descouvemont 2004]
Activation measurement o 4 He beam @ 350 ke. V o <I> ~ 230 µA o Recirculated 3 He @ 0. 7 mbar T½ =52. 2± 1. 5 d
Prompt -spectra o 4 He beam @ 400 ke. V o <I> ~ 300 µA o Irradiation time: 4. 4 d o 4 He beam @ 220 ke. V o <I> ~ 240 µA o Irradiation time: 24. 4 d
S 34(0) = 0. 560 0. 017 ke. V barn
s of 3 He( , g)7 Be down to 93 ke. V 7 Be ≈ prompt g S 34(0) = 0. 560 0. 016 ke. V barn ΔΦ( B) reduced from 12% to 10% ΔΦ( Be) reduced from 9. 4% to 5. 5% (C. Pena Garay)
LUNA 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. Rossi. Alvarez, 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)
Efficienza % HPGe Efficiency
ACTIVITY 7 Be counting efficiency PROMPT- 1. 8% Beam intensity 1. 5% Target density 1. 5% Beam intensity 1. 5% Beam heating effect 1. 3% Target density without beam 0. 6% 3 He purity 0. 1% 7 Be 0. 5% Efficiency 1. 5% Angular distribution 1. 5% backscattering Incomplete 7 Be collection 0. 4% 7 Be 0. 4% distribution in catcher 478 ke. V branching 0. 4% 7 Be half-life 0. 1% 3 He purity in target 0. 1%
25 Mg(p, g)26 Al Q=6. 3 Me. V Nucleosynthesis Mg-Al Astronomical interest of the 26 Al decay from • Cross section at 180 -400 ke. V with Ge detectors • Cross section down to 90 ke. V with BGO summing crystals
Turbo Pump 1”x 1”Na. I(Tl) 4 BGO Detector Target incl LN 2 Trap and H 2 O cooling Lead shielding LN 2 Trap (Isolated) Gate Valve Faraday Cup Beam Profile Monitor 4 Slits Wobblers Bellow
* cno from the Sun * Globular cluster age * C yield in AGB stars
15 N(p, g)16 O Q=12. 13 Me. V
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