Post on 14-Jan-2016
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transcript
Carlo Broggini, INFN-Padova
Nuclear Burning in Stars
(Estar)(E) = S(E) e–2E-1
Reaction Rate(star) (E) (E) dEGamow Peak
MaxwellBoltzmann
Extrap. Meas.
Men in pits or wells sometimes
see the stars…. Aristotle
LUNA beyond the Sun
m-2 h-1 n
cm-2 s-1
luna
LUNA2 (400 kV)
Voltage Range :50-400 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
LUNA1 ( 50 kV)
Voltage Range :1 - 50 kV
Output Current:1 mA
Beam energy spread:20 eV
Long term stability (8 h):10-4
Terminal Voltage ripple:5 10-5
p + p d + e+ + e
d + p 3He +
3He +3He +2p 3He +4He 7Be +
7Be+e- 7Li + +e 7Be + p 8B +
7Li + p 8B 2 + e++ e
84.7 % 13.8 %
13.78 % 0.02%
pp chain
0,45
0,47
0,49
0,51
0,53
0,55
0,57
80 100 120 140 160 180
Ecm [keV]
S(E
) [k
eV b
]
activation-PRL+PRC
activation
on-line
14N(p,)15O
Q=7.3 MeV
- 504
-21
278
1414N+pN+p
729772977556
7276
68596793
6176
5241
5183
01515OO
1/2 +
7/2 +
5/2 +
3/2 +
3/2 -
5/2 +
1/2 +
1/2 -
No direct strength resonance data(level structure derived from the singe particle transfer reaction: 25Mg(3He,d)26Al) 2525Mg+pMg+p
Q = 6306 keVQ = 6306 keV
0 5+
228 0+
2626AlAl00
2626AlAlmm
64965+
190
6436
6399
4-
2- 92
130
Novae explosive Burning (T9>0.1)
AGB or W-R Stars (T9~0.05)
Ex (keV) JECM (keV)6598 5+ 304
25Mg(p,)26Al
Astrophysical sitesAstrophysical sitesAGB stars;AGB stars; Novae; Novae; Massive stars.Massive stars.
Astrophysical sitesAstrophysical sitesAGB stars;AGB stars; Novae; Novae; Massive stars.Massive stars. Nucleosintesis of the elements Nucleosintesis of the elements
24<A<2724<A<27 Astronomical interest of Astronomical interest of 1809 keV1809 keV 26 26Mg Mg lineline
Nucleosintesis of the elements Nucleosintesis of the elements 24<A<2724<A<27 Astronomical interest of Astronomical interest of 1809 keV1809 keV 26 26Mg Mg lineline
MotivationMotivationMotivationMotivation
What else can be done with LUNA II (400kV) ?
proposal submitted to INFN (2008-2012)
reaction Q-value (MeV)
Gamow energy (keV)
Lowest meas. Energy (keV)
LUNA limit
15N(p,)16O 12.13 10-300 130 5017O(p,)18F 5.6 35-260 300 6518O(p,)19F 8.0 50-200 143 8923Na(p,)24Mg
11.7 100-200 240 138
22Ne(p,)23Na 8.8 50-300 250 68
D(,)6Li 1.47 50-300 700(direct)50(indirect)
50
CNO
Ne-Na
BBN
2H(,)6Li
Q=1.47 MeV
Burning energy: 50-300 keV
12C()16O
• We would have the possibility to measure angular distributions down to 600 keV and total S-factor down to 500 keV with 10% accuracy
• Theoreticians ask for 10% uncertainty on Stot(300)
Great step forward: so far,10% accuracy only over 1.5 MeV
•MV-accelerator•12C-enriched targets•Beam intensity: 500A•Detection efficiency: 50% total
2.5% single segment (angular distributions)•Detection set-up: scintillator-crystal ball
Reactions powering the astrophysical s-process
Neutron source reactions: 13C(a,n)16O and 22Ne(a,n)25Mg
- Important for nucleosynthesis of elements heavier than iron
-Take place in helium- and carbon-burning reactions in massive and AGB stars
-For 13C(a,n)16O data above 270 keV are available (Gamow peak ~170 keV, LUNA ~200 keV)
- For 22Ne(a,n)25Mg data above 850 keV are available (Gamow peak ~470-700 keV, LUNA ~630 keV)
MV-accelerator
Accelerator Accelerator requirements:
MV electrostatic acceleratorOption 1: HVEE + conventional RF ion sourceOption 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
3He(,)7Be
Solar Neutrinos:7Be,8BBBN 7Li
Q=1.6 MeV
•Cross section from prompt gammaprompt gamma down to 90 keV (CM energy) using 4He beam on 3He target•Activation via off-line radioactive decayradioactive decay measurements of the 7Be atoms collected in the beam catcher•All with a final error < 5 %
0,3
0,4
0,5
0,6
0,7
0,8
S34 (
0)
[keV
Parker et. al.1963
Robertson et. al.1983
on-line - meas.average
Hilgemeier et. al.1988
Alexander et. al.1984
Osborne et. al.1982
Krwinkel et. al.1982
Nagatani et. al.1969
Volk et. al.1983
activationaverage
Osborne et. al.1982
Hilgemeier et. al.1988
on-line - measurements activation measurements
Nara Singh et. al.2004
Summary of previous measurements
<S34(0)> = 0.51 ± 0.02 keV b <S34(0)> = 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 S34(0) values:
R-matrix analysis: 0.51 ± 0.04 keV b (8%) [Descouvemont 2004]
Activation measurement
o 4He beam @ 350 keVo <I> ~ 230 µAo Recirculated 3He @ 0.7
mbar
T½ =52.2±1.5 d
Prompt -spectra
o 4He beam @ 400 keVo <I> ~ 300 µAo Irradiation time: 4.4d
o 4He beam @ 220 keVo <I> ~ 240 µAo Irradiation time:
24.4d
ΔΔS = -1.4 S = -1.4 4.2 % 4.2 %
0,45
0,47
0,49
0,51
0,53
0,55
0,57
80 100 120 140 160 180
Ecm [keV]
S(E
) [k
eV b
]
activation-PRL+PRC
activation
on-line
S34(0) = 0.560 S34(0) = 0.560 0.017 keV barn 0.017 keV barn
of 3He(,)7Be down to 93 keV 7Be ≈ prompt
SS3434(0) = 0.560 (0) = 0.560 0.016 keV barn 0.016 keV barn
ΔΦ(B) reduced from 12% to 10%
ΔΦ(Be) reduced from 9.4% to 5.5% (C. Pena Garay)
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)
LUNALUNA
HPGe Efficiency
0.00%
0.05%
0.10%
0.15%
0.20%
0.25%
0.30%
0.35%
0.40%
0.45%
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36
511 keV
662 keV
1173 keV
1275 keV
1332 keV
Effi
cien
za %
0.00%
0.05%
0.10%
0.15%
0.20%
0.25%
0.30%
0.35%
0.40%
0.45%
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36
511 keV
662 keV
1173 keV
1275 keV
1332 keV
7Be counting efficiency 1.8%
Beam intensity 1.5%
Beam heating effect 1.3%
Target density without beam
0.6%
7Be backscattering 0.5%
Incomplete 7Be collection 0.4%
7Be distribution in catcher 0.4%
478 keV branching 0.4%
7Be half-life 0.1%
3He purity in target 0.1%
Beam intensity 1.5%
Target density 1.5%
3He purity 0.1%
Efficiency 1.5%
Angular distribution 1.5%
ACTIVITYACTIVITY PROMPT-PROMPT-
25Mg(p,)26Al
Q=6.3 MeV
Nucleosynthesis Mg-Al
Astronomical interest of the from 26Al decay
•Cross section at 180-400 keV with Ge Ge detectorsdetectors
•Cross section down to 90 keV with BGO BGO summing crystalssumming crystals
Tur
boP
ump
4 BGO Detector
1”x1”NaI(Tl)
Bea
m P
rofil
eM
onito
r
Far
aday
Cup
4 S
lits
Wob
bler
s
Bel
low
Gat
e V
alve
LN2
Tra
p(I
sola
ted)
Lead
shie
ldin
g
Tar
get
incl
LN2
Tra
p an
dH
2O c
oolin
g
* cno from the Sun * Globular cluster age * C yield in AGB stars
15N(p,)16O
Q=12.13 MeV