G. Olry for the IPN Orsay team 5 th SPL collaboration meeting, 25-26/11/2010, CERN.
Unbound states near the proton emission threshold. The case of 16 F. I. Ştefan (1), F. de Oliveira...
-
Upload
onfroi-despres -
Category
Documents
-
view
104 -
download
0
Transcript of Unbound states near the proton emission threshold. The case of 16 F. I. Ştefan (1), F. de Oliveira...
Unbound states near the proton emission threshold. The case of 16F.
I. Ştefan(1) , F. de Oliveira Santos(2)
(1) IPN Orsay(2) GANIL
Nova explosions
X-ray bursts15O
14N(p,γ)
15O(α,γ)19Ne
15O(pp,γ)17Ne
15O + p <=> 16F (unbound)15O – decay β+ ( T1/2=122 s )
The case of 16F
β+ (Qβ=15 MeV)
15O+p
16F
E0= 0.536 MeV
p
1/2-
0- Γp=25 keV
16O
β+
Qβ=15 MeV
β+ (Qβ=15 MeV)
15O+p
16F
E0= 0.536 MeV
p
1/2-
0- Γp=25 keV
16O
β+
Qβ=15 MeV
Mirror nucleus - 16N
Γβ=6.6 10-22 MeV
β+ (Qβ=15 MeV)
15O+p
16F
E0= 0.536 MeV
p
1/2-
0- Γp=25 keV
16O
β+
Qβ=15 MeV
(pp,γ) – Gorres et al 1995
(α,γ) – Taux estimé
Vc (
MeV
)
r (fm)
E0
16Fgs
Coulomb barrier
ECM (MeV)
)()( EPE lp
MeV2210*6.6
Wid
th (
MeV
)
15O+p 16F
15O+p
16O+β++ν
r (fm)
p
β+
E0
Vc (
MeV
)
ECM (MeV)
High ECM for the 15O – p system:
•Γp >> Γβ
•High probability to form 16F compound nucleus
•Beta decay improbable
)()( EPE lp
MeV2210*6.6
Wid
th (
MeV
)
15O+p 16F
15O+p
16O+β++ν
ECM (MeV)
Low ECM for 15O – p system:
•Γp << Γβ
•Decreased probability to form the 16F compound nucleus
•Beta decay branching ratio increased
)()( EPE lp
MeV2210*6.6
r (fm)
p
β+
E0
p
β+
Vc (
MeV
)
Wid
th (
MeV
)
γ
15O+p 16F
15O+p
16O+β++ν
r (fm)
Vc (
MeV
)
E0
2201 )
2
)(()(
EEEE
ctresonancetheofShape
tot
Hypothesis:
β+ (Qβ=15 MeV)
15O+p16F
E0= 0.536 MeVγ
dEEEPEPEE pppp
),()(),(),())(,(
γ
1/2-
0- Γp=25 keV
16O
pE1
p
Γp=70 keV
E0= 0.729 MeV
1-
β+
β+
Qβ=15 MeVβ+
Vc (
MeV
)
E0
γ
dEEEPEPEE pppp
),()(),(),())(,(
β+
β+
pE1
Facteur 109 !!
Vc (
MeV
)
E0
γ
dEEEPEPEE pppp
),()(),(),())(,(
β+
β+
pE1
Factor 109 !!
r (fm)
2201 )
2
)(()(
EEEE
ctresonancetheofShape
tot
Hypothesis:
Vc (
MeV
)
E0
γ
dEEEPEPEE pppp
),()(),(),())(,(
β+
β+
pE1
Factor 109 !!
r (fm)
2201 )
2
)(()(
EEEE
ctresonancetheofShape
tot
Hypothesis:
Let’s check it!
Let’s check it!!
• EURISOL 15O, 14O beam ?
• Different consequences?
p + p ↔ 2He → d + e+ +
p + 4He ↔ 5Li → γ + e+ + ν +4He + n
15O intensity = 1010 pps
E = 0.8 A MeV
N reactions = 8 / day.Continuum Shell Model
• Astro?
• Unbound state isomer !
16F radioactive??
•Non exponential decay!
•More surprises to come …
Future
Application for other unbound nuclei
- 15F (very interesting case)
- 5Li
- 4Li
- 19Na
…….
Outlook
Proposition of a new reaction pathway - 15O(p,γ)(β+)16O
- Consequences in different astrophysical scenarios
- Sequential decay ?
- Shape of the resonance ?
- γ decay between two unbound states ? σ(p,γ)~ 1 μb
- Experimental Confirmation
Questions related with the model
End
β+ (Qβ=15 MeV)
15O+2p 16F+p
0.536 MeV
p
1/2-
0-
0.732 MeV
16O+p
17Ne
2-
5/2-
1/2+ E1= 0.892 MeV
0.324 MeV
0 MeV
-0.958 MeV
-15 MeV
γ γ
γ
β+
15O(p,γ)(p,γ)17Ne
1/2-
15O(p,γ)(β+)16O
15O(β+)15N (2 min)15O(α,γ)19Ne 15O(p,γ)(β+)16O15O(p,γ)(p,γ)17Ne
Conclusions
Futur
• Astro à revoir ?
• Expérience SPIRAL 2 ?
• D’autres conséquences en astro ?p + p ↔ 2He → d + e+ +
15O intensité = 1010 pps
E = 0.8 A MeV
N réactions = 8 / jour.Continuum shell model
• Intrastate decay !
• Isomère de noyaux non liés ! 16F radioactif ??
• Décroissance non exponentielle !
• Test Heisenberg ?????
• D’autres surprises …
Futur
En physique nucléaire 1%
Ex(keV) Γp (keV) Jπ
0 25 ± 10 0-
193 (10) 70 ± 5 1-
424 (2) 6 ± 3 2-
721 (4) 15± 5 3-
1H(15O,p)15O
~1.4 107 pps 15O1+ SPIRAL beam
E = 1.2 MeV/A
Thick polypropylene target (CH3)
e-print at the address:
http://arxiv.ccsd.cnrs.fr/abs/nucl-ex/0603020
General context
Astrophysical motivation
Experimental measurements
Implications Conclusions
β+ (Qβ=15 MeV)
15O+2p 16F+p
0.536 MeV
p
1/2-
0-
0.732 MeV
16O+p
17Ne
2-
5/2-
1/2+ E1= 0.892 MeV
0.324 MeV
0 MeV
-0.958 MeV
-15 MeV
γ γ
γ
β+
15O(p,γ)(p,γ)17Ne
1/2-
15O(p,γ)(β+)16O
15O(p,β+)16O
Contexte général
Motivation astrophysique
Mesures expérimentales
Résultats obtenus
Conséquences Conclusions
β+ (Qβ=15 MeV)
15O+p
16F
E0= 0.536 MeV
p
1/2-
0- Γp=25 keV
16O
β+
Qβ=15 MeV
E (MeV)ECM (MeV)
σ(p,β)=(Facteur Géométrique) Γp(E)(Forme de la résonance)Γβ
22
2)(
1
rEE
résonanceladeForme )()( EPE lp
MeV2210*6.6
ECM (MeV)
15O(p,γ)(β+)16O15O(p,β+)16O
Contexte général
Motivation astrophysique
Mesures expérimentales
Résultats obtenus
Conséquences Conclusions
p
r (fm)
p
β+
E0
p
β+
γE1
Vc (
MeV
)
Lar
geur
(M
eV)
Contexte général
Motivation astrophysique
Mesures expérimentales
Résultats obtenus
Conséquences Conclusions
Théorie matrice R
Canal d’entré
15N+p Canal sortie 15N+p
Canal sortie
12 C+αRégion intérieure
16O
Paramètre de la matrice R (ra)
• r > ra les seules forces sont les forces coulombiennes;
• r < ra les forces nucléaires et coulombiennes;