1. Study of the resonance states in 27P by using
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Study of the resonance states in 27P by using
elastic scattering of 26Si + p

2. 1.809 g-ray image, made by COMpton TELescope
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1.809 g-ray image, made by COMpton TELescope
Estimation of the abundance of 26Al under different stellar sites, i.e., Novae, Supernovae, etc.
: Important for building a model of stellar evolution, or identifying the main origin of the g-sources
26mAl and 26gAl have different paths.
Then, they should be dealt with as different species??

3. Under higher temperature of T > 0.4 GK, they can communicate
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Under higher temperature of T > 0.4 GK, they can communicate
through internal transitions.
(Ward80, Coc00, and Runk01)
Therefore the abundance of 26mAl become s important and
we should know the reaction rate of 26Si (p, g)27P, which
competes with 26Si(b+n)26mAl.
More contributable, the resonance reaction rate needs
the information of the resonances within Gamow window,
such as E i (resonance energy), J (spin).

4. To get the resonance parameters of resonance states in 27P,
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To get the resonance parameters of resonance states in 27P,
• Probe : Elastic scattering with a radioactive ion beam 26Si,
because of its large scattering cross section
• Physical quantity to be measured :
Excitation function of the elastic scattering of 26Si + p
using thick target scan technique
• Tool for analysis :
R-matrix based code SAMMY M6-beta
• Physical quantities to be extracted :
Resonance parameters, such as energy, spin-parity, and
proton decay width for each observed resonance
• Astrophysical Information to be presented :
Reaction rate for resonant capture as a function of temperature

5. RI beams at F3 : 25Al (33 kcps, 61.8 % purity), 26Si (12kcps, 23.2 %)
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1st experiment
Date : June ~ June
RI beams at F2 : 25Al (11.1 kcps, 5.1 % purity), 26Si (2.32kcps, 1.1 %)
for full 24Mg beam of 600enA
2nd experiment
Date : Jan ~ Jan
RI beams at F3 : 25Al (33 kcps, 61.8 % purity), 26Si (12kcps, 23.2 %)
for full 24Mg beam of 1600enA

6. Brief introduction of experimental setup in 2003
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Brief introduction of experimental setup in 2003
CRIB (CNS Radioactive Ion Beam RIKEN, Japan
24Mg beam (7.439 MeV/u, ~ 600 emA) + 3He gas (1atm)
3He (24Mg, n)26Si D2 D1
PPAC
Target holder
DE-E 0 deg.
DE-E 17 deg.
PPAC

7. E cm (26Si) = 3.606 MeV on target Beam Intensity = 2 .32 kcps
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Depending on different Br, the fragments are
separated by two dipole magnets.
E cm (26Si) = MeV on target
Beam Intensity = kcps
By using position sensitive
detectors, proton spectra
can be converted to those
in C.M. frame.

8. Brief introduction of experimental setup in 2011
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Brief introduction of experimental setup in 2011
26Si14+
- Energy ~ 3.710MeV/u
- Purity ~ 23 %
- Intensity ~ 1.2X104 pps

9. 26Si RIB 3.710MeV/u recoiled protons H2 gas target (30cm, 330torr)
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26Si RIB
3.710MeV/u
recoiled protons
H2 gas target
(30cm, 330torr)
DSSDs at 0o and 15o
for DE-E telescope
PPACs

10. Overview • • •
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The excitation function of 26Si + p can be analyzed by R-matrix theory and Shell model calculation to extract the resonance parameters.

11. Preliminary result Excitation function of 26Si+p In 2003 In 2011 0o
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Excitation function of 26Si+p
In 2003 0o
Preliminary result
In 2011

12. R-matrix analysis It was hard to determine a good spin-parity
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R-matrix analysis
It was hard to determine a good spin-parity
combination for the observed peaks, because of
large statistical error. So all candidates were taken and
used in determining the important resonance parameters.

13. Comparison with the shell model calculation (OXBASH)
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Comparison with the shell model calculation (OXBASH)
Iliadis et al., NPA 618, 166 (1997) :
~ 0.2 for 1d3/2, 5/2 ~ 0.4 for 2s1/2
Spectroscopic factor Calculation (Oxbash)
- Model space : sdpn
- Interaction : wpn
- Core : 26Si(g.s., 0+)

14. Overview • • •
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15. ** 26Si + p  27P radiative capture reaction rate calculation
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26Si + p  27P radiative capture reaction rate calculation
1. Parameters, used in the resonant capture reaction rate calc. **
** Weisskopf width, calculated and based on the transition information of 27Mg
2. Direct capture reaction rate
So = from Caggiano et al. (PRC , 2001)
3. Total capture reaction rate
Resonant capture + Direct capture reaction rate

16. Not including new levels
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Not including new levels
1.2 MeV
1.631 MeV
Including new levels

17. X-ray burst model 1.35Msun 1.25Msun 26Si + p  27P 26Si b-decay
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Competition between 26Si + p  27P and 26Si  26mAl b-decay
solid and dashed line : rXH<sv>/AH = /T1/2 (XH = 0.5, T1/2 = s)
X-ray burst model
1.35Msun
1.25Msun
26Si + p  27P
26Si b-decay
For T > 2GK and r < 10-2 g cm-3 , the newly found states become more significant.

18. [Collaborators]