Center for Nuclear Study Univ of Tokyo Hidetoshi Yamaguchi D Kahl T NakaoY Wakabayashi S Kubono T Hashimoto S Hayakawa T Kawabata N Iwasa ID: 935756
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Slide1
Studies on alpha-induced astrophysical reactions using the low-energy RI beam separator CRIB
Center for Nuclear Study, Univ. of TokyoHidetoshi Yamaguchi, D. Kahl, T. Nakao,Y. Wakabayashi, S. Kubono, T. Hashimoto, S. Hayakawa, T. Kawabata, N. Iwasa, T. Teranishi, Y.K. Kwon, D.N. Binh, L.H. Khiem, and N.G. Duy
Slide2OutlineCRIB…low-energy RI beam facility of the Univ. of Tokyo, located in RIBF of RIKEN Nishina
center.Recent projects…emphasis on a-induced astrophysical reactionsAlpha resonant scattering for (a,g) reaction study [e.g. 7Li/7Be+a]Direct measurement of (a, p) reactions [e.g. 18Ne/30S(a, p)]2013 Jun 4INPC 2013
Slide3CRIB CNS
Radio-Isotope Beam separator , operated by CNS (Univ. of Tokyo), located at RIBF (RIKEN Nishina Center). Low-energy(<10MeV/u) RI beams by in-flight method.Primary beam from K=70 AVF cyclotron. Momentum (Magnetic rigidity) separation by “double achromatic” system, and velocity separation by a Wien filter. Orbit radius: 90 cm, solid angle: 5.6 msr, momentum resolution: 1/850.INPC 20132013 Jun 4
Slide4Low-Energy RI beam Productions at CRIB
Direct reactions such as (p,n), (d,p) and (3He,n)
in inverse kinematics are mainly used for the production….large cross sectionMany RI beams
have been produced at CRIB:
typically
10
4
-10
6
pps
7
Be…
2 x 10
8
pps available with a cryogenic target.H. Yamaguchi et al., NIM A (2008)
RI beam at CRIB /Stable nuclei
INPC 2013
2013 Jun 4
Slide5International collaborations at CRIBCRIB experiments performed in 2007-2011,
by collaborated members of CNS and other institutes: INPC 20132013 Jun 4
Slide6Recent research projects
Proton/alpha resonant scattering26Si+p (Collaborated with Chung-Ang, Korea) H.S. Jung et al., published at PRC (2012).7Li/7Be+a (CNS) H. Yamaguchi et al., PRC (2011&2013).21Na+p, 22Na+p [18Ne(a,p), Ne-Na cycle] (IMP/CIAE, China)17F+p [Resonances for 14O(a,p)](IMP/CIAE, China) (α,p) reaction measurement, Active target (GEM-MSTPC)18Ne(a,p) (CNS, Hashimoto (now at RCNP))30S(α,p) (CNS, Daid Kahl)22Mg(α,p) (IOP, Vietnam , Nguyen Ngoc Duy
)44Ti(a,p) (KEK,
Ishiyama
)
…
44
Ti beam test
successful.
(
a,g
)
16
N
⇒
16O*⇒12C+a for 12C(a,g) (Catania, Italy, S. Cherubini)Reaction mechanism8B+Pb (Padova, Italy, C. Signorini)β-decay
7Be lifetime in metal (Tohoku Univ, Otsuki)2013 Jun 4INPC 2013
Slide77Li+a/ 7Be+a study
7Li(a,g)11B …important at high-T, as a production reaction of 11B (the n-process in core-collapse supernovae).7Be(a,g)11B … one of the reaction in hot p-p chain, relevant at high-T. Contribution of higher-lying resonances unknown. a-cluster structure in 11B/11C :2a+t / 2a+3He cluster states are known to exist (similar to the dilute cluster structure in 12C.)Several “bands” which have
a-cluster structure could be formed. We can study the band and cluster structure more in detail.INPC 2013
2013 Jun 4
Slide87
Be(a,g)np-process calculation (T9>1) shows considerable contribution by 10B(a,p)13C and 7Be(a,g)11C as much as the triple-alpha process.S. Wanajo et al., Astrophys. J (2010)2013 Jun 4INPC 2013
Slide97Li/7Be+α; method
“Thick target with inverse kinematics” Resonant elastic scatterings can be measured at qcm=180 deg. MCP2013 Jun 4INPC 2013
Slide107Be+a Excitation functions4 excitation functions… new information on resonant widths, spin, and parity.
H. Yamaguchi et al., PRC, Published in Mar. 2013.2013 Jun 4INPC 2013
Slide11Resonant contribution to 7Be(a,g)
Small but not negligible contribution compared to lower-lying states (~10%).2013 Jun 4INPC 2013
Slide12(Rotational) bands in 11C2
rotational bands (K=3/2+,5/2+) were suggested in Soic. et al. (2004).Jp=9/2+ was assigned for the resonance at 12.4 MeV, and it can be the member of K=3/2+ band. A negative-parity band is proposed. 2a+3He cluster?2013 Jun 4INPC 2013
Slide13Interpretation of the new negative-parity band (11B case)
2013 Jun 4INPC 2013
Slide14Study on the ap-processap-process: (a,p),(p,g) reactions occur faster than β-decay at high temperature. Accelerates the rp-process (Wallace and Woosley, 1981).Suitable objective for CRIBNot many direct measurements of (a,p) reactions have been performed in other facilities. Involves A=18-30, proton richunstable nuclei.T=1.5GK, close to the beam energy at CRIB.2013 Jun 4INPC 2013
Slide1518
Ne(a,p) (T. Hashimoto; RCNP)
11C
12
C
13
C
13
N
14
N
15
N
12
N
16
O
17
O18O
9
C
10
C
11
N
15
O
14
O
19
F
18
F
17
F
20
Ne
21
Ne
22
Ne
19
Ne
18
Ne
stable
unstable
hot-CNO
12
C(p, γ)
13
N(p, γ)
14
O(
b
)
14
N(p,
g
)
15
O(
b
)
15
N(p,
a
)
12
C
second hot CNO cycle
14
O(α, p)
17
F(p, γ)
18
Ne(
b
)
18
F(p, α)
15
O(
b
)
15
O(p, α)
12
C
18
Ne(α, p)
21
Na
22
Na
22
Na
23
Na
21
Na
20
Na
18
Ne(
a
, p)
21
Na is an important breakout reaction from hot-CNO cycle
to the
rp
-process
(B to C in the figure)
A: hot-CNO
B: second hot-CNO
C:
18
Ne(
a
, p)
21
Na
D:
18
Ne(2p,
g
)
20
Mg
E:
15
O(2p,
g
)
17
F
J. Phys. G: Nucl. Part. Phys. 25 (1999)R133
17
Ne
X-ray bursts
2013 Jun 4
INPC 2013
Relevant energy (temperature):
E
cm
= 0.5 - 3.8 MeV (T = 0.6 - 3 GK).
Slide16Experimental Setup
He (90%) +CO2 (10%) mixture gas(160 torr)
z
x
y
Acts as a He target and a detector (TPC) simultaneously
3-dimentional trajectory and energy loss can be measured
⇒
Good event identification.
18
Ne beam
Beam monitor
INPC 2013
2013 Jun 4
Slide17Typical event of
18Ne(a, p)21Na reaction PreliminarySi telescopes
Total energy (MeV)
p
a
(
Stopped in first layer)
Energy loss in first layer (MeV)
Pad No.
Pad No.
Pad No.
dE/Pad (MeV)
X position (cm)
Y position (cm)
Analysis is in progress …
18
Ne
21
Na
18
Ne
21
Na
18
Ne
18
Ne
18
Ne
21
Na
18
Ne
Preliminary
2013 Jun 4
INPC 2013
Reaction events are observed !
Slide18CRIB - Recent PublicationsProton resonant scattering13
N+p; Teranishi et al., PLB (2007), 21Na/22Mg+p; J.J. He et al., PRC (2007/2009), Eur. Phys. J (2010), 7Be+p; H. Yamaguchi et al., PLB (2009).26Si+p (Chung-Ang Univ., SNU) H.S. Jung et al., Phys. Rev. C (2012). 25Al+p; Jun Chen et al., Phys. Rev. C(2012): related to galactic gamma-ray from 26Al.Alpha resonant scattering7Li+a; H. Yamaguchi et al., Phys. Rev (2011).7Be+a; H. Yamaguchi et al., Phys. Rev. C (2013).Other reactions21Na(a,p) direct reaction measurement; Dam N. Binh, Dr. thesis of Univ. of Tokyo (2009).11C(a,p) direct reaction measurement; S. Hayakawa, Dr. thesis of Univ. of Tokyo (2012), another paper in preparation.17F+12C; Quasi-elastic scattering G.L. Zhang et al., Eur. Phys. J. A (2012).12N(p,g) by ANC B. Guo et al., Phys. Rev. C (2013).
2013 Jun 4
INPC 2013
Slide19INPC 2013
2013 Jun 4Summary CRIB is a low-energy RI beam facility operated by CNS, University of Tokyo, providing RI beams of good intensity and purity.Standard experiments: Proton/alpha resonant scattering, direct (a,p) reaction measurement using an active target (GEM-MSTPC) 7Li+a,7Be+aStrong resonances were observed. The “thick target method with inverse kinematics” could be applied to many nuclides. We can study astrophysical reactions and alpha-cluster structures.Active target Has been used in several (a,p) measurements, analysis is in progress.
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