AARHUSUNIVERSITY

1

HANS FYNBOAarhus UniversityDenmark

12C and 3a studied with small accelerators

496th WE-Heraeus-Seminar

Bad Honnef

February 6-10 2012

• Introduction to the 3a reaction

• 3a breakup of the Hoyle state

• Search for “missing” states in 12C

AARHUSUNIVERSITY

2

4He+4He-0.092 g.s. 0+

8Be

12Cg.s. 0+

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3

4He+4He-0.092 g.s. 0+

8Be

7.65 0+

g.s. 0+

12C

7.27

g4.44 2+

g

3

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Q1 = -92 keV a + a

Gg

GpQ2= -287 keV a +8Be

Hoyle state

Quantity Value Error(%)Q3a 379.4(2)keV 1.2

Grad/G 4.12(11) ×10-4 2.7

Ge+e-/G 6.7(6) × 10-4 9.2

Ge+e- 52.0(1.4) meV 2.7 Crannell 2005

Ge+e- 59.6(1.5) meV 2.5 Chernykh 2010

G(8Be)/Gtot >0.96 4 Freer 1994

G(8Be)/Gtot 0.83(5) 6 Raduta 2011

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12C+40Ca 25MeV/u5

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6arXiv:1112.2136v1 [nucl-th]

3a-rate at low temperatures

8Be resonance

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12C

≈10.3 (0+)

4.44 2+

g.s. 0+

7.65 0+

9.64 3-

10.84 1-

a+a+a7.27Haruhiko Morinaga (TUM)

Jp=2+ E≈9.7 MeV

2+ ?

3a-rate at high temperatures

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Phys. Lett. B 2011.Phys. Rev. C36 (1987) 54..

The et al. APJ 1998

Tur et al. APJ 2010Magkotsios et al. APJs 2010Magkotsios et al. APJ 2011

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• 3a breakup of the Hoyle state

• Search for “missing” states in 12C

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CMAM, Madrid

3He+11B d+12C* d+3a @ 8.5 MeV

3He

Oliver Kirsebom(now at Triumf)

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115000 events12C

12.71 1+

≈10 0,2+

4.44 2+

g.s. 0+

7.65 0+

9.64 3-

10.84 1-

11.83 2-

7.27

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Limits:

Raduta et al.

DDE = 7.5±4 %DDE = 9.5±4 %SD = 83±5 %

(O. Kirsebom et al. to be submitted)

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• 3a breakup of the Hoyle state

• Search for “missing” states in 12C

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2+?

Stellenbosch: Freer et al. (2009): 12C(p,p´)12C

Yale : Zimmerman et al. (2011): 12C(p,p´)12C

3-

1-

3- 1-

Osaka: Itoh et al. (2011): 12C(a, a´)12C

3- 3-

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Journal of Physics: Conference Series 202 (2010) 012016Journal of Physics: Conference Series 267 (2011) 012046

AARHUSUNIVERSITY Idea 1 : Remove 3- state using b-decay

Only 0+, 1+, and 2+ states

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a b

12N/12BMagnetp/d12N/12B+X

12C/11B Direct Kinematics+ISOL

12N/12B+X12N/12B

a bp/d12C/11B

Magnets

Inverse Kinematics+Separator

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R.Raabe

12N/12B

K. JungmannH. Wilschut

TRImP separator

Solveig Hyldegaard

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1+

12C

12.71 1+

≈10 0+

4.44 2+

g.s. 0+

7.65 0+

15.11 1+

12N Qbeta=16.32

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12C

12.71 1+

≈10 0+

4.44 2+

g.s. 0+

7.65 0+

15.11 1+

12B Qbeta=13.37

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C. Diget(York)

Solveig Hyldegaard

12N/12B

IGISOL Experiment

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12C

12.71 1+

≈10

4.44 2+

g.s. 0+

7.65 0+

15.11 1+

12N Qbeta=16.32

Natural parity states

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12C

12.71 1+

≈10 0+

4.44 2+

g.s. 0+

7.65 0+

15.11 1+

12B Qbeta=13.37

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PL B678, 459 (2009)PR C80, 044304 (2009)PR C80, 034316 (2009)PR C81, 024303 (2010) S. Hyldegaard, C. Diget

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How to get selectivity between 0+ and 2+ ?

×

×2+

Only 0+, 1+, and 2+ states Only 1+, 2+, and 3+ states

AARHUSUNIVERSITY “g-delayed” a breakup

g

a

C

Oliver Kirsebom(Triumf)

Martin Alcorta(Argonne)

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3He+10B p+12C* p+3a @ 4.9 MeV

M. Alcorta et al., NIM A 605, 318–325 (2009)

CMAM, Madrid

3He+11B d+12C* d+3a @ 8.5 MeV

3He

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O. S. Kirsebom et al., Phys. Lett. B680, 44-49 (2009)

1st case : g-decay of 1+ states (proof-of-principle)3He+10B p+12C* p+3a3He

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1st case : g-decay of 1+ states (proof-of-principle)

M1 g-decay ≈ GT b-decay

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2nd case : g-decay of 2+ T=1 state

+ M1 >> E2 1+ ,2+, 3+ no 0+ !

− E1 decay populate negative parity 1- ,2-, 3-

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2+2-

1-

2+2-1-

11B(p,a)aa

400keV van de Graafin Aarhus.

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12C

12.71 1+

≈10 0,2+

4.44 2+

g.s. 0+

7.65 0+

9.64 3-

10.84 1-

11.83 2-

13.35 (2-)

14.08 4+

15.11 1+

7.27

16.1 2+

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12C

12.71 1+

≈10 0,2+

4.44 2+

g.s. 0+

7.65 0+

9.64 3-

10.84 1-

11.83 2-

13.35 (2-)

14.08 4+

15.11 1+

7.27

16.1 2+

240h 1nA @ 165keV

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12C

12.71 1+

≈10 0,2+

4.44 2+

g.s. 0+

7.65 0+

9.64 3-

10.84 1-

11.83 2-

13.35 (2-)

14.08 4+

15.11 1+

7.27

16.1 2+

16.6 2-3rd case : g-decay of 2- T=1 state

40h 1nA @ 350keV

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C. Zemach, Phys Rev. 133 (1964) 1201 : Decay to 3pFynbo et al. Phys Rev C79 (2009) 054009 : Decay to 3a

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2+ 16.11MeV

2- 16.57MeV11B(p,a)aa

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Outlook

5 MV van de Graaf in Aarhus (HV 1965)

Upgrade of detector setup

Other case where the method can be used?• 8Be• 16O• …..

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Quantity Value Error(%)Q3a 379.38(20)keV 1.2

Grad/G 4.12(11) ×10-4 2.7

Ge+e-/G 6.74(62) × 10-4 9.2

Ge+e- 52.0(1.4) meV 2.7 Crannell 2005

Ge+e- 59.6(1.5) meV 2.5 Chernykh

G(8Be)/Gtot >0.96 4 Freer 1994

G(8Be)/Gtot 0.83(5) 6 Raduta 2011

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THANK YOU FOR YOUR ATTENTION !

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BONUS MATERIAL…

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Decay channels

4He+4He+4

He

7.65 0+

3.03 2+

g.s. 0+ -0.092

8Be+4He

12C7.27

12.71 1+

15.11 1+

≈10 0+/2+

aThe 1+ states cannot decay via the 8Be ground state because it would require L=1 and therefore a change in parity

Natural parity states

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0+ 2+ 0+2 2+2 0+3 1+ 2+ 2+0.0002

0.002

0.02

0.2

2

B(GT)

B(M1)1+,T=1

B(M1)2+,T=1

0+ 2+ 0+2 2+2 0+3 1+ 2+ 2+0.0002

0.002

0.02

0.2

2 Data FMD

0+ 2+ 0+2 2+2 0+3 1+ 2+ 2+0.001

0.01

0.1

1

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12C

12.71 1+

≈10.3 (0+)

4.44 2+

g.s. 0+

7.65 0+

9.64 3-

10.84 1-

11.83 2-

13.35 (2-)

14.08 4+

15.11 1+

16.11 2+

a+a+a7.27

p+11B15.96

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12C

12.71 1+

≈10.3 (0+)

4.44 2+

g.s. 0+

7.65 0+

9.64 3-

10.84 1-

11.83 2-

13.35 (2-)

14.08 4+

15.11 1+

16.11 2+

a+a+a7.27

p+11B15.96

Experimental Dalitz plots

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12C

12.71 1+

≈10.3 (0+)

4.44 2+

g.s. 0+

7.65 0+

9.64 3-

10.84 1-

11.83 2-

13.35 (2-)

14.08 4+

15.11 1+

16.11 2+

a+a+a7.27

p+11B15.96

The 13.35 MeV state

2– 4–

√X

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12C

12.71 1+

≈10.3 (0+)

4.44 2+

g.s. 0+

7.65 0+

9.64 3-

10.84 1-

11.83 2-

13.35 (2-)

14.08 4+

15.11 1+

16.11 2+

a+a+a7.27

p+11B15.96

The 11.83 MeV state

2–

2–

1) A.A.Korsheninnikov, Sov. J. Nucl. Phys. 52 (1990)2) H.Fynbo et al., PRL 91 (2003)3) R.Alvarez-Rodriguez et al., PRL 99 (2007)

1) 2)

2)3)

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4He+4He

3.03 2+

-0.092 g.s. 0+

8Be

7.65 0+

≈10 0+,2+

g

8Be10-16s

g.s. 0+

12C

7.2712C* g

4.44 2+

g

47

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12C* a1+ 8Be a1+a2+a3

E1 = m23/(m1+m23) x QI = 2/3 xQI

12C

8Be

a2 + a3

QI

QII

E1

E2 E3

ai

2/3QI

R.H. Dalitz, Philos. Mag. 44, 1068 (1953).

Energy conservation

Momentum conservatio

n

Dalitz plot