ALPHA CLUSTER STRUCTURE IN 13C AND

16,17OMarcia Regina Dias Rodrigues

Institute of Physics

University of São Paulo

W. von Oertzen, M. Freer, Y. Kanada-En’yo, Physics Reports 432, 43 (2006).K. Ikeda, N. Takigawa, and H. Horiuchi, Prog. Theor. Phys. Suppl. E68, 464 (1968); H. Horiuchi, K. Ikeda, and Y. Suzuki, ibid. 44, 225 (1978).

Alpha Cluster

19/04/2023 2NN2012 - M. R. D. Rodrigues

Microscopic a cluster model

Molecular model

a-particle gas like-states

-cluster phenomenon on light mass nuclei

Nuclear Spectroscopy with Light Ions Group

Investigation of a-clustering on (xa) and (xa + n) nuclei through (6Li,d) reaction.

Scarce experimental information on: – even-even nuclei resonant states near the thresholds.– odd-even nuclei .

Odd A nuclei:13C(6Li,d)17O and 9Be(6Li,d)13CEven A nuclei:12C(6Li,d)16O

19/04/2023 3NN2012 - M. R. D. Rodrigues

Experimental set up Pelletron-Enge-Spectrograph system 25.5 MeV 6Li beam Detection: nuclear emulsion

(Fuji G6B, 50 μm thick): covering 50 cm along the focal surface.

Target Thickness (g/cm2 )

9Be 13113C 9312C 112 / 52

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IFUSP-LAFNPelletron-Enge-Split-Pole-Spectograph facility

University of Sao Paulo – campus viewInstitute of Physics

19/04/2023 5NN2012 - M. R. D. Rodrigues

Pelletron-Enge-Split-Pole-Spectograph facility

Tandem 9MV

Maximum field 17 kG

Solid angle 2,68 msr

E max /E min 7.3

E/DE 275019/04/2023 6NN2012 - M. R. D. Rodrigues

19/04/2023 7NN2012 - M. R. D. Rodrigues

Pelletron-Enge-Split-Pole-Spectograph facility

Nuclear emulsion plates

No magnification(three spectra on each

emulsion plate)

View under 500x magnification(120x110m2)

819/04/2023 NN2012 - M. R. D. Rodrigues

Plates were scanned in strips of 200μm. Absolute cross section through elastic

scattering of 6Li on the same target.

Data

Reaction Energy resolution

(keV)

Dlab

(deg.)Number

of lab

DEexc (MeV)

9Be(6Li,d)13C 50 7º-20º 7 0-1513C(6Li,d)17O 50 5º-20º 5 0-1712C(6Li,d)16O 25 5º-29º 7 0-17

19/04/2023 9NN2012 - M. R. D. Rodrigues

0 10 20 30 40 500

100

200

300

400

5000 10 20 30 40 50

0

25

50

75

100

125

16

.71

8

16

.54

8

16

.47

81

6.3

2916

.05

4

15

.66

3

15

.48

7

15

.14

1

15

.04

6

14

.95

31

4.9

07

14

.68

8

14

.61

5

14

.43

2 14

.38

0

14

.32

61

4.2

03

14

.01

51

3.9

02

13

.86

91

3.7

40

/ 1

3.7

76

13

.61

513

.58

0

13

.31

3

13

.19

2

13

.09

4 /

13

.12

5

12

.84

2

12

.72

1

12

.65

5

12

.28

1

11

.93

8

11

.81

7

11

.12

7

10

.98

4

10

.49

81

0.4

10

10

.54

9

10

.35

0

10

.19

8 /

10

.22

7

L(cm)

9.8

10

10

.07

5

9.7

49

9.1

57

/ 9

.18

4

8.8

97

/ 8

.93

5

8.7

01

8.4

38

/ 8

.47

4

8.5

23

8.2

57

8.1

84

7.9

187.7

367.6

76

7.5

93

7.3

82

7.1

93 7

.21

9

6.9

72

6.8

53

6.1

97

5.8

71

/ 5

.93

9

G.S

.

Co

un

ts /

0.2

0 x

10

mm2

13C(6Li,d)17O E6Li= 25.5 MeV

Lab=110

3.8

40

4.5

48

3.0

53

0.8

71

5.2

30

5.1

22

5.6

95

/ 5

.73

5

α threshold

13C(6Li,d)17O

preliminary19/04/2023 10NN2012 - M. R. D. Rodrigues

0 10 20 30 40 500

100

200

300

400

500

Co

un

ts /

0.2

0 x

10

mm2

10

.82

6

9.8

91

10

.75

3

9.4

92

7.5

53

7.4

90

6.8

68

3.8

51

3.6

84

9Be(6Li,d)13C E6Li= 25.5 MeV

Lab=80

L(cm)

3.0

90

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9Be(6Li,d)13C ELi = 25.5 MeV , qLab= 5o

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19/04/2023 13NN2012 - M. R. D. Rodrigues

9Be(6Li,d)13C ELi = 25.5 MeV , qLab= 5o

19/04/2023 14NN2012 - M. R. D. Rodrigues

Preliminary Analysis

One step a transfer finite-range DWBA calculations.– Optical model in entrance and exit channels: global

parameters of Cook and Daehnick et al. – Binding potential (a+d) of Kubo and Hirata.– Resonant states assumed a bound by 100 keV in WS

potential (r0 = 1.25 fm, a = 0.65 fm). Relative to 9Be core for negative (G=4) and positive (G=5) parity a states were considered

J. Cook, Nucl. Phys. A388, 153 (1982) W.W. Daehnick, J.D. Childs and Z. Vrcelj, Phys. Rev. C 21, 2253 (1980)K.I. Kubo and M. Hirata, Nucl. Phys. A187, 186 (1972)

19/04/2023 15NN2012 - M. R. D. Rodrigues

19/04/2023 16NN2012 - M. R. D. Rodrigues

Resonances 7/2- at 10.753MeV and (5/2-) at 10.818MeV are now resolved and reached by an L = 4 transfer

Resonances 7/2- is also described using in the DWBA form factor the wave function obtained by a simplified calculation of the a+9Be system.

Local cluster – core potential, B. Buck, A.C.Merchant and S.M. Perez Phys. Rev. C51, 559 (1995)H. Miyake and M.A. Souza - IFUSP

a+ 9Be13C(inert core G.S.)

Resonance at 12.3 MeV, consistent with an L = 2 transfer, in agreement with 1/2- attribution of Kawabata - Strongly excited by (a,a’), present a large E0 transition.

19/04/2023 NN2012 - M. R. D. Rodrigues 17

12C(6Li,d)16O ELi = 25.5 MeV

Position deuteron spectrum and corresponding scattering angle. The Jp and excitation energies in MeV associated with each state from D. R. Tilley et al., Nucl. Phys. A 565 , 1-184 (1993) are indicated.

Position deuteron spectrum. Indicated is the region of the 4a threshold.

12C(6Li,d)16O reaction at 48.2MeV by A. Belhout et al., Nucl. Phys. A793, 178 (2007)

19/04/2023 18NN2012 - M. R. D. Rodrigues

12C(6Li,d)16O reaction at 42 MeV by C. Weldon et al.

Q3D deuteron spectrum at -21.5º

Q3D deuteron spectrum at -21.5º gated to select states decaying to the 12C ground state.

Q3D deuteron spectrum at -21.5º gated to select states decaying to the 12C 21

+ state at 4.439 MeV.

C. Wheldon et al., Phys. Rev. C 83, 064324 (2011).

19/04/2023 19NN2012 - M. R. D. Rodrigues

Elastic angular distribution and optical model predictions. The fitted parameters are rR = 1.70 fm and aR =0.66 fm.

19/04/2023 20NN2012 - M. R. D. Rodrigues

States with natural parities and indicated before as a direct process.

16O resonances in 12C(a,a0)12C (g.s.) excitation function.

L. L. Ames et al., Phys. Rev. C 25,729 (1982)

Experimental angular distributions not previously reported.

19/04/2023 21NN2012 - M. R. D. Rodrigues

Eexc (MeV) Jp Sa

14.62 4(+) 0.305(13)

14.66 5- 0.324(14)

14.81 (2+) 1.10(4)

14.81 6+ 1.27(6)

14.92 2+ 1.51(6)

19/04/2023 22NN2012 - M. R. D. Rodrigues

2- 4(-)

5+ 2-

C. Wheldon et al., Phys. Rev. C 83, 064324 (2011)

Ressonances decaying to 12C 21

+ state.

Experimental angular distributions not previously reported.

19/04/2023 23NN2012 - M. R. D. Rodrigues

K p =

K p =

K p =

Experimental alpha rotational bands on 16O.

was not seen

19/04/2023 24NN2012 - M. R. D. Rodrigues

Theoretical rotational band with a + 12C (0+2) cluster structure

S. Ohkubo and Y. Hirabayashi, Phys. Lett. B 684,127 (2010).

Next Steps Obtain detailed angular distributions and

complete the analysis of the data. Pursue the study of a-cluster states

populated through 13C(6Li,d)17O and 11B(6Li,d)15N reactions.

Extend structure calculation.

19/04/2023 25NN2012 - M. R. D. Rodrigues

Nuclear Spectroscopy with Light Ions, IFUSP, Brasil

Thereza Borello Lewin Marcia Regina Dias Rodrigues Hideaki Miyake José Luciano Miranda Duarte

Lighia Brighitta Horodynski Matsushigue Gilberto Mitsuo Ukita Cleber Lima Rodrigues Marco Antonio de Souza

MAGNEX Large-Aceptance Spectrometer, Laboratori Nazionali Sud, INFN, Catania, Italy

Angelo Cunsolo, Francesco CappuzzelloManuela CavallaroAntonino Foti

Clementina Agodi Diana Carbone

19/04/2023 26NN2012 - M. R. D. Rodrigues

19/04/2023 NN2012 - M. R. D. Rodrigues 27

Thanks

Obrigada