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PACS numbers: 21.10Re, 21.60.Ev, 23.20.Lv, 27.60+j

Keywords: Ùþ˜ìøÍ6£x¹¹⁸Sn(⁶Li, 4n)¹²⁰I, c”¤èl yŒ™‚ ìrFg†<Æ, Ùþ˜½¨›¸, |9éߖ {, ’<H@/gA s×æ {, TRS >íߖ, q

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l

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6Li

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Fusion Heavy-Ion Beam

Target

Evaporation

Gamma-ray emission

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Fig. 8“ É r

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Cs [15],

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Pr [14],

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 „  s Ö  ¦ (electromagnetic reduced transition ratios)“   B(M1)/B(E2)_  Ä » $ í \ " f  8¹ ¡ ¤ [ O 1 p q`  ¦ % 3   H . Fig.

10“ É r 0 A\ " f ƒ  / å L ) a Ù þ ˜[ þ tõ 

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T

_1/2

= 81 min ^T

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^{= 244 ns}

T_1/2= 9.2 ns

1

D1

5

3

2

4

Fig. 5. Partial level scheme of

¹²⁰

I as obtained from the present work. Transition and excitation energies are given in keV. The widths of the arrows are proportional to the relative intensities of γ-ray transitions.

|

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 ×  æ$ í   à º N=67`  ¦ ° ú   H

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0 100 200 300 400 500 0

500 1000 1500 2000

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0 20 40 60

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0 500 1000

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208

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86

(a) 59-keV gate (+/- 140 ns)

(b) 59-keV gate (early delayed 150-850 ns)

(c) 72-keV gate (early delayed 150-850 ns)

Channel Number

C o u n ts /C h a n n e l

*

*

Fig. 6. (a) γ rays in a prompt coincidence with the 59- keV transition. (b) and (c) γ rays in an early delayed (150-850 ns) coincidence with the 59-keV transition and the 72-keV transition, respectively. Energies are given in keV and the peaks labeled with asterisks are contam- inants from other nuclei.

0 500 1000 1500

0 5000 10000 15000 20000 ¹

24

81 319

235

65 553 566

112 668

355 389

144 246

203 589

159 184 652

313293 332 406 601

223 432 720

516

1000 1100 1200 1300 1400

0 500 1000 1500 2000 2500

652

601 720

589

553 566 615

516 560 644

607

549 575 705

668

642

Channel Number

C o u n ts /C h a n n e l

Fig. 7. Coincidence spectrum representing the γ-ray transitions belonging to bands 1 and D1 when gating on the 113-keV transition. The peaks indicated with the arrows represent the transitions in the states of band D1 and the peaks indicated with the asterisks correspond to the inter-transitions between band 1 and band D1.

Energies are given in keV.

|

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120

I

136

Pm

132

Pr

124

Cs

E n e rg y s e p a ra ti o n ( k e V )

10 11 12 13 14 15 16 17 18 19 100

200 300 400 500

Angular Momentum I (h)

Fig. 8. Energy separation between the πh

_11/2

νh

_11/2

bands and their side bands in

¹²⁰

I (squares),

¹²⁴

Cs (cir- cles),

¹³²

Pr (triangles), and

¹³⁶

Pm (diamonds) nuclei.

It is noted that these nuclei have the same number of proton-neutron difference, namely N - Z = 14.

11 12 13 14 15 16 17 6

8 10 12 14 16 18

11 12 13 14 15 16 17 6

8 10 12 14 16 18

11 12 13 14 15 16 17 6

8 10 12 14 16 18

11 12 13 14 15 16 17 18 19 6

8 10 12 14 16 18

Angular Momentum I (h)

[E (I )- E (I -1 )] /2 I ( k e V /h )

120

I

124

Cs

132

Pr

¹³⁶

Pm

Fig. 9. Energy staggering in the form of [E(I) - E(I- 1)]/2I versus angular momentum I for the main πh

_11/2

νh

_11/2

bands (squares) and their side bands (circles) in

120

I,

¹²⁴

Cs,

¹³²

Pr, and

¹³⁶

Pm nuclei.

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12 13 14 15 16 0

1 2 3 4

Angular Momentum, I band 2

band 1

2 N

B (M 1 )/ B (E 2 ) ( /e b ) m

Fig. 10. Reduced electromagnetic ratios, namely B(M1)/B(M2) values for the main πh

11/2

νh

11/2

band (band 1; squares with solid line) and its partner band (band D1; circles with dashed line) in

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Doublet Rotational Bands in Odd-odd ¹²⁰ I

C.-B. Moon

^∗

Department of Display Engineering, Hoseo University, Chung-Nam 336-795 (Received 2 January 2008)

The excited states of the doubly odd

¹²⁰

I nucleus have been studied by using in-beam gamma-ray spectroscopy with the

¹¹⁸

Sn(

⁶

Li, 4n)

¹²⁰

I reaction at E

lab

= 48 MeV. The beam provided by the 14UD Pelletron accelerator at the Australian National University was a 1-ns pulsed beam with a pulse separation of 1.7 µs. We established several collective bands associated with different proton and neutron quasiparticle configurations. Among them, a positive-parity collective band built on the 10

⁺

state and its side band with the same parity were observed to associated with the πh

11/2vh11/2

configuration. The side band is thought to be a candidate for the chiral twin band, leading to a doubling of states for this πh

11/2vh11/2

configuration.

PACS numbers: 21.10Re, 21.60.Ev, 23.20.Lv, 27.60+j

Keywords: Nuclear reactions¹¹⁸Sn(⁶Li, 4n)¹²⁰I, In-beam gamma ray spectroscopy, Nuclear structure, Col- lective bands, Chiral doublet bands, Total routhian surface calculations, Cranked shell model

∗E-mail: [email protected]