Rotation and alignment of Rotation and alignment of high-j orbitls in transfermium high-j orbitls in transfermium

nucleinuclei

Rotation and alignment of Rotation and alignment of high-j orbitls in transfermium high-j orbitls in transfermium

nucleinuclei

Dr. Xiao-tao HeDr. Xiao-tao He College of Material Science and Technology, College of Material Science and Technology,

Nanjing University of Aeronautics and Nanjing University of Aeronautics and AstronauticsAstronautics

Huzhou • China ， 2012,04,12-16

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MotivationMotivation

Exploration of the island of stability with high mass and charge, i.e. the region of superheavy elements (SHE) has been one of the fundamental questions in nature science ！！

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α-decays: life time, spin, parity … …Spectroscopy of collective rotation: spin, parity,

configurations, deformations, single-particle orbiting … …

! Difficulty: The extremely low production cross-sections. It can rarely reveal the detailed spectroscopic information of SHE in the experiments.

Tansfermium nuclei (Z > 100) are the heaviest system accessible in present in-beam experiment.

MotivationMotivation

How to get structure information about superheavy elements (SHE) ??

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εε22=0.25=0.25

100100

102102

MotivationMotivation

The study of these deformed transfermium nuclei may provide an indirect way to access the single particle states of the next closed spherical shells.

εε22=0.30=0.30

5P. Reiter, et al., PRL82 (1999) 509.

254254NoNo

β2=0.27±2

Some experimental resultsSome experimental results

Even-even nuclei:Even-even nuclei:

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R.-D. Herzberg, et al., PRC, 65 (2001) 014303

252252NoNo

β2=0.28±2

Even-even nuclei:Even-even nuclei:

Rotational BandRotational Band

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250250FmFm

β2=0.28±2

J. E. Bastin, et al., PRC 73 (2006)

024308.

Even-even nuclei:Even-even nuclei:

Rotational BandRotational Band

R.-D. Herzberg, et al., Eur. Phys. J. A 15, 205

(2002)

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P. Reiter, et al., PRL 95, 032501 (2005).

253253NoNoOdd-neutron Odd-neutron nuclei:nuclei:

R.-D. Herzberg, et al., Eur. Phys. J. A 42, 333 (2009).

Rotational BandRotational Band

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251251MdMd

A. Chatillon, et al., PRL 98, 132503 (2007).

Odd-proton nuclei:Odd-proton nuclei:

This band: 1/2[521]Ground state band: 7/2[514]

Rotational BandRotational Band

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255255LrLr

S. Ketelhut, et al., PRL 102, 212501 (2007).

Odd-proton nuclei:Odd-proton nuclei:

The structures are tentatively assigned to be based on the 1/2[521] and 7/2[514] Nilsson states, respectively.

Rotational BandRotational Band

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R.D. Herzberg et al., Nature 442 (2006) 896

High-High-K K structurestructure

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250250FmFm

High-High-K K structurestructure

B. Sulignano, et al., EPJA 33 (2007) 327.

P. T. Greenlees, et al., PRC 78 (2008) 021303

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High-High-K K structurestructure

H. B. Jeppesen,et al.,

PRC 79, 031303(R) (2009). J. Qian, et.al., PRC 79, 064319 (2009).

the ground-state configuration in 257Rf is 11//2+[620].2+[620].

11/2−[725]

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H. B. Jeppesen, et al., PRC 80, 034324 (2009).

Odd-proton nuclei:Odd-proton nuclei:

Assuming the quadrupole deformation of the band to be ββ22 = 0 = 0..33 (typical for nuclei in this region).

the lowest observed sequence is built upon the [624]9[624]9//2+2+ Nilsson state.

255255LrLr

High-High-K K structurestructure

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with Particle number conserving method treatment for the pairing correlation: Hp

pxSPpCSM HJHHHH 0

ii hH ))(( 00 xNil jhh )(0

)2()0( ppp HHH

Cranked Shell Model

single particle part : H0

Theoretical studyTheoretical study

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In rotating frame ：

HCSM is diagonalized in the Cranked Many-Particle Configuration (CMPC) space, we get the solution of CSM Hamiltonian ：

Di ： Real

pCSM HHH 0

i

i iD

Theoretical studyTheoretical study

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The angular momentum alignment in ：

Kinematic MoI ：

Dynamic MoI ：

ji

xjii

xix jJiDDiJiDJ 22

xJ

J )1(

d

JdJ x)2(

Theoretical studyTheoretical study

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ParameterParameterss• The Nilsson parameters (κ,μ) are taken from:

S.G. Nilsson, et al., Nucl. Phys. A131 (1969) 1.

* The deformation parameters ε2 =0.29 , ε4=0.02 for 252,253,254No and 250Fm, ε2 =0.30 , ε4=0.02 for 251Md.

• The effective pairing interaction strengths (in unite of MeV),

G0p=0.45, G0n=0.35, G2p=0.02, G2n=0.02

* Proton: Ecut : 0.60 ω0 CMCP space ~ 1000~ 1000 Neutron: Ecut : 0.50 ω0 CMCP space ~ 1000 ~ 1000

Theoretical studyTheoretical study

通过拟合 Z=96-103(A=240-255) 的 30 多个原子核的带头能量以及转动惯量，确定了一组主量子数，轨道角动量量子数依赖的 (κ,μ)

Zhen-Hua Zhang et al., Phys. Rev. C 85, 014324 (2012); 83, 011304 (2011).

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0.0 0.1 0.2 0.3

60

80

100

120

140

0.0 0.1 0.2 0.3 0.0 0.1 0.2 0.3

60

80

100

120

140

Experiment - symbolTheoretical - line

250Fm

Experiment - symbolTheoretical - line

252No

Kin

emat

ical

mom

ent o

f in

ertia

J(1

) (2 M

eV-1)

(MeV)

Experiment - symbolTheoretical - line

254No

Theoretical resultsTheoretical resultsEven-even nuclei:Even-even nuclei:

Experimental and theoretical J(1) of the bands in 250Fm, 252No and 254No.

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Theoretical resultsTheoretical resultsOdd-proton nuclei Odd-proton nuclei 251251MdMd

εε22=0.30=0.30

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Theoretical resultsTheoretical results

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Theoretical resultsTheoretical results

The cranked proton Nilsson orbitals near the Fermi surface in 251Md

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Theoretical resultsTheoretical resultsOdd-neutron nuclei Odd-neutron nuclei 253253No:No:

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* The observed bands are reproduced very well by the theoretical results.

* Exploration of behaviors of these bands at high spin shows that there is backbending taking place at hω ≈ 0.275 MeV in bands of 252,253,254No.

* α = −1/2 band in 251Md is predicted. It is very encouraged to find that there is a backbending occurring at very low frequency, hω ≈ 0.15 MeV,which might be during the possible observed frequency.

* The neutron 2h11/2 (1/2[761]) and proton 1j15/2 (1/2[770]) orbitals play a very important role in the rotational properties of transfermium nuclei.

Summary

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Thank you !Thank you Thank you !!

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Welcome Welcome to to

Nanjing !Nanjing !

Welcome Welcome to to

Nanjing !Nanjing !

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Thank you !Thank you !Thank you !Thank you !

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Thank you Thank you !!

Thank you Thank you !!

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0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35

0

10

20

30

40

50

60

tot

(=-1/2)

(=+1/2)

Ang

ular

mom

entu

m a

lignm

ent

<J x>

()

(MeV)

101251Md

=+1/2 =-1/2

Experiment - solid circleTheoretical - lines

1/2-[521]

The total angular momentum alignment <Jx>, and the separate contributions to <Jx> from neutron and proton in 251Md.

Theoretical resultsTheoretical results

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0.0 0.1 0.2 0.3-5

0

5

10-10

-5

0

5

10

15

0.0 0.1 0.2 0.3-5

0

5

10 -10

-5

0

5

10

15

[521] 1/2[532] 3/2

[541] 3/2[523] 7/2[532] 5/2

[541] 1/2

[550] 1/2

[725]11/2 [734] 9/2

[734] 9/2 [743] 7/2

[750] 1/2 [761] 1/2

[761] 1/2

(MeV)

[734] 9/2

[752] 5/2[761] 3/2

[770] 1/2

[624] 7/2

[642] 5/2

[640] 1/2

[743] 7/2

[651] 1/2

[633] 7/2

[651] 3/2

[660]

1/2

253No NeutronA

ngul

ar m

omen

tum

alig

nmen

t (

)

[770

] 1/2

253No Proton

Theoretical resultsTheoretical results

The contributions to <Jx> from the particle in each proton cranked orbitalμ, jx(μ) and the interference term jx(μν) between cranked orbitals μ and ν for the 7/2+[624] band in 253No, which are simply denoted by μ and μν, respectively.

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Theoretical resultsTheoretical results

Nilsson S G et al., NPA, 131 (1969) 1.

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Theoretical resultsTheoretical results

Nilsson S G et al., NPA, 131 (1969) 1.

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Theoretical resultsTheoretical results

Nilsson S G et al., NPA, 131 (1969) 1.

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Theoretical resultsTheoretical results

Nilsson S G et al., NPA, 131 (1969) 1.

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Theoretical resultsTheoretical results

Nilsson S G et al., NPA, 131 (1969) 1.

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Theoretical resultsTheoretical results

Nilsson S G et al., NPA, 131 (1969) 1.

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Theoretical resultsTheoretical results

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Theoretical resultsTheoretical results

T. Bengtsson, I. Ragnarsson, NPA436 (1985) 14-82

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Theoretical resultsTheoretical results

T. Bengtsson, I. Ragnarsson, NPA436 (1985) 14-82

rotation and alignment of high-j rotation and alignment of high-j orbitls in transfermium nucleiorbitls in transfermium nuclei

rotation and alignment of high-j rotation and alignment of high-j orbitls in transfermium nucleiorbitls in transfermium nuclei

Dr. Xiao-tao HeDr. Xiao-tao He College of Material Science and Technology, College of Material Science and Technology,

Nanjing University of Aeronautics and AstronauticsNanjing University of Aeronautics and Astronautics

Prof. Zhong-zhou RenProf. Zhong-zhou RenDepartment of Physics, Nanjing UniversityDepartment of Physics, Nanjing University

Prof. En-guang ZhaoProf. En-guang ZhaoInstitute of Theoretical Physics, Chinese of Academy of Sciences.

Prof. Shu-xin Liu Prof. Shu-xin Liu & Jin-yan Zeng& Jin-yan ZengSchool of Physics, Peking University

Chifeng • China ， 2010,07,25-31

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Odd-mass transfermium nuclei are seldom studied;Cranked shell model are seldom used.

We used the cranked shell model to calculate the collective rotation of SHE.

Collective rotational bands provide important

testing ground to check the extrapolations of

current models to SHE region!

Theoretical studyTheoretical study