Rotational bands in the rare-earth proton

emitters and neighboring nuclei

Darek Seweryniak

Argonne National Laboratory

PROCON-2003

1. Rotational landscape in the rare-earth region.

2. Recoil-Decay Tagging.3. Excited states in the proton emitters

147Tm,141Ho and 131Eu.4. Particle-Rotor calculations.5. GAMMASPHERE+Ball+nWall.6. Excited in 143Ho and neighboring

nuclei.7. Summary and outlook.

CollaborationCollaborationD.Seweryniak, C.N.Davids, M.P.Carpenter, D.Seweryniak, C.N.Davids, M.P.Carpenter,

S.Freeman, A.Heinz, G.Mukherjee, S.Freeman, A.Heinz, G.Mukherjee, A.Sonzogni, J.J.Uusitalo, R.V.F.Janssens, A.Sonzogni, J.J.Uusitalo, R.V.F.Janssens,

T.L.Khoo, F.G.Kondev, T.Lauritsen, T.L.Khoo, F.G.Kondev, T.Lauritsen, C.J.Lister, G.L.Poli, P.Reiter, I.WiedenhoeverC.J.Lister, G.L.Poli, P.Reiter, I.Wiedenhoever

Argonne National LaboratoryArgonne National Laboratory

P.J. Woods, T. DavinsonP.J. Woods, T. DavinsonUniversity of EdinburghUniversity of Edinburgh

J.J. Ressler, J. Shergur, W.B. WaltersJ.J. Ressler, J. Shergur, W.B. WaltersUniversity of MarylandUniversity of Maryland

J.A. Cizewski, K.Y. Ding, N. FotiadesJ.A. Cizewski, K.Y. Ding, N. FotiadesRutgers UniversityRutgers University

Proton drip lineProton drip line

131Eu

141Ho

147Tm

Nilsson diagramNilsson diagram

147Tm

135Tb141Ho

131Eu

145Ho?

Strong couplingStrong couplingCoupling to the deformation axis:

• K is a good quantum number• j precesses around the symmetry axis• Coriolis introduces K-mixing• signature splitting• 4 and enhances K-mixing

R

j

K

KK+1

K+2

K+3

K+1K+2

K+3

K+4

K=1 Coriolismixing

K+4

E2M1

E2

K-band K+1 band

Rotational couplingRotational couplingCoupling to the rotational axis:

• j precesses around the rotational axis• energies similar as in the gs band in the daughter• small deformation, high-j, low-K

Rj

Strong Coriolis interaction

jj+2j+4

j+6

E2

Recoil-Decay TaggingRecoil-Decay Tagging

Prompt rays RecoilsImplants and p decays

GAMMASPHERE

Spatial and timecorrelationsin the DSSD

Excited states in Excited states in 147147TmTm

p (h11/2) p (d3/2)

620||=0.13

GS data - 4 hours

Aye-ball data

141141Ho spectraHo spectra

141141Ho level schemeHo level scheme

7/2-[523] ½+[411]

D. Seweryniak et al., PRL C86(2001)1458

Unexpectedly large

signature splitting!

=0.25(4) Harris

formula

p p

Particle-Rotor Model InputParticle-Rotor Model Input

Tri-axial RotorTri-axial Rotor Woods-Saxon potential with the Woods-Saxon potential with the

universal set of parametersuniversal set of parameters Coriolis attenuation factor 0.85Coriolis attenuation factor 0.85 Proton pairing strength 0.136 MeVProton pairing strength 0.136 MeV Moments of inertia adjusted to the Moments of inertia adjusted to the

2+ energy in the daughter nucleus2+ energy in the daughter nucleus

Coriolis matrix elements are attenuatedby the pairing factor:

u1u2+v1v2

=0.

25-0

.31

=0o -

(-20

o )

=10

0-90

%

=10

0-90

%

=

0-(-

0.06

)

7/2-

9/2-

11/2-

13/2-

15/2-

=

180-

200

exp =0.29, 4=0, =0o

PR model sensitivityPR model sensitivity

141141Ho Particle-Rotor Ho Particle-Rotor calculations calculations

Best fit:

2=0.25E(2+)=190 keV

4=-0.06=-10o

Another fit:

2=0.29E(2+)=140 keV

4=-0.06=-20o

Total Routhian Surface Total Routhian Surface CalculationsCalculations

=0.25 MeV

=0.05 MeV =0.15 MeV

=0.35 MeV

141Ho is soft and develops triaxiality at

higher angular momentum

131131Eu spectraEu spectra

M1M1

E2

h11/2 band

131131Eu level schemeEu level scheme

5/2+[413] or 3/2+[411] ground state?

3/2+[411] band in 159Tb94 after A5/3 scaling gives:

189

72

105

7/2+

5/2+

9/2+

5/2+[413] band in 159Eu96 after A5/3 scaling gives:

237

104

134

7/2+

5/2+

9/2+

We observe 72 keV and 105 keV.Low energy transitions present in the spectrum

suggest the 3/2+[411] assignment

Population of proton rich nuclei Population of proton rich nuclei along the proton drip-linealong the proton drip-line

Z=72154Hf

153Lu152Lu151Lu

150Yb

149Tm148Tm147Tm

150Lu

146Tm

146Er

145Tm

145Ho144Ho143Ho142Ho141Ho140Ho

144Dy143Dy142Dy141Dy140Dy139Dy

143Tb142Tb141Tb140Tb139Tb138Tb

142Gd141Gd140Gd139Gd138Gd137Gd

141Eu140Eu139Eu138Eu137Eu136Eu

CN

CN

CN

CN

136GdCN

pp

p p p

p p

N=82

135Eu131Eu …

50b

300 nb 500 mb

1 out of 10 million rays!

5b

100 mb

p

GAMMASPHEREGAMMASPHEREBall+nWallBall+nWall

http://wunmr.wustl.edu/~dgs/mball/

p,

n

54Fe

P

n

Ball - 96 CsI

nWall 30 NE203

92Mo

Gamma spectraGamma spectra

143Tb(3p)

143Dy(2p1n)

142Dy(2p2n)

63Zn(2p1n) on C

143143Ho level schemeHo level scheme

143Ho(p1n2)

318

508

663

143Ho11/2-

15/2-

19/2-

23/2-

E(2E(2++,0) and ,0) and E(15/2E(15/2--,11/2,11/2--))systematicssystematics

149Tm148Tm147Tm146Tm

146Er

145Tm

145Ho144Ho143Ho142Ho141Ho140Ho

144Dy143Dy142Dy141Dy140Dy139Dy

143Tb142Tb141Tb140Tb139Tb138Tb

142Gd141Gd140Gd139Gd138Gd137Gd

141Eu140Eu139Eu138Eu137Eu136Eu

464

318

203

487

145Er144Er

323 526273

307 521

316 493

515329221

169

145Tm similar to 143Ho!

SummarySummary1.1. Studies of excited states proved to be a very useful Studies of excited states proved to be a very useful

source of complementary information on proton source of complementary information on proton emitters.emitters.

2.2. Ground state band in Ground state band in 147147Tm confirmed and Tm confirmed and extended.extended.

3.3. Lower Lower 22 deformation in deformation in 141141Ho, Ho, 44 and and important. important.

Single –particle configurations in agreement with Single –particle configurations in agreement with adiabatic decay-rate calculations.adiabatic decay-rate calculations.

4.4. Rotational bands in Rotational bands in 131131Eu observed. Fine structure Eu observed. Fine structure confirmed. The 3/2+[411] assignment is favored.confirmed. The 3/2+[411] assignment is favored.

5.5. The hThe h11/211/2 band in band in 143143Ho observed, more to come ….Ho observed, more to come ….

OutlookOutlook

1. Recent upgrades of the FMA implantation station and GAMMASPHERE promise next successful RDT campaign.

2. GAMMASPHERE+FMA will allow to study excited states in other, recently discovered deformed proton emitters such as 117La or 145Tm.

3. GAMMASPHERE+Ball+nWall will allow to fill up considerably the gap between the stability line and the proton drip line.

4. Other methods such as RDT using -delayed proton emitters or isomer studies could also contribute.