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Phenomena occurring in neutron deficient nuclei at N~50 M.G órska. location of the proton drip line single particle energy evolution spin-gap isomers: gamma and beta decaying valence and core excited states 100 Sn core excitation and shell gap measurement

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slide1

Phenomena occurring in neutron deficient nuclei at N~50M.Górska

  • location of the proton drip line
  • single particle energy evolution
  • spin-gap isomers:
  • gamma and beta decaying
  • valence and core excited states
  • 100Sn core excitation and shell gap measurement
  • enhanced collectivity in Sn isotopes
  • enhanced collectivity in Z>50 neutron deficient nuclei

RISING experimental data and many others

slide2

Experimental conditions and techniques

  • Fusion symmetric

reaction

EUROBALL, GASP

+ Ancillaries

- in-beam

- alpha decay

MSEPat GSI

- β decay

- spin-gap isomers

  • Fragmentation

- Coulex

- Transfer

- Isomers

- β decay

experiments with stopped beams
Experiments with Stopped Beams

production

selection

spectroscopy

identification

stopping

~300MeV/u

A,Z event-by-event ID

Time correlation >50ns - min

Rate < 1 ion/hour

slide4

prompt g flash

  • isomeric ratio
  • gray sequence
  • spin-parity assignment
  • -
  • A,Z event-by-event ID
  • Time correlation ns - min
  • Rate < 1 ion/hour
  • Alignment → g, Q moment
  • +

+

-

rising active stopper measurements
RISING Active Stopper Measurements

Passive Stopper: g-ray from isomer cascades with T1/2 ~ 10 ns  1 ms.

Active Stopper measurements: b-particles, internal conversionelectrons, alphas.

T1/2 up to ~ minutes; associated with delayed g-rays.

5 cm x 5 cm DSSSD (16 strips x 16 strips = 256 pixels) x 3 = 758 total pixels or x2 layers or x3 layers.

experiments with fast beams
Experiments with fast beams

production

spectroscopy

selection

<1GeV/u

identification

reaction

identification

100-700MeV/u

35m

Bρ - ∆E - Bρ

CATE

SI-CsI

rising g array for fast beams

Ge Cluster

Ge Miniball

RISING g-array for fast beams

Scattering experiments : Coulomb excitation,

One-, two-neutron knock-out

Typically: 100MeV/u, εg=0.06, ∆Eg/Eg=0.02

Target chamber

CATE

beam

slide8

Experimental conditions and techniques

  • Fusion symmetric

reaction

EUROBALL, GASP

+ Ancillaries

- in-beam

MSEPat GSI

- β decay

- spin-gap isomers

  • Fragmentation

- Coulex

-Transfer

- Isomers

- β decay

rp process
Scenario: high temperature and density

(x-ray bursts in neutron stars)

Nuclei can be synthesized successively by binding more and more protons until proton dripline is reached.

Continuation to heavier nuclei after β+-decay.

β+ emitters with longer half lives are called waiting point nuclei

rp-process

rp process

waiting points

N = Z

H. Schatz et al. PRL 86, 2001

slide10

The closed SnSbTe cycle

Where does the rp-process end?

rp process

H. Schatz et al. PRL 86, 2001

waiting points

  • Measurement
  • total life time of waiting point nuclei
  • exact position of proton dripline

N = Z

slide11

Te

Sb

Sn

In

Cd

Ag

Pd

Rh

Ru

Probing the proton dripline

T.Faestermann

TU München

analysis: K.Eppinger, C.Hinke

100Sn setting

100Sn

what s new
what‘s new?

103Sb

T1/2 < 50 ns !

99Sn?

T1/2 > 0.2 ms

97In

95Cd

93Ag

slide13

100Sn region

100Sn region

Tensor interaction monopole

νh11/2 – πg9/2, νg7/2 – πg9/2

T. Otsuka et al., PRL 95, 232502 (2005)

EXP: h11/2<30% spectroscopic strength

very old measurements

h11/2›50% spectroscopic strength

h11/2<30% spectroscopic strength

New !

πν interaction tuned for the model space 88Sr,p(p1/2,g9/2) n(d5/2, g7/2, d3/2, s1/2, h11/2) gives the correct description of the evolution of SPEs

M. Górska et al., Proc. ENPE99, AIP CP495 (2000) 217

M. Hjorth-Jensen et al., Phys. Rep. 261 (1995) 125 and priv. comm.

M. Górska et al., Proc. ENPE99, AIP CP495 (2000) 217

M. Hjorth-Jensen et al., Phys. Rep. 261 (1995) 125 a

slide14

56Ni and 100Sn analogy 1ћw apart: (nlj) → (n+1,l+1,j+1)

If the orbits are the same the physics cannot be (much) different !

The Jan Blomqvist correspondence principle

slide15

Spin gap isomers

below N = Z = 50

with RISING and

GSI - ISOL

  • proton – neutron

hole-hole interaction

in pn g9/2-n

  • core excitation

in large-scale SM

in pn g9/2-1 (d5/2 ,g7/2)1

100 sn setting check 98 cd

8+

2428

6+

2281

2083

4+

1395

2+

0+

0

100Sn setting check : 98Cd

12+

6635

M.G. et al., PRL 79 (1997) 2415

198

A. Blazhev et al., PRC 69, 064304 (2004)

688

147

s.e.

4207

1395

d.e.

N. Braun, U. Cologne

Ch. Hinke, TUM

slide17

SM calculation

●gds LSSM t=1,5 (FN) in comparison to

●truncated to

1p1h in any orbit

in model spaces

●pgdg:

pνp3/2f5/2p1/2g9/2d5/2g7/2

●pgndg:

pνp3/2f5/2p1/2g9/2nd5/2g7/2

with TBME from OXBASH package (SNA+GF) and SPE tuned to 100Sn

4157

slide18

100Sn core excitation in 98Cd

  • LSSM smoothly converged at t=5
  • 100Sn neutron shell gapN=50 inferred
  • 6.46 (15) MeV
  • remaining E2,E4 deficiency is due to
  • interaction and/or proton gap Z=50
  • effective E2 charge will
  • not help !

pairing

E2

ph states

pg9/2-2ng9/2-t (d5/2,g7/2)t

E4

  • Valence excitation energy
  • increases with t
  • ph excitation energy
  • decreases with t
  • Exception t=2 : pairing
  • overbinds valence states

preliminary !

E2

Valence states

pg9/2-2

slide20

Core excitation in 97Ag

No possibility for shell gap measurement?

58Ni + 45Sc -> 103In* -> 97Ag + 1a2n

M. Palacz et al., preliminary results

EUROBALL 2003

17/2-

96 ag

Tf<1 ms

known

new

Counts

Eg[keV]

Tf[ms]

R. Grzywacz et al. PRC 55 (1997) 1126

96Ag

4000

Eg[keV]

96 ag1

DTc< 1 ms; E>4MeV have Tf<1 ms gate 4168 keV

gate 470 keV

DTc< 0.2 ms

470

668

96

Counts

Eg[keV]

Eg[keV]

96Ag

Counts

96 ag2
96Ag

0.27(14) ms

4168

SE: 4168 - 511

4264

1.58(3) ms

78(8) ms

slide24

96

Ag

47

49

E[MeV]

GF: model space: (g9/2, p1/2) interaction: R.Gross and A.Frenkel,NPA 267(1976)85→ 13-, 15+ isomers

Shell Model Calculations: H.Grawe

fpg: GF

+ 1p1h excitation

from f5/2 and p3/2

slide26

Need for LSSM

T = 0

M. Górska et al., ZPA353,233(95)

M. La Commara et al., NPA708,167(02)

I. Mukha et al., PRC 70,044311(04)

C. Plettner et al., NPA733,20(04)

slide27

96

Ag

47

49

Shell Model Calculations: H.Grawe

fpg: GF + 1p1h excitation

from f5/2 and p3/2

fpndg:fpg

+ 1p1h excitation

from vg9/2 to (g7/2 ,d5/2)

6 isomer in 102 sn

Lipoglavsek et al., PLB 1998

E(6-4) = 48keV

B(E2)=3.6 W.u.

6+ isomer in 102Sn

88keV

search for 6 isomer in 100 sn

5

4

Eg/MeV

3

3 isomers after ToF=200ns

decaying within 25 ns ?

2

1

T/ms

0

15

5

20

10

Search for 6+ isomer in 100Sn

Eg/MeV

slide31

100,102Sn ß+/EC decay

Ip = 6+ isomerism

Decay scheme

(shell model)

10050Sn50

1969+D 1969

1472

Decay scheme

M. Karny et al. EPJA 27, 129 (2006)

GT

10250Sn52

M1

GT

E2

M1 conversion

10049In51

10249In53

slide36

T. Faesterman et al., to be published

B.A. Brown et al.

L. Batist et al., EPJA submitted

slide37

asymmetry:

p-h excitation?

N=64 subshell closure?

M. Hjorth-Jensen, ν(d5/2g7/2s1/2h11/2), eν = 1e

Relativistic Coulomb excitation of nuclei towards 100Sn

  • 112,108Sn secondary beam with ~150MeV/u
  • Au – Coulex target

2003

A. Banu, PhD thesis, PR C72, 061305(R) (2005)

slide38

From N=Z100Sn to N» Z132Sn -- LSSM vs. SM

Truncationlevel t : total number ofph excitations relative to valence configuration

B(E2;2+→ 0+) :

SM: full neutron space

n(g7/2,d,s,h11/2), en=1.0 e

p phmissing !

LSSM: proton-neutron space

p(g,d,s),n(g7/2,d,s,h11/2), t = 4

ep=1.5 e, en=0.5 e

n ph missing !

Z=50 gap must be calculated

on the same footing !

Seniority fit

SM en=1.0

LSSM de=0.5

Gap reduction vs. B(E2) increase !

  • Z=50 shell gap :
  • Extrapolation
  • by quadratic fit
  • of precisedataN ≥ 58
  • and
  • all data including 100Sn
  • extrapolation
sn chain enhanced b e2 systematics towards 100 sn
Sn chain: Enhanced B(E2) systematics towards 100Sn

GSI

RISING

P. Doornenbalet al., PRC(R) in print

A. Banu et al, PRC 72 061305(R) 2005

J. Cederkäll et al., PRL98, 172501(2007)

A. Ekström et al., PRL 101, 012502(2008)

C. Vaman et al., PRL 99, 162501(2007),

Shell Model: F. Nowacki et al.,

ν(d5/2g7/2s1/2h11/2), eν = 0.5e,

π(g9/2g7/2d5/2d3/2s1/2), eπ = 1.5e

πν monopoles tuned to

πESPEs and Z=50 shell gap

slide41

Importance of the isoscalar neutron-proton interactions for the development of nuclear collectivityB. HADINIA et al. PHYSICAL REVIEW C 72, 041303(R) (2005)

Same mechanism as in Sn isitopes?

slide42

Summary and conclusions

  • ●Precision spectroscopy of exotic nuclei near 100Sn
  • → tuning/extraction of effective NN interaction(mainly monopoles)
  • ●"Pre"-mass shell gap determination by high-spin core excited isomers (98Cd-> gap in 100Sn)
  • High spin isomeric (pure) core excited states may serve as SPE info?
  • valence space corespondence principle for high spin states/isomers/beta decaying isomers (56Fe<->98Cd, ...)
  • -> global interaction
  • enchanced collectivity near closed shells
slide43

Collaboration:

A. Blazhev2, P. Boutachkov1, T. Brock3, N. Braun2, L. Caceres1, K. Eppinger4,

T. Faestermann4, J. Gerl1, H. Grawe1, Ch. Hinke4, M. Hjorth-Jensen5

A. Jungclaus6, Z. Liu7, G. Martínez-Pinedo1,B.S. Nara Singh3, R. Krücken4,

F. Nowacki8, S. Pietri1, M. Pfützner9, Zs. Podolyak10, P.H. Regan10,

D. Rudolph11, K. Sieja1, R. Wadsworth3, H.J. Wollersheim1

for the Rising collaboration

1GSI Darmstadt, Germany

2IKP, University of Cologne, Germany

3Department of Physics, University of York, UK

4Physics Department E12, TUM, Germany

5Oslo University, Norway

6Universidad Aut´onoma de Madrid, Spain

7University of Edinburgh, Edinburgh, UK

8 IPHC Strasbourg, France

9IEP, University of Warsaw, Poland

10Department of Physics, University of Surrey, UK

11Department of Physics, Lund University, Sweden

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