Research group:

R.Broda, B.Fornal, W.Królas, T.Pawłat, J.Wrzesiński

H.Niewodniczanski Institut of Nuclear Physics PAN-KRAKOW

Collaboration with the INFN LNL Legnaro

Tandem and ALPI LinacGASP, PRISMA-CLARA spectrometer

Spectroscopy of hard-to-reach nuclei with

deep-inelastic heavy-ion reactions

Neutron-rich nuclei produced Neutron-rich nuclei produced in deep-inelastic processes in deep-inelastic processes

Beams of heavy-ions at energies above the Coulomb barrier

Transfer of nucleons – trend to equilize N/Z ratio

Population of Yrast states in final fragments

Thick target experimentsThick target experiments

R. Broda et al., JPG 32, 151 (2006)

W. Królas et al., NPA 724, 289 (2003)

Fragments stopped in the target, no isotopic identification

Aquisition of high statistics - coincidence data sets

Level structure from coincidence analysis, ID from cross-coincidences and/or known transitions

GAMMASPHERE

48Ca (330 MeV) + 238U (thick target)GAMMASPHERE at Argonne

48Ca

66Ni

GASP at LEGNARO

64Ni (275 MeV) + 130Te (thick target)

64Ni

130Te

R.Broda et al., Phys.Rev. Lett. 74, 868 (95)

5-

-

4+

2+

(2+)

0+

70Ni4272Ni44

1.261.10

1114

(4+, 3-)

(5-)

-ray thick target measurements with DIC

advantages Gamma rays from all reaction products

Gamma rays from the stopped nuclei – narrow lines – easy analysis of coincidences

Detection of cross-coincidences – some potential for identification

CLARAPRISMA

~ advantages

~ limitations

limitations

Gamma spectra very complicated(hundreds of sources)

Gamma rays from the short lived states smeared out by the Doppler effect (emitted before a product is stopped)

Difficulties of identifications withouta starting point.

Angular distribution of rays almost isotropic

andGASP88

PRISMA spectrometerPRISMA spectrometer A magnetic heavy ion

spectrometer designed to fully identify (A, Z) fragments deflected at large angles

CLARA: an array of 24 Clover detectors

238U + 330 MeV 48Ca

Complementary sets of data: PRISMA – (A,Z) identification, fast transitionsand GAMMASPHERE – -coincidence data

_

p1/2

f5/2

0

2

4

(4 )

(5 )

(7 )

(5 )+

-

(5 )-

-

-

+

-

+

+

1 0 2 7

2 9 7 13 4 8 8

0

1 0 2 6 .8

3 9 9 7 .4

4 8 3 0 .8

4 5 1 5 .3

5 1 4 7 .65 5 1 7 .3

6 8 7 0 .1

1 76 01 35 3

1 0 88

8 33

5 18

4 07 4 325 11 0 .15 0 8 5 .0(4 )-

6 32

1 00 2

5 95

111 3

1 51 9

Ca5020 30

2+

Evolution of Nuclear Structure with Evolution of Nuclear Structure with the Increase of Neutron Richnessthe Increase of Neutron Richness

Changes in shell structure – rearrangements of orbitals

Vanishing of shell gaps, appearance of new „magic numbers”

Experimental evidence needed

Experimental challenge – nuclei not easily accessible

Shell model description Shell model description of neutron-rich Potassium isotopesof neutron-rich Potassium isotopes

48Ca double closed-shell configuration

For Potassium (Z=19): a proton-hole, nearest shells are s1/2, d3/2 and d5/2

For neutron-rich (N > 28): neutrons in p3/2, p1/2 and/or f5/2

shells

Evidence of a 7/2Evidence of a 7/2–– isomer in isomer in 4747KK

(7/2 )-

3511

655

3152

2147

4433

3339

1094

267

1319

2020

360 3/2 +

0 +

1660

360

1/2

4166

K4719 28

1660 M2

1/2+

3/2+

1660 keV line not in prompt gamma spectrum, assigned as an M2 isomeric transition: 7/2–

3/2+

7/2– isomer,T1/2 = 7 ns

(7/2 )-

3511

655

3152

2147

4433

3339

1094

267

1319

2020

360 3/2 +

0 +

1660

360

1/2

4166

K4719 28

7ns

M2

Shell model configurations in Shell model configurations in 4848KK

47K28

πs1/2–1

πd3/2–1

πf7/2

+ νp3/2

1–2–

2–

0–

1–3–

4+3+

2+

5+

48K29

πf7/2 υp3/2

πs1/2 –1

υp3/2

πd3/2–1

υp3/2

First experimental identification First experimental identification of excited states in of excited states in 4848KK

PRISMA

GAMMASPHERE

Identification of 48K gamma lines from PRISMA

Level scheme established from GAMMASPHERE coincidence data

New 6.5 ns isomer placed in 48K

πs1/2 υp3/2

πd3/2 υp3/2

πf7/2 υp3/2 π-2

First observation of excited states in First observation of excited states in 4949KK

Gamma lines identified from PRISMA Level scheme from coincidence analysis

πf7/2

πs1/2–1

πd3/2–1

PRISMA

Energies of lowest Energies of lowest 1/21/2++, , 3/23/2++ andand 7/27/2––

states in odd K isotopesstates in odd K isotopes

2814

1/2+

MeV

2

1

0

360

7713/2+

2522

980

561474

1294

738

1081

20202107

7/2–

39K2041K22

43K2445K26

47K2849K30

exc

itatio

n e

ne

rgy

Evolution of relative Evolution of relative ππss1/21/2–1–1 andand ππdd3/23/2

–1 –1

pproton single particle energiesroton single particle energies

As neutrons occupy the f7/2 orbital, proton orbitals are shifted – interaction f7/2 ↔ d3/2 is attractive, f7/2 ↔ s1/2 is repulsive

πs1/2–1

πd3/2–1

MeV1

0

-1

-2

-3

N=20 22

3028

2624

This behaviour consistent with the predicted monopole effect of the tensor force

KrakKraków group and collaboratorsów group and collaborators

R. Broda, B. Fornal, W. Królas, T. Pawłat, J. Wrzesiński IFJ PAN Kraków

S. Lunardi, A. Gadea, N. Marginean, L. Corradi, A.M. Stefanini, F. Scarlassara, G. Montagnoli, M. Trotta, D. Napoli, E. Farnea Laboratori Nazionali di Legnaro and INFN Padova

R.V.F. Janssens, M.P. Carpenter, T. Lauritsen, D. Seweryniak, S. Zhu Argonne National Laboratory

0

360

2020

47K28

πs1/2

πd3/2

πf7/2

+ νp3/2 0-

1-

2-

3-

1-2-

5+4+

3+

2+

48K29

279

449

1-

2-

3-

New experimental openingNew experimental opening

Thick target data insufficient:difficult isotopic identification,fast gamma transitions unobserved

PRISMA spectrometer designed for identification of deep-inelastic reaction fragments

PRISMA

New excited states and New excited states and their configuration their configuration assignment in assignment in 4848KK

(1–)

(3–)

(5+) 6.5nsπf7/2 υp3/2

πs1/2 –1

υp3/2

πd3/2–1

υp3/2