Prezentacja%20programu%20PowerPoint

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Research group R.Broda, B.Fornal, W.Królas,
T.Pawlat, J.Wrzesinski H.Niewodniczanski
Institut of Nuclear Physics PAN-KRAKOW Collaborat
ion with the INFN LNL Legnaro Tandem and ALPI
Linac GASP, PRISMA-CLARA spectrometer Spectroscop
y of hard-to-reach nuclei with deep-inelastic
heavy-ion reactions
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Neutron-rich nuclei produced 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

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Thick target experiments

• Fragments stopped in the target, no isotopic
  identification
• Aquisition of high statistics g-g coincidence
  data sets
• Level structure from coincidence analysis, ID
  from cross-coincidences and/or known transitions

GAMMASPHERE
4 R. Broda et al., JPG 32, 151 (2006)
4 W. Królas et al., NPA 724, 289 (2003)
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48Ca (330 MeV) 238U (thick target) GAMMASPHERE
at Argonne
48Ca
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GASP at LEGNARO 64Ni (275 MeV)
130Te (thick target)
130Te
64Ni
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R.Broda et al., Phys.Rev. Lett. 74, 868 (95)
-
5-
4
(4, 3-)
(5-)
2
1114
(2)
0
8
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g-ray thick target measurements with DIC
advantages
GASP
Gamma rays from all
reaction products Gamma rays from the stopped
nuclei narrow lines easy analysis of g-g
coincidences Detection of cross-coincidences
some potential for identification
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PRISMA 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 g transitionsand
  GAMMASPHERE g-g coincidence data

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f5/2
p1/2
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2
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Evolution of Nuclear Structure with the 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

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Shell model description of neutron-rich
Potassium isotopes

• For Potassium (Z19) a proton-hole, nearest
  shells are ps1/2, pd3/2 and pd5/2
• For neutron-rich (N gt 28) neutrons in np3/2,
  np1/2 and/or nf5/2 shells

48Ca double closed-shell configuration
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Evidence of a 7/2 isomer in 47K
7/2 isomer, T1/2 7 ns
1660 M2
3/2
1/2
1660 keV line not in prompt gamma spectrum,
assigned as an M2 isomeric transition 7/2 ?
3/2
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7ns
M2
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Shell model configurations in 48K
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First experimental identification of excited
states in 48K

• Identification of 48K gamma lines from PRISMA
• Level scheme established from GAMMASPHERE
  coincidence data
• New 6.5 ns isomer placed in 48K

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pf7/2 ?p3/2 p-2
pd3/2 ?p3/2
ps1/2 ?p3/2
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First observation of excited states in 49K

• Gamma lines identified from PRISMA
• Level scheme from coincidence analysis

PRISMA
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Energies of lowest 1/2, 3/2 and 7/2 states in
odd K isotopes
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Evolution of relative ps1/21 and pd3/21 proton
single particle energies

• As neutrons occupy the nf7/2 orbital, proton
  orbitals are shifted interaction nf7/2 ? pd3/2
  is attractive, nf7/2 ? ps1/2 is repulsive

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

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Kraków group and collaborators
R. Broda, B. Fornal, W. Królas, T. Pawlat, J.
Wrzesinski 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
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3-
449
2-
279
1-
3
4
2
pf7/2
2020
5
?p3/2
0-
3-
1-
360
pd3/2
2-
2-
0
ps1/2
1-
47K28
48K29
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New experimental opening

• Thick target data insufficientdifficult
  isotopic identification,fast gamma transitions
  unobserved
• PRISMA spectrometer designed for identification
  of deep-inelastic reaction fragments

PRISMA
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New excited states and their configuration
assignment in 48K