Nuclear Isomerism

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• Different nuclear isomers
  
• Shape isomer, spin isomer, K isomer

  Systematics of K-Forbidden Gamma-Ray Transitions

  P.G. Thirolf: Spektroskopie im 2. und 3. Minimum von Aktinidenkernen

  • Kernspaltung: Gestaltsänderung und Potential
    
  • Energieniveaus im 1. und 2. Minimum
    
  • 240-Pu: Kernpotential
    
  • unterschiedliche Kernformen
  P.G. Thirolf:Conversion Electron Spectroscopy in the Second Minimum of Actinides

• Search for K-Isomers in Radioactive Nuclei Produced at Relativistic Energies

• Production Cross Sections for Radioactive Beams
  • cross sections for isotopic production in U+Be and U+Pb collisions
    
  • Projectile Fragmentation of Au+Be: Hf,Ta,W,Re,Os
    
  • FRS beams (EPAX-calculation)

Experimental Setup

• Fragment Separator (FRS) Homepage
  
• Schematic View of the FRS-Gamma Setup
  
• Photograph of the Ge-Clover Array
  
• Clover set-up (Al-catcher)
  
• Clover set-up (plastic catcher)
  

Data Analysis

• In-Flight Separation of Fragments at Focus "S2" and "S4"
  
• In-Flight Separation ("S4") for Charge States Q=Z and Q=Z-1
  
• Fragmentation reaction ²⁰⁸Pb on ⁹Be at 1GeV/nucleon
  
• Correlation SC41 versus SC42 (for ¹³⁶Sb M.N.Mineva)
  
• Atomic gamma-background due to the slowing down
  
• Time measurement between the implantation and gamma-ray detection

Experimental Results

• 177Ta, 179W setting, fully stripped
  
• High-Spin Isomers in 179W
  
• Population of K-Isomers in 179W
  
• Theoretical Interpretation
  • Abrasion-Ablation Model
    
  • Angular Momentum Distribution in a Fragmentation Process

Short Lived States in 200Pt

191W setting

Population of Ground State Band in 190W

Theoretical Interpretation

• Blocked BCS-calculation of 190W
  
• Systematics of Ground State Band in Tungsten Nuclei
  
• Comparison with Triaxial Rotator Model
  
• Asymmetric rotor model (pdf)

^125,127Cd ^126,128,130In ^125,127,129In ¹²⁹Sn ¹³⁰Sn ¹³⁶Sb, ¹³⁵Te

Conference contributions:

• Int. Conf. on Achievements and Perspectives in Nuclear Structure, Crete 1999
  
• Int. Symposium on Exotic Nuclear Structures, Debrecen 2000
  
• Recent isomer spectroscopy experiments at the FRS
  M. Hellström (Surrey 2004)

Publications:

• The GSI projectile fragment separator (FRS): a versatile magnetic system for relativistic heavy ions
  H. Geissel et al. NIM B70, 286 (1992)
• Einfluss der Umladung beim Abbremsen von Schwerionen im Energiebereich (100-1000) MeV/u
  H. Weick, PhD thesis

• High-resolution detectors in nuclear spectroscopy
  J. Gerl Nucl. Instr. Meth. Phys. Res. A442, 238 (2000)
• Isomer spectroscopy of neutron rich ¹⁹⁰W
  Zs. Podolyák et al. Phys.Lett. 491B, 225 (2000)
• Nuclear structure of heavy neutron rich systems: Fragmentation spectroscopy with a 1 GeV per nucleon ²⁰⁸Pb beam
  M. Caamaño et al. Nucl.Phys. A682, 223c (2001)
• Isomeric Decay in ²⁰⁰Pt
  M. Caamaño et al. Acta Phys.Pol B32, 763 (2001)
• Population of High Spin States in Relativistic Fragmentation
  M.Pfützner et al. Acta Phys.Pol B32, 2507 (2001)
• A new ms isomer in ¹³⁶Sb produced in the projectile fission of ²³⁸U
  M.N. Mineva et al. Eur.Phys.J. A11, 9 (2001)
• Angular momentum population in the fragmentation of ²⁰⁸Pb at 1 GeV/nucleon
  M.Pfützner et al. Phys. Rev. C65, 064604(2002)
• Heavy nuclei studied in projectile fragmentation
  Zs. Podolyak et al. Nucl. Phys. A722, 273c (2003)
• Isomer spectroscopy in the neutron-deficient lead region following projectile fragmentation
  K.A. Gladnishki et al. Phys. Pol. B34, 2395 (2003)
• Angular momentum population in the projectile fragmentation of ²³⁸U at 750 MeV/nucleon
  K.A. Gladnishki et al. Phys. Rev. C69, 024617 (2004)
• Isomeric decay studies with fragmentation beams
  Zs. Podolyak Acta Phys. Pol. B36, 1269 (2005)
• High angular momentum states populated in fragmentation reactions
  Zs. Podolyak et al. Phys. Lett. B632, 203 (2006)
• K-isomers populated by projectile fragmentation in the neutron-rich A=180-200 mass region
  P. Mayet PhD-thesis
• A new ms isomer in ¹³⁶Sb produced in the projectile fission of ²³⁸U
  M.N. Mineva PhD-thesis

Electromagnetic Excitation of K-Isomers

• Coulomb Excitation of K=8 Isomer (T1/2=4.0 s) in Hf-178

• L.I. Rusinov: "Nuclear Isomerism"; Soviet Phys. USPEKHI 4 (1961), 282
  
• K.E.G. Loebner: "Systematics of Absolute Transition Probabilities of K-Forbidden Gamma-Ray Transitions" Phys. Lett. 26B (1968), 369

• Projectile Fragmentation:
  • J.Benlliure et al.: "Production of Neutron-Rich Isotopes by Cold Fragmentation in the Reaction 197Au + Be at 950 A MeV" Nucl. Phys. A660 (1999), 87
    
  • M. de Jong et al.:"Angular Momentum in Peripheral Fragmentation Reactions" Nucl. Phys. A613 (1997), 435

• Pt-200:
  • S.W. Yates et al.: "Nuclear Structure of 200Pt from In-Beam Conversion-Electron and Gamma-Ray Spectroscopy" Phys. Rev. C37 (1988), 1889 and Nucl. Data Sheets 75(1995), 667

• Hf-178:
  • R.G. Helmer and C.W. Reich: "Decay of an Isomer in Hf-178 with K=16" Nucl. Phys. A114 (1968), 649
    
  • F.W.N. de Boer et al.: "The Four Quasi-Particle Hf-178 Isomeric State, Its Excitation Energy and Multipolarities of Deexciting Transitions" Nucl. Phys. A263 (1976), 397
    
  • T.L. Khoo and G. Lovhoiden: "Structural Changes in the Yrast States of Hf-178" Phys. Lett. 67B (1977), 271
    
  • J. van Klinken et al.: "K-Forbidden Decays in Hf-178; M4 Decay of an Yrast State" Nucl. Phys. A339 (1980), 189
    
  • W.Z. Venema et al.: "The Use of Hf-178m (31 y) for Intensity Calibration" NIM 201 (1982), 531
    
  • J.H. Hamilton et al.: "Isomeric Trapping Following Coulomb Excitation of High Spin States in Hf-178" Phys. Lett. 112B (1982), 327
    
  • H. Postma et al.: "Brute-Force Orientation of Hf-178m2 and Magnetic Moments of Hf-178m1 and Hf-178m2" Hyperfine Interactions 52 (1989), 79
    
  • H. Xie et al.: Coulomb Excitation of the K=8 Isomer in Hf-178 Phys. Rev C48 (1993), 2517
    
  • Yu.Ts. Oganessian et al.: "Production, Chemical and Isotopic Separations of the Long-Lived Isomer Hf-178m2 (T1/2=31 yr)" J. Phys. G18 (1992), 393
    
  • N. Boos et al.: "Nuclear Properties of the Exotic High-Spin Isomer Hf-178m2 from Collinear Laser Spectroscopy" Phys. Rev. Lett. 72 (1994), 2689
    
  • S. Deylitz et al.: "Inelastic Deuteron Scattering from the High-Spin Isomer Hf-178m2 (16+)" Phys. Rev. C53 (1996), 1266
    
  • E. Lubkiewicz et al.: Coulomb Excitation of the K=16 Rotational Band in 178Hf Z. Phys. A355 (1996), 377
    
  • S.M. Mullins et al.: Rotational band on the 31 yr 16+ isomer in Hf-178 and Erratum Phys. Lett. B393 (1997), 279 and Phys. Lett. B400 (1997), 401
    
  • A.B. Hayes: Coulomb excitation paths of high-K isomer bands in 178Hf Phys.Rev.Lett. 89 (2002), 242501
    

• Ta-180:
  • C.B. Collins et al.: "Resonant Excitation of the Reaction Ta-180(gamma,gamma')Ta-180" Phys. Rev. C42 (1990), R1813
    
  • C. Schlegel et al.: Phys. Rev. C50 (1994), 2198
    
  • M. Loewe et al.: Z. Phys. A356 (1996), 9
    
  • G.D. Dracoulis et al.: "Structure and Decay of a Four-Quasiparticle 15- Isomer in Ta-180" Phys. Rev. C53 (1996), 1205