1 / 17

Exploration of Shears Bands in 204At and 206Fr Nuclei with Magnetic Rotation

This study delves into shears bands in 204At and 206Fr nuclei, highlighting unique magnetic rotation properties and opportunities for further research. Analysis of experimental data and future directions are discussed in detail.

maxines
Télécharger la présentation

Exploration of Shears Bands in 204At and 206Fr Nuclei with Magnetic Rotation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Possible Shears Bands in 204At and 206Fr Evan Seyfried

  2. N=120 S. Frauendorf, Z. Phys. A 358, 163–167 (1997) Motivation • Shears bands known along Z=82 Pb nuclei • Predicted along N=120 series of nuclides

  3. S. Frauendorf, Nuc. Phys. A 601 (1997) 41-55 Background • Quick Shears Band Review High-j, proton-particle / high-j, neutron-hole interaction: Perpendicular at lowest energies  Off-axis total angular momentum Large magnetic dipole moment develops Magnetic Rotation: Tilted Axis Cranking (TAC) model: Quantized precession of the magnetic dipole moment, μ┴) about the total angular momentum ( J ) Closing of Shears  Shows I(I+1) rotation-like behavior in near-spherical nuclei

  4. Experiment • Argonne National Lab • ATLAS accelerator, GAMMASPHERE • Fusion-evaporation reaction • 30Si + 181Ta  211Fr* • Beam Energy: 152 MeV • 15E6 γ-γ coincidences • 20 hrs beam time • Nuclei of interest produced: 204At  α3n 206Fr  5n

  5. W. Reviol, D.G. Sarantites, et. al., Nuclear Instruments and Methods in Physics Research A 541 (2005) 478-500 Experiment WashU’s HERCULES • High-efficiency Evaporation-Residue Counter Under Lots of Elastic Scattering (ratio σE-R/σfission ~ 1/200) • 64 thin fast-plastic scintillators in 4 concentric rings

  6. Data Projection of Coincidence Matrix X-rays used for Isotopic ID

  7. Data Francium (86 keV) & Astatine (79 keV) X-ray gates Fr 205Fr 206Fr 207Fr At 203At 204At

  8. Data Shears Bands 206Fr Shell Model States 204At Shell Model States

  9. Level Schemes

  10. Why Shears? • Characteristic low-energy energy-level spacing • Band sits high in energy above the shell model states • Possible alignment:

  11. J (ħ) ħω (MeV)

  12. Fr Shears Bands from light Pb and Bi to the N=119 isotones Rn At Po J (ħ) Bi ħω (MeV) Pb

  13. Future Direction • Evidence for shears bands, floating above expected odd-odd shell model states in both 204At and 206Fr (N=119 isotones) • More evidence needed, but we consider them possible shears bands 1. Longer run to find linking transitions to shell model states • Angular correlation for M1 confirmation • Confirm configurations for the band 2. Lifetime measurement to determine B(M1)’s

  14. Thanks to: • U.S. Naval Academy: D.J. Hartley • Washington University: W. Reviol, D.G. Sarantites, C.J. Chiara, O.L. Pechanaya • CSNSM: K. Hauschild, A. Lopez-Martens • Argonne: M.P. Carpenter, R.V.F. Janssens, D. Seweryniak, S. Zhu Sponsored by grants from the NSF and DOE

  15. Nilsson Diagrams

  16. Data • Level Schemes:

  17. S. Chmel, S. Frauendorf, and H. Hubel, Phys. Rev. C 75, 044309 (2007) Shears Bands • Demonstrates back-bending seen in shears bands in the light-Pb nuclei • B(M1)/B(E2) values limited to >___ (μ┴)2/(eb)2 • Longer data run needed to observe B(E2) values • S. Chmel, et. al. report same problem with light Pb nuclei • Lifetime measurements required to get B(M1) values

More Related