Manipulation of Giant Multipole Resonances via Vortex γ Photons.

Area of Science:

• Nuclear Physics
• Strong Laser Physics
• Nuclear Astrophysics

Background:

• Traditional photonuclear reactions primarily excite giant dipole resonances.
• Measuring higher multipole isovector giant resonances is challenging.
• Collective excitations in even-even nuclei require advanced techniques.

Purpose of the Study:

• Investigate manipulation of collective excitations using vortex gamma photons.
• Develop a calculation method for photonuclear cross sections with vortex gamma beams.
• Enable precise measurement of isovector giant resonances with higher multipolarities.

Main Methods:

• Utilized a fully self-consistent random-phase approximation plus particle-vibration coupling (RPA+PVC) model.
• Calculated photonuclear cross sections induced by vortex gamma photon beams.
• Applied Skyrme density functional for theoretical calculations.

Main Results:

• Electromagnetic transitions with multipolarity J < |mγ| are forbidden for vortex gamma photons due to angular momentum conservation.
• Vortex gamma photons with mγ=2 allow probing isovector giant quadrupole resonance without dipole interference.
• Specific multipolarity giant resonances can be extracted by controlling vortex gamma photon properties.

Conclusions:

• The developed method allows for the extraction of specific multipolarity giant resonances.
• Vortex properties of gamma photons can be diagnosed via nuclear photon-absorption cross sections.
• Opens new avenues for photonuclear excitations, coherent gamma photon laser generation, and vortex particle detection.