Proof of the Feasibility of Coherent and Incoherent Schemes for Pumping a Gamma-Ray Laser
Abstract
Recent approaches to the problem of the gamma-ray laser have focused upon upconversion techniques in which metastable nuclei are pumped with long wave length radiation. At the nuclear level the storage of energy can approach tera-Joules 10 to the 12th power per liter for thousands of years. This report focuses on an approach to the gamma-ray laser that depends upon incoherent pumping. This nuclear analog of the ruby laser embodies the simplest concept for a gamma-ray laser and it is not surprising that the greatest rate of achievement toward a sub-Angstrom laser has continued in this direction. Emphasis has remained upon the giant pumping resonances that enabled us to dump populations of the only available sample of the 29 candidates, Ta 180 sub m, through a cross section that was 10,000 times more favorable than even the most optimistic estimates. The lessons taught by that major milestone have been extended throughout the region of mass-180 nuclides. Reported is the success in pumping of only two of the candidates that are accidentally available, together with 17 other comparison isomers with the bremsstrahlung x-rays from a MeV linac. Previous excitations of the giant resonances pumping these materials had been made with a continum of photon energies reaching to 6 MeV and concern had lingered that the full 6 MeV of energy might have been actually needed. At such values the density of nuclear states is high and the onset of evaporation of particles from nuclei is near. Either would make the resonances useless to laser development. The significance of this work is that neither detrimental effect can occur at energies as low as the value of 4 MeV at which performance has now been achieved.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1989
- Accession Number
- ADA208071
Entities
People
- Carl B. Collins
Organizations
- University of Texas at Dallas