A new concept for background rejection in gamma-ray astronomy — the supershield

Expanding the scientific successes of GRO and SIGMA will require significant improvements in sensitivity for the next generation of gamma-ray instruments. The conventional approach of increasing detector areas and shield thicknesses will reach a practical limit with the current generation of instruments, especially as moderate-sized aunch vehicles will certainly be the norm in the future. Further sensitivity improvements require novel approaches for reducing detector background. e describe some concepts for advanced shielding configurations which we call “supershields”. Supershields combine layers of materials designed to moderate and absorb neutrons, along with conventional, active gamma-ray shields. Due to contradictory demands placed on shield designs by neutrons and gamma-rays, supershields afford significant flexibility to optimize shield geometry compared to conventional shielding methods. If properly designed, supershields have the potential to significantly reduce overall detector backgrounds using passive, inexpensive materials.