R. Hackenburg

Experimental observation of the Σ hypernuclei, Σ6H and Σ16C

Abstract The hypernuclei Σ 6 H and Σ 16 C were observed by the (K − , π + ) reaction on targets of 6 Li and liquid O, respectively, at 713 MeV/ c incident K − momentum. Structure is seen in Σ 6 H which may be interpreted in terms of particle-hole excitations similar to the previously observed states in Λ 6 Li. The inablitity to resolve individual Σ hypernuclear levels in Σ 16 C, due in part to the excitation of non-coherent states as a result of the large momentum transfer of about 130 MeV/ c , precludes the extraction of the Σ-nucleus spin-orbit potential strength. The Σ-nucleus well depth appears to be 7 to 10 MeV less than that for the Λ.

Characteristics of a pressed silica powder Cherenkov detector

Abstract A Cherenkov detector, using pressed silica power as a radiator, has been developed and tested for indices of refraction in the range 1.05–1.1. The results indicate that a large area (200 cm2) detector can be made with a preselected and uniform index of refraction, and that these detectors can operate with high efficiency for particles above the Cherenkov threshold. This study demonstrates that pressed silica powder provides a useful source of Cherenkov radiators with velocity thresholds in a range difficult to obtain with naturally occurring materials.