  This paper presents the results of a search for brown dwarfs in the Upper
Scorpius Association using data from the UKIRT Infrared Deep Sky Survey
(UKIDSS) Galactic Cluster Survey. Candidate young brown dwarfs were first
chosen by their position in colour magnitude diagrams with further selection
based on proper motions to ensure Upper Scorpius membership. Proper motions
were derived by comparing UKIDSS and 2MASS data. Using that method we identify
19 new brown dwarfs in the southern part of the association. In addition there
are up to 8 likely members with slightly higher dispersion velocity. The ratio
of brown dwarfs to stars was found to be consistent with other areas in Upper
Scorpius. It was also found to be similar to other results from young clusters
with OB associations, and lower than those without, suggesting the brown dwarf
formation rate may be a function of environment.
