There are 150 plaques placed here for the 150th anniversary of the founding of South Australia. This one stood out as for a moment I thought it will Billy Bragg but he's from Essex,UK.
"for their services in the analysis of crystal structure by means of X-rays" The mineral Braggite is named after him and his son. He was knighted in 1920. - Wikipedia
Plaque reads:
Bragg
Sir William Bragg OM 1862-1942
Sir Lawrence Bragg CH, MC 1890- 1971
Joint Noble Prize for physics 1915
Sponsor: University of Adelaide, Physics Department
Submitted: @ianthorp