First in-beam demonstration of a hybrid LaBr 3 /CeBr 3 /BGO array to measure radiative capture resonance energies in an extended gas target using a novel time of flight technique

We have deployed a new hybrid array of LaBr 3 , CeBr 3 , and BGO scintillators for detecting γ rays at the DRAGON recoil separator at TRIUMF. The array was developed to improve γ -ray timing resolution over the existing BGO array. This allows the average position of resonant capture in an extended gas target to be determined with ∼ 15 mm precision or better, even with five or fewer detected capture events. This, in turn, allows determination of resonant capture energies with statistical uncertainties below ∼ 1 % . Here we report the results of a first in-beam demonstration of the array, measuring the E c m = 0 . 4906 ( 3 ) MeV resonance in the 23 Na ( p , γ ) 24 Mg reaction, focusing on the timing properties of the array and its anticipated performance in future experiments with radioactive beams.