  At the n\_TOF experiment at CERN a dedicated single-crystal chemical vapor
deposition (sCVD) Diamond Mosaic-Detector has been developed for (n,$\alpha$)
cross-section measurements. The detector, characterized by an excellent time
and energy resolution, consists of an array of 9 sCVD diamond diodes. The
detector has been characterized and a cross-section measurement has been
performed for the $^{59}$Ni(n,$\alpha$)$^{56}$Fe reaction in 2012. The
characteristics of the detector, its performance and the promising preliminary
results of the experiment are presented.
