As an application of nanotechnologies in High Energy Physics, we have proposed a novel type of radiation detector with an ordered array of carbon nanotubes (CN) placed between an active medium and the read-out electronics. The charge produced in a thin layer of active medium crossed by an ionizing particle is driven, via the CN, to the read-out electronics. CN highly uniform in size and spacing and electrically insulated from each other are required for the optimization of charge collection. CN having diameter in the range 10÷ 100 nm and metal electrical properties will enable a sub-micron spatial resolution. A layer of porous alumina acts as mechanical framework, with suitable dielectric properties, for the growth of the conductive array of CN. Highly ordered arrays of parallel nanochannels in alumina have been obtained, with size and pitch in the range 10÷ 200 nm and 40÷ 400 nm, respectively for alumina …