Measurement of the monitored drift tubes response to energetic neutrons

We have measured the response of an array of ATLAS muon spectrometer drift tubes to fast neutrons, produced by a t(d,n)/sup 4/He reaction at the 5.5-MV TANDEM Van de Graaff accelerator of the National Centre of Scientific Research "Demokritos." The setup consisted of 24 drift tubes in a 6/spl times/4 arrangement. The neutron energy was 18.3 MeV. The anode wire voltage varied from 2200 to 2800 V. For a neutron flux of about 2.75 kHz/cm/sup 2/, the drift tube sensitivity to 18.3-MeV neutrons ranged from 0.031% to 0.606% for anode voltages between 2200 and 2800 V, respectively.