Status of the neutron diagnostic experiment for Alcator C-Mod

The Alcator C-Mod experiment is expected to produce neutrons at a rate of up to 1 x 1016 n/s during its highest performance operation. The global neutron detection system must provide accurate measurement of this production over the full operating regime of the experiment, 1011--1016 n/s. This is accomplished using a series of uranium fission detectors enriched in U235 of staggered sensitivity. These are distributed in two moderator assemblies. A BF3 detector is added to each moderator to cover the lowest operational range. Preliminary calibration of the system has been accomplished using a 65.4 μg Cf252 source placed inside the Alcator C-Mod vacuum vessel. The system design and calibration is discussed herein