In the presence of high gamma fields (l(105 to 107 R/h), the neutron sensitivity of a fission counter is drastically reduced because of gamma pulse pileup in the counter and in its associated preamplifier, thereby limiting the effective application of measurement techniques such as reactor neutron noise analysis in situations where gamma intensities of ≥l(106 R/h are encountered. To overcome this limitation a detector-preamplifier system with current-mode signal processing was developed. The detector, which contains electrode plates coated with enriched uranium, has a neutron sensitivity of 0.56 count/(sec nv). It is connected with 40 ft of cable to a low-noise preamplifier. This detector is designed to reduce alpha pulse pileup and gamma sensitivity and to have a fast charge-collection time. Current-mode signal processing required the development of a lownoise preamplifier. Measurements made with the system in gamma fields of 5 * 106 and 1 * 107 R/h showed a neutronsensitivity loss of 17 and 34%, respectively.