Background: Because 235U fission cross-section with neutrons remains almost constant in the fission neutron energy region

the neutron-induced fission fragments detection system with flat neutron energy response will be widely used in pulsed fission neutron yield measurement. Purpose: The neutron-induced fission target chamber detection system consisting of 235U target and PIN detector is designed and investigated experimentally. Methods: The fission fragment energy spectrum and average energy deposited in the PIN detector are calculated by Monte Carlo simulation coupling with TRIM2000. Average deposit energy of 235U fission fragment in PIN detector is measured by recording fragment energy spectrum at K-400 accelerator neutron source. Results: The experimental results are compared with theoretical calculation. The calculated average deposited energy is in fact over-estimated because of pulse height defect of fission fragments in PIN detector. With the calculated neutron detecting efficiency and the calibrated average effective deposited energy available

the neutron sensitivity can be determined

and neutron energy response curve of fission target chamber detection system can be obtained. Conclusion: The present results can furnish theoretical and experimental indication for design of fission target chamber detection system. Abstract