Alpha/Triton Detection in the BL3 Experiment

The BL3 apparatus is being constructed with the capability to measure the in-flight decay neutron lifetime with statistical uncertainty better than 1 s in less than one day. This will support a comprehensive study of systematic effects, which may be responsible for discrepancy with measurements using trapped ultra-cold neutrons. The alpha/triton collimation and detection system was redesigned in the neutron and alpha-gamma detectors to accommodate higher rates and a larger beam spot on the NIST NG-C neutron guide. The new geometry and symmetry offer near perfect neutron detection uniformity, advanced neutron beam diagnostics, and high enough detection rates to test a new singles-coincidence calibration mode.