An atomic particle detection assembly (10) includes one or more detectors (30) that detect atomic particles, particularly neutrons. The detectors are positioned within a first chamber (22) having a first operating pressure. The atomic particle detection assembly includes a junction apparatus (40) supporting the detectors. The junction apparatus defines a second chamber (100) having a second operating pressure that is different from the first operating pressure. Sensing electronics (50) are attached to the detectors and the sensing electronics are housed within the second chamber of the junction apparatus.