Components of scientific analytical equipment, such as electron multipliers and modifications thereto, for extending the operational lifetime or otherwise improving performance by way of improved construction. A detector includes one or more electron emissive surfaces and one or more detector elements configured to define on one side an environment internal the detector and on the other side an environment external the detector. The one or more detector elements are configured to inhibit or prevent flow of a gas from the environment external the detector to the environment internal the detector. Such detectors may be used in a mass spectrometry instrument, for example.