A pen size dosimeter designed to be viewed longitudinally for reading dosage of neutron radiation and gamma radiation and that is reset by being charged through a conductor pin carried by a longitudinally compressible spring urged assembly near one end of the dosimeter but which may lose the correct dosage reading under shock and vibration conditions is improved by the addition of a novel latch for the spring-urged asembly to release the spring urged assembly to permit displacement for charging and to relatch when charging is terminated.