Abstract: An infra-red remote personal alarm system consists of a portable transmitter unit (10) which is intended to be worn or to be manually carried by the user, and which is operable by the user at any particular location to transmit an alarm signal in an emergency and which is to be received by a central receiving station (41) so that appropriate action can be initiated in response thereto. The transmitter unit is electrically operable and includes means (15) for transmitting pulsed infra-red alarm signals which can be picked-up by an infra-red signal receiver at the location of the user, and then retransmitted as an oscillating electrical signal via direct wiring (38, 39, 40, 42, 43) to the central receiving station (41) as a warning signal indicative at location monitoring points (43, 44) of the location from which the emergency call has been made.

Abstract: A dosimeter for measuring the intensity of high energy electron, photon, or other particle radiation has ion, electron, and radiation shields about at least respectively sensitive components of the dosimeter. The entire dosimeter, therefore, can be assembled as a unit and portably placed in the radiation to be measured. Ruggedness for this desirable partability is provided by the use in the dosimeter of a pancake ionization chamber which also eliminates the need to calibrate radiologically the dosimeter.