TECHNOLOGY AREA(S): Nuclear Technology
OBJECTIVE: Develop a real-time detector capable of accurately measuring the dose from prompt gamma and prompt neutron from a nuclear blast.
DESCRIPTION: The Defense community has a need for detecting and measuring the prompt gamma and prompt neutron from a nuclear blast. When a nuclear weapon detonates, it creates both prompt (also called initial) and residual radiation. Prompt neutrons result almost exclusively from the energy producing fission and fusion reactions, while prompt gamma radiation includes that arising from these reactions as well as that resulting from the decay of short-lived fission products (Ref. 1, FM 8-9). For small tactical nuclear weapons (under 50 kT), the prompt radiation is one the most predominate causes of casualties, more than the blast wave and thermal (Ref. 1, FM 8-9 table 3-I).
The prompt radiation occurs in a very short pulse, lasting only a few microseconds. Thus it is exceedingly hard to accurately measure real-time. Currently, the warfighters have both passive dosimeters and real-time dosimeters. Passive dosimeters such as as film badges, Thermo luminescent Dosimeters (TLDs), or Optically Stimulated Luminescence (OSL) detectors accurately measure the prompt radiation. The Army’s PDR-75A uses OSL technology and can accurately measure the prompt radiation. However, it is not a real-time system. The warfighter must stop what they are doing and read the dosimeter in a reader to determine their dose. The current real-time dosimeters such as the UDR-13 can provide real-time measurements, but are extremely inaccurate (sensitivity around 30 cGy). The warfighters currently do not have capability to accurately measure prompt radiation accurately in real-time.
There are several technologies that have been developed or advanced in the last few years that make real-time measurement of prompt doses possible, feasible, and affordable. Recent advances in OSL devices along with advances in optic sources and measurement devices may allow the development of a device that can accurately measure prompt gamma and neutron in real-time or near real-time. There have also been advances in MOSFET and Pin-diodes that may allow the use of those technologies for the needed measurements. The goal of this research would be the development of such an innovative detector for eventual use on radiation detectors for vehicles and personal.
PHASE I: Demonstrate the proposed technology can accurately measure the prompt gamma and prompt neutron doses in real-time (or near real-time) via breadboard validation in laboratory environment (TRL 4). The initial step is to design and fabricate a breadboard prototype using the proposed technology. The next step is to test the breadboard prototype against prompt gamma and prompt neutron environment (i.e. the pulse reactor at White Sands Missile Range (WSMR)) to assess the capability of proposed technologies to meet the need. The final step is to review and analyze the data to determine the feasibility of the proposed technology to fulfill the Army’s need to accurately measure the prompt gamma and prompt neutron doses in real-time.
PHASE II: In Phase II, demonstrate the proposed technology can accurately measure the prompt gamma and prompt neutron doses in real-time (or near real-time) through high-fidelity breadboard validation in a relevant environment (TRL 5 or greater). Design and fabricate a high-fidelity breadboard prototype apparatus with the proposed technology integrated with reasonably realistic supporting elements. Test the breadboard prototype apparatus in a relevant environment to include prompt gamma and prompt neutron as well as other relevant challenges such as temperature, EMP, and vibration. The purpose of testing is to ensure the ability of the technology demonstrates the needed capability to accurately measure the dose from prompt gamma and prompt neutron in real-time, but also to determine if any potential limitations of the technology prevent the eventual fielding of the technology. The final step is to review and analyze the data to determine if the technology will fulfill the Army’s need to accurately measure prompt gamma and prompt neutron doses in real-time in a relevant environment.
PHASE III DUAL USE APPLICATIONS: If Phase II is successful, Phase III will further refine a final deployable design, incorporating design modifications based on results from tests conducted during Phase II, and improving engineering/form-factors, equipment hardening, and manufacturability designs to meet U.S. Army CONOPS and end-user requirements.
KEYWORDS: nuclear radiation detection, prompt gamma, prompt neutron, real-time detection