Radiation exposure is a critical concern for human activities at high altitudes and in space. Accurate measurement of this exposure is essential for ensuring the safety of astronauts, pilots, and other such individuals. Traditional instruments like the Geiger counter have limitations in mimicking human tissue responses to ionizing radiation, prompting the development of more sophisticated devices like the Tissue Equivalent Proportional Counter (TEPC).
Building on this foundation, researchers at Oklahoma State University (OSU), led by Dr. Eric Benton and graduate student Tristen Lee, have developed three innovative projects: SpaceTED, AirTED, and AirSiD. These projects extend the functionality of TEPCs to different altitudes, providing precise radiation dose measurements that more accurately reflect potential human exposure.
Central to all three devices is the Red Pitaya STEMlab 125-14 4-Input, a versatile instrument that handles spectroscopy measurements and real-time data analysis, driven by its powerful Zynq 7020 system. These innovations represent a significant advance in radiation dosimetry, with each project addressing the unique challenges posed by different operational environments.
SpaceTED is a low-cost, self-contained, portable Tissue Equivalent Proportional Counter (TEPC). More specifically, SpaceTED is also capable of measuring secondary neutrons of the types and energies found in space, providing real-time dosimetric data on the radiation exposure of the space crew. A Si PIN diode is used to detect lower LET radiation. It basically functions as a combined TECP and Si spectrometer. The entire device is extremely compact, about the size of a small shoebox (25.5 cm x 15.5 cm x 12.5 cm), and requires only external power to function properly. Data is periodically downloaded to the ground via an ISS laptop. Developed by Dr. Eric Benton and graduate student Tristen Lee of OSU’s Department of Physics, it is currently located inside the habitable volume of the ISS near an airlock inside the Japanese Experiment Module (JEM). It was launched on SpX-29 on 1 November 2023. The project is funded by NASA through an Established Program to Stimulate Competitive Research (EPSCoR) award.
Figures 1 and 2: Images of SpaceTED, with two Red Pitaya devices in the bottom right corner.
AirTED is very similar to SpaceTED in its basic functionality. It is an enhanced version of the ATED (Active Tissue Equivalent Dosimeter) and is a compact, low-cost, portable TEPC for high LET radiation, specifically for the detection of high-energy neutrons which dominate the dose equivalent at aviation altitudes. The AirTED is actively used to monitor atmospheric radiation exposure onboard the NASA WB-57 special research aircraft. It is being designed for mass production so that it can be used for radiation monitoring onboard a variety of commercial, business and military aircraft, as well as high-altitude UAVs, balloons and suborbital vehicles. The data collected from the flights will be used for space weather application projects.
Figure 3: From left to right, the inside of AirTED, the new detector head design, and the NASA WB-57 aircraft in the bottom two images.
The AirSiD is a third product developed by the OSU’s Department of Physics, similar to Liulin and AirDos, designed to be sensitive to low LET radiation including electromagnetic cascade component (electrons/protons, x/g) and relativistic electrons, based on the OSI Optoelectronics RD-100 Si PIN photodiode. The new charge sensitive pre-amplifier and pulse shaping amplifier circuit designs were developed by OSU physics students and the new prototypes are based on the Red Pitaya 4 channel programmable digitizer.
Figure 4: Design and launch of the latest AirSiD prototype by space balloon.
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