Direct-response ultraviolet thermoluminescent dosimeter

Electromagnetic Radiation Effects on MgO-Based Magnetic Tunnel Junctions: A Review

Magnetic tunnel junctions (MTJs) have been widely utilized in sensitive sensors, magnetic memory, and logic gates due to their tunneling magnetoresistance. Moreover, these MTJ devices have promising potential for renewable energy generation and storage. Compared with Si-based devices, MTJs are more tolerant to electromagnetic radiation. In this review, we summarize the functionalities of MgO-based MTJ devices under different electromagnetic irradiation environments, with a focus on gamma-ray radiation. We explore the effects of these radiation exposures on the MgO tunnel barriers, magnetic layers, and interfaces to understand the origin of their tolerance. This review enhances our knowledge of the radiation tolerance of MgO-based MTJs, improves the design of these MgO-based MTJ devices with better tolerances, and provides information to minimize the risks of irradiation under various irradiation environments. This review starts with an introduction to MTJs and irradiation backgrounds, followed by the fundamental properties of MTJ materials, such as the MgO barrier and magnetic layers. Then, we review and discuss the MTJ materials and devices' radiation tolerances under different irradiation environments, including high-energy cosmic radiation, gamma-ray radiation, and lower-energy electromagnetic radiation (X-ray, UV-vis, infrared, microwave, and radiofrequency electromagnetic radiation). In conclusion, we summarize the radiation effects based on the published literature, which might benefit material design and protection.

Ultraviolet-induced thermoluminescence and phosphorescence in Mg2SiO4:Tb

Among the common TLD materials studied (Mg2SiO4:Tb, Al2O3:Si, Ti, CaSO4:Tm, CaSO4:Dy, Li2B4O7:Mn and LiF TLD-100), Mg2SiO4:Tb was found to have the highest intrinsic TL sensitivity to UV radiation (wavelength 253.7 nm). The TL response of the dosimetric peak (approximately 200 degrees C) of virgin Mg2SiO4:Tb was studied as a function of UV exposure in the range 10--10(4) J m-2. The UV-induced TL was not affected by room-light and no appreciable fading was observed up to 20 days after irradiation indicating that this is a promising TL phosphor for UV dosimetry. The UV sensitivity was found to increase with increasing preliminary gamma exposure above 10(-2)Ckg-1 (after a post-irradiation anneal at 300 degrees C for 1 h). The degree of sensitisation was found proportional to the intensity of the residual TL peak at 450 degrees C. A study of the TL response of the sensitised sample as a function of UV test exposure has demonstrated the transfer of charge carriers from the deep traps to the dosimetry traps. Both virgin and gamma-exposed Mg2SiO4:Tb were found to exhigit phosphorescence decay at room temperature after UV stimulation. The intensity of the UV stimulated phosphorescence was found to increase with the gamma exposure above 10(-2) C kg-1.

Photostimulated thermoluminescence of Al2O3 (Si, Ti) and its application to ultraviolet radiation dosimetry

Intrinsic photostimulated thermoluminescence (PSTL) in the range 200-320 nm and radiation sensitized PSTL for 200-425 nm have been studied in Al2O3 (Si, Ti) phosphor. Causes of the effects found, partly attributed to phototransfer of electrons are described. Linearity in the intrinsic and radiation sensitized response of the 280 degree C TL peal for both pellet and powder forms has been studied with regard to ultraviolet dosimetry over the range 10(-2) to 5 x 10(4) mJ cm-2. Details of the use of powder and pellet forms for dosimetry are given.