Optimization of preparation procedure of LiF:Mg,Cu,Si TLD for improving the reusability

OPTIMIZING THE TLD-100H READOUT SYSTEM UNDER VARIOUS RADIOACTIVE I-131 DOSES VIA THE REVISED TAGUCHI DYNAMIC QUALITY LOSS FUNCTION

The TLD-100H readout system performance under various radioactive I-131 exposure doses was optimized by four key factors via the revised Taguchi dynamic quality loss function. Taguchi dynamic analysis and the orthogonal array reorganizing the essential factors are crucial for the optimization of the thermoluminescent dosimeter (TLD) readout system given strict criteria of multiple irradiated environments and long-term exposure for calibrated TLDs. Accordingly, 96 TLD-100H chips were selected and randomly categorized into three batches with eight groups (four TLD chips in each group). Four factors, namely (1) initial temperature, (2) heating rate, (3) maximal temperature, and (4) TLD preheat time before reading were organized into eight combinations according to Taguchi suggestion, whereas each factor was preset at two levels. All 96 [Formula: see text] chips were put in three concentric circles with 30, 60, and 90 cm radii for 48 h, surrounding the radioactive 150[Formula: see text]mCi ([Formula: see text][Formula: see text]MBq) I-131 capsule and exposed to the cumulative doses of 88.2, 18.6, and 8.6[Formula: see text]mSv for the respective radii, accordingly. The TLD readings obtained from each group were analyzed to derive the sensitivity, coincidence, and reproducibility, then those were reorganized to draw four fish-bone-plots for the optimization. The optimal option for the TLD readout system implied the combination of A1 (a [Formula: see text]C initial temperature), B1 (a [Formula: see text]C/s heating rate), C1 (a [Formula: see text]C maximal temperature), and D2 (a 15[Formula: see text]s preheat time), which was further verified by the follow-up measurements. The dominant factors were A (initial temperature) and B (heating rate), whereas C (maximal temperature) and D (preheat time) were minor and provided negligible contributions to the system performance optimization.

Investigation of Optically Stimulated Luminescence and Signal Fading Properties of Several Materials

Optically stimulated luminescence (OSL) dosimetry involves the illumination of an irradiated sample on an appropriate material to produce a stimulated emission of light, whose intensity is indicative of the radiation dose. This technique is currently used for personnel dosimetry, environmental dosimetry, and geological dating applications. While a great deal of published research focusing on α-Al2O3:C and natural materials used for geological dating exist, relatively little is known about the OSL properties of thermoluminescent (TL) materials. This paper reports the results of an experiment conducted to characterize the OSL behavior of KBr, CaSO4:Tm, CaSO4:Dy, CaSO4:Dy+P, LiF:Mg,Cu,Na,Si, and LiF:Mg,Cu,Si. The OSL signal responses to seven excitation wavelengths from 625 nm to 455 nm for each material were measured at 12 time periods post-irradiation from 6 h to 120 d. The magnitude and fading characteristics of the OSL response of each material were then analyzed. The data demonstrated that significant OSL responses exist for CaSO4:Tm, LiF:Mg,Cu,Na,Si, and LiF:Mg,Cu,Si. In addition, it was found that the fading rates of OSL signals depend on the excitation wavelength used to elicit the signals and that these fading rates and the corresponding excitation wavelengths correlate well with the material's TL behavior. Thus, the various fading rates with respect to the excitation wavelengths could be used to obtain temporal dose information.

Highlights and pitfalls of 20 years of application of computerised glow curve analysis to thermoluminescence research and dosimetry

The technical and dosimetric aspects of computerised glow curve analysis are described in detail including a review of the current 'state-of-the-achieved' in applications to environmental and personal dosimetry, clinical dosimetry, quality control, characterisation of new materials, continuing characterisation of 'old' materials, heavy charged particle dosimetry, mixed field n-gamma dosimetry, X-ray dosimetry and other aspects of thermoluminescence dosimetry. Fearless emphasis is placed on 'pitfalls' as well as successes.