Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment: Editorial

The polarized optical spectra of the ions Ti3+, V3+, Cr3+, Mn3+, Co3+, and Ni3+ in corundum single crystals have been studied at temperatures from 4.2° to 1200°K. A theory of the band strength based on the point‐charge model and p‐d mixing has been developed and applied to the data with results in fair agreement with experiment. The effects of temperature show that the vibrational‐electronic contribution to band strength is quite small at low temperature but may be appreciable at high temperatures. The crystal‐field parameters have been calculated as convergent lattice sums. The observed trigonal‐field parameter has the opposite sign from that calculated by the point‐charge model if the impurity ion is assumed to occupy an Al3+ ion position in the lattice, but has the same sign as calculated for an ion 0.1 A displaced along the c3 axis toward the empty octahedral site. Details of the spectra have been interpreted as showing that the surroundings of an ion are distorted in some electronic states.

Optical spectra of transition-metal ions in corundum

Optically Stimulated Luminescence (OSL) technique has emerged as a serious competitor to Thermally Stimulated Luminescence (TSL) technique in various dosimetric applications, especially after the development of crystalline alumina (Al2O3:C) doped with carbon. Since then, several attempts are being made to develop other possible materials for OSL based dosimetric applications. Efforts conducted in our laboratory in this direction have led to the development of a new phosphor, Lithium Magnesium Phosphate doped with terbium and boron (LiMgPO4:Tb,B). This phosphor is prepared by solid-state diffusion method involving conventional air furnaces with operating temperature 1000 °C and easily amenable to large scale production without compromising primary dosimetric advantages. In this work we present some of the dosimetric OSL characteristics of this phosphor. The phosphor exhibits a main TSL peak at 250 °C. The phosphor also emits OSL, when the irradiated phosphor is stimulated with 470 nm light with the OSL sensitivity 1.3 times that of commercially available Al2O3:C. Photoluminescence (PL) emission spectrum consists of sharp lines characteristics of Tb3+ emission. The OSL discs made out of this phosphor are reusable up to at least 50 cycles, the phosphor exhibits dose linearity up to 1 kGy. Minimum detectable dose is found to be 20 μGy and fading of the OSL signal is found to be about 16% in four days, after which the OSL signal stabilizes.

LiMgPO4:Tb,B – A new sensitive OSL phosphor for dosimetry

State of art: Optically stimulated luminescence dosimetry – Frontiers of future research

Retrospective and emergency dosimetry in response to radiological incidents and nuclear mass-casualty events: A review

An alternative method of preparation of dosimetric grade α-Al2O3:C by vacuum-assisted post-growth thermal impurification technique

A versatile integrated reader system for TL and OSL measurements of phosphor materials has been described for luminescence research applications. The developed integrated reader system works either in TL or OSL or TL–OSL mode. In the OSL operation, besides the conventional CW-OSL, POSL and LM-OSL modes a novel non-linear OSL (NL-OSL) method has been incorporated in the reader system. The optical stimulation unit consists of four high power LEDs fitted in four channels and optically focused on the sample. Each of the LED is capable of delivering up to 80 mW/cm2 light power at the sample position. The LEDs with peak wavelength λp ≈ 470 nm and 530 nm and Δλ ≈ 20 nm have been used for optical stimulation of the samples. A PID temperature controller has been used for generating and controlling user defined heating profiles for the TL measurements in the reader system. The reader system covers a wide dynamic dose range of 10 μGy to 103 Gy for TL/OSL measurements. The OSL grade α-Al2O3:C phosphor was used to test the reader system and investigate its impact on low dose assessment for personnel and environmental monitoring. The design concept of the reader system and the results of dose measurements are discussed.

D.R. Mishra

Papers

An alternative method of preparation of dosimetric grade α-Al2O3:C by vacuum-assisted post-growth thermal impurification technique

A versatile integrated system for thermoluminescence and optically stimulated luminescence measurements

TL and OSL studies on lithium borate single crystals doped with Cu and Ag

Optimization of CW-OSL parameters for improved dose detection threshold in Al2O3:C

Optically stimulated luminescence (OSL) and thermally assisted OSL in Eu2+ – Doped BaSO4 phosphor