Principal and secondary luminescence lifetime components in annealed natural quartz

Time-resolved luminescence spectra from quartz can be separated into components with distinct principal and secondary lifetimes depending on certain combinations of annealing and measurement temperature. The influence of annealing on properties of the lifetimes related to irradiation dose and temperature of measurement has been investigated in sedimentary quartz annealed at various temperatures up to $900{}^{\circ }\mathrm{C}$. Time-resolved luminescence for use in the analysis was pulse stimulated from samples at 470 nm between 20 and $200{}^{\circ }\mathrm{C}$. Luminescence lifetimes decrease with measurement temperature due to increasing thermal effect on the associated luminescence with an activation energy of thermal quenching equal to $0.68\pm 0.01\mathrm{eV}$ for the secondary lifetime but only qualitatively so for the principal lifetime component. Concerning the influence of annealing temperature, luminescence lifetimes measured at $20{}^{\circ }\mathrm{C}$ are constant at about $33\mathrm{\mu }\mathrm{s}$ for annealing temperatures up to $600{}^{\circ }\mathrm{C}$ but decrease to about $29\mathrm{\mu }\mathrm{s}$ when the annealing temperature is increased to $900{}^{\circ }\mathrm{C}$. In addition, it was found that lifetime components in samples annealed at $800{}^{\circ }\mathrm{C}$ are independent of radiation dose in the range 85–1340 Gy investigated. The dependence of lifetimes on both the annealing temperature and magnitude of radiation dose is described as being due to the increasing importance of a particular recombination centre in the luminescence emission process as a result of dynamic hole transfer between non-radiative and radiative luminescence centres.     

YbNi2: A heavy fermion ferromagnet

Measurements of the magnetization and specific heat of YbNi₂ binary alloy are reported. The DC magnetic susceptibility displays a ferromagnetic behavior with a Curie temperature T_C=10.5 K, one of the highest found in Yb compounds. Moreover, the temperature dependence of the specific heat exhibits a lambda anomaly with a peak of 5.12 J/mol K at 9.4 K. The analysis also shows an additional magnetic contribution around 32 K stemming from the crystalline electric field of a quartet at ${\Delta }_1=72\mathrm{K}$ and a doublet at ${\Delta }_2=126\mathrm{K}$, according to the splitting of the Yb³⁺ ion in cubic symmetry. From the magnetic contribution to the specific heat, a relatively high Kondo temperature $T_K=27\mathrm{K}$ is estimated. Below the magnetic transition, the specific heat shows a huge value of the electronic coefficient ${\gamma }_{\mathit{LT}}=573\mathrm{mJ}/\mathrm{mol}\mathrm{K}$, which is a signature of a heavy fermion behavior. Therefore, this alloy is a fine example of enhanced ferromagnetism and heavy fermion behavior among Yb compounds.     

Neutron induced alpha radiography

A radiography technique which makes use of $\alpha$-particles as penetrating radiation has been developed. The images were registered in the solid-state nuclear track detector CR-39 and the conditions to obtain the best radiography image were 2.2 h of irradiation and 25 min of etching in a KOH (30%) aqueous solution at $70{}^{\circ }\mathrm{C}$. For such conditions the resolution in the image was $23\mathrm{\mu }\mathrm{m}$. Some radiographs are shown and demonstrate the potential of the technique to inspect samples with thickness in the $\mathrm{\mu }\mathrm{m}$ range.     

Aspartame tablets—gamma dose response and usability for routine radiation processing dosimetry using spectrophotometry

Aspartame tablets were studied for gamma dose response, using spectrophotometric read-out method. The optimum concentration for ferrous ions was $2\times {10}^{-4}\mathrm{mol}{\mathrm{dm}}^{-3}$ and xylenol orange with $2.5\times {10}^{-1}\mathrm{mol}{\mathrm{dm}}^{-3}$ of sulphuric acid for the optimum acidity in FX solution. Wavelength of maximum absorbance is 548 nm. Post-irradiation stability is appreciable i.e. for not less than one month. Dose response is non-linear with third order polynomial fit, in the dose range of 1000–10000 Gy. This system of aspartame was further used for carrying out relative percentage dose profile measurement in Gamma Cell-220. Results obtained were inter-compared with that of a glutamine dosimeter, which showed that maximum difference between the values of aspartame and glutamine systems is within $\pm 10\%$.     

Fast intrinsic emission in Cs2CdI4 single crystal

The spectral-luminescent studies of the ${\mathrm{Cs}}_2{\mathrm{CdI}}_4$ single crystals are reported. The fast luminescence in the 3.6–2.0 eV energy range with decay time $\tau =4.6\mathrm{ns}$ was revealed in the crystal under high-energy excitation $(E_{\mathrm{exc}}>8\mathrm{eV})$ at 9 K. This luminescence is supposed to be caused by the hole transitions between subbands of the split valence band. The energy-band picture for ${\mathrm{Cs}}_2{\mathrm{CdI}}_4$ crystals was calculated as a proof of the luminescence model.     

Examining the fragmentation of 158 A GeV lead ions on copper target: Charge-changing cross sections

A stack of plastic CR-39 Track Detectors were exposed to 158 A GeV ²⁰⁷Pb ions at the CERN-SPS beam facility. The exposure of stack was performed at normal incidence with a fluence of about $1500\mathrm{ions}/{\mathrm{cm}}^2$. The total number of lead ions in each spill was about $7.8\times {10}^4$ with eight spills on each stack. For the stack with the Cu target, the lengths of etched cones on one face of the CR-39 detectors (before and after the target) were measured. Using these measurements and charge identification methodology in CR-39 track detectors, total and partial charge changing cross sections of 158 A GeV ${\mathrm{Pb}}^{82+}$ ions on Cu and CR-39 targets are determined in the charge region $63⩽Z⩽82$. The possibilities of presence and absence of odd–even effect in measured partial charge changing cross sections of 158 A GeV Pb ions for Cu and CR-39 targets are described. The charge resolution $({\sigma }_Z)$ achieved in the present experiment is $\sim 0.18\mathrm{e}$–0.21e. The analysis of discrepancies between our experimental results and other published results for the identical reaction is also presented.     

Thermoluminescence properties of copper doped zirconium oxide for UVR dosimetry

The synthesized ${\mathrm{ZrO}}_2$:Cu particles were characterized using X-ray diffraction (XRD) to determine the nanocrystallite size and crystal structure, respectively. The ${\mathrm{ZrO}}_2$:Cu powder with a crystallite size of 30–40 nm has a monoclinic structure and exhibit a thermoluminescent (TL) glow curve with two peaks centered at 130 and $180{}^{\circ }\mathrm{C}$. The TL response of ${\mathrm{ZrO}}_2$:Cu as a function of wavelength exhibited two maxima at 260 and 290 nm. The TL response of ${\mathrm{ZrO}}_2$:Cu as a function of the UV light spectral irradiance was linear in the range from 10 to $2300\mathrm{mJ}/{\mathrm{cm}}^2$. Fading and reusability of the phosphor were also studied. The results showed that ${\mathrm{ZrO}}_2$:Cu nanopowder has potential to be used as a UV dosimeter in UV radiation monitoring.     

222Rn concentrations of water in the Balaton Highland and in the southern part of Hungary,and the assessment of the resulting dose

In this study the ²²²Rn concentration of mains water in 120 settlements in Hungary (Southern Hungary, the Balaton Highland region) was measured. The average ²²²Rn concentration was 5.56 $(0–24.3)\mathrm{Bq}{\mathrm{l}}^{-1}$. On the basis of the ²²²Rn concentration of mains water inspected in the Southern Great Plain region, it can be stated that the ²²²Rn concentration of mains water here is, as an average, half of the ²²²Rn concentration of fountains in the same region. This decrease in radon probably happens during the water management and storage of mains drinking water. The ²²²Rn concentration of spring-water examined in the region of the Balaton Highland exceeds the average ²²²Rn concentration of drinking water (average $27.1\mathrm{Bq}{\mathrm{l}}^{-1}$).The radiation dose originating from the consumption of mains drinking water in case of adults does not reach the value of $0.1\mathrm{mSv}{\mathrm{year}}^{-1}$, even as a conservative assessment ($1\mathrm{l}{\mathrm{day}}^{-1}$ water consumption and ${10}^{-8}\mathrm{Sv}{\mathrm{Bq}}^{-1}$ dose conversion factor).     

Memory effect in MIS structures with amorphous silicon nanoparticles embedded in ultra thin SiOx matrix

Metal/${\mathrm{SiO}}_2$/a-Si-${\mathrm{SiO}}_x$/c-Si structures containing amorphous silicon nanoparticles (a-Si NPs) embedded in ultra thin ${\mathrm{SiO}}_x$ matrix are fabricated by thermal evaporation of ${\mathrm{SiO}}_x$ and sputtering of ${\mathrm{SiO}}_2$ layers followed by thermal annealing at $700{}^{\circ }\mathrm{C}$. A memory effect, due to charging of a-Si NPs in ${\mathrm{SiO}}_x$, is observed. The processes of NP charging and discharging are accomplished by applying pulses with alternative polarities. The observed shift of the flat band voltage of the high-frequency C–V curve caused by a voltage pulse of $-15\mathrm{V}$ having duration of 1 s is more than 3 V. In addition, the structures show good retention characteristics which make them promising for application in non-volatile memory devices.