Broadband light source based on highly nonlinear non-circular core photonic crystal fiber for medical applications

We present a highly nonlinear non-circular core photonic crystal fiber (HNL-NCPCF) with all normal group velocity dispersion (GVD) to design a supercontinuum (SC) light source for optical coherence tomography (OCT) system. Nonlinear coefficient $\gamma$ is increased as large as 66 W^?1 km^?1 at $1.31\mathrm{\mu }\mathrm{m}$ by reducing the effective mode area and core is made non-circular to increase birefringence by putting the square lattice of air-holes inside the silica host. About 85 nm 10 dB spectral bandwidths for 2.5 ps input optical pulse and 140 nm 10 dB spectral bandwidths for 1.0 ps input optical pulse have been observed using the same fiber length of 200 m and input optical power of 15 W. Coherent lengths of the generated supercontinuum light sources are found $8.91\mathrm{\mu }\mathrm{m}$ for 2.5 ps input optical pulse and $5.41\mathrm{\mu }\mathrm{m}$ for 1.0 ps input optical pulse. Therefore, the highest longitudinal resolution for dental OCT at $1.31\mathrm{\mu }\mathrm{m}$ is found about $3.28\mathrm{\mu }\mathrm{m}$ for tooth enamel.     

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.     

Indentation measurements on the eardrum with automated projection moiré profilometry

Computer modeling of middle ear mechanics is an important tool to investigate its complex behavior, but correct mechanical and elastic parameters are needed to obtain realistic simulations. A possible way to determine eardrum elasticity in situ is the use of point indentation measurements. The eardrum is, however, a small fragile membrane, so a non-contacting high-resolution technique is needed to measure the shape change caused by point indentation. We have developed a projection moiré interferometer combined with an indentation actuator and a high-resolution force sensor. The apparatus applies deformations up to 1 mm with a resolution of $1\mathrm{\mu }\mathrm{m}$, while the indentation force is measured with a resolution better than 1 mN. The moiré setup delivers height data on $512\times 512$ points through phase-shifting, with a height resolution of $15\mathrm{\mu }\mathrm{m}$. Shape recordings are made on a rabbit eardrum at different indentation distances, and indentation force is recorded simultaneously.     

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.     

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 $\pm 10\%$.     

The effect of gamma-irradiation on the activation energy of bulk and track etching in CR-39 plastic track detector

Systematic studies have been made concerning the effects of gamma dose on the track registration properties of CR-39 plastics solid-state track detector (SSTD). The changes in bulk and track etch rates as well as in sensitivity due to gamma rays in the dose range of $0–{10}^3\mathrm{kGy}$ at different temperatures (338–353 K) are discussed on the basis of degradation and cross-linking mechanisms. The increase in bulk and track etch rates with gamma dose has been found while a rapid fall off in sensitivity at higher dose is also seen. From these measured values of bulk and track etch rates, the activation energies associated with them have also been calculated which show a decrease from unirradiated to ${10}^3\mathrm{kGy}$ gamma dose.     

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.     

Dynamic temperature rise of shielded MR sensors during simulated electrostatic discharge pulses of variable pulse width

The temperature rise from electrical over-stress (EOS) and electrostatic discharge (ESD) of shielded AMR sensors used for magnetic tape storage devices is studied using square wave voltage pulses with widths from 35 ns to 2 ms. A phenomenological model has been developed to describe the dynamic stripe temperature versus pulse width and power for the time range studied as well as for a wide range in sensor geometries. The temperature required to melt the stripes was determined to be $1437\pm 69{}^{\circ }\mathrm{C}$. The activation energy required to achieve a 2% increase in stripe resistance for pulses between 100 ns and 1 ms was determined to be 2.8 eV and is associated with interdiffusion of the stripe metals.     

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.     

Po and Pb concentration of cigarettes traded in Hungary and their estimated dose contribution due to smoking

It is known that tobacco leaves may contain ²¹⁰Pb and ²¹⁰Po in significant concentrations. The cumulative alpha-radiation dose due to the radioactive content of inhaled cigarette smoke and the increasing number of lung cancer cases explain the importance of the investigation. The present study investigated the activity concentrations of these two radionuclides in 29 Hungarian cigarette samples. The relation between ²¹⁰Po/²¹⁰Pb activity and nicotine/tar content of these cigarettes was also examined. ²¹⁰Po was determined by alpha spectrometry using a PIPS detector after chemical leaching and spontaneous deposition of ²¹⁰Po on a high nickel-content (25%) stainless steel disk. The ²¹⁰Pb activity was calculated from the ²¹⁰Po originated from the decay of ²¹⁰Pb after a waiting period of eight months. The ²¹⁰Po activity concentrations of the measured types of cigarettes ranged from 10.0 to 33.5 mBq/cigarette, and the activity of ²¹⁰Pb varied from 9.6 to 32.5 mBq/cigarette. The average annual committed effective dose is estimated to be $185.6\pm 70.6\mathrm{\mu }\mathrm{Sv}/\mathrm{y}$ and $58.7\pm 22.7\mathrm{\mu }\mathrm{Sv}/\mathrm{y}$ due to cigarette smoking (20 cigarettes/day) for ²¹⁰Po and ²¹⁰Pb, respectively.     

Pressure behaviour of birefringence in [(CH3)2CHNH3)]4Cd3Cl10 crystal

The studies of birefringence of [(CH₃)₂CHNH₃)]₄Cd₃Cl₁₀ single crystal were carried out in the temperature interval 240–420 K and in the hydrostatic pressure range up to 570 MPa. The shift of temperature of phase transition at T₁ to higher temperature is observed with increase of pressure with the pressure coefficient ${\mathit{dT}}_1/\mathit{dp}=0.233\mathrm{K}/\mathrm{MPa}$. The shift of phase transition at T₂ to higher temperatures with the pressure coefficient ${\mathit{dT}}_2/\mathit{dp}=0.063\mathrm{K}/\mathrm{MPa}$ is observed up to about 250 MPa. At temperature T_PCP=310 K and pressure p_PCP=310 MPa the character of continuous phase transition changes to there first order and it corresponds to the tricritical point existence. Based on the studies of the temperature and pressure dependences of birefringence of [(CH₃)₂CHNH₃)]₄Cd₃Cl₁₀ crystal, its (p,T) phase diagram was constructed and its main features were discussed.