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Indoor radon level measurements were carried out in 42 dwellings in Bethlehem, Palestine, using CR-39 solid state nuclear track detectors. The measurements were performed during winter and spring seasons of the year 2010, for a period ranging from 97-118 d using a total of 100 detectors. The detectors were installed in living rooms, bedrooms, kitchens, and storage areas of 39 houses, as well as in three schools, selected randomly in the surveyed area. The results of indoor radon levels and the annual effective dose in houses were found to vary from 26 - 611 Bq m(-3) and 0.65 - 14.1 m Sv y(-1), with average values of 117.0 Bq m(-3) and 2.95 m Sv y(-1), respectively. The mean values of radon concentration levels in bedrooms, kitchens, living rooms, basements, and storage areas are, respectively, 106.5, 113.1, 101.5, and 164.2 Bq m(-3). The corresponding mean values of annual effective dose for the bedrooms, kitchens, living rooms, basements, and storage areas are 2.66, 2.83, 2.54, 14.1 m Sv y(-1), respectively. In schools, the radon levels are found to vary from 31 - 400 Bq m(-3) with an average value of 125.1 Bq m(-3). The average annual effective dose in schools is found to be 3.12 mSv y(-1). This value is higher than the assigned international value. In general, the results show that radon concentration levels in 83% of the investigated dwellings are lower than the indoor radon action level of 150 Bq m(-3) for the United States.

In this study we report on the measurements of the Verdet constant for olive and other vegetable oils. Study of samples stored for different periods at different storage conditions showed that each olive oil sample has a Verdet constant value depending on: production year, history of the sample (i.e. storage conditions) and geographical region. Photo and auto oxidations are found to have reverse effects on the value of the measured Verdet constant, on the one hand, photo-oxidation tends to decrease the Verdet constant, but on the other hand auto-oxidation tends to increase it. It is known that oils stored in room light had significantly lower tocopherol, carotenoid, and chlorophyll contents than did the same oils kept in the dark. For other vegetable oil samples, each vegetable oil was found to have a distinct Verdet constant value. Thus it is possible to differentiate vegetable oils making use of their respective Verdet constants. Preliminary results indicated the possibility to detect olive oil adulteration using the Faraday Effect, i.e. the effect could be suggested as a food authentication technique if calibration curves and standard Verdet constants values could be prepared for comparison with those of samples under investigation.

A systematic investigation of the ac susceptibility of polycrystalline RuSr 2 GdCu 2 O 8 was carried out with different field amplitudes and various frequencies. The study covered a wide range of frequencies between 0.020 to 12.5 kHz and temperatures from 7 to 50 K. The first derivative of susceptibility curves indicated the presence of a superconducting intragranular transition coupled by weak links distribution of intergranular transitions. The intragranular-, χg, and intergranular-, χi contribution to susceptibility were estimated and found to be consistent with the prediction of the critical state model. Variation of the peak temperature of the imaginary part with frequency was employed to determine the vortex activation energy. The derived low activation energy values provide clear evidence of the thermally activated flux creep process in the superconducting state. Qualitative analysis of the χ′′ - χ′ parametric relation was carried out.

The ac susceptibility data was employed to extract the temperature dependence of the critical current density, Jc(T), as well as the variation of flux-creep exponent n(T,Hac) with temperature and ac field amplitude in bulk samples of polycrystalline magnetic superconductor RuSr2GdCu2O8 (Ru-1212). The critical state models and the collective flux-creep approximation model were successfully accounted to describe such behavior below the transition temperature. The calculated values of n(T,H) are well fitted to a power law of the following form: n(T,H)=n0(H)T−s(H), where s is field dependent exponent whose values varied from −2.4, −1.01 for field amplitudes ranging from 0.5 G and 3.8 G. The power law describing the frequency dependence of χ′ is found to be consistent with the results of the current-dependent effective activation energy of the form U(J)=U0ln (Jc/J).

Measurements of the complex ac susceptibility components were employed to extract inter- and intragrain superconductive transition temperatures as well as the average transition temperature of RuSr 2 GdCu 2 O 8 polycrystalline superconductor. The intra- and intergranular components of the granular susceptibility components were also estimated. It was found that both the intra- and intergranular transition temperatures increase by increasing field frequencies and decrease by increasing the field amplitudes. This might be an indication that the grains of RuSr 2 GdCu 2 O 8 behave differently from a homogeneous bulk superconductor. The nature of d χ ′/d T curves indicated the presence of a superconducting transition between grains, coupled by weak links with a distribution of critical temperatures, and the superconducting transition within the grains. The two transitions observed are linked to the typical intra- and intergrain transitions of a granular superconductor. The weak coupling between grains might be modeled in terms of Josephson-junction arrays.

The applicability of theoretical models for the ac susceptibility measurements of polycrystalline RuSr2GdCu2O8 superconductor has been examined within the temperature range between 8–50 K, ac magnetic field 0.5–25 G, and frequency 20–12500 Hz. In general, a reasonable qualitative agreement between theory and experiment was attained. An evident and detectable asymmetry was observed within the Cole–Cole polar plots with a peak enhancement for both theoretical and experimental data. The modified critical state models are found to generate much better explanation of the ac susceptibility measured data than Bean’s model. For fields above 20 G, the results are agreed roughly with the Bean critical state model, while below 20 G, the Kim–Anderson model is more suitable to account of the magnetic performance. The temperature and field amplitude dependencies of the flux-creep exponent, n, were extracted from the real part of susceptibility, χ′, dependence on frequency. The flux-creep exponent was found to decrease with both temperature and ac field amplitude in accordance to a power-law of the form: n(T,H)=n 0(H)T −s(H). Such dependence might be an indication of a crossover to flux-creep bundles regime.

In this study, we report on the indoor radon concentration levels in a number of locations scattered in the Hebron province, Palestine. The measurements were performed during the winter season of the year 1999/2000 using the CR-39 detectors. The radon concentration levels were found to vary from 23 to 580 Bq m(-3). The arithmetic average of the obtained radon concentration levels was found to be 91 Bq m(-3). It was found that most of the radon concentration levels in houses and school rooms are below the low reference levels limits. Most of the high-radon concentration levels were found in unpainted storage rooms.

A systematic investigation of the electrical parameters of Bi2Sr2CaCu2Ox thick tapes in the vortex and superconducting states was carried out. The tapes were grown on either single crystals of MgO or silver foil under different heat treatment conditions. The temperature dependence of the electrical resistivity in the vortex state was found to follow an Arrhenius-like relation of the form ρ(T, H) = ρ0exp(−U0(H)/kBT). The activation energy, U0, showed a strong dependence on the applied field and the growth conditions of the sample. Its average values were between 10 and 300 meV. The current–voltage characteristics (I–V) for various samples of different growth conditions and applied fields were also investigated. The study revealed a current dependence on the applied voltage was found to fit a power law of the form: I ∼ Vα, where α is an exponent whose values are strongly dependent on growth conditions. At constant voltages, the current was found to decrease exponentially with the applied magnetic field according to I(B) ∼ exp(−cB/B∗), where c is a constant depending on growth conditions and B∗ is a characteristic field of the sample. This exponential decay of the current is attributed to strong flux pinning centers. The dependence of the current on field and voltage could be written as I ∼ Vαexp(−cB/B∗). Furthermore, the heat treatment conditions and annealing atmosphere had strong influence on the I–V characteristic of the sample.

In this study, we report on the current–voltage characteristics of a bridge cut out from YBCO single crystal. The de-pinning critical current and the flux flow resistance dependencies on temperature have been investigated for samples placed in a zero magnetic field and in a magnetic field of 1.5 T applied parallel to the c-axis of the crystal (H∥c). The overall observed general behavior is similar to the flux creep and flux flow behaviors that have been observed in “cold” superconductors. Down to 78 K, the glass-like behavior of used crystals is absent. Between the irreversible and the shoulder temperatures, the existence of spatially inhomogeneous vortex phase is very plausible: solid phase––in the vicinity of twins and liquid––far from twin planes. Direct measurements of the shear modulus and plastic flow of vortex lattice were performed and included.

Magnetization measurements of laser-ablated Al-doped YBa2Cu3O7 superconducting thin films in fields up to 12 T were performed for different dopant concentrations. The critical current density Jc was strongly dependent on both applied magnetic field and Al concentration. However, in all samples with different concentrations, Jc was found to scale very well to a formula Jc=Jc(0)[1−T/Tc]n. In addition, the pinning force ( F ⇀ p= J ⇀ cx H ⇀ ) extracted from magnetization loops scaled well to a relation of the form Fp~hp(1−h)q, where h is the reduced field and p and q are scaling parameters [p∼0.70 and q∼1.70]. This type of scaling can be easily discussed in terms of flux line shear model. The extracted scaling law was not affected greatly by thermal fluctuations or vortex phase transition near Tc, suggesting a small effect of thermal fluctuations on superconducting properties in the vortex state.

Systematic magnetization measurements were performed on laser ablated Al-doped YBCO thin films in the temperature range from 4 to 80 K and fields up to 12 T. The magnetization as a function of logarithmic time in the temperature range from 10 to 80 K generally showed a linear behavior. This type of performance allows us to determine the temperature and field dependence of the apparent pinning potential on the basis of the Kim–Anderson model for thermal activation of flux motion. The relaxation rate values are calculated from the time-dependent magnetization curves. The relaxation rate dependence on temperature, magnetic field, and doping concentrations has been investigated for different Al concentrations and applied fields up to 5 T. A strong nonlinearity was observed for the relaxation rate dependence on both temperature and applied fields. The apparent pinning potential values, Uo, are estimated from the dependence of relaxation rates temperature curves using Uo=kBT/S expression. The dependence of Uo on both temperature and fields is elaborated and discussed in detail. The pinning potential, Uo, increases with temperature up to 40 K, however, above 40 K, a rapid decrease of Uo has been observed. Besides, a noticeable decrease in Uo as the applied field increases up to 0.1 T for temperatures below 40 K, and it is almost field independent for temperatures exceeding 40 K.

Systematic measurements of the AC magnetic susceptibility of polycrystalline RuSr 2 GdCu 2 O 8 (Ru-1212) samples are reported for various frequencies and magnetic field amplitudes. The study covered frequency range from 22 Hz to 12.5 kHz and field amplitudes between 0.5 and 25 G. The variation of the real part, χ ′ , as well as, the imaginary part, χ ″ , of AC susceptibility for Ru-1212 samples has been investigated as a function of temperature for different magnetic field amplitudes and frequencies. A qualitative analysis of AC susceptibility response for Ru-1212 superconductor near the transition temperature, T c , is presented. A single distinct peak in the imaginary part of AC magnetic susceptibility versus temperature is typically observed upon entering the superconducting state. The dependence of peak temperature, T p , of the χ ″ on magnetic field amplitude and frequency has been also investigated. It was found that the peak temperature, T p , is shifted to higher temperatures by increasing frequency and to lower temperatures by increasing magnetic fields.

In this study, the measured curves of AC susceptibility (ACS) components, χ′(T) and χ″(T), of polycrystalline RuSr2GdCu2O8 (Ru-1212) superconductor were scaled onto a single curve using the peak temperature of its imaginary part (T p) as the scaling parameter for various AC field amplitudes from 0.5 to 24 G. The dependence of the AC magnetic field amplitude on T p is scaled as: H ac ∼ (1−T p/T c)2.25. Similarly, the current density J c, extracted from the AC field amplitude is also scaled as: J c ∼ (1 − T p/T c)2.25. The dependencies of T p on frequency and AC field amplitude are also investigated and the time parameter t 0 of the order of 10−8 s is estimated from the dependence of T p on frequency. The dependencies of activation energy on temperature, T, and the field amplitude, H ac, are obtained from the Arrhenius-like semilog plot of frequency (ν) and T p. Such dependencies on temperature and field amplitude can be described by a scaling law of the form: U(H ac,T) = U 0[1 − T/T p]H ac −0.17.

Using a simple kinetic model we study whether a pion condensate can be formed during the hadronization of the quark-gluon plasma in ultrarelativistic heavy-ion collisions. If hadronization proceeds fast and the pion effective mass is close to zero, some pions condense into the zero momentum state. On the other hand, for the pion effective mass equal to the vacuum one or larger no onset of the Bose-Einstein condensation is observed. The constraints on the condensation process coming from the requirement of the entropy increase are discussed in detail., Comment: Raw PS file replaced by uuencoded one.

This study presents the seasonal variations of indoor radon levels in dwellings located in the Ramallah province and East Jerusalem suburbs, Palestine. The measurements were performed during the summer and winter of the year 2006/2007 using CR-39 solid-state-nuclear-track detectors. The total number of investigated buildings is 75 in summer and 81 in winter. A total number of 142 dosemeters are installed in dwellings for each season for a period of almost 100 d. The radon concentration levels in summer varied from 43 to 192 Bq m(-3) for buildings in the Ramallah province and from 30 to 655 Bq m(-3) for East Jerusalem suburbs. In winter, the radon concentration levels are found to vary from 38 to 375 Bq m(-3) in the Ramallah buildings and from 35 to 984 Bq m(-3) in East Jerusalem suburbs. The obtained results for radon concentration levels in most places are found to be within the accepted international levels.

The Boltzmann collision term with the Uehling-Uhlenbeck-Nordheim modification for fermion statistics is computed in nuclear matter. The initial distribution function is in momentum space either two Fermi spheres separated by a relative momentum as in a collision between two heavy ions or some other specified deformation. Relaxation times for the equilibration is obtained as a function of density and final temperature of the equilibrated system. The mode dependence of the relaxation times is calculated by expanding the angular dependence of the distribution in spherical harmonics. Transport coefficients for viscosity and thermal conductivity are also calculated as well as their temperature and density dependences.

The dielectric function of some phthalocyanine compounds (ZnPc, H2Pc, CuPc, and FePc) were inves- tigated by analyzing the measured capacitance and loss tangent data. The real part of the dielectric constant, "1, varies strongly with frequency and temperature. The frequency dependence was expressed as: "1 D A! n , where the index, n, assumes negative values (n < 0). In addition, the imaginary part of the dielectric constant, "2, is also frequency and temperature dependent. Data analysis confirmed that "2 D B! m with values of m less than zero. At low frequencies and all temperatures, a strong dependence is observed, while at higher frequencies, a moderate dependence is obvious especially for the Au-electrode sample. Qualitatively, the type of electrode material had little effect on the behavior of the dielectric constant but did affect its value. Analysis of the AC conductivity dependence on frequency at different temperatures indicated that the correlated barrier hopping (CBH) model is the most suitable mechanism for the AC conduction behavior. Maximum barrier height, W , has been estimated for ZnPc with different electrode materials (Au and Al), and had values between 0.10 and 0.9 eV. For both electrode types, the maximum barrier height has strong frequency dependence at high frequency and low temperatures. The relaxation time, , for ZnPc and FePc films increases with decreasing frequency. The activation energy was derived from the slopes of versus 1/T curves. At low temperatures, an activation energy value of about 0.01 eV and 0.04 eV was estimated for ZnPc and FePc, respectively. The low values of activation energy suggest that the hopping of charge carriers between localized states is the dominant mechanism.