A passive radon dosimeter based on the combination of a track etch detector and activated charcoal

The aim of this work is to test a combination of a Makrofol track detector with a new type of charcoal (Carboxen-564) to design a personal radon dosimeter. The intention is to use this dosimeter as a personal radon dosimeter to measure the monthly radon exposure in workplaces, especially when the occupancy is not ecactly known. The proposed combination was exposed to low and high concentrations of radon in a large range of relative humidity (RH). For the optimal layer thickness, a charcoal bed of 2.2 mm, a specific track density of 5.1 tracks cm⁻²/kBq h m⁻³ was obtained. For a monthly working exposure (170 h) at an average radon concentration of 100 Bq/m³, this means 87 tracks/cm² or 10 times the background of the Makrofol detector, with a statistical uncertainty of 15%.     

Effect of gamma irradiation on the structural,thermal and optical properties of Makrofol BL 2–4

Makrofol BL 2–4 is an extrusion film based on Makrolon polycarbonate. It comprises excellent die-cutting performance combined with high light transmission and moderate light scattering properties. It is a class of polymeric solid state nuclear track detectors which has many applications in various radiation detection fields. In the present work, Makrofol samples were irradiated using different gamma doses ranging from 10 to 350 kGy. The structural modifications in the gamma-irradiated Makrofol samples have been studied as a function of dose using different characterization techniques such as X-ray diffraction, intrinsic viscosity, Fourier transform infrared spectroscopy, thermogravimetric analysis, refractive index and color difference studies. The gamma irradiation in the dose range 20–200 kGy led to a more compact structure of Makrofol polymer, which resulted in an improvement in its thermal stability with an enhancement in its structural and optical properties.     

几种典型国产活性炭吸附各种烃类的NMR研究I、活性炭吸附汽油的1H NMR研究

本工作测量了五种国产活性炭上吸附汽油的¹H NMR参数。发现质子化学位移值与汽油解吸度,谱线半高宽与活性炭对汽油的饱和吸附容量,自旋晶格弛豫时间与活性炭表面酸性基团总量分别有紧密的联系。对此进行了讨论。     

烃在四种典型活性炭中吸附状态随温度变化的~1H NMR和~2H NMR的研究

本文观察了吸附在四种孔结构活性炭中苯,环已烷和正已烷的~1H NMR和笊代苯的~2H NMR谱线在297～195 κ温度范围内的变化。在室温下被吸附的上述各种化合物的~1H NMR及~2H NMR谱均为一条线宽不同的单峰,且随温度下降而增宽。在~2H NMR谱中发现,当以对数表示的谱线半高宽和绝对温度倒数的直线关系上出现拐点时,同时可观察到固体粉末谱线。除2~#活性炭外,最初出现固体粉末谱的温度大致相同。这暗示粉末谱是毛细管中三维类液体固化的结果。文内就所观察到的现象进行了初步讨论。     

Investigation of growth responses in saprophytic fungi to charred biomass

We present the results of a study testing the response of two saprophytic white-rot fungi species, Pleurotus pulmonarius and Coriolus versicolor, to charred biomass (charcoal) as a growth substrate. We used a combination of optical microscopy, scanning electron microscopy, elemental abundance measurements, and isotope ratio mass spectrometry (¹³C and ¹⁵N) to investigate fungal colonisation of control and incubated samples of Scots Pine (Pinus sylvestris) wood, and charcoal from the same species produced at 300 °C and 400 °C. Both species of fungi colonise the surface and interior of wood and charcoals over time periods of less than 70 days; however, distinctly different growth forms are evident between the exterior and interior of the charcoal substrate, with hyphal penetration concentrated along lines of structural weakness. Although the fungi were able to degrade and metabolise the pine wood, charcoal does not form a readily available source of fungal nutrients at least for these species under the conditions used in this study.     

Effect of fast neutron irradiation on the structural and optical properties of Makrofol DE 1-1 CC polycarbonate

Samples from sheets of the polymeric material Makrofol DE 1-1 CC have been exposed to neutrons of incident energy in the range of 0.8–19.2 MeV. The modifications induced in Makrofol samples due to neutron irradiation have been studied through different characterization techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, intrinsic viscosity, refractive index and color difference studies. Infrared spectroscopy indicated that cross-linking is the dominant mechanism in the energy range of 2.3–19.2 MeV. The cross-linking reported by FTIR spectroscopy destroyed the degree of ordering in the Makrofol samples, as revealed by the XRD technique. Also, this cross-linking led to an increase in the values of intrinsic viscosity from 0.41 to 0.68 at 28 °C, indicating an increase in the average molecular mass, associated with an increase in the refractive index. Additionally, the non-irradiated Makrofol samples showed significant color sensitivity toward neutron irradiation. The sensitivity toward neutron irradiation can be seen by the change in the blue color component of the non-irradiated Makrofol film to yellow after the samples are exposed to neutrons up to 19.2 MeV. This is accompanied by a net increase in the darkness of the samples.     

Structural and optical studies of electron beam-irradiated Makrofol nuclear track detector

The effect of electron beam irradiation on the structural and optical properties of Makrofol solid state nuclear track detector (SSNTD) was investigated. Samples from Makrofol detector were irradiated with electron beam with doses at levels between 10 and 400 kGy. Structural and optical property studies using X-ray diffraction, FTIR spectroscopy, color difference measurements and electron paramagnetic resonance were performed on non-irradiated and irradiated Makrofol samples. The transmission of these samples in the wavelength range 200–2500 nm, as well as any color changes, was studied. A characteristic absorption bands with different intensities was observed. Using the transmission data, both the tristimulus and the Commission Internationale de l’Eclairage (CIE) LAB coordinate values were calculated. In addition, the color differences between the non-irradiated sample and those irradiated with different doses were calculated. The results indicate that the Makrofol detector is a material that does not have a high resistance to degradation, and its tendency to crosslinking is much lower than that of several other SSNTDs.     

Thermoluminescence induced in Plastics above Room Temperature as a Means of Gamma Ray Dosimetry

The gamma-induced thermoluminescence (TL) in five types of plastics has been studied. The plastics used are Lexan, Makrofol, CA 80-15, LR 115 and CR-39. The result showed that the TL response for Makrofol and Lexan is linear in the range 5 …700 krad, 5 … 3000 krad, respectively. This suggests the possible use of these plastics for gamma dosimetry in the dose range 5 … 3000 krad.

Die gammastrahlen-induzierte Thermolumineszenz wurde an fünf Plastmaterialien untersucht, und zwar an Lexan, Makrofol, CA 80-15, LR 115 und CR-39. Die Ergebnisse zeigten, daβ die Thermolumineszenz-Reaktion für Makrofol und Lexan in Bereich 5 … 700 krad bzw. 5 … 3000 krad war. Das ermöglicht die Verwendung dieser Plastematerialien zur Gamma-Dosimetrie im Dosisbereich von 5 … 3000 krad.     

Gamma induced changes in the structural and optical properties of Makrofol LS 1–1 polycarbonate

ABSTRACT

Samples from sheets of the polymeric material Makrofol LS 1–1 have been exposed to gamma radiation in the dose range 10–250?kGy. The modifications induced in Makrofol samples due to gamma irradiation have been studied through different characterization techniques such as intrinsic viscosity as a measure of the average molecular mass, Fourier Transform Infrared spectroscopy FTIR, refractive index and color difference studies. The results indicate that the crosslinking dominates at the dose range 50–250?kGy. The crosslinking reported by viscosity measurements is supported by the trend of the function groups present in the sample with the gamma dose. Also, the increase in intrinsic viscosity indicating an increase in the average molecular mass was associated with an increase in the refractive index. Additionally, the non-irradiated Makrofol samples showed significant color sensitivity towards gamma irradiation. The color intensity ΔE, which is the color difference between the non-irradiated sample and those irradiated with different gamma doses, increased (0–5.56) with increasing the dose up to 250?kGy, convoyed by an increase in the red and yellow color components.     

The reactions of NO with diesel soot, fullerene, carbon nanotubes and activated carbons doped with transition metals

This work investigates the reactions of NO with eight different types of carbon particles: activated pinewood charcoal, activated charcoals doped with iron, nickel, copper or platinum nitrates, fullerene, carbon nanotubes and soot produced from a heavy duty diesel engine. For this mixtures of NO and argon were passed through a fixed bed of carbonaceous particles mixed with quartz sand, held at a temperature between 25 and 850 °C. The concentrations of CO, CO₂, NO, NO₂ and N₂O in the off-gases were measured; the concentration of N₂ was inferred by atomic balance. The balance on atomic oxygen closed well for all the materials studied. The results are discussed in terms of an elementary reaction mechanism; estimates are made of apparent activation energies for the overall reactions forming CO and CO₂.     

Permeability of oxygen through polycarbonate in water

The permeability of oxygen in water through polycarbonate is observed for thin Makrofol KG and Polyethylenterephthalat (PETP) foils of different thicknesses.

For each thickness the oxygen permeability through the polymer foils has been measured for unirradiated and with a high fluence irradiated foils. It was found that the permeability of oxygen through irradiated Makrofol KG foils is up to a factor of two higher than unirradiated foils.

The foils were irradiated with ⁷⁹Au ions at the energy of 11.65 MeV/u at GSI Darmstadt, Germany.     

Stopping power of 1.0–2.6 MEV protons in Mylar, Makrofol and cellulose nitrate foils

Stopping powers of 1.0 – 2.6 MeV protons in Mylar, Makrofol and Cellulose nitrate were measured. The results have been compared with scanty experimetnal data in the literature and with calculated values obtained by using the TRIM 92 computer code. These values agree well with each other within uncertainties. In the case of Mylar and LR 115, maximum deviations of 9.5% and 4.5% from the semi-emperical curves were observed. In the case of Makrofol foils, a maximum deviation of 3% was found. Considering the accuracy of theories this discrepancy is not that significant.     

Thermal,electrical and optical properties of proton-irradiated Makrofol DE 7-2 nuclear track detector

Samples from sheets of the polymeric material Makrofol DE 7-2 have been exposed to 1 MeV protons of fluences in the range 2.5×10¹³–5×10¹⁵ p/cm². The resultant effect of proton irradiation on the thermal properties of Makrofol has been investigated using thermogravimetric analysis and differential thermal analysis (DTA). The onset temperature of decomposition T _o and the activation energy of thermal decomposition E _a were calculated, and the results indicated that the Makrofol detector decomposes in one weight loss stage. Also, the proton irradiation in the fluence range 7.5×10¹³–5×10¹⁵ p/cm² led to a more compact structure of Makrofol polymer, which resulted in an improvement in its thermal stability with an increase in the activation energy of thermal decomposition. The variation of transition temperatures with proton fluence has been determined using DTA. The Makrofol thermograms were characterized by the appearance of an endothermic peak due to the melting of the crystalline phase. The melting temperature of the polymer, T _m, was investigated to probe the crystalline domains of the polymer. At a fluence range of 7.5×10¹³–5×10¹⁵ p/cm², the defect generated destroys the crystalline structure, thus reducing the melting temperature. In addition, the V–I characteristics of the polymer samples were investigated. The electrical conductivity was decreased with the increasing proton fluence up to 5×10¹⁵ p/cm². Further, the refractive index, transmission of the samples and any color changes were studied. The color intensity Δ E was greatly increased with the increasing proton fluence and was accompanied by a significant increase in the red and yellow color components.     

Fundamentals of optical amplifiers

The minimum noise figure of linear phase-insensitive amplifiers is 3 dB, according to the constraint of the uncertainty principle. Laser amplifiers, parametric amplifiers and Raman amplifiers obey the general quantum limit in an ideal case. A degenerate parametric amplifier is a phase-sensitive linear amplifier, and thus is a noiseless amplifier with a noise figure of 0 dB. The noise figure degradation in a practical amplifier and the signal-to-noise ratio design of an optical amplifier system are presented. Several other amplifier characteristics, such as signal gain, frequency bandwidth and saturation output power, are also discussed.     

Surface and Bulk Structure Characterization of Proton (3 MeV) Irradiated Polycarbonate

Polycarbonate (Makrofol‐N) thin films were irradiated with protons (3 MeV) under vacuum at room temperature with the fluence ranging from 1×10¹⁴ to 1×10¹⁵ protons cm^?2. The change in surface morphology, optical properties, degradation of the functional groups, and crystallinity of the proton‐irradiated polymers were investigated with atomic force microscopy (AFM), UV‐VIS, and Fourier‐transform infrared (FTIR) spectroscopy, and X‐ray diffraction (XRD) techniques, respectively. AFM shows that the root mean square (RMS) roughness of the irradiated polycarbonate surface increases with the increment of ion fluence. The UV‐VIS analysis revealed that in Makrofol‐N the optical band gap decreased by 30% at highest fluence of 1×10¹⁵ protons cm^?2. The band gap can be correlated to the number of carbon atoms, M, in a cluster with a modified Robertson's equation. The cluster size in the proton‐irradiated Makrofol‐N increased from 112 to 129 atoms with the increase of fluence from 1×10¹⁴ to 1×10¹⁵ protons cm^?2. FTIR spectra of proton (3 MeV) irradiated Makrofol‐N showed a strong decrease of almost all absorption bands at about 1× 10¹⁴ protons cm^?2. However, beyond a higher critical dose an increase in intensity of almost all characteristic bands was noticed. The appearance of a new peak at 3,500 cm^?1 (‐OH groups) was observed at the higher fluences in the FTIR spectra of proton‐irradiated polycarbonate. XRD measurements showed an increase of full width at half maximum (FWHM) and the average intermolecular spacing of the main peak, which may be due to the increase of chain scission and the introduction of ‐OH groups in the proton irradiated polycarbonate.     

Opto-chemical response of Makrofol-KG to swift heavy ion irradiation

In the present study, the effects of swift heavy ion beam irradiation on the structural, chemical and optical properties of Makrofol solid-state nuclear track detector (SSNTD) were investigated. Makrofol-KG films of 40 μm thickness were irradiated with oxygen beam (O^8 +) with fluences ranging between 10¹⁰ ion/cm² and 10¹² ion/cm². Structural, chemical and optical properties were investigated using X-ray diffraction, FTIR spectroscopy and UV–visible spectroscopy methods. It is observed that the direct and indirect band gaps of Makrofol-KG decrease after the irradiation. The XRD study shows that the crystalline size in the films decreases at higher fluences. The intensity plots of FTIR measurements indicate the degradation of Makrofol at higher fluences. Roughness of the surface increases at higher fluence.     

Surface modification of Makrofol-DE induced by α-particles

In the present work, Makrofol DE samples were irradiated with different doses of alpha particles. The optical and mechanical modifications in the alpha-irradiated Makrofol samples as a function of alpha irradiation time have been investigated. Different characterization techniques, UV–vis spectroscopy, photoluminescence spectroscopy and Vickers micro hardness tester have been used. UV–vis spectra of bombarded samples reveal that the optical absorption increases with increasing the irradiation time. The direct and indirect optical band gap was found to decrease from 3.4 and 2.81?eV for pristine sample to 3.1 and 2.35?eV for that bombarded with alpha particles at the highest irradiation time (15?h), respectively. The number of carbon atoms per conjugated length (N) and the number of carbon atoms per cluster (M) have been estimated. An increase in both N and M with increasing the irradiation time was noticed. A remarkable decrease in PL intensity with increasing the alpha irradiation time was observed. This decrease is attributed to ion beam-induced change in molecular structure and/or defects in the modified layer. The surface hardness for unmodified and modified polymeric material has been studied.     

带自检显示功能的中频放大器的研制

文中介绍带自检显示功能的中频放大器的设计思路和测试结果.该组件具有技术性能稳定、可靠、自检显示功能反应灵敏、直观等特点.     

Qualitative analysis of ion tracks in Makrofol E

The track radius calculation reported by Tombrello was applied to experimental data of tracks from several ions and energies in Makrofol E. Qualitative analysis of ion tracks in this material is discussed. These data were also compared with values calculated using the Continuum Distorted Wave-Eikonal Initial State approximation     

A High-Gain, 28GHz, 200kW Gyroklystron Amplifier

A design study of a high efficiency/gain gyroklystron amplifier is performed to demonstrate amplified radiation power of 200kW operating at 28GHz. A key design feature of the present gyroklystron amplifier is that the amplifier is designed to be high gain so that it can be saturated by a low power solid state power amplifier. A non-linear, time-dependent, large signal numerical code is used to predict tube performance. Simulations predict that a stable amplifier radiation power of 214kW is produced with a saturated gain of 54dB, an electronic efficiency of 37%, and a frequency bandwidth of 0.3% from a five-cavity gyroklystron amplifier. The amplifier gain is found to be very sensitive to a beam velocity spread.