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Photoluminescence and novel thermoluminescence dosimetric properties of NaYF4:Ln3+ (Ln = Tb, Eu and Dy).

Erosion studies of polyimide, exposed to high energy electrons and atomic oxygen, is necessary in view of its application in space vehicles. Here we present the erosion studies and degradation characteristics of polyimide after its sequential exposure to 1 MeV pulsed electron beam from Microtron accelerator and ~12 eV oxygen ions from a plasma reactor in the laboratory. The fluence of electrons was varied from 5 × 1014 to 2.0 × 1015 electrons/cm2 and that of oxygen ions from ~5 × 1016 to 2 × 1017 ions cm−2. The post irradiated and virgin polyimide samples were characterized by gravimetric analysis and contact-angle measurements. The morphological and spectroscopic information were obtained with Scanning Electron Microscopy, Fourier Transform Infra-Red spectroscopy, and photo-absorption spectroscopy. The erosion yield, surface wettability and the surface roughness were seen to be much higher when exposed to both the radiations as compared to either of them, reflecting the synergetic effects.

The cross sections of 89Y(n, 3n)87m,87gY and 209Bi(n, 4n)206Bi reactions at a neutron energy of 30 MeV are measured by making use of neutron beams of continuous energy spectra and a subtraction method. By impinging proton beams of 30 and 35 MeV to a thick beryllium target, neutron beams of continuous and broad energy spectra are produced and are guided to Y and Bi sample targets. The difference between the two neutron spectra generated by two neighboring proton energies is found to be peaked in a narrow energy range and thus can be regarded as quasi-monoenergetic, which can be used to extract (n, xn) cross sections. The uncertainty in the neutron fluence is reduced by analyzing the activities of aluminum and niobium reference samples placed on top of the Y and Bi samples. The use of a subtraction method by employing neutron beams of continuous energy spectra gives us the 89Y(n, 3n)87m,87gY and 209Bi(n, 4n)206Bi cross sections in fair agreement with the existing experimental data and nuclear data libraries.

We report the irradiation effects on rf reactive magnetron sputter deposited TiO2/Al2O3 hetero-structured thin films. These films are irradiated with 6 MeV electron beams by maintaining the dose ra...

Samples like p-type silicon and metallic glasses containing boron, were taken and used as target to induce the reaction 10B (n,α)7Li. In addition, samples containing lithium were also irradiated with thermal neutrons to induce 6Li (n,α)3H reaction. The alpha particles emitted through the reactions lose energy while traversing through the sample from point of emission to the surface and can be detected using a surface barrier detector. The out coming alpha particle spectrum can give the depth profile of boron or lithium atoms in the sample, if the energy loss of alpha particle within the matrix is known.

Polyimide (PI) films were irradiated by 120 MeV iron (Fe+9) ions and variations in its optical, chemical, surface morphology and anti-bacterial properties were studied. UV-Visible spectroscopic res...

The hexagonal phase β-NaGdF4:x% Tb3+ (x = 0 to 5%) phosphor crystals with uniform morphology and considerable monodispersity were synthesized via a tri-sodium citrate-assisted hydrothermal route. The photoluminescence studies showed the strong emission lines corresponding to 5D4 → 7FJ (J = 6, 5, 4, 3) transitions with a prominent 5D4 → 7F5 green emission transition at 540 nm. The as-prepared samples were annealed at different temperatures (200–800 °C), and the effect of thermal treatment on their structural, morphological, surface, photoluminescence and thermoluminescence properties were studied. A comparative study of pristine and annealed samples revealed phase alteration to the mixed (i.e. cubic and hexagonal) phase along with morphology transformation at higher annealing temperatures. The photoluminescence emission intensity was remarkably enhanced (∼9 times) at 700 °C owing to the reduction in non-radiative processes from the surface and the volatilization of luminescence quenching (–OH) groups, which were corroborated by surface FTIR studies. The systematic study of the optimum concentrations of impurities and thermal treatment were studied to achieve high thermoluminescence (TL) efficiency. The best TL dosimetric glow curve was obtained for NaGdF4:3% Tb3+ annealed at 700 °C, which peaked at 230 °C, signifying deeper traps. The NaGdF4:3% Tb3+ phosphor showed a linear response over a very wide range of gamma doses from 100 Gy to 20 kGy, revealing that the NaGdF4:Tb3+ phosphor was quite well suited for high gamma dose measurements and their respective applications. Fading and reproducibility studies showed low fading and excellent reproducibility characteristics. The Tm–Tstop technique in combination with the Initial Rise Method (IRM) was used to identify the number of overlapped TL glow peaks and trap level analysis. The kinetic parameters, such as activation energy (E), frequency factor (s), and order of kinetics (b), were estimated by the Glow Curve Deconvolution (GCD) method. The Figure of Merit (FOM) value was found to be 2.2%. The trapping parameters resulting from the experimental Tm–Tstop study and theoretical GCD match closely and are in good agreement with each other. Thus, along with high luminescence efficiency, the newly explored strong thermoluminescence properties of NaGdF4:Tb3+ make them potential phosphor materials and could provide new avenues into other applications in radiation dosimetry such as agriculture/food sciences, archeological sciences, space dosimetry, etc.

Polyimide (PI, PMDA-ODA, C22H11N2O5, Kapton-H), is a class of polymer, extensively used in microelectronics and space technology, due to its exceptional mechanical, dielectric, and chemical properties. In space, PI heat shield experiences a harsh environment of energetic electrons, ultra-violet radiation, and atomic oxygen, causing degradation and erosion. Radiation-assisted physicochemical surface modulations in PI, in view of understanding and reducing the degradation in laboratory-based systems, are discussed in the chapter. Strategies for the design and development of 2D, flat, and flexible electromechanical devices by swift heavy ion induced bulk modifications in PI are also described. Fabrication of a couple of such devices, including their performance analysis, is presented.

Silver nanoparticles were successfully synthesized by 6 MeV electron irradiation process in aqueous solution containing poly(vinyl alcohol) to produce a composite. The resulting composite characterized by UV–Vis spectroscopy, X-Ray diffraction and transmission electron microscopy reveals nucleation and growth of silver nanoparticles with an average diameter of 12 nm and having surface plasmon resonance peak at 395 nm. The nano-silver/poly(vinyl alcohol) composite was then coated on p-type conducting silicon by drop casting method and the ability of the resulting device as a optical sensor was investigated. The novelty of prepared sensor device is its reversible and rapid response, which is proportional to incident light intensity within the range of 20–80 mW/cm2 over a wide optical wavelength region. The Schottky junction showed good rectification and photo-response characteristics within the applied voltage. The photo-current developed was found to increase with increasing incident light intensity. The novelty of the device is its photo-response, which was found to be in good agreement with the transport of optically (surface plasmon) generated charge carriers though charge transfer complexes formed in composite.

Powder sample of Cubic phase BaF2:Ce phosphor was synthesized by chemical co-precipitation method and annealed at 500 °C for 2 h. The synthesized powder of BaF2:Ce phosphor was characterized by XRD, which shows FCC structure with 30 nm crystallite size. TEM images show a cubic structure and FTIR contains the existence of F-Ba-F, C-H, C˭C, and O-H bonds. Glow curve of the Thermoluminescence contains two major peaks, one at 175 °C and another at 275 °C. The intensity of the major dosimetric peak (175 °C) observed to be increased linearly from 1 Gy to 3 kGy for the doses of 60Co gamma rays and then saturates. Overall, the new BaF2:Ce phosphor shows good material properties for the high gamma dose measurement applications.

Silicon ions, of energy 150 MeV and fluence ∼1012 ions/cm2, were used to register latent tracks in 40 µm thick polyimide samples. Different sizes of tracks were obtained by etching the ion irradiat...

Poly-dimethylsiloxane (PDMS) is known to provide ubiquitous platform for micro Total Analysis System (μ-TAS) and Lab-On-Chip (LOC) development. Although soft lithography is extensively accepted as a fabrication tool for PDMS, direct write lithography techniques also have drawn considerable attention due to some of its own advantages. Even though e-beam lithography in PDMS is reported previously, the present manuscript reveals establishment of doped PDMS as a positive tone, self-standing and self-developable resist platform for 6 MeV e-beam lithography in normal ambience. For microstructures fabrication, undoped PDMS and photoinitiator doped PDMS as resist materials are processed using contact printing mode lithography with use of the mask containing array of circles on it. Effects of lithography processing parameters on various resist compositions are investigated to achieve improved geometry and surface profile of the fabricated microstructures. Lithographic investigations on the undoped PDMS shows microstructures with sloppy sidewalls depicting inverted bell shape geometry and cone like nanostructures inside it deteriorating surface profile. Whereas in case of doped PDMS cone like nanostructures are completely vanished and inverted bell shape geometry transformed into clean and uniform concave shape profile, which is then identified as finely produced micro lens array (MLA). The lensing quality of MLA is tested and the images produced by MLA are clear and uniform in size and shape, which confirms formation of microlenses accountable as an optical component in many applications. The observed concave geometry of fabricated MLA is resulted out of energy gradient generated during the e-beam exposure of resist stamp through mask. Similarly, an electrostatic interaction is recognized as governing mechanism for e-beam interaction with PDMS. Photoinitiator plays crucial role in energy absorption and distribution which resulted in seamless control over formation of lateral and vertical dimensions thereby giving optical smoothness to surface of MLA. The optimized lithographic parameters and composition of the resist platform, can be used to fabricated MLA with fine imaging quality and desired location of focal plane according to demand of application.

Polycarbonate (PC) films were irradiated by 100 MeV gold (Au 7+ ) ions and characterized to study changes in its optical, chemical, surface morphology and thermal properties. UV–Visible spectroscopic results revealed the decrease in the optical band gap of PC after ion irradiation due to chain scission mainly at the carbonyl group which is corroborated by Fourier Transform Infrared spectroscopic results. X-ray diffractogram study showed decrease in crystallinity of PC film after irradiation. Scanning electron microscopic results showed the micropores formation in PC which results in surface roughening. Differential scanning calorimetric results revealed decrease in glass transition temperature indicating the decrease in molecular weight of PC corroborated by rheometric studies. PC films irradiated by 100 MeV Au 7+ ions showed increased anti-biofilm activity against the human pathogen, Salmonella typhi ( S. typhi ). Morphology of S. typhi was changed due to stress of Au 7+ irradiated PC. Cells length was increased with increasing fluences. The average cell length, cell volume and surface area was increased significantly (P 7+ irradiated PC.

The reaction cross sections of 55Mn(n, γ)56Mn and 65Cu(n, γ)66Cu have been measured over a neutron energy range from 1 keV to 4 MeV. The racetrack microtron accelerator-based neutron source was used for the cross-section measurement, which generates a neutron spectrum from 1 keV to 4 MeV. Moreover, the cross-sections of the nuclear reaction were calculated using TALYS-1.2 and EMPIRE nuclear codes. It has been observed that the experimental cross sections of manganese and copper are 8.5 mb and 4.5 mb, respectively, and they are quite close to the TALYS, EMPIRE, and evaluated data of ENDF/B-VII.0, ENDF/B-VII.1, JEFF-3.1.2, and EXFOR. For (n, γ) reactions studied in the present work, the results obtained using TALYS and EMPIRE codes are in agreement with literature values when the radiative capture width Гγ and the width fluctuation parameter, respectively, functioned by being adjusted to a suitable value. Further, the deviation factor for measured and theoretical cross sections has also been determi...

Irradiation-induced modifications of excess minority carrier recombination time (lifetime) τ in CZ-grown crystalline n-Si (111) with resistivity 60 Ω cm are reported. Samples were irradiated with 65 and 100 MeV fluorine ions in the fluence range of 2×10 10 –10 14 ions/cm 2 . The surface and depth profile of lifetime was measured using photoconductive decay (PCD) technique. In the entire set of ion-irradiated samples, lifetime was found to decrease monotonously with increasing ion fluence. This decrease in lifetime is attributed to the electronic energy loss S e induced generation of carrier traps and vacancies. Moreover, the higher S e in 65 MeV energy fluorine ions is responsible for the rapid decrease in lifetime as compared to the 100 MeV ions. The excess S e in 65 MeV fluorine ions is consumed in defect production over the ion track as well as surface and sub-surface recrystallization, thus exhibiting S e dependence. The variation in the surface lifetime is associated to the competition between surface defects and S e dependent recrystallization. Almost complete recovery in the lifetime towards the pre-irradiation level after annealing at 750 °C for a period of 1 h, confirms that the lifetime modification is due to irradiation-induced carrier trapping centers.

Sm3+ (3 mol%) ions doped Y2O3 nanophosphors were synthesized by green synthesis route using Aloe Vera gel as fuel. The final product was irradiated by 6 MeV electron beam (E-beam) to different fluences in the range (2–10 × 1013 e− cm−2) and well characterized. Powder X-ray Diffractogram (PXRD) results revealed the loss of crystalline nature due to lattice disorder created during irradiation. Fourier Transform Infrared (FTIR) spectroscopic results showed absorption peaks around 688–843 cm−1 (Y-O bond), 1076 and 1398 cm−1 (C-O bond), 1505–1765 cm−1 and 3498 cm−1 (O-H bond). Scanning Electron Microscopic (SEM) images showed flake like morphological features. The Photoluminescence (PL) emission spectrum recorded at 407 nm excitation showed magnetic and electric dipole transitions at ∼569–575 (4G5/2 → 6H5/2), ∼607–623 (4G5/2 → 6H7/2) and ∼655–668 nm (4G5/2 → 6H9/2) respectively. Thermoluminescence (TL) glow curve consists of three peaks in E-beam irradiated nanophosphors at 158, 243 and 352 °C due to creation of more number of trapping and luminescent centers. The E-beam irradiated Y2O3:Sm3+ nanophosphors showed strong PL emission with color co-ordinate values lying in the orange-red region. Therefore, this material can be potentially used as a red component in WLEDs (White LEDs).

A new Dy doped CaNa2(SO4)2 nanophosphor has been synthesized using simple co-precipitation method and claimed to have good Thermoluminescence (TL) dosimetric properties. Structural, morphological, optical, compound identification and thermal analysis of the nanophosphor was studied by X-ray diffraction (XRD), High-Resolution Transmission electron microscope i.e. (HRTEM), UV–Visible, FTIR and TGA-DSC techniques. XRD studies showed a monoclinic structure and size of the particle found to be around ∼45 nm. HRTEM confirms the nanosize of the particles of the same order and SEAD pattern shows fringes perfectly match with inter planner spacing distance “d” of XRD i.e. 2.74 A. UV–Visible and FTIR analysis revealed the absorption wavelength 246 nm which corresponds to the band gap of around ∼5.03 eV and formation of the compounds of different bonds such as S-O, S=O, SO4 stretch, S S disulfide, respectively. The percentage of weight loss-gain, endothermic changes of the nanophosphor was measured using TGA-DSC analysis and corresponding weight loss of such a nanophosphor with increasing temperature was observed around 12.60%. The TL analysis shows that the CaNa2(SO4)2:Dy has a typical single glow curve at 164 °C and gives excellent linear response curve over a wide range of gamma dose from 10 Gy to 10 kGy. Moreover, the reproducibility of the CaNa2(SO4)2:Dy nanophosphor did not change after numerous cycles of exposures and readouts. Fading has been observed at around 9.55% for 30 days. Theoretical analysis of glow curves of samples irradiated by γ-rays was done by computerized glow curve deconvolution (CGCD) method to find out trapping parameters of various peaks. Finally, CaNa2(SO4)2:Dy nanophosphor could be a potential candidate for applications in the field of accidental and reactor dosimetry.

We report an in situ synthesis of ruthenium-reduced graphene oxide (Ru-rGO) using 6 MeV electron beam assisted radiolytic reduction method and its supercapacitive behavior. X-ray diffraction (XRD), transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM) explore Ru nanoparticles of size ~2 nm are decorated on rGO sheets. Raman spectroscopy shows I D/I G ratio increased and formation of bilayer rGO after electron beam irradiation. The defect density in Ru-rGO is increased due to the electron beam irradiation as compared to its counterpart GO. The Ru-rGO based supercapacitor exhibits specific capacitance (128.1 ± 5.59) F g−1 at 10 mV s−1 scan rate. The specific capacitance retention of Ru-rGO is up to 99.4% at 900 cycles while it increases to 130% at 5000 cycles. Discharge curve of the supercapacitor involves three current decay processes viz. activation polarization, ohmic polarization and concentration polarization. The highest energy density of (4.125 ± 0.19) W h kg−1 and power density of 1.44 kW kg−1 are achieved with Ru-rGO supercapacitor. This unique electron beam assisted techniques illustrates a promising method of the fabrication of high performance supercapacitor. BRNS (Research project Number 34/14/05/2015/BRNS), Government of India

Herein, we report the thermoluminescence properties of novel SrDy2O4: Eu microphosphor synthesized via facile solid state diffusion method. The phase purity, crystal structure, surface morphology, photoluminescence, and dosimetric properties were examined by XRD, SEM, photoluminescence spectroscopy, and thermoluminescence techniques, respectively. The as-prepared microphosphor revealed an orthorhombic phase having irregular shaped particles with an average size of approximately ~1.4–1.6 μm. The photoluminescence studies showed emission bands in the red region with prominent peaks centered at ~594 nm and ~625 nm corresponding to 5D0→7F1 and 5D0→7F2 transitions of Eu3+ ion. The thermoluminescence properties of gamma-irradiated SrDy2O4: Eu phosphors were investigated. The systematic study on optimum concentrations of dopants was performed by varying the Eu concentration from 0.5 to 3 mol %. The favorable thermoluminescence glow curve was obtained for 1% Eu doped SrDy2O4 phosphor at 203 °C. The SrDy2O4: 1% Eu phosphor showed a linear TL response in the range from 1 Gy to 4 kGy gamma dose. The whole peak method, variable heating rate method, Tm –Tstop technique and Initial Rise Method (IRM) is carried out for trap level analysis and to experimentally determine the activation energy. The trapping parameters of glow curves i.e. frequency factor (s), order of kinetics (b), etc are estimated by Glow Curve Deconvolution (GCD) method. The potential thermoluminescence dosimetric properties of SrDy2O4: Eu phosphor provides a promising system for high dose radiation and environmental dosimetric application.

One-step gamma radiation assisted method has been used for the synthesis of Silver-Gold (Ag-Au) alloy nanoparticles with simultaneous reduction of graphene oxide (GO). UV–vis spectroscopic results along with X-ray diffraction analysis, X-ray Photoelectron spectroscopy and Transmission electron microscopy confirmed the decoration face centered cubic structured Ag-Au nanoparticles of size (5–19) nm on reduced graphene oxide (rGO) sheets. The increase in disorder parameter in Raman spectroscopy indicates the formation of more number of small sp 2 domains. The synthesized Ag-Au-rGO nanocomposite showed enhanced catalytic activity towards the reduction of 4-Nitrophenol compared to individual Ag-Au and rGO components.

Polycarbonate (PC) polymers were investigated before and after high energy heavy ion irradiation for anti-bacterial properties. These PC films were irradiated by Fe heavy ions with two energies, viz, 60 and 120 MeV, at different fluences in the range from 1 × 1011 ions/cm2 to 1 × 1013 ions/cm2. UV-Visible spectroscopic results showed optical band gap decreased with increase in ion fluences due to chain scission mainly at carbonyl group of PC which is also corroborated by Fourier transform infrared spectroscopic results. X-ray diffractogram results showed decrease in crystallinity of PC after irradiation which leads to decrease in molecular weight. This is confirmed by rheological studies and also by differential scanning calorimetric results. The irradiated PC samples showed modification in their surfaces prevents biofilm formation of human pathogen, Salmonella typhi.

A tertiary nanocomposite, PEDOT:PSS/NiFe 2 O 4 /reduced graphene oxide (rGO) (GNP) has been synthesized in one-step for super-capacitor application and its electrochemical performance has been compared with NiFe 2 O 4 /rGO, NiFe 2 O 4 /CNT/rGO and NiFe 2 O 4 /CNT. The specific capacitance of GNP nanocomposite is found to be 1090 Fg −1 and energy density of 660 Whkg −1 at a current density of 0.5 Ag −1 with cyclic stability of 94% of capacitance retention which are excellent values in its class. The well designed nanostructure and the synergetic effects of individual component results in enhanced electrochemical performance of GNP nanocomposite.

Silver-reduced graphene oxide (Ag-rGO) nanocomposite was prepared in the presence of Isopropyl alcohol (IPA) and polyvinyl pyrrolidone (PVP) by gamma irradiation assisted method. UV–Visible spectroscopic results showed the peak of rGO and surface plasmon resonance of Ag nanoparticles. X-ray powder Diffraction (XRD) results revealed the formation of face centered cubic structured Ag nanoparticles along with rGO signature after irradiation. Transmission electron microscopy (TEM) results showed the decoration of Ag nanoparticles of size 10 nm on rGO sheet corroborating the UV–Visible spectroscopic and XRD results. Raman spectroscopic results of Ag-rGO showed the increase in the ratio of D to G band (I D /I G ) after gamma irradiation. The prepared Ag-rGO nanocomposite was tested for the degradation of methylene blue (MB) and results distinctly enhanced photocatalytic degradation compared to bare Ag nanoparticles and graphene oxide. The prepared Ag-rGO nanocomposites act as photo-catalysts that utilize visible light as an energy source.

Electron beam assisted method has been employed for the synthesis of silver-reduced graphene oxide (Ag–rGO) nanocomposite in the presence of isopropyl alcohol and polyvinyl pyrrolidine. The decoration of face centered cubic silver nanoparticles (AgNPs) of size 8 nm on reduced graphene oxide has been confirmed by UV–visible spectroscopy, X-ray Diffractogram and Transmission electron microscopy. Raman spectra showed the increase in the disorder parameter ( I D / I G ) of Ag–rGO after electron irradiation due to the formation of large number of small sp 2 domains. Moreover, as an application of the synthesized Ag–rGO sample showed an enhanced photo-catalytic degradation of methylene blue compared to graphene oxide, rGO and AgNPs under sunlight.

Dysprosium-doped calcium sulphate (CaSO 4 :Dy) microphosphor was synthesized by acid re-crystallization method and its thermoluminescence (TL) properties irradiated with thermal neutrons was studied. Structural and morphological characteristics have been studied using X-ray diffraction and SEM which mainly exhibits a orthorhombic structure with particle size of 200 to 250 µm. Moreover, thermal neutron dosimetric characteristics of the microphosphor such as thermoluminescence glow curve, TL dose–response have been studied. This microphosphor powder represents a TL glow peak ( T max ) centered at around 240 °C. The TL response of CaSO 4 :Dy microphosphor as a function of thermal neutron fluence is observed to be very linear upto the fluence of 52×10 11 n/cm 2 and further saturates. In addition, TL glow curves were deconvoluted by computerized glow curve deconvolution (CGCD) method and corresponding trapping parameters have been determined. It has been found that for every deconvoluted peak there is change in the order of kinetics. Overall, the experimental results show that the CaSO 4 :Dy microphosphor can have potential to be an effective thermal neutron dosimetry.

CaF2:Dy phosphor was prepared by ball milling method over particle size ranging from 140 nm to 35 nm, and their thermoluminescence properties were studied by irradiation with 60Co gamma rays. The XRD revealed that the crystallite size was of ∼45 nm for pristine, 19.1 nm for 10 h and 9.99 nm for 50 h ball-milled phosphor samples and confirmed by FESEM. The UV–visible spectra indicate that the absorption and scattering of radiation increased with a decrease in the particle size along with the blue shift in the absorption peak. CaF2:Dy particles of different sizes were irradiated with gamma dose from 1 Gy to 20 kGy and respective thermoluminescence response was studied. It was observed that the ∼65 nm particle size phosphor showed a linear response with gamma dose range from 1 Gy to 12 kGy. These results reveal that the CaF2:Dy phosphor can be used for high gamma radiation measurement and food irradiation dosimetry.

In this work, the study on gamma ray exposed Thermoluminescence (TL) response in the range 1 Gy–3 kGy has been carried out on BaB4O7:Ce phosphor. Optimization of Ce doping concentrations in BaB4O7 phosphor was done by varying the Ce concentration from 0.5 to 3 mol %. A facile solid-state diffusion method was used to synthesize the phosphor material. Structural and morphological properties were studied using X-ray diffraction spectroscopy (XRD) and scanning electron microscopy (SEM), respectively, which revealed its monoclinic crystal structure and average particle size of ∼2 μm was observed. Optical characterization was carried out using photoluminescence (PL), which shows a blue color emission band, with maximum intensity at ∼ 450 nm and ∼500 nm. In dosimetric studies, two main peaks in the TL glow curve were observed at 176 °C and 311 °C. The intensities of these peaks found to be increasing linearly with an increase in gamma doses. To know about trap levels, the TL glow curve study was carried out through the activation energy -Tstop method in combination with the Initial Rise Method (IRM). The trapping parameters, Order of kinetics, frequency factor, and Figure of Merit were obtained by Glow Curve Deconvolution (GCD) method. The efficient thermoluminescent properties of BaB4O7:Ce phosphor makes them promising dosimetric phosphor material and provides a gateway for potential medical and radiation dosimetric applications.

Neutrons over a wide range of energies are produced by bombarding a 1.05 cm thick beryllium target with protons of different energies delivered by the MC-50 Cyclotron of the Korea Institute of Radiological Medical Sciences (KIRAMS). The neutron flux Φ(En) versus neutron energy En, produced by protons of 30, 35, and 40 MeV energies, was obtained by using the GEANT4 code with a data-based hadronic model. For the experimental validation of the simulated neutron spectra, a number of pure aluminum and iron oxide samples were irradiated with the neutrons produced by 30, 35, and 40 MeV protons at 20 μ A beam current. The gamma-ray activities of 24Na and 56Mn produced, respectively, through 27Al(n,α)24Na and 56Fe(n,p)56Mn reactions were measured by a HPGe detector. The neutron flux Φ(En) at each neutron energy from the simulation was multiplied with the evaluated cross-sections σ(En) of the respective nuclear reaction, and the summation ∑ Φ ( E n ) σ ( E n ) was calculated over the neutron spectrum for each proton energy of 30, 35, and 40 MeV. The measured gamma-ray activities of 24Na and 56Mn were found in good agreement with the activities estimated by using the summed values of ∑ Φ ( E n ) σ ( E n ) along with other parameters in a neutron activation method.

Gold (Au)–Polycarbonate (PC) matrix was prepared by gamma radiation assisted diffusion of Au nanoparticles in PC matrix. UV–Visible spectroscopy showed the surface plasmon resonance around 550 nm which corresponds to Au and this peak shift towards lower wavelength i.e. blue shift indicating the decrease in particle size of Au. Rutherford Backscattering (RBS) experiment confirmed the diffusion of Au in PC and depth of diffusion is found to be around 0.85 µm. X-ray Diffractogram (XRD) results also revealed the diffusion of Au in PC where the peak observed at 2θ∼38.29° which correspond to the FCC structure. Scanning Electron Microscope (SEM) images showed the hexagonal shaped Au nanoparticles and average particle size is found to be around 110 nm. These samples also showed anti-bacterial properties with both gram positive and gram negative bacteria's and revealed the inhibition of the overall growth of the bacteria with gamma dose.

Diffusion of lithium from a LiCl aqueous solution into polyether ether ketone (PEEK) and polyimide (PI) assisted by in situ irradiation with 6.5 MeV electrons was studied by the neutron depth profiling method. The number of the Li atoms was found to be roughly proportional to the diffusion time. Regardless of the diffusion time, the measured depth profiles in PEEK exhibit a nearly exponential form, indicating achievement of a steady-state phase of a diffusion–reaction process specified in the text. The form of the profiles in PI is more complex and it depends strongly on the diffusion time. For the longer diffusion time, the profile consists of near-surface bell-shaped part due to Fickian-like diffusion and deeper exponential part.

Polypropylene (PP) and polyimide (PI), which belong to entirely different classes of polymers, are irradiated by Co-60 gamma radiation under similar doses and similar conditions in the dose range v...

A few silica glass samples having 1 cm 2 area and 0.1 cm thickness were irradiated with 100 MeV energy Ag 7+ ions for the fluences ranging from 1 × 10 12 ions/cm 2 to 5 × 10 13 ions/cm 2 . The optical properties and the corresponding induced defects were characterised by the techniques such as UV–Visible, Photoluminescence (PL), Fourier transform infrared (FTIR), and Electron spin resonance (ESR) spectroscopy. The UV–Visible absorption spectra show two peaks, one at 5 eV and another weak peak at 5.8 eV. A peak observed at 5.0 eV corresponds to B 2 band (oxygen deficiency in SiO 2 network) and the peak at 5.8 eV is due to the paramagnetic defects like E′ centre. The intensities of these peaks found to be increased with increase in ion fluence. It attributes to the increase in the concentration of E′ centres and B 2 band respectively. In addition, the optical band gap energy, Urbach energy and the defects concentration have been calculated using Urbach plot. The optical band gap found to be decreased from 4.65 eV to 4.39 eV and the Urbach energy found to be increased from 60 meV to 162 meV. The defect concentration of nonbridging oxygen hole centres (NBOHC) and E′ centres are found to be increased to 1.69 × 10 13 cm −3 and 3.134 × 10 14 cm −3 respectively. In PL spectra, the peak appeared at 1.92 eV and 2.7 eV envisage the defects of nonbridging oxygen hole centres and B 2α oxygen deficient centres respectively. ESR spectra also confirms the existence of E′ and NBOHC centres. FTIR spectra shows scissioning of Si O Si bonds and the formation of Si H and Si OH bonds, which supports to the co-existence of the defects induced by Ag 7+ irradiation.

Diffusion of silver and iodine from aqueous solution into three synthetic polymers, HDPE, PI, and PEEK was studied. The samples, fully immersed in the respective chemical solution, were irradiated with 6.5 MeV electrons at room temperature to fluencies from 1.0 to 5.0×1015 cm−2. Concentration depth profiles of the diffused Ag and I atoms were determined by the RBS method. The content of the silver and iodine atoms was found to be a monotonously increasing function of the diffusion time, but it does not follow dependence expected for pure Fickian diffusion. The measured depth profiles exhibit a nearly exponential form and differ significantly from what is expected for the Fickian diffusion. Moreover, on silver depth profiles, two components are observed corresponding to particles with different mobilities. The anomalies are attributed to radiation defects created by electron irradiation, which are supposed to act as effective trapping centers for the diffusing particles. The depth profiles were simulated by a simple reaction-diffusion model and the parameters controlling the diffusion process were estimated. The diffusion coefficients under electron irradiation for both silver and iodine are higher by orders of magnitude than those reported for the common diffusion of metals in polymers.

A simple and controllable method to synthesize nanoparticles in the surface region of polymers was used by low energy electron irradiation. Using this method, gold nanoparticles have been synthesized by irradiating gold coated PVA (Polyvinyl Alcohol) sheets. This method was easy in operation and even period of few minutes was sufficient to obtain the nanoparticles. The coatings (~10 μm) made from a mixture of ethanol and HAuCl 4 on PVA sheets (~150 μm) by simple drop cast method were irradiated with 30 keV electrons, at room temperature and 10 −6 mbar vacuum level. The electron fluence was varied from coating to coating in the range of 0 to 24×10 15 e/cm 2 . The irradiated samples were characterized by the UV–Vis, XRD, SEM and RBS techniques. The plasmon absorption peak at ~539 nm in UV–Vis spectra was an evidence for the initiation of the growth of gold nanoparticles. The X-ray diffraction results and the blue shift in the plasmon absorption peak reveal that the size of nanoparticles could be tailored in the range from 58 to 40 nm by varying the electron fluence. The diffusion of gold in the PVA was confirmed by the Rutherford backscattering spectroscopy and scanning electron microscopy techniques. This method of synthesis of metal nanoparticles by low energy electron beam irradiation has the key importance in the development of new fabrication techniques for nanomaterials.

Nanocrytstalline K 2 Ca 2 (SO 4 ) 3 :Cu phosphor was synthesized by the chemical co-precipitation method and annealed at different temperatures (400–900 °C) for 2 h. The XRD spectrum shows the cubic structure with crystallite size ~20 nm. The same was also confirmed from the TEM image which shows the formation of nanorods having diameter ~20 nm and length of ~200 nm. They are found to be quite uniform in shapes and sizes. These samples were irradiated with gamma radiation for the doses varying from 0.01 Gy to 10 kGy and their thermoluminescence (TL) characteristics and continuous wave optically stimulated luminescence (CW-OSL) have been studied. The sample annealed at 700 °C was found to be most sensitive than others. The glow curves of the nanophosphor show a major peak at around 175 °C and other two peaks of low intensity at around 85 °C and 305 °C. The traps responsible for the three thermoluminescence peaks in K 2 Ca 2 (SO 4 ) 3 :Cu are also found to be sensitive to the OSL. The qualitative correlation between TL peaks and CW-OSL response is established. The TL response of the sample annealed at 700 °C for 2 h and irradiated with different gamma doses shows a linear behavior from 0.01 up to 300 Gy and become sublinear in the range of 300 Gy–1 kGy before it saturates with further increase in the dose, while, the OSL response of the same sample shows linearity up to 1 kGy. Simple glow curve structure, easy method of synthesis, and linear dose response make the nanocrystalline phosphor a good candidate for radiation dosimetry, especially for the estimation of high doses of gamma rays where the microcrystalline phosphors generally saturate.

The isomeric cross section of 137 Ba(n, n′) 137m Ba reaction over the neutron energy from 1 keV to 4 MeV has been calculated using TALYS-1.2 nuclear code. The variations of cross section with level densities and effective imaginary potentials have been studied to obtain the best fit with the excitation function. The reaction cross section for Barium was also measured in continuous neutron energy using the Microtron accelerator based neutron source. In this case, the bremsstrahlung radiation emitted by impinging 6 MeV electrons on the e–γ primary target (tungsten) was allowed to fall on the γ–n secondary target (beryllium) to produce continuous neutrons and further barium was irradiated at 0 0 with respect to the incoming neutrons. It is observed that the experimental cross section for Barium is in good agreement with TALYS code and also evaluated data of EXFOR. Deviation factor has been determined for measuring and theoretical cross sections by TALYS-1.2 found to be around 14.71.

The 238 U(n, γ) 239 U reaction cross-sections at average neutron energies of 5.9 ± 0.5 and 15.5 ± 0.7 MeV from the 7 Li(p, n) reaction have been determined using neutron activation and off-line γ-ray spectrometric technique. The 238 U(n, 2n) 237 U reaction cross-section at neutron energy of 15.5 ± 0.7 MeV has also been determined using the same technique. The 238 U(n, γ) 239 U and 238 U(n, 2n) 237 U reaction cross-sections have been calculated theoretically using nuclear reaction model based TALYS-1.4 code and are found to be in general agreement with measured experimental data. The present data are compared with the values from the latest available evaluated nuclear data libraries and found to be agreement with the data of ENDF/B-VII.1, JENDL-4.0 and JEFF-3.1/A but not with that of CENDL-3.1.

Cu doped SnO2 (SnO2:Cu) nano phosphor (NP) was successfully synthesized by one-step simple hydrothermal method and it was characterized by XRD (x-ray Diffraction) for structural, FESEM (Field Emission Scanning Electron Microscopy) for morphological and EDS (Electron Dispersive Spectroscopy) for elemental analysis. NP was annealed at 700 °C for 2 h and its crystallinity for tetragonal phase was confirmed through XRD. The crystallite size was ~10.39 nm for un-annealed and ~18.16 nm for annealed samples which has been calculated using Scherer equation. The particle size was estimated to be ~43 nm and the elemental composition of Sn, O, Cu was obtained by EDS. In addition, to study the dosimetric properties, the SnO2:Cu phosphors were irradiated with 6 MeV electron beam at fluences ranging from 10 × 1011 e cm−2 to 20 × 1012 e cm−2 which is equivalent to the 1.55 kGy to 31 kGy. The irradiated sample showed Thermoluminescence (TL) dosimetric glow peaks at 170 °C, 263 °C and 303 °C. SnO2:Cu NP was found to be sensitive enough for energetic electrons. Further, it has been noticed that the TL dose response found sensitive upto 10 × 1012 e cm−2 (15.50 kGy) with fading of 5.1% for 2 months. Hence, SnO2:Cu can be used for the measurement of electron doses.

By irradiating two macromolecules, namely polypropylene and polyimide having notably different physicochemical properties, with the same radiation under identical conditions, it is inferred that the mechanical and thermal degradation or the stability of the macromolecule exposed to high-energy radiation strongly correlates with its physicochemical structure. This is well supported by two distinct characterizations, namely stress–strain analysis and thermogravimetric analysis.

Nanocrystalline K2Ca2(SO4)3:Cu was synthesized by chemical coprecipitation method and annealed at 700 °C. XRD of this sample shows the cubic structure and the crystallite size ∼20 nm. The same was also confirmed with TEM and shows the formation of nanorods of quite uniform in shape having diameter ∼20 nm and length in the range of 200 nm. The FTIR spectrum exhibits the bands corresponding to sulphate anions around 1015 and 600 cm−1. These samples were irradiated with gamma radiation for the dose varying from 0.1 Gy to 50 kGy and their TL characteristics have been studied. The glow curves of the pristine samples consists of two peaks one at around 139 °C while another one around 185 °C while the glow curve of samples annealed at 700 °C show a major peak at around 165 °C and other two peaks of low intensity at around 300 °C and 390 °C. The change in glow curve structures around 700 °C is due to the phase transition (from orthorhombic P212121to cubic P213 phase). The energy levels (trapping levels) get reorganized due to phase transition after the phase transition temperature (260 °C) and remain the same at higher temperatures (700 °C). TL dose response shows a linear behavior up to 1 kGy and further saturates with increase in the dose. Simple glow curve structure, easy method of synthesis, linear dose response and low fading make the nanocrystalline phosphor a good candidate for radiation dosimetry and especially, for the estimation of high doses of gamma rays where the microcrystalline phosphors generally saturate.

The cross sections of 127 I(n, γ) 128 I, 23 Na(n, γ) 24 Na and 51 V(n, γ) 52 V reactions for Iodine, sodium and vanadium were measured at continuous energy spectrum using a Microtron accelerator based neutron source. In this case, the bremsstrahlung radiation emitted by impinging 6 MeV electrons on the e–γ primary target (tungsten) was allowed to fall on the γ–n secondary target (beryllium) to produce continuous neutrons. The optimization of bremsstrahlung and neutron producing targets along with their spectra were estimated using FLUKA code. The cross sections of 127 I(n, γ) 128 I, 23 Na(n, γ) 24 Na and 51 V(n, γ) 52 V reactions over the neutron energy from 1 keV to 4 MeV have been also calculated using the TALYS-1.2 and EMPIRE nuclear model codes. The variations of the cross sections with the level densities and effective imaginary potentials were studied to obtain the best fit of the excitation function. It is observed that the experimental cross sections for iodine, sodium and vanadium are in good agreement with the TALYS-1.2 and EMPIRE codes.

The 56Fe(n, p)56Mn reaction cross-section at neutron energies of 5.9 ± 0.6, 9.85 ± 0.38, 14.8 ± 0.1 and 15.5 ± 0.7 MeV from the 7Li(p, n) as well as 3H(d, n) reactions has been experimentally measured using activation and off-line γ-ray spectrometric technique. The experimentally determined 56Fe(n, p)56Mn reaction cross-sections from the present work were compared with the latest available evaluated nuclear data libraries of ENDF/B-VII.1, JENDL-4.0 and JEFF-3.1/A. The present data along with the literature data in a wide range of neutron energies were interpreted in terms of competition between different reaction channels. The measured cross-sections were also estimated theoretically using TALYS-1.4 and EMPIRE-2.19 computer codes over neutron energies from near threshold to 20 MeV to compare with the experimental data.

A Telecobalt unit has wide range of applications in cancer treatments and is used widely in many countries all around the world. Estimation of surface dose in Cobalt-60 teletherapy machine becomes important since clinically useful photon beam consist of contaminated electrons during the patient treatment. EGSnrc along with the BEAMnrc user code was used to model the Theratron 780E telecobalt unit. Central axis depth dose profiles including surface doses have been estimated for the field sizes of 0×0, 6×6, 10×10, 15×15, 20×20, 25×25, 30×30 cm 2 and at Source-to-surface distance (SSD) of 60 and 80 cm. Surface dose was measured experimentally by the Gafchromic RTQA2 films and are in good agreement with the simulation results. The central axis depth dose data are compared with the data available from the British Journal of Radiology report no. 25. Contribution of contaminated electrons has also been calculated using Monte Carlo simulation by the different parts of the Cobalt-60 head for different field size and SSD's. Moreover, depth dose curve in zero area field size is calculated by extrapolation method and compared with the already published data. They are found in good agreement.