Thin CaF2 targets with carbon backing are fabricated for the first time using physical vapour deposition technique at the target laboratory of IUAC, New Delhi to perform a multi nucleon transfer reaction on 10,11B+40Ca systems using General Purpose Scattering Chamber (GPSC) facility. Ca being an oxidizing material, we have used molecular CaF2 as the target material instead of Ca. Using turbo-molecular pump based coating unit (TMPU), carbon is deposited on cleaned glass slide and then CaF2 is deposited on diffusion pump based coating unit (DPU). We are successful in fabricating CaF2 targets of thickness approximate to 264.4 mu g/cm2 on carbon backing of thickness approximate to 21.5 mu g/cm2. The thickness and purity measured by the crystal thickness monitor equipped with the vacuum chamber is verified by different techniques like alpha energy loss, Rutherford Back Scattering (RBS), Electron Diffraction Spectroscopy (EDS) and X-ray Diffraction (XRD). Small impurity level were smeared during the observation and the target is successfully used for nuclear reaction experiment. The fabrication of molecular Ca target is found to be more conducive to experimentation since they exhibit less oxidation and herewith we discuss about fabrication technique, experimentation and characterization.

Summary Ocean bottom node (OBN) seismic is getting more popular for providing greater interpretation certainty in areas of complex reservoirs. Its full azimuth (FAZ), high fold count, high repeatability and broadband character prove to be beneficial especially in areas with complex geological structures and these factors were a driver to record the first 4C OBN survey in D1 field, western offshore India. Despite several attempts of reprocessing legacy narrow-azimuth marine seismic with more advanced processing techniques, it was difficult to use the legacy data to resolve the thin plays of the multi-layered limestone reservoir and understand fluid distribution in the reservoir section. We present a case study of seismic processing of PP-PS data, acquired with sparsesly distributed multicomponent ocean-bottom nodes in a shallow water environment, in order to resolve the production issues, anisotropy mapping, reservoir development, thin pay mapping and basement fracture detection. We review a number of processing and imaging challenges and demonstrate corresponding solutions using optimum processing workflows that produced a cleaner and higher resolution final image with improved reservoir characterization.

The preparation of chitosan-aluminum-doped zinc oxide (AZO) composite thin films for transparent resistive random access memory applications is reported. The variation in optical transmission, refractive index and optical bandgap of the composite films as a function of concentration of Al in ZnO and AZO weight percent in chitosan is investigated. Independent of composition, optical transmission is of the order of 87–89% at 550 nm. The refractive index at this wavelength is in the range of 1.71–1.86. The composite films exhibit reversible resistive switching behavior which is dependent on the Al concentration in ZnO as well as the weight percent of AZO in chitosan. There is a threshold Al concentration in ZnO, below and above which resistive switching is not observed. At the threshold concentration, resistive switching behavior is stable over several cycles. The co-existence of unipolar and bipolar switching controlled by Al concentration in ZnO is also observed. The current study establishes the potential of chitosan-AZO composite thin films for transparent resistive random access memory application.

We studied the low-field microwave absorption (LFMA) in polycrystalline pellet and powdered (0.1–0.2 µm particle size) samples with a nominal composition of Zn1 − x(Mn:Fe(Ni))xO (x = 0.02). LFMA signals are stronger in the case of Mn:Fe co-doped ZnO, as compared to that of Mn:Ni co-doped ZnO. While the bulk samples show hysteresis, it disappears in the case of powdered samples. Further the line shapes of LFMA were modified with powdering, leading to small saturation fields for LFMA. This indicates that the microwave absorption in these powders is more sensitive than in the pellet form. We interpret these results in terms of interparticle–interfacial pinning. In this work, we clearly establish the low-field tunability of microwave absorption in the Zn1 − x(Mn:Fe(Ni))xO (x = 0.02) system, which is good for the applications as microwave absorbers with small field tunability as a functionality. This means LFMA can give inputs for the right choice of material for field-tunable microwave absorber design.

Polycrystalline Zn1-xCrxO (0.01 <= x <= 0.09) samples synthesised by solid state reaction technique were sintered at different temperatures following slow step sintering schedule, investigated for optical and magnetic properties using suitable characterisation techniques. Cr2O3 and CrO2 phases have been detected in the Raman spectra of Zn1-xCrxO samples with x >= 0.05. Photoluminescence study indicated improved optical property of the samples compared to undoped ZnO. While low percentage Cr doped samples show diamagnetic behaviour, different types of magnetic orderings are observed in the samples with higher percentage of dopants (x >= 0.05) for different sintering temperatures. The spin system and magnetic properties were analysed through Electron Spin Resonance study; g-value of 1.97 indicates Cr in 3+ valence state in ZnO. Presence of both Cr3+ and Cr4+ in ZnO understood to facilitate super exchange interactions to promote room temperature ferromagnetism. ESR study ensures improved magnetic homogeneity through slow step sintering process.

Polycrystalline Zn1-x(Mn:Ni)(x)O sample for x = 0.02 were synthesized by solid state route. We have observed low field microwave absorption in these powder samples. Low field microwave absorption signal is out of phase with the regular resonance signal indicating the microwave absorption has a minimum at zero field and the absorption of microwaves increases with increase of magnetic field. Low field microwave absorption in these powders is qualitatively different from their bulk pellets. Temperature dependence of the low field microwave absorption indicates a line shape evolution and a non-monotonic peak to peak intensity change. Further, we have observed the absence of 2nd harmonic in this low field microwave absorption, indicating low field microwave absorption in these transition metal co-doped ZnO powders is not non-linear in nature.

Considering the potential of polymer nanocomposites in resistive memory application, electrical conduction in poly methyl methacrylate thin films embedded with Al doped ZnO nanoparticles has been investigated. This polymer nanocomposite was spin coated on indium tin oxide coated glass plate and a titanium film was coated on top of this to form a device. Current-voltage characteristics of the fabricated device was measured. The current increased gradually with the increase of voltage, reaching a peak and dropped down to the low current (OFF) state. Upon further increase of voltage, a sharp increase of current (three orders of magnitude) or switching from low current (OFF) state to high current (ON) state occurred at similar to 2:9 V. Current-voltage characteristics have shown Ohmic behaviour in the low voltage regime followed by hopping type of conductivity prior to switching.

Fusion cross-section measurements were performed for system 40Ca + 70Zn around the Coulomb barrier energies using Heavy Ion Reaction Analyzer (HIRA). The observed enhancement in experimental fusion cross-sections was investigated via coupled-channels formalism. The coupling of inelastic excitations alone could not reproduce the experimental data, however, the effect of octupole state of the projectile was observed to be significant. The multi-neutron positive Q-value transfer channels were also included in the calculations using semi-classical model. It was observed that two neutrons pick-up channel gave a major contribution to the fusion enhancement and successfully reproduce the experimental data at above as well as below barrier energies. The coupling of more than two neutrons transfer could not give any significant enhancement to subbarrier fusion.

‘Non-resonant Microwave Absorption’ (NRMA) or the ‘Low field microwave absorption’ (LFMA) measurements on high-quality polycrystalline SmFeAsO0.80F0.20 superconducting sample were carried as functions of temperature and microwave power. The LFMA line shape is complex with two peaks namely; broad peak 1 and narrow peak 2 akin to one reported in SmFeAsO0.88F0.12 as reported by Onyancha et al (Supercond. Nov. Magn. 28, 2927–2934, 2015). This unquestionably illustrates that these peaks are a common feature in F-doped SmFeAsO. The LFMA signal as a function of temperature reveals that T c − T ∗ = 1K in SmFeAsO0.80F0.20 compared to 4 K in SmFeAsO0.88F0.12 (T ∗ is the characteristic temperature at which the narrow peak appears as we cool down the sample below T c); hence inferring that the narrow peak is fluorine doping dependent. Furthermore, LFMA signal evolution with microwave power does not show phase reversal (anomalous absorption) at 2.227 mW which is a stark contrast to what was observed in SmFeAsO0.88F0.12 as reported by Onyancha et al (Physica C: Supercond. Appl. 533:49–52, 2017). The absence of phase reversal within measured microwave power indicates presence of hysteretic Josephson junction. These findings establish few non-superconducting inclusions in SmFeAsO0.80F0.20 system.

The magnetic state of multiferroic Bi 1− x Dy x FeO 3 (where x = 0.0, 0.05) nanoparticles that synthesized by the sol-gel method has been probed by electron spin resonance (ESR) spectroscopy. Systematic analysis of the obtained ESR spectra revealed that the strong signal with asymmetric line shape is due to the cycloidal spin structure in the bismuth ferrite (BFO) system. While the magnetic behaviour of BFO is intriguing with conflicting reports that attribute to its ‘spin glass’ and ‘domain pinning’ effects etc., our ESR data of line width temperature independence supports the spin glass scenario. Further, we have observed a dip or minimum with a narrow valley in the temperature dependence of Δ g / g at 75 K for Bi 0.95 Dy 0.05 FeO 3 (BDFO), indicating an abrupt disruption and decrease of canting spin order at that particular temperature.

We report on the non-resonant microwave absorption in the system of a nominal 2 wt % nano nickel particles added into YBCO powders (Ni–YBCO). With this dilute mixture of nano nickel particles, one is expected to have groups of normal Josephson junctions (JJs) and π JJs due to YBCO–nickel–YBCO interparticle weak links and as nickel is ferromagnetic. We experimentally show, for the first time multiple phase reversals in the non-resonant microwave absorption (NRMA) spectra from Ni–YBCO possibly due to the formation of π JJs. We also showed that these multiple phase reversals then depend on microwave power and temperature. We argue that microwave power induced coherence among some groups of JJs and breaking of some of the weaker JJs can then lead to the disappearance of multiple phase reversals at higher microwave power levels. Further, we also reported a role of pair breaking effects that shall give a linear field dependence of the derivative microwave absorption signal, essentially which is the NRMA signal. This pair breaking effect dominates at closer temperatures to T c which is expected thermodynamically.

Al doped nanocrystalline ZnO (similar to 30 nm) with composition Zn1-xAlxO (0.005 < x < 0. 03) were synthesised by pyrophoric technique and sintered at 650 degrees C. We performed detailed electron spin resonance (ESR) studies on this system to understand the spin ordering and magnetism. The spin canting order and magneto-crystalline anisotropy obtained through ESR measurements follow each other and have a broad peak for Al doping concentration of 0.02, which also matches with the saturation magnetisation 'M-s' maximum, that is obtained by direct magnetisation measurement using VSM. However, it is intriguing that the spin susceptibility has a broad minimum around the same doping level (0.02). Through the ESR measurement this observed weak ferromagnetism is attributed to the spin canted magnetism in the system. Other supportive experimental data from UV-Vis, PL and Raman analysis give a clear picture of defect structures in the form of oxygen vacancies that faciliates the occurrence of room temperature ferromagnetism which of course is through spin canting mechanism. (C) 2017 Elsevier B.V. All rights reserved.

Bi1-xScxFeO3 (x = 0.0, 0.1, 0.15, 0.25) nano particles were synthesized by sol gel method. We then probed the spin system in these nano particles using electron spin resonance technique. Our ESR results strongly suggest the scenario of modified spin canted structures. Spin canting parameter Δg/g as a function of temperature for Scandium doped BFO is qualitatively different from undoped BFO. A broad peak is observed for all the Scandium doped BFO samples and an enhanced spin canting over a large temperature range (75–210K) in the case of x = 0.15 doping. We also showed that the asymmetry parameter and thereby the magneto-crystalline anisotropy in these BSFO nanoparticles show peaks around 230K for (x = 0.10 and 0.15) and beyond 300K for x = 0.25 system. Thus, we established that the Sc doping significantly modifies the spin canting and magneto crystalline anisotropy in the BFO system.

We report on the electron spin resonance (ESR) studies in the Mn:Ni and Mn:Gd co-doped ZnO system sintered at 500 and 800 °C. We found that sintering temperature has strong effect on the ESR line widths, with the Mn-Gd co-doped ZnO system showing the largest effect. Increasing sintering temperature has increased the line widths considerably, running into Kilo Oersted range. These large line widths indicate magnetic in-homogeneities and disorder and are consistent with the occurrence of secondary phases due to high-temperature sintering. Further analysing the asymmetry parameters, together with Δ g / g -values, we explain the weak ferromagnetism at low temperatures in 500°C sintered Mn:Gd-ZnO system to be due to spin canting which is the parasitic or the ‘spin-canted magnetism’. The ESR line intensity which is the spin susceptibility shows a paramagnetic behaviour in the range 300–100 K and shows a sharp rise and a peak around 40 K consistent with the magnetization data reported earlier. In the case of Mn:Ni–ZnO system, the Δ g / g and P asc parameters, which are proportional to spin canting and magneto-crystalline anisotropy, closely follow each other representing the classic picture of Moriya-Dzyaloshinsky.

Linear gas stopping cells have been used "successfully at NSCL to slow down ions produced by projectile fragmentation from the 100 MeV/u to the keV energy range. These 'stopped beams' have first been used for low-energy high precision experiments and more recently for NSCLs re-accelerator ReA. A gas-filled reverse cyclotron is currently under construction by the NSCL to complement the existing stopping cells: Due to its extended stopping length, efficient stopping and fast extraction is expected even for light and medium-mass ions, which are difficult to thermalize in linear gas cells. The device is based on a 2.6 T maximum-field cyclotron-type magnet to confine the injected beam while it is slowed down in approximate to 100 mbar of LN2-temperature helium gas. Once thermalized, the beam will be transported to the center of the device by a traveling-wave RF-carpet system, extracted along the symmetry axis with an ion conveyor and miniature RF-carpets, and accelerated to a few tens of keV of energy for delivery to the users.The superconducting magnet has been constructed on a 60 kV platform and energized to its nominal field strength. The magnet's two cryostats use 3 cryo-refrigerators each and liquid-nitrogen cooled thermal shields to cool the coil pair to superconductivity. This concept, chosen not to have to rely on external liquid helium, has been working well. Measurements of axial and radial field profiles confirm the field calculations. The individual RF-ion guiding components for low-energy ion transport through the device have been tested successfully. The beam stopping chamber with its 0.9 m-diameter RF carpet system and the ion extraction system are being prepared for installation inside the magnet for low-energy ion transport tests. (C) 2016 Elsevier B.V. All rights reserved.

Polycrystalline bulk samples of Zn1-xMnxO with x=0.02, 0.04, 0.05 and sintered at different temperatures (500 degrees C & 800 degrees C) were studied to investigate the doping effect on the structural, optical properties and spin dynamics in ZnO system. The crystallite size was seen to decrease with no significant change in other structural parameters. FTIR study showed a small effect on the Zn-C) stretching bond and other bonds due to presence of Mn. Calculation from-UV-Vis spectra showed increase in the optical band gap in the low temperature sintered samples due to Mn doping. In the PL spectra, the UV emission seen to dominate for the 500 degrees C sintered sample, for 800 degrees C sample the visible emission dominate indicating increase in non-radiative emission. ESR signals obtained from the microwave absorption shows ferromagnetic signal for the low temperature sintered sample only with a g value of 2.004 for the 2% Mn doped sample. The number of spin participation for resonance is calculated from the ESR signal, which supports the magnetic behaviour of this particular sample.

With a motivation to compare the magnetic property, we synthesised undoped, transition metal (TM) Mn doped and (Mn:Fe) co-doped ZnO ceramics in the compositions ZnO, Zn0.98Mn0.02O and Zn0.96(Mn0.02Fe0.02)O. Systematic investigations on the structural, microstructural, defect structure and magnetic properties of the samples were performed. Low temperature as well as room temperature ferromagnetism has been observed for all our samples, however, enhanced magnetisation at room temperature has been noticed when ZnO is co-doped with Fe along with Mn. Particularly the sample with the composition Zn0.96Mn0.02Fe0.02O showed a magnetisation value more than double of the sample with composition Zn0.98Mn0.02O, indicating long range strong interaction between the magnetic impurities leading to higher ferromagnetic ordering. Raman and PL studies reveal presence of higher defects in form of oxygen vacancy clusters created in the sample due to Fe co doping. PL study also reveals enhanced luminescence efficiency in the co doped sample. Temperature dependent magnetisation study of this sample shows the spin freezing temperature around 39K indicating the presence of small impurity phase of Mn2−xZnxO3 type. Electron Spin Resonance signal obtained supports ferromagnetic state in the co doped sample. Enhancement of magnetisation is attributed to interactions mediated by magnetic impurities through large number of oxygen vacancies created by Fe3+ ions forming bound magnetic polarons (BMP) and facilitating long range ferromagnetic ordering in the co- doped system.

Nanocrystalline Mn-doped ZnO of compositions Zn1–x Mn x O (0 ≤ x ≤ 0.08) has been synthesised by chemical route for uniform substitution of Mn in Zn site and then sintered at 1300 °C. Systematic investigations show the effect of Mn doping level and the sintering temperature on the structural, electrical and magnetic properties of ZnO. The average size of the nanocrystalline particles is in the order of 30–50 nm, whereas the grain sizes of the sintered specimen are of the order of few microns. Substitution of Mn in ZnO has been confirmed from the X-ray diffraction peak shift. A few peaks related to secondary phases of MnO have been observed in the X-ray diffraction patterns of the doped samples. ZnO and Mn-doped ZnO show Ohmic behavior and increased resistivity value with the increasing concentration of Mn. Effect of Mn concentration in ZnO has also been reflected in the dielectric constant and dielectric loss values. All the sintered samples show paramagnetic behavior even though the presence of MnO with oxygen vacancies is evident in X-ray photoelectron spectroscopic study.

An attempt has been made in the present work to provide an ample opportunity to explore the information about the influence of incomplete fusion (ICf) reaction dynamics on complete fusion in heavy ion induced nuclear reactions. excitation functions for several evaporation residues produced in the interaction of projectile O with target lu have been measured over the wide projectile energy range ≈ 70-100 MeV. the recoil-catcher activation technique followed by the offline γ-ray spectroscopy has been used for the present measurements. In case of precursor decay, we have made use of Cavinato et al. formulation to calculate the independent cross-section of the identified residues. the measured efs are compared with theoretical predictions of statistical model code PACe-2 and any enhancement in the measured cross-section from theoretical prediction may be due to ICf reaction process. An attempt has been made to estimate the ICf contribution of the cross-section from the measured excitation function data and the dependence of ICf cross-section on projectile energy.