Ashish Kumar Agrawal

A multi-contrast x-ray imaging facility with a single x-ray absorption grating is developed at the X-ray Imaging beamline (BL-04), Indus-2 synchrotron radiation source, India, and implemented in both monochromatic and white beam operation modes of the beamline for versatile utilization of this technique in structural characterization of a wide range of samples from soft biological to metallic, dense, and thick materials. The developed facility is characterized by resolution, visibility, and signal-to-noise ratio and tested for static and dynamic morphological analysis under different experimental conditions. The qualitative and quantitative analysis of extracted multi-contrast x-ray images of different samples demonstrates the relative merits of various experimental conditions. This unique multi-contrast facility with a single x-ray absorption grating that operates in dual modes of the X-ray Imaging beamline enables the study of both static and transient phenomena across a wide range of applications at the beamline.

Trans-stilbene (TSB) crystals are important for the detection of high energy photons and neutrons through the process of scintillation. To fulfil the requirement of large area scintillator detector elements, TSB/PMMA composites have been developed. These plastic scintillator materials can be prepared in a relatively simpler manner as compared to the single crystals. The detailed optimization of the synthesis parameters has been reported. Using the optimal parameters, the TSB/PMMA composites having different TSB concentrations, up to a maximum of 35 wt% TSB, have been successfully fabricated. The fabricated composites were stable at room temperature, optically homogeneous, and transparent in a wide spectral range. The device relevant properties of the synthesized TSB/PMMA plastic scintillator, important for their deployment in optical imaging applications such as the index of refraction, UV–Vis–NIR transmission and photoluminescence properties have been characterized as a function of TSB concentration in the polymer matrix and the behavior observed has been analyzed. Thin wafers of 0.5 mm thickness having different TSB concentrations were fabricated and used for demonstrating x-ray imaging with a resolution of 100 μm, using x-ray imaging beamline of Indus-2 synchrotron radiation facility. In addition, samples of 5 mm thickness having two different concentrations were used for the detection of neutrons using thermal neutron beamline of Dhruva research reactor facility at BARC, Trombay. The results demonstrate that TSB/PMMA composite is a potential plastic scintillator material for x-ray imaging and neutron scintillation applications.

Paneer is one of the popular heat-acid coagulated indigenous milk product in Indian cuisine. Traditionally, it is prepared by removing whey from acidified milk by pressing method. The present investigation was performed to study the effect of independent parameters like initial thickness of curd (1.5, 3.0 and 4.5 cm), speed of rotation of centrifuge (500, 1000 and 1500 rpm) and time of rotation (5, 10 and 15 min.) on centrifugal pressing of curd for paneer making. The effect of initial thickness, speed of rotation and pressing time of curd on moisture, solid loss and hardness ratio of centrifugal pressing were determined. A dimensionless number called as ‘centrifugal pressing number’ was formed to assess the changes occurred during pressing. It was found that pressing time had the maximum effect on solid loss and hardness ratios but the rotational speed had maximum effect on moisture ratio. The thickness of curd had the least effect on moisture and solid loss ratio of pressing.