Ramesh Chandra Tiwari

Correlation of radon anomalies with seismic events along Mat fault in Serchhip District, Mizoram, India

Radon emanation from the soil gas was studied using a deep red coloured cellulose nitrate LR-115 type II film. The study was carried out from March 2012 to February 2013 at Mat Bridge (23°18΄ N, 92°48΄ E) along Mat Fault in Serchhip district, Mizoram (India). Changes in radon concentrations have been observed. Effects of meteorological parameters on radon emission were also studied. The measured radon data shows a moderate positive correlation with relative humidity but no specific relation with air temperature and rainfall. Data obtained have been correlated to the earthquakes that occurred around the measuring sites.

Variations of soil radon concentrations along Chite fault in Aizawl district, Mizoram, India.

The present study concerns measurements of radon emissions from soil carried out during March to July 2013 at Chite fault in Aizawl district, Mizoram, India. In this study, continuous radon monitoring in soil was done by using LR-115 type II nuclear track detector (Kodak-Pathe, France make), and the exposed films were replaced weekly. A negative correlation coefficient (-0.47) between radon concentration and barometric pressure was found during the investigation period. The average radon concentration was observed to be 1785.71 Bq m(-3) with a standard deviation of 633.07 Bq m(-3). The maximum and minimum values of radon concentration during this period were found to be 3693.88 and 904.76 Bq m(-3), respectively. An anomalous increase in radon concentration was observed on 112th day (i.e. on 14 June 2013) during the investigation period just 1 d prior to the event of M 3.5, which occurred within 120-km distance from the monitoring site.

Radon and thoron anomalies along Mat fault in Mizoram, India

In this study, radon and thoron concentrations in soil gas has been monitored using LR-115(II) solid state nuclear track detectors since 15th July 2011 to February 2012. The study was carried out along Mat fault in Serchip district, Mizoram, India at two different sites – Mat Bridge (23°18′N, 92°48′E) and Tuichang (23°13′N, 92°56′E). The results obtained have been correlated to the seismic events that occurred within 800 km from the measuring sites over the mentioned period of time. Anomalous behaviour in radon concentrations have been observed prior to some earthquakes. Interestingly, some thoron anomalies were also recorded.

Fading Studies of Natural Salt for Dosimetry Applications

Fading at room temperature is one of the most important properties of TL material. The purpose of the present studies is to find out the suitability of natural salt extracted from rivers of Mizoram for dosimetry applications. TL analysis of the gamma irradiated samples stored at room temperature was done within 2 hours, after 48 hours and 96 hours of irradiation. Experimental glow curves were fitted by using Kitis et al general order expression and the fitting parameters were obtained by authors using GCD method. TL analysis of samples showed good dosimetry peaks at about 205 C. Our studies indicate that the natural salt may be considered for dosimetry applications within 48 hours after gamma irradiation.

Time Series Analysis of Soil Radon Data Using Multiple Linear Regression and Artificial Neural Network in Seismic Precursory Studies

This paper reports the analysis of soil radon data recorded in the seismic zone-V, located in the northeastern part of India (latitude 23.73N, longitude 92.73E). Continuous measurements of soil-gas emission along Chite fault in Mizoram (India) were carried out with the replacement of solid-state nuclear track detectors at weekly interval. The present study was done for the period from March 2013 to May 2015 using LR-115 Type II detectors, manufactured by Kodak Pathe, France. In order to reduce the influence of meteorological parameters, statistical analysis tools such as multiple linear regression and artificial neural network have been used. Decrease in radon concentration was recorded prior to some earthquakes that occurred during the observation period. Some false anomalies were also recorded which may be attributed to the ongoing crustal deformation which was not major enough to produce an earthquake.

Pulse width modulator using CDBA based relaxation oscillator

This paper presents a pulse width modulator (PWM) designed using current differencing buffered amplifier (CDBA) based relaxation oscillator. The theoretical propositions are verified through SPICE Simulations Experimental results are also presented which are in tune with the proposed theory.

Thermoluminescence (TL) Analysis and Fading Studies of Naturally Occurring Salt Irradiated by 500 mGy Gamma Rays

The aim of the present study was to investigate the potential of the naturally occurring salt for the dosimetry purposes, using TL. The fine powder samples (20 mg) were irradiated by γ‐ rays from 500 mGy to 2500 mGy by using Theratron‐780C Cobalt‐60 source, however, this paper discusses about 500 mGy only. The TL glow curve peak parameters were studied by using Chen’s peak shape equation. TL glow curves were compared with fitted curves using glow curve deconvolution (GCD) method by using Kitis expression. The kinetic parameter values (E, b and s) so calculated, are in good agreement with those available in literature. The calculated energy values were also verified by using various heating rate (VHR) method. χ2 test and figure of merit (FOM) calculation was done to accept the goodness of fit between the curves. Fading studies of the sample showed a good fitting between the curves. The analysis suggests that natural salt should be considered for dosimetry purposes.