The Cadmium Zinc Telluride Imager (CZTI) on board AstroSat has been regularly detecting gamma-ray bursts (GRBs) since its launch in 2015. Its sensitivity to polarization measurements at energies above 100 keV allows CZTI to attempt spectropolarimetric studies of GRBs. Here, we present the first catalog of GRB polarization measurements made by CZTI during its first five years of operation. This includes the time-integrated polarization measurements of the prompt emission of 20 GRBs in the energy range 100–600 keV. The sample includes the bright GRBs that were detected within an angle range of 0°–60° and 120°–180° where the instrument has useful polarization sensitivity and is less prone to systematics. We implement a few new modifications in the analysis to enhance the polarimetric sensitivity of the instrument. The majority of the GRBs in the sample are found to possess less/null polarization across the total bursts’ duration in contrast to a small fraction of five GRBs that exhibit high polarization. The low polarization across the bursts might be due either to the burst being intrinsically weakly polarized or to a varying polarization angle within the burst even when it is highly polarized. In comparison to POLAR measurements, CZTI has detected a larger number of cases with high polarization. This may be a consequence of the higher energy window of CZTI observations, which results in the sampling of a shorter duration of burst emissions than POLAR, thereby probing emissions with less temporal variation in polarization properties.
The Cadmium Zinc Telluride Imager (CZTI) onboard AstroSat consists of an array of a large number of pixellated CZT detectors capable of measuring the polarization of incident hard X-rays. The polarization measurement capability of CZTI for on-axis sources was experimentally confirmed before the launch. CZTI has yielded tantalizing results on the X-ray polarization of the Crab nebula and pulsar in the energy range of 100 -380 keV. CZTI has also contributed to the measurement of prompt emission polarization for several Gamma-Ray Bursts (GRBs). However, polarization measurements of off-axis sources like GRBs are challenging. It is vital to experimentally calibrate the CZTI sensitivity to off-axis sources to enhance the credence of the measurements. In this context, we report the verification of the off-axis polarimetric capability of pixellated CZT detectors through the controlled experiments carried out with a CZT detector similar to that used in CZTI and extensive Geant4 simulations of the experimental set-up. Our current results show that the CZT detectors can be used to measure the polarization of bright GRBs up to off-axis angles of ∼60 • . However, at incidence angles between 45-60 • , there might be some systematic effects which needs to be taken into account while interpreting the measured polarisation fraction.
The present study attempts to analyze the effect of utilization of Moringa oleifera seed meal (MOSM) with or without supplementation of acidifier on haematological parameters of broiler chicks. A feeding trial of 42 days was conducted for five iso-nitrogenous and iso-caloric rations having MOSM at 0, 1, 2, 3 and 4% level with or without supplementation of acidifier using 300 broiler chicks in 5X2 factorial design. Broiler chicks were assigned randomly to various experimental groups. The dietary treatments were basal diet as control without MOSM (T1), basal diet with MOSM at 1% (T2), 2% (T3), 3% (T4), 4% (T5), basal diet with Acidifier at 1g/kg feed (T6), basal diet with MOSM at 1, 2, 3 and 4% with Acidifier at 1g/kg feed for T7, T8, T9 and T10, respectively. Blood samples for haematological analysis were collected aseptically from randomly selected birds (two birds per replicate) at 21 and 42 day of experiment. Results showed that highly significant (p<0.01) effect of MOSM in diets of broiler chicks on Hb, RBC, WBC and PCV at 21 day of age as well as 42 day of age in broilers were observed. The effect of supplementation of acidifier as feed additive in ration of broiler chicks were found to be highly significant (p<0.01) on Hb, RBC, WBC and PCV at 21 day of age. Whereas, at 42 day of age, highly significant (p<0.01) effect of acidifier in the ration of broilers on Hb, RBC and PCV and significant (p<0.05) effect on WBC were observed. It was concluded that MOSM with or without acidifier can be incorporated in the diet of the broiler chicks without any harmful effect on the health status of the broiler chicks.
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