Spatial correlations in two neutral kaon decays

Relativistic propagators, the natural tools in field theory to describe the space-time development of a quantum system, are used to study correlations and interferences present in the neutral kaon system due to time-reversal violations. The method allows for a general wave-packet treatment of the problem. While standard results are obtained for singleK decays, quite different results are derived for the interference phase in two kaon decays such as those at DAΦNE.     

Working group report: Neutrino and astroparticle physics

This is the report of neutrino and astroparticle physics working group at WHEPP-8. We present the discussions carried out during the workshop on selected topics in the above fields and also indicate progress made subsequently. The neutrino physics subgroup studied the possibilities of constraining neutrino masses, mixing and CPT violation in lepton sector from future experiments. Neutrino mass models in the context of Abelian horizontal symmetries, warped extra dimensions and in the presence of triplet Higgs were studied. Effect of threshold corrections on radiative magnification of mixing angles was investigated. The astroparticle physics subgroup focused on how various particle physics inputs affect the CMBR fluctuation spectrum, and on brane cosmology. This report also contains an introduction on how to use the publicly available code CMBFAST to calculate the CMBR fluctuations.     

Implications of cosmic string-induced density fluctuations at the quark-hadron transition

We show that cosmic strings moving through the plasma at the time of a first-order quark-hadron transition in the early universe generate baryon inhomogeneities, which can survive till the nucleosynthesis epoch. We find out how these inhomogeneities actually affect the calculated values of the light element abundances. Recently a wealth of observational data from various experiments have helped to reduce the uncertainties in the values of these abundances. Using these we show that it is possible to derive constraints in the presence of cosmic strings during the quark-hadron transition.     

Vibrational dynamics of polyurydilic acid

A study of the normal modes of vibration and their dispersion in polyurydilic acid (polyU) is reported using Wilson's GF Matrix method as modified by Higgs. This is done for the `bare' as well as for the helix `loaded' with uracil. Confusion that has prevailed regarding the assignments of the observed modes at 810 and 572 cm⁻¹ is cleared and it is shown that the so called bare helix (polyU-U) has a different minimum energy state and hence spectrally different. Dispersion of the normal modes in the two helices shows marked differences which are characteristic of the extent of electrical/mechanical coupling along the chain and between the chain and the base. Values predicted for the heat capacity as a function of temperature for polyU is also reported.     

Effect of gamma rays on PADC detectors

The effect of Gamma radiation in Polyallydiglycol carbonate (PADC) detectorrs has been studied in the dose range of 10⁰–10⁶ Gy. Some of the properties like bulk-etch rate, track-etch rate, activation energy for bulk and track-etching have been found out for different gamma doses from ⁶⁰Co Source in PADC. The experimental results are presented and discussed.     

Instrumentation for PSD-based neutron diffractometers at Dhruva reactor

Linear position sensitive detectors (PSDs) are widely used to configure neutron diffractometers and other instruments. Necessary front-end electronics and a data acquisition system [1] is developed to cater to such instruments built around the Dhruva research reactor in BARC. These include three diffractometers with multiple PSDs and four with single PSD. The front-end electronics consists of high voltage units, preamplifiers [2],shaping amplifiers, ratio ADCs (RDC) [3]. The data acquisition system consists of an interface card and software. Commercially available hardware like temperature controller or stepper motor controller connected over GPIB or RS232 are also integrated in the data acquisition system. The data acquisition is automated so that it can continue unattended for control parameter like temperature, thus enabling optimum utilization of available beam time. The instrumentation is scalable and can be easily configured for various instrumental requirements. The front-end electronics and the data acquisition system are described here.     

Behavior of adhesive joints in corrosive environment

An experimental study was undertaken to determine the effect of corrosive environments on the strength of adhesive joints between pairs of glass-fiber-reinforced-plastic (GRP) plates and plates of GRP bonded to aluminum (Al). Two corrosive agents, each in three concentrations, were used: sulphuric acid (30, 50 and 60 percent) and sodium chloride (15, 20 and 25 percent). The results indicate a loss of strength with immersion time that levels off after a certain time. This loss of strength was more severe for the sulphuric acid than for sodium chloride. Ultrasonic attenuation of the adhesive joints was also monitored and it was found to increase with the immersion time, suggesting that the corrosion created inhomogenieties in the bond. The loss of strength and the increase in ultrasonic attenuation were both greater for greater concentrations of each of the corrosive agents.