Status and perspectives of the COBRA double-beta decay experiment

The COBRA experiment is going to use a large amount of CdZnTe semiconductor detectors to perform a search for various double-beta-decay modes. The current status of the experiment is presented, as well as first results. Improved half-life limits for the ground-state transitions of ⁶⁴Zn and ¹²⁰Te for 0νβ ⁺/EC and 0νECEC have been obtained and the rate of the 4-fold forbidden ¹¹³Cd decays has been measured. A short outlook on future activities is also given.     

India-based Neutrino Observatory (INO)

We present some physics possibilities with an iron calorimeter detector (ICAL) and a status report on the feasibility study to construct such a detector at a future possible India-based Neutrino Observatory (INO). This talk was given at the workshop on high energy physics phenomenology, WHEPP-8, in Jan. 2004, at IIT Bombay.     

Theoretical prediction of latent track regression in neutrino experiment with nuclear emulsions

We try to predict the sight of neutrino interaction inside nuclear emulsion after long exposure. It is very important because regression decreases the grain density on charge particle tracks.     

Atom Capture by Nanotube and Scaling Anomaly

The existence of bound state of the polarizable neutral atom in the inverse square potential created by the electric field of a single walled charged carbon nanotube (SWNT) is shown to be theoretically possible. The consideration of inequivalent boundary conditions due to self-adjoint extensions lead to this nontrivial bound state solution. It is also shown that the scaling anomaly is responsible for the existence of such bound state. Binding of the polarizable atoms in the coupling constant interval η ²∈[0,1) may be responsible for the smearing of the edge of steps in quantized conductance, which has not been considered so far in the literature.     

Improvement of amorphous silicon n-i-p solar cells by incorporating double-layer hydrogenated nanocrystalline silicon structure

We develop a double-layer p-type hydrogenated nanocrystalline silicon (p-nc-Si:H) structure consisting of a low hydrogen diluted i/p buffer layer and a high hydrogen diluted p-layer to improve the hydrogenated amorphous silicon (a-Si:H) n-i-p solar cells. The electrical, optical and structural properties of p-nc-Si:H films with different hydrogen dilution ratio (R_H) are investigated. High conductivity, low activation energy and wide band gap are achieved for the thin films. Raman spectroscopy and high-resolution transmission electron microscopy (HRTEM) analyses indicate that the thin films contain nanocrystallites with grain size around 3-5 nm embedded in the amorphous silicon matrix. By inserting a p-nc-Si:H buffer layer at the i/p interface, the overall performance of the solar cell is improved significantly compared to the bufferless cell. The improvement is correlated with the reduction of the density of defect states at the i/p interface.     

Can a non-unitary effect be prominent In neutrino oscillation measurements?

Subject to neutrino experiments, the mixing matrix of ordinary neutrinos can still have small vi-olation from unitarity. We introduce a quasi-unitary matrix to interpret this violation and propose a natural scheme to parameterize it. A quasi-unitary factor △QF is defined to be measured in neutrino oscillation exper-iments and the numerical results show that the improvement in experimental precision may help us figure out the secret of neutrino mixing.     

A possible scenario of the Pioneer anomaly in the framework of Finsler geometry

The weak field approximation of geodesics in Randers–Finsler space is investigated. We show that a Finsler structure of Randers space corresponds to the constant and sunward anomalous acceleration demonstrated by the Pioneer 10 and 11 data. The additional term in the geodesic equation acts as “electric force”, which provides the anomalous acceleration.