Long-term stability test of a triple GEM detector

The main aim of the study is to perform the long-term stability test of gain of the single mask triple GEM detector. A simple method is used for this long- term stability test using a radioactive X-ray source with high activity. The test is continued till accumulation of charge per unit area > 12.0 mC/mm2. The details of the chamber fabrication, the test set-up, the method of measurement and the test results are presented in this paper.Comment: 8 pages, 5 figure

Efficient transport of femtosecond laser-generated fast electrons in a millimeter thick graphite

We demonstrate efficient transport of fast electrons generated by ∼1018 W/cm2, 30 fs, 800 nm laser pulses through a millimeter thick polycrystalline graphite. Measurements of hot electron spectra at the front side of the graphite target show enhancement in terms of the electron flux and temperature, while the spectra at the rear confirm the ability of the graphite to transport large electron currents over a macroscopic distance of a millimeter. In addition, protons of keV energies are observed at the rear side of such a macroscopically thick target and attributed to the target-normal-sheath-acceleration mechanism

Controlling femtosecond-laser-driven shock-waves in hot, dense plasma

Ultrafast pump-probe reflectometry and Doppler spectrometry of a supercritical density plasma layer excited by 1017-1018 W/cm2 intensity, 30 fs, and 800 nm laser pulses reveal the interplay of laser intensity contrast and inward shock wave strength. The inward shock wave velocity increases with an increase in laser intensity contrast. This trend is supported by simulations as well as by a separate independent experiment employing an external prepulse to control the inward motion of the shock wave. This kind of cost-effective control of shock wave strength using femtosecond pulses could open up new applications in medicine, science, and engineering

Neutrino oscillations with disentanglement of a neutrino from its partners

We bring attention to the fact that in order to understand existing data on neutrino oscillations, and to design future experiments, it is imperative to appreciate the role of quantum entanglement. Once this is accounted for, the resulting energy-momentum conserving phenomenology requires a single new parameter related to disentanglement of a neutrino from its partners. This parameter may not be CP symmetric. We illustrate the new ideas, with potentially measurable effects, in the context of a novel experiment recently proposed by Gavrin, Gorbachev, Veretenkin, and Cleveland. The strongest impact of our ideas is on the resolution of various anomalies in neutrino oscillations and on neutrino propagation in astrophysical environments.Comment: 6 page

Dirac field in topologically massive gravity

We consider a Dirac field coupled minimally to the Mielke-Baekler model of gravity and investigate cosmological solutions in three dimensions. We arrive at a family of solutions which exists even in the limit of vanishing cosmological constant.Comment: 12 pages. Title changed. Conclusion extended. Appendix added. To appear in Gen. Rel. Gra

Attenuation of electromagnetic radiation in Nuclear Track Detectors

A systematic study of the attenuation of electromagnetic radiation in Nuclear Track Detectors (NTDs) is carried out. The attenuation of gamma-ray, X-ray, UV, visible, and infrared radiation in NTDs are investigated using NaI(Tl) detector, Gas Electron Multiplier (GEM) detector, UV-Vis spectrophotometer, and FTIR spectrophotometer respectively. The values of some important parameters (e.g., optical depth, attenuation coefficient, etc.) of three commercially available NTDs (PET, Makrofol r and CR-39 r ), at the relevant region of the electromagnetic spectrum, is determined. The details of the experimental techniques and the results are also presented in this paper.Comment: 10 page

Returns to Foreign Language Skills in a Developing Country: The Case of Turkey

Foreign language skills represent a form of human capital that can be rewarded in the labor market. Drawing on data from the Adult Education Survey of 2007, this is the first study estimating returns to foreign language skills in Turkey. We contribute to the literature on the economic value of language knowledge, with a special focus on a country characterized by fast economic and social development. Although English is the most widely spoken foreign language in Turkey, we initially consider the economic value of different foreign languages among the employed males aged 25 to 65. We find positive and significant returns to proficiency in English and Russian, which increase with the level of competence. Knowledge of French and German also appears to be positively rewarded in the Turkish labor market, although their economic value seems mostly linked to an increased likelihood to hold specific occupations rather than increased earnings within occupations. Focusing on English, we also explore the heterogeneity in returns to different levels of proficiency by frequency of English use at work, birth-cohort, education, occupation and rural/urban location. The results are also robust to the endogenous specification of English language skills

Gravitational field around a screwed superconducting cosmic string in scalar-tensor theories

We obtain the solution that corresponds to a screwed superconducting cosmic string (SSCS) in the framework of a general scalar-tensor theory including torsion. We investigate the metric of the SSCS in Brans-Dicke theory with torsion and analyze the case without torsion. We show that in the case with torsion the space-time background presents other properties different from that in which torsion is absent. When the spin vanish, this torsion is a $\phi$-gradient and then it propagates outside of the string. We investigate the effect of torsion on the gravitational force and on the geodesics of a test-particle moving around the SSCS. The accretion of matter by wakes formation when a SSCS moves with speed $v$ is investigated. We compare our results with those obtained for cosmic strings in the framework of scalar-tensor theory.Comment: 22 pages, LaTeX, presented at the "XXII - Encontro Nacional de Fisica de Particulas e Campos", Sao Lourenco, MG, Brazi