A new way to explain the 511 keV signal from the center of the Galaxy and its possible consequences

The first gamma-ray line originating from outside the solar system that was ever detected is the 511 keV emission from the center of our Galaxy. The accepted explanation of this signal is the annihilation of electrons and positrons. However, despite 30 years of intense theoretical and observational investigation, the main sources of positrons have not been identified up to now. In this paper I propose an alternative explanation: the observed signal is due to atomic transitions to "small hydrogen atom," where electron is captured by proton on a small tight orbit around proton. I describe the status of the experimental search to find the small hydrogen atom both in astrophysics data and the lab, and propose new methods how to discover it in the lab directly. The reason we are interested in this problem is that it could explain some astrophysics observations. Key words: 511 keV peak at the galactic center, small hydrogen atom, DDL atom, dark matterComment: 10 page

Optical Properties of the DIRC Fused Silica Cherenkov Radiator

The DIRC is a new type of Cherenkov detector that is successfully operating as the hadronic particle identification system for the BABAR experiment at SLAC. The fused silica bars that serve as the DIRC's Cherenkov radiators must transmit the light over long optical pathlengths with a large number of internal reflections. This imposes a number of stringent and novel requirements on the bar properties. This note summarizes a large amount of R&D that was performed both to develop specifications and production methods and to determine whether commercially produced bars could meet the requirements. One of the major outcomes of this R&D work is an understanding of methods to select radiation hard and optically uniform fused silica material. Others include measurement of the wavelength dependency of the internal reflection coefficient, and its sensitivity to surface contaminants, development of radiator support methods, and selection of good optical glue.Comment: 36 pages, submitted to Nuclear Instruments and Methods

High Voltage in Noble Liquids for High Energy Physics

A workshop was held at Fermilab November 8-9, 2013 to discuss the challenges of using high voltage in noble liquids. The participants spanned the fields of neutrino, dark matter, and electric dipole moment physics. All presentations at the workshop were made in plenary sessions. This document summarizes the experiences and lessons learned from experiments in these fields at developing high voltage systems in noble liquids.Comment: 64 pages, 41 figures, 2 table

A simple argument that small hydrogen may exist

This paper discusses a possible existence of small hydrogen, which may have been created during the Big Bang before formation of normal hydrogen

Sub MeV Particles Detection and Identification in the MUNU detector ((1)ISN, IN2P3/CNRS-UJF, Grenoble, France, (2)Institut de Physique, Neuch\^atel, Switzerland, (3) INFN, Padova Italy, (4) Physik-Institut, Z\"{u}rich, Switzerland)

We report on the performance of a 1 m$^{3}$ TPC filled with CF$_{4}$ at 3 bar, immersed in liquid scintillator and viewed by photomultipliers. Particle detection, event identification and localization achieved by measuring both the current signal and the scintillation light are presented. Particular features of $\alpha$ particle detection are also discussed. Finally, the ${54}$Mn photopeak, reconstructed from the Compton scattering and recoil angle is shown.Comment: Latex, 19 pages, 20 figure

Energy loss of pions and electrons of 1 to 6 GeV/c in drift chambers operated with Xe,CO2(15%)

We present measurements of the energy loss of pions and electrons in drift chambers operated with a Xe,CO2(15%) mixture. The measurements are carried out for particle momenta from 1 to 6 GeV/c using prototype drift chambers for the ALICE TRD. Microscopic calculations are performed using input parameters calculated with GEANT3. These calculations reproduce well the measured average and most probable values for pions, but a higher Fermi plateau is required in order to reproduce our electron data. The widths of the measured distributions are smaller for data compared to the calculations. The electron/pion identification performance using the energy loss is also presented.Comment: 15 pages, 10 figures, accepted for publication in Nucl.Instrum.Meth.