A lead-glass hodoscope calorimeter that was constructed for use in the Jefferson Lab Real Compton Scattering experiment is described. The detector provides a measurement of the coordinates and the energy of scattered photons in the GeV energy range w
ith resolutions of 5 mm and 6%/sqrt(E{gamma} [GeV]). Features of both the detector design and its performance in the high luminosity environment during the experiment are presented.
Three experimental concepts investigating possible anisotropy of the speed of light are presented. They are based on i) beam deflection in a 180 degree magnetic arc, ii) narrow resonance production in an electron-positron collider, and iii) the ratio
of magnetic moments of an electron and a positron moving in opposite directions.
We propose an experiment to search for a new gauge boson, A$^prime$, in $e^+e^-$ annihilation by means of a positron beam incident on a gas hydrogen target internal to the VEPP-3 storage ring. The search method is based on a missing mass spectra in t
he reaction $e^+e^-rightarrow gamma$ A$^prime$. It allows observation of the A$^prime$ signal independently of its decay modes and life time. The projected result of this experiment corresponds to an upper limit on the square of coupling constant $|f_{etext{A}{^prime}}|^2=1cdot 10^{-8}$ with a signal-to-noise ratio of five to one at an A$^prime$ mass of 15 MeV.
We report on the design and commissioning of two silica aerogel Cherenkov detectors with different refractive indices. In particular, extraordinary performance in terms of the number of detected photoelectrons was achieved through an appropriate choi
ce of PMT type and reflector, along with some design considerations. After four years of operation, the number of detected photoelectrons was found to be noticeably reduced in both detectors as a result of contamination, yellowing, of the aerogel material. Along with the details of the set-up, we illustrate the characteristics of the detectors during different time periods and the probable causes of the contamination. In particular we show that the replacement of the contaminated aerogel and parts of the reflecting material has almost restored the initial performance of the detectors.
