Direct Observation of the Hyperfine Transition of the Ground State Positronium

We report the first direct measurement of the hyperfine transition of the ground state positronium. The hyperfine structure between ortho-positronium and para-positronium is about 203 GHz. We develop a new optical system to accumulate about 10 kW power using a gyrotron, a mode converter, and a Fabry-P\'{e}rot cavity. The hyperfine transition has been observed with a significance of 5.4 standard deviations. The transition probability is measured to be $A = 3.1^{+1.6}_{-1.2} \times 10^{-8}$ s$^{-1}$ for the first time, which is in good agreement with the theoretical value of $3.37 \times 10^{-8}$ s$^{-1}$

Instability of the Fast Cyclotron Wave in a Spiral Beam-Plasma System

The excitation of the fast cyclotron wave is observed in a magnetized plasma penetrated by a spiral electron beam. For the excitation to occur, the beam energy component perpendicular to the magnetic field is larger than about 20 percent of the total energy, which is consistent with the theoretical consideration

Observation of Bernstein Wave Propagating Obliquely to the Magnetic Field in a Streaming Plasma

Bernstein wave propagating obliquely to the magnetic field is excited by a coaxial antenna in a streaming plasma and detected by the interferometer system, which shows that the dispersion relation for the wave is consistent with the theoretical result. The other wave-like signal with shorter 'wavelength' is observed only on the downstream of the exciting antenna and its 'phase velocity' is approximately equal to the velocity of plasma stream calculated from tbe Doppler shifts of Bernstein waves on both UP- and down-streams, which may show that the signal does not propagate as the wave but floats down the plasma stream as the modulation of plasma particles

Cyclotron Damping of the Space Charge Wave of Beam in a Nonuniform Magnetic Field Region

The space charge wave of electron beam excited by the reactive medium instability in a uniform magnetic field region is observed to propagate into the increasing magnetic field region. When the wave passes through the cyclotron resonance region, it suffers a heavy cyclotron damping

A Dual-Beam Irradiation Facility for a Novel Hybrid Cancer Therapy

In this paper we present the main ideas and discuss both the feasibility and the conceptual design of a novel hybrid technique and equipment for an experimental cancer therapy based on the simultaneous and/or sequential application of two beams, namely a beam of neutrons and a CW (continuous wave) or intermittent sub-terahertz wave beam produced by a gyrotron for treatment of cancerous tumors. The main simulation tools for the development of the computer aided design (CAD) of the prospective experimental facility for clinical trials and study of such new medical technology are briefly reviewed. Some tasks for a further continuation of this feasibility analysis are formulated as well.Comment: 18 pages, 3 tables, 8 figures, 50 reference