4,840 research outputs found
Electron-cyclotron maser and solar microwave millisecond spike emission
An intense solar microwave millisecond spike emission (SMMSE) event was observed on May 16, 1981 by Zhao and Jin at Beijing Observatory. The peak flux density of the spikes is high to 5 x 100,000 s.f.u. and the corresponding brightness temperature (BT) reaches approx. 10 to the 15th K. In order to explain the observed properties of SMMSE, it is proposed that a beam of electrons with energy of tens KeV injected from the acceleration region downwards into an emerging magnetic arch forms so-called hollow beam distribution and causes electron-cyclotron maser (ECM) instability. The growth rate of second harmonic X-mode is calculated and its change with time is deduced. It is shown that the saturation time of ECM is t sub s approx. equals 0.42 ms and only at last short stage (delta t less than 0.2 t sub s) the growth rate decreases to zero rather rapidly. So a SMMSE with very high BT will be produced if the ratio of number density of nonthermal electrons to that of background electrons, n sub s/n sub e, is larger than 4 x .00001
Revisiting the as a hadronic molecule and its strong decays
Recently, the Belle collaboration measured the ratios of the branching
fractions of the newly observed excited state. They did not
observe significant signals for the decay, and reported an upper limit for the ratio of the three
body decay to the two body decay mode of . In
this work, we revisit the newly observed from the molecular
perspective where this resonance appears to be a dynamically generated state
with spin-parity from the coupled channels interactions of the and in -wave and in -wave. With
the model parameters for the -wave interaction, we show that the ratio of
these decay fractions reported recently by the Belle collaboration can be
easily accommodated.Comment: Published version. Published in Eur.\ Phys.\ J.\ C {\bf 80}, 361
(2020
Statistical analysis of fast hard X-ray bursts by SMM observations and microwave bursts by ground-based observations
In order to understand the relationship between fast hard X-ray bursts (HXRB) and microwave bursts (MWB), data were used from the following publications: NASA Technical Memorandum 84998; Solar Geological Data (1980 to 1983); monthly report of Solar Radio Emission; and NASA and NSF: Solar Geophysical Data (1980 to 1983). For analyzing individual events, the criterion of the same event for HXRB and MWB is determined by peak time difference. There is a good linear correlation between the physical parameter of HXRB and MWB
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