The origin of the highest energy Galactic cosmic rays is still not understood, nor is the transition to EeV extragalactic particles. Scientific progress requires enhancements of existing air-shower ...arrays, such as: IceCube with its surface detector IceTop, and the low-energy extensions of both the Telescope Array and the Pierre Auger Observatory.
We report on the measurement of coherent radio emission from the electron beam sudden appearance at the Telescope Array Electron Light Source facility. This emission was detected by four independent ...radio detector setups sensitive to frequencies ranging from 50 MHz up to 12.5 GHz. We show that this phenomenon can be understood as a special case of coherent transition radiation by comparing the observed results with simulations. The in-nature application of this signal is given by the emission of cosmic ray or neutrino induced particle cascades traversing different media such as air, rock and ice.
The Ulysses High Energy Telescope (HET) allows for a comprehensive study of galactic cosmic-ray manganese due to the telescope's excellent mass resolution and large collecting area. The cosmic rays ...offer a direct sample of extra-solar material for chemical and isotopic study. However, the source of the cosmic rays cannot be examined directly. The observations in the solar system must be deconvolved with the effects of transport through the interstellar medium in order to calculate the source. Manganese isotopes in the cosmic rays provide a means of studying the parameters of this galactic propagation for the cosmic rays. Each of the the isotopes probes a separate aspect of the propagation model. $\rm\sp{53}Mn,$ a long-lived electron capture species, measures the time between the nucleosynthesis and acceleration of the cosmic rays. There is no evidence found for a source of $\rm\sp{53}Mn,$ but sensitivity to this is limited. The isotope $\rm\sp{54}Mn$ decays in the laboratory with $\tau\sb{1/2}=312$ days by electron capture, but in the cosmic rays it has a $\beta\sp-$ decay mode with a partial life-time which has not been experimentally measured. From the HET data, this partial half-life is found to be 1-2 Myr, if the iron-group cosmic rays propagate like the lighter cosmic rays. This raises the lower limit on the $\rm\sp{54}Mn\ \beta\sp-$ partial half-life by nearly a factor of 10, and more importantly, places an upper limit on the partial half-life. Finally, the stable $\rm\sp{55}Mn$ is found to have a source abundance, relative to iron, consistent with a solar system abundance at the source. The systematics in the propagation technique are discussed in order to understand these measurements. A general approach for determining the uncertainties in the transport equations is formulated.
Astropart.Phys.11:429-435,1999 Cosmic rays at the Earth include a secondary component originating in
collisions of primary particles with the diffuse interstellar gas. The
secondary cosmic rays are ...relatively rare but carry important information on
the Galactic propagation of the primary particles. The secondary component
includes a small fraction of antimatter particles, positrons and antiprotons.
In addition, positrons and antiprotons may also come from unusual sources and
possibly provide insight into new physics. For instance, the annihilation of
heavy supersymmetric dark matter particles within the Galactic halo could lead
to positrons or antiprotons with distinctive energy signatures. With the
High-Energy Antimatter Telescope (HEAT) balloon-borne instrument, we have
measured the abundances of positrons and electrons at energies between 1 and 50
GeV. The data suggest that indeed a small additional antimatter component may
be present that cannot be explained by a purely secondary production mechanism.
Here we describe the signature of the effect and discuss its possible origin.
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