XXth International Conference on Neutrino Physics and Astrophysics

Poster Abstract


Long-Wavelength Transition Radiation Application for High-Energy Neutrino Detection

Recently, the number of experiments concerned with investigations of ultrahigh-energy cosmic ray neutrinos striking the Earth's or Moon's soil has been performed [1,2]. Electromagnetic showers in a media are expected to set up centimeter coherent Transition and Cherenkov radiation. Generation of coherent long-wavelength transition and Cherenkov radiation is caused by the charge asymmetry in electromagnetic particles cascade ("Askaryan effect"). For wavelengths larger than shower size the radiation intensity will be proportional to the squared number of excess electrons in cascade, in contrast to the linear dependence for shorter wavelength region. This effect gives the tool for neutrino detection problem. Some new searches of radio-frequency emission by particles cascades resulted by high-energy cosmic particles from the lunar regolith and Antarctic ice are planned now [2]. The theoretical background for implications of coherent transition radiation for high-energy neutrino detection problem is proposed. We have showed that for performed experiments [2] (typical electron's energies in cascade 30-100MeV), as well transversal as longitudinal sizes of region where radiation is formed can reach some meters or tens of meters correspondingly. Therefore, for "forward" direction, detector will be placed in the "formation region". We showed that the strong distortion for well-known results caused by the interference between own electrons field and fields of transition radiation will occur [3]. Moreover, it is shown, that for various detectors' arrangements and various angles of observation the sufficiently different situation connected with electron's fields or transition radiation fields dominating will observe. Both effect of small-size detector and effect of finite transversal size of experimental setup aren't considered earlier for this problem. We have obtained the simple analytical formulae for "forward" electromagnetic energy flux through the detector place in the formation region. Taking into account these effects can help to the more correct experimental data analyzing for the performed and planned neutrino detection experiments.


1. G.M.Frichter, J.P.Ralston & D.W.McKay, "Radio-frequency emission from electromagnetic cascades", Phys. Rev. D 53 (1996) 1684.
2. P.Gorham et al., "Radio-frequency measurements of coherent transition and cherenkov radiation: implications for high-energy neutrino detection", hep-ex/0004007
3. S.N.Dobrovolsky & N.F.Shul'ga, "On the distrubution of long-wave transition and diffraction radiation by relativistic electrons in the formation zone", Proc. 5-th International Symposium RREPS 01, Lake Aya, Russia, Sept. 2001, p35.

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