Čerenkov radiation from a finite trajectory of electrons

Takahashi, Toshiharu; Kanai, T.; Shibata, Yukio; Ishi, K.; Ikezawa, Mikihiko; Nakazato, T.; Oyamada, M.; Urasawa, S.; Yamakawa, Tetsu; Takami, Kiyoshi; Matsuyama, T.; Kobayashi, Katsuhei; Fujita, Yoshiaki

doi:10.1103/physreve.50.4041

Cited by 35 publications

(42 citation statements)

References 16 publications

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“…Cherenkov radiation from a finite electron track length is treated by Tamm [25], and discussed more recently in the context of coherent radiation from a LINAC beam by Takahashi et al [20] For electrons traversing a track of length L in a medium of index of refraction n [20]:…”

Section: B Cherenkov Radiationmentioning

confidence: 99%

“…In fact similar statements can be made about treatments of Cherenkov radiation for the case of a finite track length. Takahashi et al [20] have shown that this relation can be interpreted in terms of a CR-like component from the continuous portion of the track added to TR-like components from the end-points of the track. We have not attempted to make such a distinction, but we note again the strong physical connection between TR and CR.…”

Section: B Cherenkov Radiationmentioning

confidence: 99%

“…The spatial form factors can be estimated via a three-dimensional Fourier transform of the electron distribution (here assumed to have cylindrical symmetry); the angular form factor is somewhat more complex but can also be numerically evaluated if an estimate of the angular emittance of the beam is available [20].…”

Section: Coherent Emission From Electron Bunchesmentioning

confidence: 99%

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Radio-frequency measurements of coherent transition and Cherenkov radiation: Implications for high-energy neutrino detection

et al. 2000

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(To be published in Physical Review E)We report on measurements of 11-18 cm wavelength radio emission from interactions of 15.2 MeV pulsed electron bunches at the Argonne Wakefield Accelerator. The electrons were observed both in a configuration where they produced primarily transition radiation from an aluminum foil, and in a configuration designed for the electrons to produce Cherenkov radiation in a silica sand target. Our aim was to emulate the large electron excess expected to develop during an electromagnetic cascade initiated by an ultra-high-energy particle. Such charge asymmetries are predicted to produce strong coherent radio pulses, which are the basis for several experiments to detect high-energy neutrinos from the showers they induce in Antarctic ice and in the lunar regolith. We detected coherent emission which we attribute both to transition and possibly Cherenkov radiation at different levels depending on the experimental conditions. We discuss implications for experiments relying on radio emission for detection of electromagnetic cascades produced by ultra highenergy neutrinos.

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Section: B Cherenkov Radiationmentioning

confidence: 99%

Section: B Cherenkov Radiationmentioning

confidence: 99%

Section: Coherent Emission From Electron Bunchesmentioning

confidence: 99%

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Radio-frequency measurements of coherent transition and Cherenkov radiation: Implications for high-energy neutrino detection

et al. 2000

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“…The plausibility of Askaryan's arguments combined with more recent modeling and analysis 2{4] has led to a number of experimental searches for high energy neutrinos by exploiting the e ect at energies from 10 16 eV in Antarctic ice 5,6] up to 10 20 eV or more in the lunar regolith, using large ground-based radio telescopes 7{9]. Radio frequency pulses have been observed for many years from extensive air showers 10,11].…”

Section: Introductionmentioning

confidence: 99%

Observation of the Askaryan Effect

Saltzberg¹

2004

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Abstract. We present direct experimental evidence for the charge excess in high energy particle showers and corresponding radio emission predicted nearly 40 years ago by Askaryan. We directed picosecond pulses of GeV bremsstrahlung photons at the SLAC Final FocusTest Beam into a 3.5 ton silica sand target, producing electromagnetic showers several meters long. A s e r i e s o f a n tennas spanning 0.3 to 6 GHz detected strong, sub-nanosecond radio frequency pulses produced by the showers. Measurements of the polarization, coherence, timing, eld strength vs. shower depth, and eld strength vs. frequency are completely consistent with predictions. We also show t h e emission peaks at the Cherenkov angle in sand. These measurements thus provide strong support for experiments designed to detect high energy cosmic rays such as neutrinos via coherent radio emission from their cascades in dense dielectric media. I INTRODUCTIONDuring the development of a high-energy electromagnetic cascade in normal matter, Compton scattering knocks electrons from the material into the shower. In addition, positrons in the shower annihilate in ight. The combination of these processes should lead to a net 20-30% negative charge excess for the comoving compact body of particles that carry most of the shower energy. Askaryan 1] rst described this e ect, and noted that it should lead to strong coherent radio and microwave Cherenkov emission for showers that propagate within a dielectric. The range of wavelengths over which coherence obtains depends on the form factor of the shower bunch|wavelengths shorter than the bunch length su er from destructive interference and coherence is lost. However, in the fully coherent regime the radiated energy scales quadratically with the net charge of the particle bunch, and hence with the incoming energy. At ultra high energies the resulting coherent radio emission may carry o a signi cant fraction of the total energy in the cascade.The plausibility of Askaryan's arguments combined with more recent modeling and analysis 2{4] has led to a number of experimental searches for high energy eV or more in the lunar regolith, using large ground-based radio telescopes 7{9]. Radio frequency pulses have been observed for many years from extensive air showers 10,11]. However, it has been shown 12,13] that the dominant source of this emission is due to geomagnetic separation of charges, rather than the Askaryan e ect. Thus neither the charge asymmetry nor the resulting coherent Cherenkov radiation has ever been observed.In a previous paper 14] we described initial e orts to measure the coherent r a d i ofrequency (RF) emission from electron bunches interacting in a solid dielectric target of 360 kg of silica sand. That study, done with low-energy electrons (15 MeV), demonstrated the presence of coherent radiation in the form of extremely short and intense microwave pulses detectable over a wide frequency range. These results, while useful for understanding the coherent RF emission processes from relativistic charged pa...

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“…Takahashi et al 1994) from the charge excess of the shower, if the cascade breaks through the local surface. TR has spectral properties that make it more favorable for an array at lower frequencies: it produces equal power per unit bandwidth across the coherence region.…”

Section: Neutrino Interactions In the Earthmentioning

confidence: 99%

Prospects for radio detection of ultra-high energy cosmic rays and neutrinos

Falcke

Gorham

Protheroe

2004

New Astronomy Reviews

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The origin and nature of the highest energy cosmic ray events is currently the subject of intense investigation by giant air shower arrays and fluorescent detectors. These particles reach energies well beyond what can be achieved in ground-based particle accelerators and hence they are fundamental probes for particle physics as well as astrophysics. One of the main topics today focuses on the high energy end of the spectrum and the potential for the production of high-energy neutrinos. Above about 10 20 eV cosmic rays from extragalactic sources are expected to be severely attenuated by pion photoproduction interactions with photons of the cosmic microwave background. Investigating the shape of the cosmic ray spectrum near this predicted cut-off will be very important. In addition, a significant high-energy neutrino background is naturally expected as part of the pion decay chain which also contains much information.Because of the scarcity of these high-energy particles, larger and larger ground-based detectors have been built. The new generation of digital radio telescopes may play an important role in this, if properly designed. Radio detection of cosmic ray showers has a long history but was abandoned in the 1970's. Recent experimental developments together with sophisticated air shower simulations incorporating radio emission give a clearer understanding of the relationship between the air shower parameters and the radio signal, and have led to resurgence in its use. Observations of air showers by the SKA could, because of its large collecting area, contribute significantly to measuring the cosmic ray spectrum at the highest energies. Because of the large surface area of the moon, and the expected excellent angular resolution of the SKA, using the SKA to detect radio Cherenkov emission from neutrino-induced cascades in lunar regolith will be potentially the most important technique for investigating cosmic ray origin at energies above the photoproduction cut-off.

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Čerenkov radiation from a finite trajectory of electrons

Cited by 35 publications

References 16 publications

Radio-frequency measurements of coherent transition and Cherenkov radiation: Implications for high-energy neutrino detection

Radio-frequency measurements of coherent transition and Cherenkov radiation: Implications for high-energy neutrino detection

Observation of the Askaryan Effect

Prospects for radio detection of ultra-high energy cosmic rays and neutrinos

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