Observation of the Askaryan Effect: Coherent Microwave Cherenkov Emission From Charge Asymmetry in High-Energy Particle Cascades

Technical Report · Wed Jan 24 04:00:00 EST 2001

DOI:https://doi.org/10.2172/784853· OSTI ID:784853

Field, Clive ^[1]

---

1. SLAC

We present the first direct experimental evidence for the charge excess in high energy particle showers predicted nearly 40 years ago by Askaryan. We directed bremsstrahlung photons from picosecond pulses of 28.5 GeV electrons at the SLAC Final Focus Test Beam facility into a 3.5 ton silica sand target, producing electromagnetic showers several meters long. A series of antennas spanning 0.3 to 6 GHz were used to detect strong, sub-nanosecond radio frequency pulses produced whenever a shower was present. The measured electric field strengths are consistent with a completely coherent radiation process. The pulses show 100% linear polarization, consistent with the expectations of Cherenkov radiation. The field strength versus depth closely follows the expected particle number density profile of the cascade, consistent with emission from excess charge distributed along the shower. These measurements therefore provide strong support for experiments designed to detect high energy cosmic rays and neutrinos via coherent radio emission from their cascades.

• Research Organization: Stanford Linear Accelerator Center, Menlo Park, CA (US)
• Sponsoring Organization: USDOE Office of Energy Research (ER) (US)
• DOE Contract Number: AC03-76SF00515
• OSTI ID: 784853
• Report Number(s): SLAC-PUB-8768
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANTENNAS
ASYMMETRY
BREMSSTRAHLUNG
CASCADE SHOWERS
CHERENKOV RADIATION
COHERENT RADIATION
COSMIC SHOWERS
ELECTRIC FIELDS
ELECTRONS
NEUTRINOS
PHOTONS
POLARIZATION
SILICA
TARGETS