Measurements of Coherent Cerenkov Radiation in Rock Salt: Implications for GZK Neutrino Underground Detector
We present results of the study of coherentČerenkov radiation from negative charge excess in electromagnetic cascades (Askaryan effect) in synthetic rock salt. In the first part of this work, the accelerator measurement was performed in the Stanford Linear Accelerator with pulsed bunches of 28.5 GeV electrons passing through Aluminum radiators, which produced a beam of bremsstrahlung photons in direction of the salt. Measurements cover the range of shower energies from 2.7 × 10 14 eV up to 8.0
... 10 14 eV up to 8.0 × 10 18 eV . With three different types of radio frequency receivers which altogether span the range of 200 -20000 MHz, we analyzed coherency of radiation produced within the target salt. In the second part, we conducted a search for the coherent radio pulses induced by high energy cosmic-rays. As a medium for detection ofČerenkov radiation, we use a 22 ton target of synthetic rock salt contained within a scintillation counter cosmic-ray hodoscope. Two parallel arrays of crossed bowtie antennas are put inside the salt bed and used as a detection tool. Here, we present expected rate for detection of cosmic ray protons and secondary muons above 'Salt Factory' sensitivity of 1.8 TeV. These measurements provide an excellent baseline for the Monte Carlo simulation of the performance of the 15.6 km 3 GZK neutrino detector placed inside a salt-dome formation. Results of the simulations show that this kind of detector can be used to put constraints on all GZK neutrino models in one year of work.