Research

Telescope Array

Telescope Array (TA) is the largest cosmic ray detector in the northern hemisphere, located just to the west of Delta, UT. It detects cosmic-ray-induced extensive air shiowers for cosmic rays with energies above about 1 EeV (a sixth of Joule). The detector has two main components: an array of 500 surface detectors spaced every 1.2 km and covering 700 km² of the desert floor, and three sets of air-fluorescence telescopes which view the atmosphere above the surface array. The two detectors work together to produce a very accurate reconstruction of the air-shower geometry and size.   Learn More

TALE

TA Low Energy (TALE) is an extension of TA which has a much lower energy thrshold, but covers a much smaller area. By placing surface detectors only 400 m apart and pointing fluorescence telescopes to look higher in the sky, the energy thrshold of the detector is lowered to about 30 PeV (0.03 EeV). The telescopes pointed at high elevation angles also obeserve air Cherenkov radiation from air showers, with a threshold of about 2 PeV.   Learn More

NICHE

The air Cherenkov radiation from air showers can also be sampled at the ground with an array of photodetectors. This allows shower to be detected with a threshold as low as 0.1 PeV with large enough detectors ("light buckets"). The Non-Imaging CHErenkov (NICHE) array is a planned array of light buckets which will be placed in the field of view of TALE. The energy thrshold for NICHE will be about 0.5 PeV.   Learn More

UHECR Spectral Modeling

UHE cosmic rays are thought to come from extra-galactic sources since galactic magnetic fields are too low to contain cosmic rays of this energy for very long and because the arrival directions are nearly isotropic. Cosmic rays propagating of cosmological distances are subject to various energy-loss effects, so that the energy we observe for a cosmic ray at earth may be quite different that the energy it was created with. Modeling what the observed spectrum should look like given an input spectrum involves extensive Monte Carlo modeling.   Learn More

Non-Imaging Cherenkov Reconstruction Using Shower Universality Models

Determining bulk extensive air-shower parameters such as size (energy) and depth of shower maximum (X_max) from sampling the Cherenkov shower front is not straightforward. However, by using Shower Universality, the idea that all showers are the same near their maximum, should allow one to determine bulk parameters from samples of the shower front.   Learn More

HiRes

The High Resolution Fly's Eye detector (HiRes) was a predecessor experiment to TA. It used only air-fuorescence telescopes to observe extensive air showers, but relied on seeing the same shower from two different point (seeing in stereo).   Learn More

Rare Kaon Decays

Once upon a time Dr. Bergman worked as an accelerator-based particle physicist. In particular he worked on fixed target, kaon decay experiments: KTeV, at Fermilab; and E865 at BNL.   Learn More