Aim of the TA-EUS0 project is to install a prototype of the JEM-EUSO telescope on the Telescope Array site in Black Rock Mesa, Utah and perform observation of natural and artificial ultraviolet ...light. The detector consists of one Photo Detector Module (PDM), identical to the 137 present on the JEM-EUSO focal surface. Each PDM is composed by 36 Hamamatsu multi-anode photomultipliers (64 channels per tube), for a total of 2304 channels. Front-End readout is performed by 36 ASICS, with trigger and readout tasks performed by two FPGA boards that send the data to a CPU and storage system. Two, 1 meter side square Fresnel lenses provide a field-of-view of 8 degrees. The telescope will be housed in a container located in front of the fluorescence detector of the Telescope Array collaboration, looking in the direction of the ELF (Electron Light Source) and CLF (Central Laser Facility). Aim of the project is to calibrate the response function of the EUSO telescope with the TA fluorescence detector in presence of a shower of known intensity and distribution. An initial run of about six months starting from end 2012 is foreseen, during which we expect to observe, triggered by TA electronics, a few cosmic ray events which will be used to further refine the calibration of the EU SO-Ground with TA. Medium term plans include the increase of the number of PDM and therefore the field of view.
In association with the large solar flare of April 15, 2001, the Chacaltaya neutron monitor observed a 3.6
σ enhancement of the counting rate between 13:51 and 14:15 UT. Since the enhancement was ...observed beginning 11
min before the GLE, solar neutrons must be involved in this enhancement. The integral energy spectrum of solar neutrons can be expressed by a simple power law in energy with the index
γ
=
-
3.0
±
1.0
. On the other hand, an integral energy spectrum of solar protons has been obtained in the energy range between 650
MeV and 12
GeV. The spectrum can also be expressed by a power law with the power index
γ
=
-
2.75
±
0.15
. The flux of solar protons observed at Chacaltaya (at ⩾12
GeV) was already one order less than the flux of the galactic cosmic rays. It may be the first simultaneous observation of the energy spectra of both high-energy protons and neutrons. Comparing the
Yohkoh soft X-ray telescope images with the observed particle time profiles, an interesting picture of the particle acceleration mechanism has been deduced.
We report on a measurement of the cosmic ray energy spectrum by the Telescope Array Low-Energy Extension (TALE) air fluorescence detector (FD). The TALE air FD is also sensitive to the Cherenkov ...light produced by shower particles. Low-energy cosmic rays, in the PeV energy range, are detectable by TALE as Cherenkov events. Using these events, we measure the energy spectrum from a low energy of ∼2 PeV to an energy greater than 100 PeV. Above 100 PeV, TALE can detect cosmic rays using air fluorescence. This allows for the extension of the measurement to energies greater than a few EeV. In this paper, we describe the detector, explain the technique, and present results from a measurement of the spectrum using ∼1000 hr of observation. The observed spectrum shows a clear steepening near 1017.1 eV, along with an ankle-like structure at 1016.2 eV. These features present important constraints on the origin of galactic cosmic rays and on propagation models. The feature at 1017.1 eV may also mark the end of the galactic cosmic ray flux and the start of the transition to extragalactic sources.
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