Cotton Variety Experiments at the Main Station 1912 to 1922.

22 p

Heritable Chlorophyll Deficiencies in Seedling Cotton.

22 p

Search for Anisotropy of Ultra-High Energy Cosmic Rays with the Telescope Array Experiment

We study the anisotropy of Ultra-High Energy Cosmic Ray (UHECR) events collected by the Telescope Array (TA) detector in the first 40 months of operation. Following earlier studies, we examine event sets with energy thresholds of 10 EeV, 40 EeV, and 57 EeV. We find that the distributions of the events in right ascension and declination are compatible with an isotropic distribution in all three sets. We then compare with previously reported clustering of the UHECR events at small angular scales. No significant clustering is found in the TA data. We then check the events with E>57 EeV for correlations with nearby active galactic nuclei. No significant correlation is found. Finally, we examine all three sets for correlations with the large-scale structure of the Universe. We find that the two higher-energy sets are compatible with both an isotropic distribution and the hypothesis that UHECR sources follow the matter distribution of the Universe (the LSS hypothesis), while the event set with E>10 EeV is compatible with isotropy and is not compatible with the LSS hypothesis at 95% CL unless large deflection angles are also assumed. We show that accounting for UHECR deflections in a realistic model of the Galactic magnetic field can make this set compatible with the LSS hypothesis.Comment: 10 pages, 9 figure

Measurement of the proton-air cross section with Telescope Array's Middle Drum detector and surface array in hybrid mode

In this work we are reporting on the measurement of the proton-air inelastic cross section sigma(inel)(p-air) using the Telescope Array detector. Based on the measurement of the sigma(inel)(p-air), the proton-proton cross section sigma(p-p) value is also determined at root s = 95(-8)(+5) TeV. Detecting cosmic ray events at ultrahigh energies with the Telescope Array enables us to study this fundamental parameter that we are otherwise unable to access with particle accelerators. The data used in this report are the hybrid events observed by the Middle Drum fluorescence detector together with the surface array detector collected over five years. The value of the sigma(inel)(p-air) is found to be equal to 567.0 +/- 70.5[Stat](-25)(+29)[Sys] mb. The total proton-proton cross section is subsequently inferred from Glauber formalism and the Block, Halzen and Stanev QCD inspired fit and is found to be equal to 170(-44)(+48)[Stat](-17)(+19)[Sys] mb.open20

Indications of intermediate-scale anisotropy of cosmic rays with energy greater than 57 EeV in the northern sky measured with the surface detector of the Telescope Array experiment

We have searched for intermediate-scale anisotropy in the arrival directions of ultrahigh-energy cosmic rays with energies above 57 EeV in the northern sky using data collected over a 5 yr period by the surface detector of the Telescope Array experiment. We report on a cluster of events that we call the hotspot, found by oversampling using 20?? radius circles. The hotspot has a Li-Ma statistical significance of 5.1??, and is centered at R.A. = 146.??7, decl. = 43.??2. The position of the hotspot is about 19?? off of the supergalactic plane. The probability of a cluster of events of 5.1?? significance, appearing by chance in an isotropic cosmic-ray sky, is estimated to be 3.7 ?? 10-4 (3.4??).open2

A NORTHERN SKY SURVEY FOR POINT-LIKE SOURCES OF EeV NEUTRAL PARTICLES WITH THE TELESCOPE ARRAY EXPERIMENT

We report on the search for steady point-like sources of neutral particles around 10(18) eV between 2008 and 2013 May with the scintillator SD of the Telescope Array experiment. We found overall no significant point-like excess above 0.5 EeV in the northern sky. Subsequently, we also searched for coincidence with the Fermi bright Galactic sources. No significant coincidence was found within the statistical uncertainty. Hence, we set an upper limit on the neutron flux that corresponds to an averaged flux of 0.07 km(-2) yr(-1) for E > 1 EeV in the northern sky at the 95% confidence level. This is the most stringent flux upper limit in a northern sky survey assuming point-like sources. The upper limit at the 95% confidence level on the neutron flux from Cygnus X-3 is also set to 0.2 km(-2) yr(-1) for E > 0.5 EeV. This is an order of magnitude lower than previous flux measurementsopen0

The Cosmic Ray Energy Spectrum Observed with the Surface Detector of the Telescope Array Experiment

The Telescope Array (TA) collaboration has measured the energy spectrum of ultra-high energy cosmic rays with primary energies above 1.6 x 10^(18) eV. This measurement is based upon four years of observation by the surface detector component of TA. The spectrum shows a dip at an energy of 4.6 x 10^(18) eV and a steepening at 5.4 x 10^(19) eV which is consistent with the expectation from the GZK cutoff. We present the results of a technique, new to the analysis of ultra-high energy cosmic ray surface detector data, that involves generating a complete simulation of ultra-high energy cosmic rays striking the TA surface detector. The procedure starts with shower simulations using the CORSIKA Monte Carlo program where we have solved the problems caused by use of the "thinning" approximation. This simulation method allows us to make an accurate calculation of the acceptance of the detector for the energies concerned.Comment: Accepted for publication by Astrophysical Journal Letter

Upper limit on the flux of photons with energies above 10(19) eV using the Telescope Array surface detector

We search for ultra-high energy photons by analyzing geometrical properties of shower fronts of events registered by the Telescope Array surface detector. By making use of an event-by-event statistical method, we derive upper limits on the absolute flux of primary photons with energies above 1019, 1019.5, and 1020 eV based on the first three years of data takenopen4