Characteristics of Four Upward-Pointing Cosmic-Ray-like Events Observed with ANITA.

We report on four radio-detected cosmic-ray (CR) or CR-like events observed with the Antarctic Impulsive Transient Antenna (ANITA), a NASA-sponsored long-duration balloon payload. Two of the four were previously identified as stratospheric CR air showers during the ANITA-I flight. A third stratospheric CR was detected during the ANITA-II flight. Here, we report on characteristics of these three unusual CR events, which develop nearly horizontally, 20-30 km above the surface of Earth. In addition, we report on a fourth steeply upward-pointing ANITA-I CR-like radio event which has characteristics consistent with a primary that emerged from the surface of the ice. This suggests a possible τ-lepton decay as the origin of this event, but such an interpretation would require significant suppression of the standard model τ-neutrino cross section.

Observation of ultrahigh-energy cosmic rays with the ANITA balloon-borne radio interferometer.

We report the observation of 16 cosmic ray events with a mean energy of 1.5 × 10¹9 eV via radio pulses originating from the interaction of the cosmic ray air shower with the Antarctic geomagnetic field, a process known as geosynchrotron emission. We present measurements in the 300-900 MHz range, which are the first self-triggered, first ultrawide band, first far-field, and the highest energy sample of cosmic ray events collected with the radio technique. Their properties are inconsistent with current ground-based geosynchrotron models. The emission is 100% polarized in the plane perpendicular to the projected geomagnetic field. Fourteen events are seen to have a phase inversion due to reflection of the radio beam off the ice surface, and two additional events are seen directly from above the horizon. Based on a likelihood analysis, we estimate angular pointing precision of order 2° for the event arrival directions.

Naturally occurring human antiglobulins with specificity for E.

Human sera have been examined for antibodies with specific reactivity for gammaE using the tanned cell hemagglutination test. Cells tanned with three different gammaE myeloma proteins provided a reproducible test system. Inhibition of agglutination reactions by gammaE proteins, but not by gammaG, gammaA, gammaM, or gammaD confirmed the specificity of these reactions. 8.5% of 304 serial serum samples obtained from miscellaneous hospitalized patients showed clear-cut anti-gamma-globulins with specificity for gammaE. In most of these instances no definite clinical history of concomitant allergic disorders could be obtained. 53% of 73 patients with well-established allergic disorders (hay fever, extrinsic asthma) showed serum anti-gamma-globulins with reactivity for gammaE. Some patients studied before and after desensitization to Bermuda grass allergen showed an increase in titer or a conversion from negative to positive reactions for anti-gammaE antibodies following several month courses of progressive desensitization. Gradient and gel filtration studies indicated that anti-gammaE globulins were 19S gammaM in all instances. No clear correlation was noted between quantitative serum gammaE levels and titer of anti-gammaE antibodies.19S serum fractions with anti-gammaE antibody activity did not release histamine from normal human peripheral blood leukocytes, whereas specific rabbit anti-gammaE antisera consistently induced leukocytic histamine release. Moreover, macroglobulin fractions with anti-gammaE activity did not block allergen-specific leukocyte histamine release induced by in vitro leukocyte challenge with allergens such as Bermuda grass and leukocytes from allergic donors. In some instances 19S human serum fractions with anti-gammaE activity appeared to potentiate histamine release when incubated concomitantly with specific allergen and leukocytes from allergic individuals.

Inhibition of precursor incorporation into nucleic acids of mammalian tissues by antimalarial aminoquinolines.

1 Chloroquine, primaquine and ethidium inhibitied thymidine incorporation into deoxyribonucleic acid of rat tissues when administered concurrently with the labelled precursor. 2 Chloroquine and primaquine inhibited the incorporation of uridine and adenine, but not orotate, into various ribonucleic acid fractions of liver of rats and mice. These drugs had no effect on leucine incorporation into hepatic protein in rats or mice. 3 Although chloroquine and primaquine are active against different stages in the life cycle of the malarial parasites, the two aminoquinolines exert similar effects in rodent tissues.

New limits on the ultrahigh energy cosmic neutrino flux from the ANITA experiment.

We report initial results of the first flight of the Antarctic Impulsive Transient Antenna (ANITA-1) 2006-2007 Long Duration Balloon flight, which searched for evidence of a diffuse flux of cosmic neutrinos above energies of E(nu) approximately 3 x 10(18) eV. ANITA-1 flew for 35 days looking for radio impulses due to the Askaryan effect in neutrino-induced electromagnetic showers within the Antarctic ice sheets. We report here on our initial analysis, which was performed as a blind search of the data. No neutrino candidates are seen, with no detected physics background. We set model-independent limits based on this result. Upper limits derived from our analysis rule out the highest cosmogenic neutrino models. In a background horizontal-polarization channel, we also detect six events consistent with radio impulses from ultrahigh energy extensive air showers.

Observations of the Askaryan effect in ice.

We report on observations of coherent, impulsive radio Cherenkov radiation from electromagnetic showers in solid ice. This is the first observation of the Askaryan effect in ice. As part of the complete validation process for the ANITA experiment, we performed an experiment at the Stanford Linear Accelerator Center in June 2006 using a 7.5 metric ton ice target. We measure for the first time the large-scale angular dependence of the radiation pattern, a major factor in determining the solid-angle acceptance of ultrahigh-energy neutrino detectors.