We report an investigation of the mass composition of cosmic rays with
energies from 3 to 100 EeV (1 EeV=$10^{18}$ eV) using the distributions of the
depth of shower maximum $X_\mathrm{max}$. The ...analysis relies on ${\sim}50,000$
events recorded by the Surface Detector of the Pierre Auger Observatory and a
deep-learning-based reconstruction algorithm. Above energies of 5 EeV, the data
set offers a 10-fold increase in statistics with respect to fluorescence
measurements at the Observatory. After cross-calibration using the Fluorescence
Detector, this enables the first measurement of the evolution of the mean and
the standard deviation of the $X_\mathrm{max}$ distributions up to 100 EeV. Our
findings are threefold:
(1.) The evolution of the mean logarithmic mass towards a heavier composition
with increasing energy can be confirmed and is extended to 100 EeV.
(2.) The evolution of the fluctuations of $X_\mathrm{max}$ towards a heavier
and purer composition with increasing energy can be confirmed with high
statistics. We report a rather heavy composition and small fluctuations in
$X_\mathrm{max}$ at the highest energies.
(3.) We find indications for a characteristic structure beyond a constant
change in the mean logarithmic mass, featuring three breaks that are observed
in proximity to the ankle, instep, and suppression features in the energy
spectrum.
We present measurements of the atmospheric depth of the shower maximum
$X_\mathrm{max}$, inferred for the first time on an event-by-event level using
the Surface Detector of the Pierre Auger ...Observatory. Using deep learning, we
were able to extend measurements of the $X_\mathrm{max}$ distributions up to
energies of 100 EeV ($10^{20}$ eV), not yet revealed by current measurements,
providing new insights into the mass composition of cosmic rays at extreme
energies. Gaining a 10-fold increase in statistics compared to the Fluorescence
Detector data, we find evidence that the rate of change of the average
$X_\mathrm{max}$ with the logarithm of energy features three breaks at
$6.5\pm0.6~(\mathrm{stat})\pm1~(\mathrm{sys})$ EeV, $11\pm
2~(\mathrm{stat})\pm1~(\mathrm{sys})$ EeV, and
$31\pm5~(\mathrm{stat})\pm3~(\mathrm{sys})$ EeV, in the vicinity to the three
prominent features (ankle, instep, suppression) of the cosmic-ray flux. The
energy evolution of the mean and standard deviation of the measured
$X_\mathrm{max}$ distributions indicates that the mass composition becomes
increasingly heavier and purer, thus being incompatible with a large fraction
of light nuclei between 50 EeV and 100 EeV.
We present measurements of the atmospheric depth of the shower maximum \(X_\mathrm{max}\), inferred for the first time on an event-by-event level using the Surface Detector of the Pierre Auger ...Observatory. Using deep learning, we were able to extend measurements of the \(X_\mathrm{max}\) distributions up to energies of 100 EeV (\(10^{20}\) eV), not yet revealed by current measurements, providing new insights into the mass composition of cosmic rays at extreme energies. Gaining a 10-fold increase in statistics compared to the Fluorescence Detector data, we find evidence that the rate of change of the average \(X_\mathrm{max}\) with the logarithm of energy features three breaks at \(6.5\pm0.6~(\mathrm{stat})\pm1~(\mathrm{sys})\) EeV, \(11\pm 2~(\mathrm{stat})\pm1~(\mathrm{sys})\) EeV, and \(31\pm5~(\mathrm{stat})\pm3~(\mathrm{sys})\) EeV, in the vicinity to the three prominent features (ankle, instep, suppression) of the cosmic-ray flux. The energy evolution of the mean and standard deviation of the measured \(X_\mathrm{max}\) distributions indicates that the mass composition becomes increasingly heavier and purer, thus being incompatible with a large fraction of light nuclei between 50 EeV and 100 EeV.
We report an investigation of the mass composition of cosmic rays with energies from 3 to 100 EeV (1 EeV=\(10^{18}\) eV) using the distributions of the depth of shower maximum \(X_\mathrm{max}\). The ...analysis relies on \({\sim}50,000\) events recorded by the Surface Detector of the Pierre Auger Observatory and a deep-learning-based reconstruction algorithm. Above energies of 5 EeV, the data set offers a 10-fold increase in statistics with respect to fluorescence measurements at the Observatory. After cross-calibration using the Fluorescence Detector, this enables the first measurement of the evolution of the mean and the standard deviation of the \(X_\mathrm{max}\) distributions up to 100 EeV. Our findings are threefold: (1.) The evolution of the mean logarithmic mass towards a heavier composition with increasing energy can be confirmed and is extended to 100 EeV. (2.) The evolution of the fluctuations of \(X_\mathrm{max}\) towards a heavier and purer composition with increasing energy can be confirmed with high statistics. We report a rather heavy composition and small fluctuations in \(X_\mathrm{max}\) at the highest energies. (3.) We find indications for a characteristic structure beyond a constant change in the mean logarithmic mass, featuring three breaks that are observed in proximity to the ankle, instep, and suppression features in the energy spectrum.
A number of cell-cycle checkpoint genes have been shown to play important roles in meiosis. We have characterized the human and mouse counterpart of the Schizosaccharomyces pombe Rad3 protein, named ...Atr (for ataxia-telangiectasia- and rad3-related), and the protein that is mutated in ataxia-telangiectasia, Atm. We demonstrate that ATR mRNA and protein are expressed in human and mouse testis. More detailed analysis of specific cells in seminiferous tubules shows localization of Atr to the nuclei of cells in the process of meiosis I. Using immunoprecipitation and immunoblot analysis, we show that Atr and Atm proteins are approximately 300 and 350 kD relative molecular mass, respectively, and further demonstrate that both proteins have associated protein kinase activity. Further, we demonstrate that Atr and Atm interact directly with meiotic chromosomes and show complementary localization patterns on synapsing chromosomes. Atr is found at sites along unpaired or asynapsed chromosomal axes, whereas Atm is found along synapsed chromosomal axes. This is the first demonstration of a nuclear association of Atr and Atm proteins with meiotic chromosomes and suggests a direct role for these proteins in recognizing and responding to DNA strand interruptions that occur during meiotic recombination.
The surface morphology of polystyrene thin films formed from various molecular weight polystyrene and solvent conditions is studied. When spin-cast from tetrahydrofuran (THF) wrinkles are formed at ...the extremities that have periodicity with wavelengths in the μm range and amplitudes in the nm range but varies with molecular weight. A mixed solvent system consisting of THF and dimethylformamide (DMF) leads to periodic structures only with THF-rich compositions. THF and DMF have similar properties relevant to spin-casting: density, surface tension, molecular weight, and viscosity but different boiling points and room temperature vapor pressures, demonstrating that formation periodicity requires a volatile solvent. The formation of the surface structures is attributed to the Marangoni effect and the film thicknesses and wave parameters are shown to be consistent with literature models.
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