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P. Buchholz

Publications and source records attributed to P. Buchholz.

101 records · Page 6Linked to original sources
arXiv2009

Lateral Distribution of the Radio Signal in Extensive Air Showers Measured with LOPES

The antenna array LOPES is set up at the location of the KASCADE-Grande extensive air shower experiment in Karlsruhe, Germany and aims to measure and investigate radio pulses from Extensive Air Showers. The coincident measurements allow us to reconstruct the electric field strength at observation level in dependence of general EAS parameters. In the present work, the lateral distribution of the radio signal in air showers is studied in detail. It is found that the lateral distributions of the electric field strengths in individual EAS can be described by an exponential function. For about 20% of the events a flattening towards the shower axis is observed, preferentially for showers with large inclination angle. The estimated scale parameters R0 describing the slope of the lateral profiles range between 100 and 200 m. No evidence for a direct correlation of R0 with shower parameters like azimuth angle, geomagnetic angle, or primary energy can be found. This indicates that the lateral profile is an intrinsic property of the radio emission during the shower development which makes the radio detection technique suitable for large scale applications.

astro-ph.HE↗
arXiv2009

The Fluorescence Detector of the Pierre Auger Observatory

The Pierre Auger Observatory is a hybrid detector for ultra-high energy cosmic rays. It combines a surface array to measure secondary particles at ground level together with a fluorescence detector to measure the development of air showers in the atmosphere above the array. The fluorescence detector comprises 24 large telescopes specialized for measuring the nitrogen fluorescence caused by charged particles of cosmic ray air showers. In this paper we describe the components of the fluorescence detector including its optical system, the design of the camera, the electronics, and the systems for relative and absolute calibration. We also discuss the operation and the monitoring of the detector. Finally, we evaluate the detector performance and precision of shower reconstructions.

astro-ph.IM↗
arXiv2009

Operations of and Future Plans for the Pierre Auger Observatory

Technical reports on operations and features of the Pierre Auger Observatory, including ongoing and planned enhancements and the status of the future northern hemisphere portion of the Observatory. Contributions to the 31st International Cosmic Ray Conference, Lodz, Poland, July 2009.

astro-ph.IM↗
arXiv2009

Upper limit on the cosmic-ray photon fraction at EeV energies from the Pierre Auger Observatory

From direct observations of the longitudinal development of ultra-high energy air showers performed with the Pierre Auger Observatory, upper limits of 3.8%, 2.4%, 3.5% and 11.7% (at 95% c.l.) are obtained on the fraction of cosmic-ray photons above 2, 3, 5 and 10 EeV (1 EeV = 10^18 eV) respectively. These are the first experimental limits on ultra-high energy photons at energies below 10 EeV. The results complement previous constraints on top-down models from array data and they reduce systematic uncertainties in the interpretation of shower data in terms of primary flux, nuclear composition and proton-air cross-section.

astro-ph.HE↗
arXiv2005

ATLAS Pixel Opto-Electronics

We have developed two radiation-hard ASICs for optical data transmission in the ATLAS pixel detector at the LHC at CERN: a driver chip for a Vertical Cavity Surface Emitting Laser (VCSEL) diode for 80 Mbit/s data transmission from the detector, and a Bi-Phase Mark decoder chip to recover the control data and 40 MHz clock received optically by a PIN diode. We have successfully implemented both ASICs in 0.25 micron CMOS technology using enclosed layout transistors and guard rings for increased radiation hardness. We present results of the performance of these chips, including irradiation with 24 GeV protons up to 61 Mrad (2.3 x 10e15 p/cm^2).

physics.ins-det↗
arXiv2003

A RICH Multiplicity Veto for the HERA-B Experiment

We present the design and commissioning of a new multiplicity veto for the HERA-B detector, a fixed-target spectrometer originally designed to study the physics of B mesons in proton-nucleus interactions. The HERA-B trigger is a message-driven multi-level track trigger. The first level trigger (FLT) consists of custom-made electronics, and the higher trigger levels are implemented as PC farms. The multiplicity veto has been designed to reject high-multiplicity events before they enter the trigger chain. A veto signal is generated based on the comparison of the number of photons in part of the HERA-B ring-imaging Cherenkov counter (RICH) with a programmable threshold. The RICH Multiplicity Veto is a modular system. First the hits in 256 detector channels are summed by Base Sum Cards (BSC), then FED Sum Cards (FSC) sum the subtotals of up to eight BSCs. Finally the Veto Board (VB) takes the veto decision based on the sum of up to 14 FSCs. The RICH Multiplicity Veto has been successfully installed and commissioned in HERA-B. The measured veto efficiency is (99.9991+/-0.0001)%, and the system is used in the routine data-taking of the HERA-B experiment.

hep-ex↗