M. Monasor

Precise measurement of the absolute fluorescence yield of the 337 nm band in atmospheric gases

Abstract A measurement of the absolute fluorescence yield of the 337xa0nm nitrogen band, relevant to ultra-high energy cosmic ray (UHECR) detectors, is reported. Two independent calibrations of the fluorescence emission induced by a 120xa0GeV proton beam were employed: Cherenkov light from the beam particle and calibrated light from a nitrogen laser. The fluorescence yield in air at a pressure of 1013xa0hPa and temperature of 293xa0K was found to be Y 337 = 5.61 ± 0.06 stat ± 0.22 syst xa0photons/MeV. When compared to the fluorescence yield currently used by UHECR experiments, this measurement improves the uncertainty by a factor of three, and has a significant impact on the determination of the energy scale of the cosmic ray spectrum.

A Search for Microwave Emission From Ultra-High Energy Cosmic Rays

We present a search for microwave emission from air showers induced by ultrahigh energy cosmic rays with the microwave detection of air showers experiment. No events were found, ruling out a wide range of power flux and coherence of the putative emission, including those suggested by recent laboratory measurements.

The impact of the air-fluorescence yield on the reconstructed shower parameters of ultra-high energy cosmic rays

An accurate knowledge of the fluorescence yield and its dependence on atmospheric properties such as pressure, temperature or humidity is essential to obtain a reliable measurement of the primary energy of cosmic rays in experiments using the fluorescence technique. In this work, several sets of fluorescence yield data (i.e. absolute value and quenching parameters) are described and compared. A simple procedure to study the effect of the assumed fluorescence yield on the reconstructed shower parameters (energy and shower maximum depth) as a function of the primary features has been developed. As an application, the effect of water vapor and temperature dependence of the collisional cross section on the fluorescence yield and its impact on the reconstruction of primary energy and shower maximum depth has been studied.

The MIDAS telescope for microwave detection of ultra-high energy cosmic rays

Abstract We present the design, implementation and data taking performance of the MIcrowave Detection of Air Showers (MIDAS) experiment, a large field of view imaging telescope designed to detect microwave radiation from extensive air showers induced by ultra-high energy cosmic rays. This novel technique may bring a tenfold increase in detector duty cycle when compared to the standard fluorescence technique based on detection of ultraviolet photons. The MIDAS telescope consists of a 4.5xa0m diameter dish with a 53-pixel receiver camera, instrumented with feed horns operating in the commercial extended C-Band (3.4–4.2xa0GHz). A self-trigger capability is implemented in the digital electronics. The main objectives of this first prototype of the MIDAS telescope – to validate the telescope design, and to demonstrate a large detector duty cycle – were successfully accomplished in a dedicated data taking run at the University of Chicago campus prior to installation at the Pierre Auger Observatory.

The Microwave Air Yield Beam Experiment (MAYBE): Measurement of GHz radiation for Ultra-High Energy Cosmic Rays detection

We present first measurements by MAYBE of microwave emission from an electron beam induced air plasma, performed at the electron Van de Graaff facility of the Argonne National Laboratory. Coherent radio Cherenkov, a major background in a previous beam experiment, is not produced by the 3 MeV beam, which simplifies the interpretation of the data. Radio emission is studied over a wide range of frequencies between 3 and 12 GHz. This measurement provides further insight on microwave emission from extensive air showers as a novel detection technique for Ultra-High Energy Cosmic Rays.

The Air Microwave Yield (AMY) experiment - A laboratory measurement of the microwave emission from extensive air showers

The AMY experiment aims to measure the microwave bremsstrahlung radiation (MBR) emitted by air-showers secondary electrons accelerating in collisions with neutral molecules of the atmosphere. The measurements are performed using a beam of 510 MeV electrons at the Beam Test Facility (BTF) of Frascati INFN National Laboratories. The goal of the AMY experiment is to measure in laboratory conditions the yield and the spectrum of the GHz emission in the frequency range between 1 and 20 GHz. The final purpose is to characterise the process to be used in a next generation detectors of ultra-high energy cosmic rays. A description of the experimental setup and the first results are presented.

The AMY experiment to measure GHz radiation for Ultra-High Energy Cosmic Ray detection

The Air Microwave Yield (AMY) project aims to measure the emission in the GHz regime from test-beam induced air-shower. The experiment is using the Beam Test Facility (BTF) of the Frascati INFN National Laboratories in Italy. The final purpose is to characterize a process to be used in a next generation of ultra-high energy cosmic rays (UHECRs) detectors. We describe the experimental apparatus and the first test performed in November 2011.

Measurements of the GHz emission by a 3 MeV electron beam

The MAYBE (Microwave Air Yield Beam) Experiment is dedicated to the study of the microwave emission from particle beams in light of its possible use for the detection of ultra high energy cosmic rays. Measurements of the microwave emission were performed at the 3 MeV electron beam in the Van de Graaff facility at the Argonne National Laboratory. Results include the measured spectrum between 1 and 15 GHz, the polarization, and the scaling of the emission power with respect to the beam intensity. MAYBE measurements provide further insight on microwave emission as a detection technique for ultra-high energy cosmic rays.

Front-end electronics and data acquisition system for the MIDAS experiment

The MIDAS (MIcrowave Detection of Air Showers) experiment, a prototype detector to characterize the microwave emission of air showers induced by high energy cosmic rays, has been recently commissioned at the University of Chicago. The receivers, 53 feed horns in the 4GHz band, send the signal to fast power detectors which have logarithmic response to the input RF power. The integrated output signal is continuously digitized in custom 14-bit 20 MHz ADC modules. Data are then processed locally with on-board Field Programmable Gate Arrays (FPGAs) where the trigger logic allows discrimination of events. Local trigger pulses are sent out to a Master Board where a system-wise trigger pulse is generated and sent back to the ADC Modules. After each trigger, a 100 us time stream of data is packed and buffered for readout via the VME back plane. A VME GPS module is also used for precise timing information. Design, specifications of the electronic components, a description of the implemented trigger logic, and preliminary test results will be presented in this contribution.

The MIDAS experiment: A prototype for the microwave emission of Ultra-High Energy Cosmic Rays

Recent measurements suggest that extensive air showers initiated by ultra-high energy cosmic rays (UHECR) emit signals in the microwave band of the electromagnetic spectrum caused by the collisions of the free-electrons with the atmospheric neutral molecules in the plasma produced by the passage of the shower. Such emission is isotropic and could allow the detection of air showers with 100% duty cycle and a calorimetric-like energy measurement, a significant improvement over current detection techniques. We have built MIDAS (MIcrowave Detection of Air Showers), a prototype of microwave detector, which consists of a 4.5 m diameter antenna with a cluster of 53 feed-horns in the 4 GHz range. The details of the prototype and first results will be presented.