P. Privitera

Measurement of the pressure dependence of air fluorescence emission induced by electrons

The fluorescence detection of ultra high energy (>10^18 eV) cosmic rays requires a detailed knowledge of the fluorescence light emission from nitrogen molecules, which are excited by the cosmic ray shower particles along their path in the atmosphere. We have made a precise measurement of the fluorescence light spectrum excited by MeV electrons in dry air. We measured the relative intensities of 34 fluorescence bands in the wavelength range from 284 to 429 nm with a high resolution spectrograph. The pressure dependence of the fluorescence spectrum was also measured from a few hPa up to atmospheric pressure. Relative intensities and collisional quenching reference pressures for bands due to transitions from a common upper level were found in agreement with theoretical expectations. The presence of argon in air was found to have a negligible effect on the fluorescence yield. We estimated that the systematic uncertainty on the cosmic ray shower energy due to the pressure dependence of the fluorescence spectrum is reduced to a level of 1% by the AIRFLY results presented in this paper.

Search for low-mass WIMPs in a 0.6 kg day exposure of the DAMIC experiment at SNOLAB

We present results of a dark matter search performed with a 0.6 kg d exposure of the DAMIC experiment at the SNOLAB underground laboratory. We measure the energy spectrum of ionization events in the bulk silicon of charge-coupled devices down to a signal of 60 eV electron equivalent. The data are consistent with radiogenic backgrounds, and constraints on the spin-independent WIMP-nucleon elastic-scattering cross section are accordingly placed. A region of parameter space relevant to the potential signal from the CDMS-II Si experiment is excluded using the same target for the first time. This result obtained with a limited exposure demonstrates the potential to explore the low-mass WIMP region (<10  GeV c-2) with the upcoming DAMIC100, a 100 g detector currently being installed in SNOLAB.

The 2pt+: an enhanced 2 point correlation function

We introduce a new method for testing departure from isotropy of points on a sphere based on an enhanced form of the two-point correlation function that we named 2pt+. This method uses information from the two extra variables that define the vector between two points on a sphere. We show that this is a powerful method to test departure from isotropy of a distribution of points on a sphere especially when the number of events is small. We apply the method to a few examples in astronomy and discuss the relevance for limited datasets, such as the case of ultra-high energy cosmic rays.

The analog signal processor of the Auger fluorescence detector prototype

The Auger Fluorescence Detector will allow to determine the longitudinal development of atmospheric showers in the range 10 19 –10 21 eV. A detector module comprises an array of 20 � 22 PMTs at the focal surface of a large-aperture telescope. Thirty such modules will be used. The PMTs pixel signal is variable in shape depending on the shower-eye geometry. The sky background light (BL) is also variable. We have developed an analog signal processor to obtain best energy and timing resolution despite those constrains. The Head Electronics (HE) bias the PMTs and keeps its pulsegain constant even for large BL. This is measured using a current-monitor of novel design. Both the signal pulse and the BL DC level are sent via a single twisted pair to the Analog Board (AB). The AB performs the compression of the 15–16 bit signal dynamic range into 12 bits of the FADC which follows the AB. A three-pole Bessel filter was adopted for antialiasing. The AB includes 16 bit sigma-delta chips to readout the BL DC level, and a test-pulse distribution system. # 2001 Elsevier Science B.V. All rights reserved. PACS: 29.40

Measurement of radioactive contamination in the high-resistivity silicon CCDs of the DAMIC experiment

We present measurements of radioactive contamination in the high-resistivity silicon charge-coupled devices (CCDs) used by the DAMIC experiment to search for dark matter particles. Novel analysis methods, which exploit the unique spatial resolution of CCDs, were developed to identify

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

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A novel method for the absolute fluorescence yield measurement by AIRFLY

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First Direct-Detection Constraints on eV-Scale Hidden-Photon Dark Matter with DAMIC at SNOLAB

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On the prospects of ultra-high energy cosmic rays detection by high altitude antennas

particles. Uranium and thorium contamination in the CCD bulk was measured through

Measurement of the ionization produced by sub-keV silicon nuclear recoils in a CCD dark matter detector

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