The observation of lightning-related events with the Surface Detector of the Pierre Auger Observatory

The Pierre Auger Observatory, designed to detect ultra-high energy cosmic rays, can be a valid instrument at the ground to study phenomena related to the atmospheric electricity. The fluorescence detector is a powerful instrument to observe ELVES thanks to its excellent time resolution, while peculiar events with a large number of triggered stations have been recorded by the surface detector. The characteristic signal of these events lasts more than 10 mu s, about two orders of magnitude more than the duration of a signal produced by a cosmic muon. Moreover, each of these events has at least one station with a signal dominated by a high-frequency noise that could be related with a lightning-induced signal. Stations with a long-lasting signal are arranged in a disk shape. There are "big" events characterized by a radius of about 6 km and few "small" events with a radius of about 2-3 km. The signal, generated by a source very close to the ground, first reaches the innermost stations and then spreads outwards. In the "big" events, a lack of signal in some of the central stations was observed. Further studies and checks are in progress to understand the origin of the lack of signal and what mechanisms occurring during the lightning evolution may provide for electric fields capable of generating and accelerating particles that can produce Cherenkov light in the stations of the surface detector

Aerosol Optical Depth from MODIS satellite data above the Pierre Auger Observatory

Aerosol optical depth can be retrieved from measurements performed by Moderate Resolution Imaging Spectroradiometer (MODIS) satellite instrument. The MODIS satellite system includes two polar satellites, Terra and Aqua. Each of them flies over the Pierre Auger Observatory once a day, providing two measurements of aerosols per day and covering the whole area of the Observatory. MODIS aerosol data products have been generated by three dedicated algorithms over bright and dark land and over ocean surface. We choose the Deep Blue algorithm data to investigate the distribution of aerosols over the Observatory, as this algorithm is the most appropriate one for semi-arid land of the Pierre Auger Observatory. This data algorithm allows us to obtain aerosol optical depth values for the investigated region, and to build cloud-free aerosol maps with a horizontal resolution 0.1 degrees x0.1 degrees. Since a sufficient number of measurements was obtained only for Loma Amarilla and Coihueco fluorescence detector (FD) sites of the Pierre Auger Observatory, a more detailed analysis of aerosol distributions is provided for these sites. Aerosols over these FD sites are generally distributed in a similar way each year, but some anomalies are also observed. These anomalies in aerosol distributions appear mainly due to some transient events, such as volcanic ash clouds, fires etc. We conclude that the Deep Blue MODIS algorithm provides more realistic aerosol optical depth values than other available algorithms

Analysis of ELVES at the Pierre Auger Observatory

In the last six years, the Fluorescence Detector (FD) of the Auger Observatory has been exploited for the study of transient luminous events occuring high above thunderstorms at large distances (250 to more than 1000 km) from the Observatory. The first ELVES candidate was discovered during a night shift in 2005, and further studies based on auxiliary subtriggers allowed to modify the third level trigger of the observatory in order to acquire them with reasonable efficiency. This report aims to briefly review the studies underway on the >4000 ELVES triggers harvested in the years 2013-18 by the Observatory

An AdS/QCD model from tachyon condensation: II

A simple holographic model is presented and analyzed that describes chiral symmetry breaking and the physics of the meson sector in QCD. This is a bottom-up model that incorporates string theory ingredients like tachyon condensation which is expected to be the main manifestation of chiral symmetry breaking in the holographic context. As a model for glue the Kuperstein-Sonnenschein background is used. The structure of the flavor vacuum is analyzed in the quenched approximation. Chiral symmetry breaking is shown at zero temperature. Above the deconfinement transition chiral symmetry is restored. A complete holographic renormalization is performed and the chiral condensate is calculated for different quark masses both at zero and non-zero temperatures. The 0++, 0¿+, 1++, 1¿¿ meson trajectories are analyzed and their masses and decay constants are computed. The asymptotic trajectories are linear. The model has one phenomenological parameter beyond those of QCD that affects the 1++, 0¿+ sectors. Fitting this parameter we obtain very good agreement with data. The model improves in several ways the popular hard-wall and soft wall bottom-up models

A systematic review of statistical process control implementation in the food manufacturing industry

This paper is a systematic review of the literature on statistical process control (SPC) implementation in the food industry. Using systematic searches across three decades of publications, 41 journal articles were selected for the review. Key findings of the review include motivations: to reduce product defects and to follow the food law and regulations (benefits); barriers: high resistance to change and lack of sufficient statistical knowledge; and (limitations) an absence of statistical thinking and a dearth of SPC implementation guidelines. Further findings highlight the predominance of publications from the USA and the UK within this topic. Future research directions concerning SPC implementation issues as well as a ready reference of the SPC literature in the food manufacturing industry are also discussed

The Auger Raman Lidar: several years of continuous observations

The Raman lidar at the Central (Raman) Laser Facility of the Pierre Auger Observatory in Argentina, has been operational since September 2013. In this paper, the Auger Raman Lidar performance is discussed in terms of the data quality for the assessment of the aerosol contribution to the atmospheric UV optical transparency, and how much this is important for the reconstruction of the UHECR properties, based on the Auger Fluorescence Detector observations

Atmospheric Monitoring at a Cosmic Ray Observatory - a long-lasting endeavour

The Pierre Auger Observatory for detecting ultrahigh energy cosmic rays has been founded in 1999. After a main planning and construction phase of about five years, the regular data taking started in 2004, but it took another four years until the full surface detector array was deployed. In parallel to the main detectors of the Observatory, a comprehensive set of instruments for monitoring the atmospheric conditions above the array was developed and installed as varying atmospheric conditions influence the development and detection of extensive air showers.The multitude of atmospheric monitoring installations at the Pierre Auger Observatory will be presented as well as the challenges and efforts to run such instruments for several decades