L. Wiencke

Measurement of the Cosmic Ray Energy Spectrum and Composition from 10^{17} to 10^{18.3} eV Using a Hybrid Fluorescence Technique

We study the spectrum and average mass composition of cosmic rays with primary energies between 10^{17} eV and 10^{18} eV using a hybrid detector consisting of the High Resolution Flys Eye (HiRes) prototype and the MIA muon array. Measurements have been made of the change in the depth of shower maximum as a function of energy. A complete Monte Carlo simulation of the detector response and comparisons with shower simulations leads to the conclusion that the cosmic ray intensity is changing f rom a heavier to a lighter composition in this energy range. The spectrum is consistent with earlier Flys Eye measurements and supports the previously found steepening near 4 \times 10^{17} eV .

Calibration of photomultiplier tubes for the fluorescence detector of telescope array experiment using a Rayleigh scattered laser beam

Abstract We performed photometric calibration of the PhotoMultiplier Tube (PMT) and readout electronics used for the new fluorescence detectors of the Telescope Array (TA) experiment using Rayleigh scattered photons from a pulsed nitrogen laser beam. The experimental setup, measurement procedure, and results of calibration are described. The total systematic uncertainty of the calibration is estimated to be 7.2%. An additional uncertainty of 3.7% is introduced by the transport of the calibrated PMTs from the laboratory to the TA experimental site.

EUSO-Balloon mission to record extensive air showers from near space

The first EUSO-Balloon stratospheric flight recorded artificial tracks and pulses that were generated using a laser and optical flashers flown in helicopter under the balloon. The time at float altitude was 5 hours. The balloon was launched from Timmins, Ontario by the French Space Agency, CNES and the helicopter underflight was supported by NASA. To make the first measurements of high energy cosmic ray extensive air showers from near space, preparations are underway for a super pressure balloon flight of several weeks duration. The proposed launch site is Wanaka, New Zealand. We describe the parameters of this mission, the updated instrument, and the expected rates of extensive air showers events produced by cosmic primaries in the energy range of 5x1017 eV to 2x1019 eV. A precursor short duration flight from Aire sur l’Adour, France is also envisioned to test improvements to the instrument.

POEMMA: Probe Of Extreme Multi-Messenger Astrophysics

The Probe Of Extreme Multi-Messenger Astrophysics (POEMMA) mission is being designed to establish charged-particle astronomy with ultra-high energy cosmic rays (UHECRs) and to observe cosmogenic tau neutrinos (CTNs). The study of UHECRs and CTNs from space will yield orders-of-magnitude increase in statistics of observed UHECRs at the highest energies, and the observation of the cosmogenic flux of neutrinos for a range of UHECR models. These observations should solve the long-standing puzzle of the origin of the highest energy particles ever observed, providing a new window onto the most energetic environments and events in the Universe, while studying particle interactions well beyond accelerator energies. The discovery of CTNs will help solve the puzzle of the origin of UHECRs and begin a new field of Astroparticle Physics with the study of neutrino properties at ultra-high energies.

The Calibration of EUSO Balloon using airborne light sources mounted to a Helicopter

The Extreme Universe Space Observatory (EUSO) Balloon was launched from Timmins, Ontario, Canada just at sunset on the moonless night of August 24, 2014. Before the balloon reached its float altitude, a helicopter carrying UV flashers and a UV laser took off. For the next 2.5 hours the helicopter circled under the balloon operating the UV flashers and a UV laser to simulate the signals from extreme energy cosmic rays. Many of these signals were recorded onboard EUSO Balloon. The laser and its use for calibrating EUSO Balloon are discussed in another paper in this conference. In this paper the helicopter operations, the flashers carried on the helicopter and the method for calibrating of EUSO Balloon using these flashers is discussed.

EUSO-Balloon: Observation and Measurement of Tracks from a Laser in a Helicopter

EUSO-Balloon is a prototype detector of the Extreme Universe Space Observatory on the Japanese Experiment Module (JEM-EUSO). EUSO-Balloon was flown successfully as a balloon payload from the Timmins Stratospheric Balloon Launch Facility in Ontario, Canada on 2014 August 24-25 at an altitude of 38 km. To simulate the optical signatures of UV fluorescence photons emitted from cosmic ray air showers generated in the atmosphere, a pulsed UV laser and two UV flashers (LED and Xe) were used. These sources were fired in the instrument field of view for about 2 hours from a helicopter that circled at an altitude of 3 km under the balloon. UV signals were effectively detected, including 270 laser track events. We describe the helicopter laser system and the geometric reconstruction of the laser events that were generated by this system. We report here on the reconstruction of the laser events starting from the information contained in the observed tracks. We note that this work represents the first observation and measurement of aircraft based laser tracks by an optical fluorescence detector flown at near space altitudes.

EUSO-SPB1 Mission and Science

The Extreme Universe Space Observatory on a Super Pressure Balloon (EUSO-SPB1) was launched April 24th 23:51 UTC 2017 from Wanaka, New Zealand as a mission of opportunity on a NASA super pressure balloon test flight planned to circle the southern hemisphere. The primary scientific goal was to make the first observations of high energy cosmic ray extensive air showers by looking down on the atmosphere with a UV fluorescence detector from the near space altitude of 33~km. After 12~days 4~hours aloft, the flight was terminated prematurely in the Pacific Ocean about 300~km SE of Easter Island. This overview presentation of the EUSO-SPB1 program will review the science of the mission, the instrument, the flight, and first looks at data. Preparations for a EUSO-SPB2 mission are underway.

Calibrating and Testing EUSO-SPB in Flight using a Laser and LEDs on an Aircraft

The EUSO-SPB (EUSO super pressure balloon) experiment is designed to make observations of fluorescence light from Extreme Energy Cosmic Ray (EECR) Extensive Air Showers (EASs) by looking down on the atmosphere from above. The flight lasted for 13 days with a total of more than 30 hours of observations on dark nights. The balloon was launched on April 24, 2017, from Wanaka New Zealand. A navigation system consists of MATLAB GUI software together with tracker beacon and Ham radio was designed to track the location of tracking the instruments field of view. This navigation system was tested prior to the flight in Huntsville, Al. An airplane carrying calibrated UV light emitting diodes (LEDs) and a UV laser was planned to fly under the balloon on a moonless night when it is at its float altitude. This under flight was to calibrate EUSO-SPB using these light sources to produce EECR-like signals. The laser pulses were to calibrate the trigger efficiency and track reconstruction accuracy of the experiment. The flashers will to determine the sensitivity of EUSO-SPB to fluorescent light near the maxima of EASs. Unfortunately, the balloon flight had to be terminated before there was an opportunity for the under flight. This paper describes preparations for the under flight including the design of tracking system and the calibration light sources that were to be carried on the airplane.

Joint elastic side-scattering LIDAR and Raman LIDAR measurements of aerosol optical properties in south east Colorado

We describe an experiment, located in south-east Colorado, USA, that measured aerosol optical depth profiles using two Lidar techniques. Two independent detectors measured scattered light from a vertical UV laser beam. One detector, located at the laser site, measured light via the inelastic Raman backscattering process. This is a common method used in atmospheric science for measuring aerosol optical depth profiles. The other detector, located approximately 40km distant, viewed the laser beam from the side. This detector featured a 3.5m2 mirror and measured elastically scattered light in a bistatic Lidar configuration following the method used at the Pierre Auger cosmic ray observatory. The goal of this experiment was to assess and improve methods to measure atmospheric clarity, specifically aerosol optical depth profiles, for cosmic ray UV fluorescence detectors that use the atmosphere as a giant calorimeter. The experiment collected data from September 2010 to July 2011 under varying conditions of aerosol loading. We describe the instruments and techniques and compare the aerosol optical depth profiles measured by the Raman and bistatic Lidar detectors.

Implementation of the first level trigger for ultra-high-energy cosmic ray (UHECR) detection from space with JEM-EUSO: Initial test results

The JEM-EUSO Collaboration aims to study Ultra-High-Energy Cosmic Ray (UHECR) using a novel approach of looking down from space and using the atmosphere as a large detector to achieve a large effective area and therefore high-statistics on these events for the first time. For this purpose we have been developing a series of pathfinders operating from the ground, high altitude balloons and space, all sharing the same electronics, in particular the central data acquisition system. We report on the implementation and successful testing of the first-level trigger (L1) within the FPGA of the photo-detection module (PDM) board, which processes the signals from 36 64-pixel MAPMTs with a time unit of 2.5 μs to detect the passage of light from cosmic ray generated air-showers.