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Progress in neutrino astronomy
Rott Carsten 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.78 No.10
The dream of observing our universe through neutrinos is rapidly becoming a reality. More than three decades after the first observation of neutrinos from beyond our solar system associated with Supernova SN1987A, neutrino astronomy is in the midst of a revolution. Extraterrestrial neutrinos are now routinely detected, following the discovery of a high-energy diffuse astrophysical neutrino flux in 2013. The detection of a high-energy neutrino in coincidence with a flaring blazar in 2017 has brought the field rapidly into the multi-messenger science era. The latest developments in the field of neutrino astronomy are reviewed and prospects with current and future detectors discussed. Particular emphasis is put on domestic programs in neutrino astronomy and the possibility to construct a large neutrino observatory in Korea.
Han, Eunkyoung,Rott, Carsten,Hong, Seung-Woo The Korean Association for Radiation Protection 2017 방사선방어학회지 Vol.42 No.4
Background: Radiation is used in a variety of areas, but it also poses potential risks. Although radiation is often used with great effectiveness in many applications, people perceive potential risks associated with radiation and feel anxious about the possibility of radiation exposure. Various methods of measuring radiation doses have been developed, but there is no way for the general public to measure their doses with ease. Currently, many people use smartphones, which provide information about the location of an individual phone through network connections. If a smartphone application could be developed for measuring radiation dosage, it would be a very effective way to measure individuals' radiation doses. Thus, we conducted a survey study to assess the social acceptance of such a technology by the general public and their intent to use that technology to measure radiation doses, as well as to investigate whether such an intention is correlated with anxiety and attitudes toward the use of radiation. Materials and Methods: A nationwide online survey was conducted among 355 Koreans who were 20 years old or older. Results and Discussion: Significant differences were found between the genders in attitudes, perceptions of radiation risk, and fears of exposure to radiation. However, a significant difference according to age was observed only in the intent to use a smartphone dose measurement application. Attitudes towards the use of radiation exerted a negative effect on radiation risk perception and exposure anxiety, whereas attitudes towards the use of radiation, risk perception, and anxiety about exposure were found to have a positive impact on the intent to use a smartphone application for dose measurements. Conclusion: A survey-based study was conducted to investigate how the general public perceives radiation and to examine the acceptability of a smartphone application as a personal dose monitoring device. If such an application is developed, it could be used not only to monitor an individual's dose, but also to contribute to radiation safety information infrastructure by mapping radiation in different areas, which could be utilized as a useful basis for radiation research.
First observation of time variation in the solar-disk gamma-ray flux with Fermi
Ng, Kenny C. Y.,Beacom, John F.,Peter, Annika H. G.,Rott, Carsten American Physical Society 2016 Physical Review D Vol.94 No.2
<P>The solar disk is a bright gamma-ray source. Surprisingly, its flux is about 1 order of magnitude higher than predicted. As a first step toward understanding the physical origin of this discrepancy, we perform a new analysis in 1-100 GeV using 6 years of public Fermi-LAT data. Compared to the previous analysis by the Fermi Collaboration, which analyzed 1.5 years of data and detected the solar disk in 0.1-10 GeV, we find two new and significant results: (1) In the 1-10 GeV flux (detected at > 5 sigma), we discover a significant time variation that anticorrelates with solar activity, and (2) we detect gamma rays in 10-30 GeV at > 5 sigma and in 30-100 GeV at > 2 sigma. The time variation strongly indicates that solar-disk gamma rays are induced by cosmic rays and that solar atmospheric magnetic fields play an important role. Our results provide essential clues for understanding the underlying gamma-ray production processes, which may allow new probes of solar atmospheric magnetic fields, cosmic rays in the solar system, and possible new physics. Finally, we show that the Sun is a promising new target for ground-based TeV gamma-ray telescopes such as HAWC and LHAASO.</P>
Solar atmospheric neutrinos: A new neutrino floor for dark matter searches
Ng, Kenny C. Y.,Beacom, John F.,Peter, Annika H. G.,Rott, Carsten American Physical Society 2017 Physical Review D Vol.96 No.10
<P>As is well known, dark matter direct detection experiments will ultimately be limited by a 'neutrino floor,' due to the scattering of nuclei by MeV neutrinos from, e.g., nuclear fusion in the Sun. Here we point out the existence of a new neutrino floor that will similarly limit indirect detection with the Sun, due to high-energy neutrinos from cosmic-ray interactions with the solar atmosphere. We have two key findings. First, solar atmospheric neutrinos. greater than or similar to 1 TeV cause a sensitivity floor for standard weakly interacting massive particles (WIMP) scenarios, for which higher-energy neutrinos are absorbed in the Sun. This floor will be reached once the present sensitivity is improved by just 1 order of magnitude. Second, for neutrinos. 1 TeV, which can be isolated by muon energy loss rate, solar atmospheric neutrinos should soon be detectable in IceCube. Discovery will help probe the complicated effects of solar magnetic fields on cosmic rays. These events will be backgrounds to WIMP scenarios with long-lived mediators, for which higher-energy neutrinos can escape from the Sun.</P>