scholarly journals Muons as a tool for background rejection in imaging atmospheric Cherenkov telescope arrays

2021 ◽  
Vol 81 (12) ◽  
Author(s):  
L. Olivera-Nieto ◽  
A. M. W. Mitchell ◽  
K. Bernlöhr ◽  
J. A. Hinton
Keyword(s):  
Gamma Rays ◽  
High Efficiency ◽  
Computing Time ◽  
Cosmic Ray ◽  
Ground Level ◽  
Cherenkov Light ◽  
High Background ◽  
Cherenkov Telescope ◽  
Background Rejection ◽  
Telescope Arrays

AbstractThe presence of muons in air-showers initiated by cosmic ray protons and nuclei is well established as a powerful tool to separate such showers from those initiated by gamma rays. However, so far this approach has been fully exploited only for ground level particle detecting arrays. We explore the feasibility of using Cherenkov light from muons as a background rejection tool for imaging atmospheric Cherenkov telescope arrays at the highest energies. We adopt an analytical model of the Cherenkov light from individual muons to allow rapid simulation of a large number of showers in a hybrid mode. This allows us to explore the very high background rejection power regime at acceptable cost in terms of computing time. We show that for very large ($$\gtrsim 20$$ ≳ 20  m mirror diameter) telescopes, efficient identification of muon light can potentially lead to background rejection levels up to 10$$^{-5}$$ - 5 whilst retaining high efficiency for gamma rays. While many challenges remain in the effective exploitation of the muon Cherenkov light in the data analysis for imaging Cherenkov telescope arrays, our study indicates that for arrays containing at least one large telescope, this is a very worthwhile endeavor.

scholarly journals Ground-Based Observations of Terrestrial Gamma Ray Flashes Associated with Downward-Directed Lightning Leaders

2019 ◽  
Vol 197 ◽  
pp. 03002
Author(s):  
Rasha Abbasi ◽  
John Belz ◽  
Ryan Le Von ◽  
Dan Rodeheffer ◽  
Paul Krehbiel ◽  
...  
Keyword(s):  
Electric Field ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Three Dimensional ◽  
Temporal Distribution ◽  
Cosmic Ray ◽  
Ground Level ◽  
High Energy ◽  
Lightning Strikes ◽  
Lightning Discharges

Terrestrial gamma-ray flashes (TGFs) are bursts of gamma-rays initiated in the Earth’s atmosphere. TGFs were serendipitously first observed over twenty years ago by the BATSE gamma ray satellite experiment. Since then, several satellite experiments have shown that TGFs are produced in the upward negative breakdown stage at the start of intracloud lightning discharges. In this proceeding, we present ground-based observation of TGFs produced by downward negative breakdown occurring at the beginning of negative cloud-to-ground flashes. The Terrestrial gamma-ray flashes discussed in this work were detected between 2014-2017 at ground level by the Telescope Array surface detector (TASD) together with Lightning Mapping Array (LMA) and the slow electric field antenna (SA). The TASD detector is a 700 km2 ultra high energy cosmic ray detector in the southwestern desert of Utah. It is comprised of 507 (3 m2) plastic scintillator detectors on a 1.2 km square grid. The LMA detector, a three-dimensional total lightning location system, is comprised of nine stations located within and around the array. The slow electric field antenna records the electric field change in lightning discharges. The observed Gamma ray showers were detected in the first 1-2 ms of downward negative breakdown prior to cloud-to-ground lightning strikes. The shower sources were observed by the LMA detector at altitudes of a few kilometers above ground level. The detected energetic burst showers have a footprint on the ground typically ~ 3-5 km in diameter. The bursts comprise of several (2-5) individual pulses, each of which have a span of a few to tens of microseconds and an overall duration of several hundred microseconds. Using a forward-beamed cone of half-angle of 16 degrees, GEANT simulation studies indicate that the showers are consistent with gamma rays of 1012 - 1014 primary photons. We hypothesize that the observed terrestrial gamma-ray flashes are similar to those detected by satellites, but that the ground-based observations are closer to the source and therefore are able to observe weaker sources and report on the structure of the temporal distribution at the source. This result and future studies will enable us to better identify and constrain the mechanisms of downward TGF production.

scholarly journals Muons as a tool for background rejection in imaging atmospheric Cherenkov telescope arrays

2021 ◽  
Author(s):  
Laura Olivera-Nieto ◽  
Alison Mitchell ◽  
Konrad Bernlöhr ◽  
James Hinton
Keyword(s):  
Cherenkov Telescope ◽  
Background Rejection ◽  
Telescope Arrays

High efficiency resonance scintillators for 23.8 keV recoilless gamma-rays of 119mSn

1983 ◽  
Vol 206 (3) ◽  
pp. 581-586 ◽  
Author(s):  
I.G. Mandjukov ◽  
B.V. Mandjukova ◽  
V.G. Jelev ◽  
N.V. Markova
Keyword(s):  
Gamma Rays ◽  
High Efficiency

scholarly journals Gamma-ray astrophysics in the MeV range

2021 ◽  
Author(s):  
Alessandro De Angelis ◽  
Vincent Tatischeff ◽  
Andrea Argan ◽  
Søren Brandt ◽  
Andrea Bulgarelli ◽  
...  
Keyword(s):  
High Efficiency ◽  
Gamma Ray ◽  
Earth Science ◽  
Technological Development ◽  
Cosmic Ray ◽  
Space Mission ◽  
Compact Objects ◽  
Medium Size ◽  
Cosmic Ray Interactions ◽  
Silicon Microstrip Detectors

AbstractThe energy range between about 100 keV and 1 GeV is of interest for a vast class of astrophysical topics. In particular, (1) it is the missing ingredient for understanding extreme processes in the multi-messenger era; (2) it allows localizing cosmic-ray interactions with background material and radiation in the Universe, and spotting the reprocessing of these particles; (3) last but not least, gamma-ray emission lines trace the formation of elements in the Galaxy and beyond. In addition, studying the still largely unexplored MeV domain of astronomy would provide for a rich observatory science, including the study of compact objects, solar- and Earth-science, as well as fundamental physics. The technological development of silicon microstrip detectors makes it possible now to detect MeV photons in space with high efficiency and low background. During the last decade, a concept of detector (“ASTROGAM”) has been proposed to fulfil these goals, based on a silicon hodoscope, a 3D position-sensitive calorimeter, and an anticoincidence detector. In this paper we stress the importance of a medium size (M-class) space mission, dubbed “ASTROMEV”, to fulfil these objectives.

scholarly journals 6Li and Gamma Rays: Complementary Constraints on Cosmic‐Ray History

2005 ◽  
Vol 623 (2) ◽  
pp. 877-888 ◽  
Author(s):  
Brian D. Fields ◽  
Tijana Prodanović
Keyword(s):  
Gamma Rays ◽  
Cosmic Ray

scholarly journals Recent Design Optimization Methods for Energy-Efficient Electric Motors and Derived Requirements for a New Improved Method—Part 1

Proceedings ◽  
2018 ◽  
Vol 2 (22) ◽  
pp. 1400
Author(s):  
Johannes Schmelcher ◽  
Max Kleine Büning ◽  
Kai Kreisköther ◽  
Dieter Gerling ◽  
Achim Kampker
Keyword(s):  
Rare Earth ◽  
Design Optimization ◽  
Energy Efficient ◽  
Degrees Of Freedom ◽  
High Efficiency ◽  
Optimization Problems ◽  
Computing Time ◽  
Optimization Methods ◽  
Electric Motors ◽  
Electric Cars

Energy-efficient electric motors are gathering an increased attention since they are used in electric cars or to reduce operational costs, for instance. Due to their high efficiency, permanent-magnet synchronous motors are used progressively more. However, the need to use rare-earth magnets for such high-efficiency motors is problematic not only in regard to the cost but also in socio-political and environmental aspects. Therefore, an increasing effort has to be put in finding the best design possible. The goals to achieve are, among others, to reduce the amount of rare-earth magnet material but also to increase the efficiency. In the first part of this multipart paper, characteristics of optimization problems in engineering and general methods to solve them are presented. In part two, different approaches to the design optimization problem of electric motors are highlighted. The last part will evaluate the different categories of optimization methods with respect to the criteria: degrees of freedom, computing time and the required user experience. As will be seen, there is a conflict of objectives regarding the criteria mentioned above. Requirements, which a new optimization method has to fulfil in order to solve the conflict of objectives will be presented in this last paper.

A novel method for spacecraft electrical fault detection based on FCM clustering and WPSVM classification with PCA feature extraction

2016 ◽  
Vol 231 (1) ◽  
pp. 98-108 ◽  
Author(s):  
Ke Li ◽  
Yalei Wu ◽  
Shimin Song ◽  
Yi sun ◽  
Jun Wang ◽  
...  
Keyword(s):  
Feature Extraction ◽  
Clustering Algorithm ◽  
High Efficiency ◽  
Computing Time ◽  
Principal Component ◽  
Component Analysis ◽  
Support Vector ◽  
Electrical Characteristics ◽  
Complex Signals ◽  
Fcm Clustering

The measurement of spacecraft electrical characteristics and multi-label classification issues are generally including a large amount of unlabeled test data processing, high-dimensional feature redundancy, time-consumed computation, and identification of slow rate. In this paper, a fuzzy c-means offline (FCM) clustering algorithm and the approximate weighted proximal support vector machine (WPSVM) online recognition approach have been proposed to reduce the feature size and improve the speed of classification of electrical characteristics in the spacecraft. In addition, the main component analysis for the complex signals based on the principal component feature extraction is used for the feature selection process. The data capture contribution approach by using thresholds is furthermore applied to resolve the selection problem of the principal component analysis (PCA), which effectively guarantees the validity and consistency of the data. Experimental results indicate that the proposed approach in this paper can obtain better fault diagnosis results of the spacecraft electrical characteristics’ data, improve the accuracy of identification, and shorten the computing time with high efficiency.

scholarly journals Molecular Clouds Observed by the EGRET Gamma-Ray Telescope

1997 ◽  
Vol 170 ◽  
pp. 22-24 ◽  
Author(s):  
Seth. W. Digel ◽  
Stanley D. Hunter ◽  
Reshmi Mukherjee ◽  
Eugéne J. de Geus ◽  
Isabelle A. Grenier ◽  
...  
Keyword(s):  
Molecular Mass ◽  
Molecular Clouds ◽  
Gamma Ray ◽  
Angular Resolution ◽  
Cosmic Ray ◽  
High Energy ◽  
Background Rejection ◽  
Γ Rays ◽  
Γ Ray ◽  
Production Mechanisms

EGRET, the high-energy γ-ray telescope on the Compton Gamma-Ray Observatory, has the sensitivity, angular resolution, and background rejection necessary to study diffuse γ-ray emission from the interstellar medium (ISM). High-energy γ rays produced in cosmic-ray (CR) interactions in the ISM can be used to determine the CR density and calibrate the CO line as a tracer of molecular mass. Dominant production mechanisms for γ rays of energies ∼30 MeV–30 GeV are the decay of pions produced in collisions of CR protons with ambient matter and Bremsstrahlung scattering of CR electrons.

scholarly journals Calculating the ionization rate induced by GCR and SCR protons in Earth’s atmosphere

2019 ◽  
Vol 5 (3) ◽  
pp. 68-74
Author(s):  
Евгений Маурчев ◽  
Evgeniy Maurchev ◽  
Юрий Балабин ◽  
Yuriy Balabin ◽  
Алексей Германенко ◽  
...  
Keyword(s):  
Primary Particle ◽  
Cosmic Ray ◽  
Ground Level ◽  
Ionization Rate ◽  
Future Research ◽  
Energy Distributions ◽  
Earth’S Atmosphere ◽  
Geomagnetic Cutoff Rigidity ◽  
Geomagnetic Cutoff ◽  
Earth's Atmosphere

This paper explores the applied use of the RUSCOSMICS software package [http://ruscosmics.ru] designed to simulate propagation of primary cosmic ray (CR) particles through Earth’s atmosphere and collect information about characteristics of their secondary component. We report the results obtained for proton fluxes with energy distributions corresponding to the differential spectra of galactic CR (GCR) and solar CR (SCR) during ground level enhancement (GLE) events GLE65 and GLE67. We examine features of the geometry of Earth’s atmosphere, parametrization methods, and describe a primary particle generator. The typical energy spectra of electrons obtained both for GCR and for GLE65 provide information that allows us to quantitatively estimate the SCR contribution to the enhancement of secondary CR fluxes. We also present altitude dependences of ionization rate for GCR and both the GLE events for several geomagnetic cutoff rigidity values. The conclusion summarizes and discusses the prospects for future research.

scholarly journals The Monitoring of Fungal Contamination in Indoor Air of Two Hospitals in Shiraz

2019 ◽  
Author(s):  
Fariba Abbasi ◽  
Mahrokh Jalili ◽  
Mohammad Reza Samaei ◽  
Ali Mohammad Mokhtari ◽  
Elahe Azizi
Keyword(s):  
Indoor Air ◽  
High Efficiency ◽  
Health Workers ◽  
Ground Level ◽  
Growth Media ◽  
Specialist Care ◽  
Effective Parameters ◽  
Emergency Rooms ◽  
Fungal Contamination ◽  
Air Contamination

Introduction: Hospitals, as one of the important elements in the health system, play an important role in patient’s health. Fungi are one of the effective parameters on indoor air quality. This study aimed to compare of fungal contamination of two hospitals in Shiraz City. Materials and Methods: Sampling was conducted based on NIOSH 0800 standard (1.5 meters above the ground level with one stage Anderson and Sabaroud dextrose agar enriched chloramphenicol as the growth media) in January-September 2017. The investigated wards included pathological laboratory, emergency rooms, neonatal specialist care, radiology, operating room, and maternity ward. The results showed that the variation and concentration of fungi were higher in hospital X than hospital Y, which was located in an agricultural area far from the city center. Results: The predominant fungi were Monillia, Aspergillus, and Penicillium in hospital Y, while they were Aspergillus and Penicillium in hospital X. The highest concentrations were found in emergency and laboratory wards. With regard to higher fungal contamination of hospital X and its different location, it can be concluded that the geographical properties and outdoor air are effective factors on indoor air contamination at hospitals.   Conclusion: Appropriate management of patients' admission and visiting time can be effective on indoor air contamination at hospitals. Furthermore, efficient ventilation using high-efficiency particulate air and appropriate devices for elimination of fungi level are recommended to this end. Moreover, these parameters can provide physical and psychometric health problems for patients’ careers and other health workers.

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