Investigation of muon, radio and fluorescence signals from high energy extensive air showers for chemical composition analyses

Orientador: Anderson Campos FauthTese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb WataghinResumo: Na busca pela compreensão da formação e desenvolvimento do Universo a detecção de raios cósmicos possui um papel fundamental. Especialmente para altíssimas energias, sua origem é fracamente conhecida. A detecção de raios cósmicos ultra energéticos pode revelar uma natureza de forças ainda desconhecida no Universo. Múons de mais altas energias podem fornecer informações acerca dos processos ocorridos no desenvolvimento do chuveiro atmosférico extenso. Devido esta componente estar acoplada à componente hadrônica, logo fornece informações cruciais acerca das propriedades dos raios cósmicos primários. Assim, múons podem ser utilizados para se estudar a composição química das partículas primárias, pois sua multiplicidade depende do número atômico da primária. Nesta tese são estudadas medidas de composição química utilizando um arranjo de detectores híbridos composto pelos detectores de superfície (SD), detectores de múons (MD), detectores de fluorescência (FD) e detectores de rádio (RD) do Observatório Pierre Auger. É apresentado um estudo detalhado do poder de separação em massa dos raios cósmicos para chuveiros induzidos por próton e ferro utilizando a densidade muônica reconstruída em diferentes distâncias em relação ao eixo do chuveiro (300 - 1000 m). A separação em massa é analisada combinando-se a densidade muônica reconstruída com a energia de SD (energia primária medida com os detectores de superfície), energia de RD (energia de radiação emitida pela componente eletromagnética do chuveiro detectada pelas antenas de rádio) e a energia de FD (energia de fluorescência emitida pelas moléculas de nitrogênio na atmosfera). Estas análises são realizadas para investigar qual distância em relação ao eixo do chuveiro e qual estimador de energia oferece uma melhor separação em massa. Como resultado, temos que a razão entre a densidade muônica reconstruída a 500 m e a energia de FD oferece uma melhor separação para chuveiros induzidos por próton e ferro. Além do mais, a densidade muônica combinada com diferentes estimadores de energia fornece uma melhor separação em massa que o Xmax, e esta separação aumenta com o aumento da energia primária. Finalmente, a medida dos observáveis sensíveis derivados da análise combinada do sinal de múons e diferentes estimadores de energia mostra uma composição compatível com as medidas do Xmax para a região do espectro onde a transição entre raios cósmicos galácticos para extragalácticos ocorreAbstract: In the search for understanding the formation and development of the Universe, the cosmic ray detection plays a key role. Especially at ultra-high energies, its origin is scarcely known. The detection of ultra high energy cosmic rays may reveal a still unknown nature of forces in the Universe. Higher energy muons can provide information about the processes involved in the development of extensive air showers. Since this component is coupled with the hadronic component, it immediately provides crucial information about the properties of the primary cosmic rays. Thus, muons can be used to study the chemical composition of primary particles as their multiplicity depends on the atomic number of the primary particle. In this thesis, the feasibility of cosmic ray mass composition measurements is studied using the hybrid detector array with surface detectors (SD), muon detectors (MD), fluorescence detectors (FD) and radio detectors (RD) of the Pierre Auger Observatory. A detailed study of the mass discrimination power for simulated showers induced by proton and iron is presented using the muon density reconstructed at different distances from the shower axis (300 - 1000 m). The mass separation power is analysed by combining the reconstructed muon density with the SD energy (primary energy measured with the surface detectors), the RD energy (radiation energy emitted by the electromagnetic component of the air shower which is detected by radio antennas) and the FD energy (fluorescence energy emitted by atmospheric nitrogen molecules). These analyses are performed to investigate which distance from the shower axis and which energy estimator gives the best mass separation. As a result, the ratio between the muon density reconstructed at 500 m and the FD energy features the best mass separation for proton and iron-induced showers. Moreover, the combined muon density with different energy estimators achieves a higher mass separation than Xmax and it increases with increasing primary energy. Finally, the measurement of the mass sensitive observables derived from the combined analysis of the muon signal with different energy estimators shows a composition compatible with the measurements of the Xmax for the spectrum region where the transition from Galactic to extragalactic cosmic ray occursDoutoradoFísicaDoutor em Ciências2013/23074-0FAPES

CONCENTRAÇÃO DE Rn-222 E FILHOS EM ÁGUAS PROVENIENTES DE POÇOS E EMERGÊNCIAS DE ÁGUA DA REGIÃO DE PRESIDENTE PRUDENTE: RESULTADOS PRELIMINARES

Neste trabalho apresentamos os resultados preliminares da atividade do Rn-222 e filhos em águas provenientes de poços e emergências de água da região de Presidente Prudente. Foram estudadas seis amostras; três amostras vindas de poços, duas amostras de emergências de água e uma amostra de água potável. Para a medida da atividade do Rn-222 e filhos, as amostras de água foram colocadas em recipientes plásticos hermeticamente fechados, nos quais detectores CR-39 foram expostos ao ar ambiental vindo da água. Para obter a densidade de traços de partículas α, provenientes do decaimento do Rn-222 e filhos, utilizamos um microscópio óptico de luz transmitida. Os resultados mostram que a amostra A-3, que corresponde à água retirada de um poço artesiano, apresenta uma quantidade de Rn-222 e filhos considerável quando comparada com as outras amostras. São levantadas algumas hipóteses sobre os efeitos provocados pela ingestão da água no estômago. (São levantadas algumas estimativas da dose recebida pelo estômago)

Micro-raman spectroscopic characterization of a CR-39 detector

Characterization by micro-Raman spectroscopy of polymeric materials used as nuclear track detectors reveals physico-chemical and morphological information on the material's molecular structure. In this work, the nuclear track detector poly(allyl diglycol carbonate), or Columbia Resin 39 (CR-39), was characterized according to the fluence of alpha particles produced by a 226Ra source and chemical etching time. Therefore, damage of the CR-39 chemical structure due to the alpha-particle interaction with the detector was analyzed at the molecular level. It was observed that the ionization and molecular excitation of the CR-39 after the irradiation process entail cleavage of chemical bonds and formation of latent track. In addition, after the chemical etching, there is also loss of polymer structure, leading to the decrease of the group density C-O-C (∼888 cm-1), CH=CH (∼960 cm -1), C-O (∼1110 cm-1), C-O-C (∼1240 cm -1), C-O (∼1290 cm-1), C-O (∼1741 cm -1), -CH2- (∼2910 cm-1), and the main band -CH2- (∼2950 cm-1). The analyses performed after irradiation and chemical etching led to a better understanding of the CR-39 molecular structure and better comprehension of the process of the formation of the track, which is related to chemical etching kinetics. Copyright © 2013 Society for Applied Spectroscopy

Chasing Gravitational Waves with the Chereknov Telescope Array

Presented at the 38th International Cosmic Ray Conference (ICRC 2023), 2023 (arXiv:2309.08219)2310.07413International audienceThe detection of gravitational waves from a binary neutron star merger by Advanced LIGO and Advanced Virgo (GW170817), along with the discovery of the electromagnetic counterparts of this gravitational wave event, ushered in a new era of multimessenger astronomy, providing the first direct evidence that BNS mergers are progenitors of short gamma-ray bursts (GRBs). Such events may also produce very-high-energy (VHE, > 100GeV) photons which have yet to be detected in coincidence with a gravitational wave signal. The Cherenkov Telescope Array (CTA) is a next-generation VHE observatory which aims to be indispensable in this search, with an unparalleled sensitivity and ability to slew anywhere on the sky within a few tens of seconds. New observing modes and follow-up strategies are being developed for CTA to rapidly cover localization areas of gravitational wave events that are typically larger than the CTA field of view. This work will evaluate and provide estimations on the expected number of of gravitational wave events that will be observable with CTA, considering both on- and off-axis emission. In addition, we will present and discuss the prospects of potential follow-up strategies with CTA

Sensitivity of the Cherenkov Telescope Array to the gamma-ray emission from neutrino sources detected by IceCube

Gamma-ray observations of the astrophysical neutrino sources are fundamentally important for understanding the underlying neutrino production mechanism. We investigate the Cherenkov Telescope Array (CTA) ability to detect the very-high-energy (VHE) gamma-ray counterparts to the neutrino-emitting Active Galaxies. The CTA performance under different configurations and array layouts is computed based on the neutrino and gamma-ray simulations of steady and transient types of sources, assuming that the neutrino events are detected with the IceCube neutrino telescope. The CTA detection probability is calculated for both CTA sites taking into account the visibility constraints. We find that, under optimal observing conditions, CTA could observe the VHE gamma-ray emission from at least 3 neutrino events per year

Variability studies of active galactic nuclei from the long-term monitoring program with the Cherenkov Telescope Array

Blazars are active galactic nuclei (AGN) with a relativistic jet oriented toward the observer. This jet is composed of accelerated particles which can display emission over the entire electromagnetic spectrum. Spectral variability has been observed on short- and long-time scales in AGN, with a power spectral density (PSD) that can show a break at frequencies below the well-known red-noise process. This break frequency in the PSD has been observed in X-rays to scale with the accretion regime and the mass of the central black hole. It is expected that a break could also be seen in the very-high-energy gamma rays, but constraining the shape of the PSD in these wavelengths has not been possible with the current instruments. The Cherenkov Telescope Array (CTA) will be more sensitive by a factor of five to ten depending on energy than the current generation of imaging atmospheric Cherenkov telescopes, therefore it will be possible with CTA to reconstruct the PSD with a high accuracy, bringing new information about AGN variability. In this work, we focus on the AGN long-term monitoring program planned with CTA. The program is proposed to begin with early-start observing campaigns with CTA precursors. This would allow us to probe longer time scales on the AGN PSD

Performance of a proposed event-type based analysis for the Cherenkov Telescope Array

The Cherenkov Telescope Array (CTA) will be the next-generation observatory in the field of very-high-energy (20 GeV to 300 TeV) gamma-ray astroparticle physics. Classically, data analysis in the field maximizes sensitivity by applying quality cuts on the data acquired. These cuts, optimized using Monte Carlo simulations, select higher quality events from the initial dataset. Subsequent steps of the analysis typically use the surviving events to calculate one set of instrument response functions (IRFs). An alternative approach is the use of event types, as implemented in experiments such as the Fermi-LAT. In this approach, events are divided into sub-samples based on their reconstruction quality, and a set of IRFs is calculated for each sub-sample. The sub-samples are then combined in a joint analysis, treating them as independent observations. This leads to an improvement in performance parameters such as sensitivity, angular and energy resolution. Data loss is reduced since lower quality events are included in the analysis as well, rather than discarded. In this study, machine learning methods will be used to classify events according to their expected angular reconstruction quality. We will report the impact on CTA high-level performance when applying such an event-type classification, compared to the classical procedure

Chasing Gravitational Waves with the Chereknov Telescope Array

Presented at the 38th International Cosmic Ray Conference (ICRC 2023), 2023 (arXiv:2309.08219)2310.07413International audienceThe detection of gravitational waves from a binary neutron star merger by Advanced LIGO and Advanced Virgo (GW170817), along with the discovery of the electromagnetic counterparts of this gravitational wave event, ushered in a new era of multimessenger astronomy, providing the first direct evidence that BNS mergers are progenitors of short gamma-ray bursts (GRBs). Such events may also produce very-high-energy (VHE, > 100GeV) photons which have yet to be detected in coincidence with a gravitational wave signal. The Cherenkov Telescope Array (CTA) is a next-generation VHE observatory which aims to be indispensable in this search, with an unparalleled sensitivity and ability to slew anywhere on the sky within a few tens of seconds. New observing modes and follow-up strategies are being developed for CTA to rapidly cover localization areas of gravitational wave events that are typically larger than the CTA field of view. This work will evaluate and provide estimations on the expected number of of gravitational wave events that will be observable with CTA, considering both on- and off-axis emission. In addition, we will present and discuss the prospects of potential follow-up strategies with CTA

Interpolation of Instrument Response Functions for the Cherenkov Telescope Array in the Context of pyirf

The Cherenkov Telescope Array (CTA) will be the next generation ground-basedvery-high-energy gamma-ray observatory, constituted by tens of Imaging AtmosphericCherenkov Telescopes at two sites once its construction and commissioning are finished. Like its predecessors, CTA relies on Instrument Response Functions (IRFs) to relate the observed and reconstructed properties to the true ones of the primary gamma-ray photons. IRFs are needed for the proper reconstruction of spectral and spatial information of the observed sources and are thus among the data products issued to the observatory users. They are derived from Monte Carlo simulations, depend on observation conditions likethe telescope pointing direction or the atmospheric transparency and can evolve with time as hardware ages or is replaced. Producing a complete set of IRFs from simulations for every observation taken is a time-consuming task and not feasible when releasing data products on short timescales. Consequently, interpolation techniques on simulated IRFs are investigated to quickly estimate IRFs for specific observation conditions. However, as some of the IRFs constituents are given as probability distributions, specialized methods are needed. This contribution summarizes and compares the feasibility of multiple approaches to interpolate IRF components in the context of the pyirf python software package and IRFs simulated for the Large-Sized Telescope prototype (LST-1). We will also give an overview of the current functionalities implemented in pyirf