Cerenkov angle and charge reconstruction with the RICH detector of the AMS experiment

The Alpha Magnetic Spectrometer (AMS) experiment to be installed on the International Space Station (ISS) will be equipped with a proximity focusing Ring Imaging Cerenkov (RICH) detector, for measurements of particle electric charge and velocity. In this note, two possible methods for reconstructing the Cerenkov angle and the electric charge with the RICH, are discussed. A Likelihood method for the Cerenkov angle reconstruction was applied leading to a velocity determination for protons with a resolution of around 0.1%. The existence of a large fraction of background photons which can vary from event to event, implied a charge reconstruction method based on an overall efficiency estimation on an event-by-event basis.Comment: Proceedings submitted to RICH 2002 (Pylos-Greece

Antiresonance and interaction-induced localization in spin and qubit chains with defects

We study a spin chain with an anisotropic XXZ coupling in an external field. Such a chain models several proposed types of a quantum computer. The chain contains a defect with a different on-site energy. The interaction between excitations is shown to lead to two-excitation states localized next to the defect. In a resonant situation scattering of excitations on each other might cause decay of an excitation localized on the defect. We find that destructive quantum interference suppresses this decay. Numerical results confirm the analytical predictions.Comment: Updated versio

Hopes and Challenges of Filipino Displaced Workers at This Covid- 19 Pandemic Period

Hopes and challenges were the focus of this study as it aimed at understanding the self-efficiency of Filipinos who were displaced at this pandemic period. Respondents were randomly taken from unaccounted pool of motor rider agents in Metro Manila and requested to respond on the survey provided to them. Results showed that in terms of hopes, Filipino- respondents Strongly Agree that they are dynamic, adaptable, and optimistic to surpass any difficulty and are very much hopeful that they will survive the challenges brought about by this Coronavirus pandemic. Likewise, when it comes to challenges, Filipino-respondents Strongly Agree that they are ready to solve difficult problems in terms of financial, health, food sustainability, spiritual/religious, and family social factors. Researchers therefore assumed that it is more than enough to say that combining the results achieved on the hopes and challenges of these Filipino-respondents, there is a strong basis that Filipinos are very much self-efficient as well as resilient as it is an innate characteristic on them with the influence of the environment and stimuli where they grow and their behaviors were molded to become better members of the society who are efficient, adaptable, ready to face the challenges, and hopeful amidst this pandemic period. This study also hope to possibly eliminate the notion about Filipinos negative values and instead strengthen and highlight the positive values that Filipinos are known for in the world which will bring constructive impact to those badly affected by the Coronavirus pandemic

Quantum interference-induced stability of repulsively bound pairs of excitations

We study the dynamics of two types of pairs of excitations which are bound despite their strong repulsive interaction. One corresponds to doubly occupied sites in one-dimensional Bose-Hubbard systems, the so-called doublons. The other is pairs of neighboring excited spins in anisotropic Heisenberg spin-1/2 chains. We investigate the possibility of decay of the bound pairs due to resonant scattering by a defect or due to collisions of the pairs. We find that the amplitudes of the corresponding transitions are very small. This is a result of destructive quantum interference and explains the stability of the bound pairs.Comment: 12 pages, 3 figure

Entanglement of excited states in critical spin chians

Renyi and von Neumann entropies quantifying the amount of entanglement in ground states of critical spin chains are known to satisfy a universal law which is given by the Conformal Field Theory (CFT) describing their scaling regime. This law can be generalized to excitations described by primary fields in CFT, as was done in reference (Alcaraz et. al., Phys. Rev. Lett. 106, 201601 (2011)), of which this work is a completion. An alternative derivation is presented, together with numerical verifications of our results in different models belonging to the c=1,1/2 universality classes. Oscillations of the Renyi entropy in excited states and descendant fields are also discussed.Comment: 23 pages, 13 figure

Las necesidades energéticas de Asia Oriental: el impacto sobre la seguridad y las pautas de gobernanza regional

Las últimas tres décadas han presenciado un espectacular y difícilmente sostenible aumento de la demanda energética global. Esta tendencia adquiere una significación especial en Asia Oriental debido a la fuerte industrialización que impulsa el elevado crecimiento económico regional, al ya de por sí delicado equilibrio de la seguridad regional y al tradicional rechazo de los estados de la región a delegar poder y gestión en entidades supranacionales. Este artículo tiene como objetivo analizar el impacto de las necesidades energéticas de Asia Oriental sobre la seguridad y sobre los instrumentos de orden y gobernanza desarrollados hasta la fecha en la región. Para ello, se estructura en dos partes. La primera analiza el panorama energético de Asia Oriental y sus rasgos más significativos: 1) la alta dependencia de las importaciones de petróleo procedentes de otras regiones, especialmente de Oriente Medio; 2) la persistencia de una elevada dependencia de combustibles fósiles contaminantes; y 3) un alto nivel de inseguridad energética. La segunda parte evalúa el impacto de la energía sobre las relaciones regionales en diferentes aspectos de la seguridad y las pautas de gobernanza regional: 1) la securitización de la energía y del medio ambiente; 2) la reactivación de algunos conflictos marítimos; 3) la transformación de algunas amenazas y desafíos convencionales y no convencionales a la seguridad regional; 4) el ascenso de actores no estatales, principalmente empresas y ONG medioambientalistas, en las relaciones internacionales de Asia Oriental; 5) el mantenimiento del bilateralismo y el impulso de iniciativas multilaterales; así como 6) la emergencia de nuevos vínculos y equilibrios geopolíticos extraregionales