Reduction of optical crosstalk in SiPMs due to coupled light guides and investigation of other properties demonstrated with the SensL MicroFJ-60035-TSV

The optical coupling of light guides to Silicon Photomultipliers (SiPMs) influences the probability for optical crosstalk. Measurements of the crosstalk probability and the relative gain of 122 SiPMs of type SensL MicroFJ-60035-TSV are presented. Semi-conductor photo sensors have replaced photo multiplier tubes in numerous applications featuring single-photon resolution, insensitivity to magnetic fields, higher robustness and enhanced photo detection efficiency at lower operation voltage and lower costs. Light guides are used to increase the comparably small photo sensitive area of SiPMs. Their optical coupling changes the surface conditions of the sensor and influences the probability for crosstalk photons to leave the sensor without inducing secondary breakdowns. This study compares properties of sensors that are optically coupled to light guides with bare sensors, operated at nominal bias voltage. It demonstrates, that the optical coupling to a light guide significantly reduces the crosstalk probability of the measured sensors

Low energy elastic and electronically inelastic electron scattering from biomolecules.

Reactions initiated by collisions with low-energy secondary electrons has been found to be the prominent\ud mechanism toward the radiation damage on living tissues through DNA strand breaks. Now it is widely accepted\ud that during the interaction with these secondary species the selective breaking of chemical bonds is triggered\ud by dissociative electron attachment (DEA), that is, the capture of the incident electron and the formation\ud of temporary negative ion states [1,2,3]. One of the approaches largely used toward a deeper understanding\ud of the radiation damage to DNA is through modeling of DEA with its basic constituents (nucleotide bases,\ud sugar and other subunits). We have tried to simplify this approach and attempt to make it comprehensible\ud at a more fundamental level by looking at even simple molecules. Studies involving organic systems such as\ud carboxylic acids, alcohols and simple ¯ve-membered heterocyclic compounds are taken as starting points for\ud these understanding. In the present study we investigate the role played by elastic scattering and electronic\ud excitation of molecules on electron-driven chemical processes. Special attention is focused on the analysis of\ud the in°uence of polarization and multichannel coupling e®ects on the magnitude of elastic and electronically\ud inelastic cross-sections. Our aim is also to investigate the existence of resonances in the elastic and electronically\ud inelastic channels as well as to characterize them with respect to its type (shape, core-excited or Feshbach),\ud symmetry and position. The relevance of these issues is evaluated within the context of possible applications\ud for the modeling of discharge environments and implications in the understanding of mutagenic rupture of DNA\ud chains. The scattering calculations were carried out with the Schwinger multichannel method (SMC) [4] and\ud its implementation with pseudopotentials (SMCPP) [5] at di®erent levels of approximation for impact energies\ud ranging from 0.5 eV to 30 eV.\ud References\ud [1] B. Boudai®a, P. Cloutier, D. Hunting, M. A. Huels and L. Sanche, Science 287, 1658 (2000). [2] X. Pan, P.\ud Cloutier, D. Hunting and L. Sanche, Phys. Rev. Lett. 90, 208102 (2003). [3] F. Martin, P. D. Burrow, Z. Cai,\ud P. Cloutier, D. Hunting and L. Sanche, Phys. Rev. Lett. 93, 068101 (2004). [4] K. Takatsuka and V. McKoy,\ud Phys. Rev. A 24, 2437 (1981); ibid. Phys. Rev. A 30, 1734 (1984). [5] M. H. F. Bettega, L. G. Ferreira and\ud M. A. P. Lima, Phys. Rev. A 47, 1111 (1993)

Software architecture for the measurement of operational risk in financial sector entities

La medición de los riesgos financieros tales como operacional, liquidez y crédito, entre otros, es una de las preocupaciones más frecuentes en el sector financiero; en este sentido, la materialización del riesgo operacional da lugar a enormes pérdidas monetarias derivadas de fallos en las personas, en los procesos y en los procedimientos que inciden en la operación de la entidad. Con el fin de sistematizar la medición del riesgo operacional se ha desarrollado el Sistema de Información Operational Risk Management, el cual facilita la medición del riesgo operacional, a partir de la obtención de la matriz de pérdidas esperadas e inesperadas y la estimación de Valor en Riesgo Operacional (Op-VaR) para los diferentes fallos que se puedan presentar en cada una de las líneas de negocio con las que cuenta la entidad. En este trabajo se muestra cómo el uso de la arquitectura basada en filtros facilita y agiliza cálculos que requieren grandes volúmenes de datos con información financiera. Actualmente el Sistema de Información es utilizado por entidades del sector financiero colombiano quienes a partir de su uso han optimizado tanto sus utilidades como la productividad del talento humano, toda vez que el sistema ha permitido generar planes de contingencia para atender una crisis por riesgo operacionalThe measurement of financial risks, such as operational, liquidity and credit, among others, is one of the most frequent concern in the bank and corporative sector, in this sense, the operational risk materialization causes large losses due to fails on the procedures that affect the functioning of the organization. With the goal of systematize the risk measurement, we has implement the Information System Financial Risk Management which facilitates the measurement of operational risk starting on the expected and unexpected loss matrix and the estimation of Value at Operational Risk (Op-VaR) for different failures that may occur in each of the business lines that the entity has. The paper shows how the use of filters based on easier and faster calculations that require large volumes of data from financial information architecture. Currently the Information System is used by Colombian financial sector entities who from their use have optimized both their profits and the productivity of human talent, since the system has allowed the generation of contingency plans to deal with a crisis due to operational ris

"Validity of a scale of Latin American perception of fear and concern transmitted by the media during the pandemic (MED-LAT-COVID-19)"

"Introduction: The pandemic has caused fear, especially due to the daily disseminated news; however, there is not an instrument to measure this fear in multiple realities. Objective: To validate a scale for Latin American perception of fear and concern transmitted by the media during the pandemic. Methodology: This is an instrumental study. The survey was based on an instrument which was pre-validated in Peru and submitted to 15 experts in almost 10 countries. Subsequently, thousands of people were surveyed in 13 Latin American countries, whose answers were used for descriptive statistics for validation. Results: Confirmatory Factor Analysis (CFA) generated two re-specifications, where four items were eliminated from the original scale. With these changes, the global goodness of fit (absolute and incremental) were satisfactory (CFI ¼ 0.978; TLI ¼ 0.964; GFI ¼ 0.976; AGFI ¼ 0.949; RMSEA ¼ 0.075 and RMR ¼ 0.029). The first factor measures the media exaggeration (three questions); the second, the fear transmitted by the media (three questions); and the third, the fear transmitted by others different from the media (two questions). The Cronbach’s alpha coefficient was higher than 0.70 for the scale and its factors. Conclusion: The MED-LAT-COVID-19 scale reported a good adjustment. It has eight items in three factors, which could be measured in an isolated way, or along with other tests that assess mental health in the current pandemic context.

Study of the Very High Energy emission of M87 through its broadband spectral energy distribution

The radio galaxy M87 is the central dominant galaxy of the Virgo Cluster.Very High Energy (VHE,$\gtrsim 0.1$ TeV) emission, from M87 has been detectedby Imaging Air Cherenkov Telescopes (IACTs ). Recently, marginal evidence forVHE long-term emission has also been observed by the High Altitude WaterCherenkov (HAWC) Observatory, a gamma ray and cosmic-ray detector array locatedin Puebla, Mexico. The mechanism that produces VHE emission in M87 remainsunclear. This emission is originated in its prominent jet, which has beenspatially resolved from radio to X-rays. In this paper, we constructed aspectral energy distribution from radio to gamma rays that is representative ofthe non-flaring activity of the source, and in order to explain the observedemission, we fit it with a lepto-hadronic emission model. We found that thismodel is able to explain non-flaring VHE emission of M87 as well as an orphanflare reported in 2005.<br

Validation of standardized data formats and tools for ground-level particle-based gamma-ray observatories

Ground-based gamma-ray astronomy is still a rather young field of research,with strong historical connections to particle physics. This is why mostobservations are conducted by experiments with proprietary data and analysissoftware, as it is usual in the particle physics field. However in recentyears, this paradigm has been slowly shifting towards the development and useof open-source data formats and tools, driven by upcoming observatories such asthe Cherenkov Telescope Array (CTA). In this context, a community-driven,shared data format (the gamma-astro-data-format or GADF) and analysis toolssuch as Gammapy and ctools have been developed. So far these efforts have beenled by the IACT community, leaving out other types of ground-based gamma-rayinstruments.We aim to show that the data from ground particle arrays, such asthe High-Altitude Water Cherenkov (HAWC) observatory, is also compatible withthe GADF and can thus be fully analysed using the related tools, in this caseGammapy. We reproduce several published HAWC results using Gammapy and dataproducts compliant with GADF standard. We also illustrate the capabilities ofthe shared format and tools by producing a joint fit of the Crab spectrumincluding data from six different gamma-ray experiments. We find excellentagreement with the reference results, a powerful check of both the publishedresults and the tools involved. The data from particle detector arrays such asthe HAWC observatory can be adapted to the GADF and thus analysed with Gammapy.A common data format and shared analysis tools allow multi-instrument jointanalysis and effective data sharing. Given the complementary nature of pointingand wide-field instruments, this synergy will be distinctly beneficial for thejoint scientific exploitation of future observatories such as the SouthernWide-field Gamma-ray Observatory and CTA.<br

HAWC Study of Very-High-Energy γ\gamma-ray Spectrum of HAWC J1844-034

Recently, the region surrounding eHWC J1842-035 has been studied extensively by gamma-ray observatories due to its extended emission reaching up to a few hundred TeV and potential as a hadronic accelerator. In this work, we use 1,910 days of cumulative data from the High Altitude Water Cherenkov (HAWC) observatory to carry out a dedicated systematic source search of the eHWC J1842-035 region. During the search we have found three sources in the region, namely, HAWC J1844-034, HAWC J1843-032, and HAWC J1846-025. We have identified HAWC J1844-034 as the extended source that emits photons with energies up to 175 TeV. We compute the spectrum for HAWC J1844-034 and by comparing with the observational results from other experiments, we have identified HESS J1843-033, LHAASO J1843-0338, and TASG J1844-038 as very-high-energy gamma-ray sources with a matching origin. Also, we present and use the multi-wavelength data to fit the hadronic and leptonic particle spectra. We have identified four pulsar candidates in the nearby region from which PSR J1844-0346 is found to be the most likely candidate due to its proximity to HAWC J1844-034 and the computed energy budget. We have also found SNR G28.6-0.1 as a potential counterpart source of HAWC J1844-034 for which both leptonic and hadronic scenarios are feasible.Comment: 13 pages, 9 figures, published in Ap

Gamma-ray Emission from Classical Nova V392 Per: Measurements from Fermi and HAWC

This paper reports on the $\gamma$-ray properties of the 2018 Galactic novaV392 Per, spanning photon energies $\sim$0.1 GeV to 100 TeV by combiningobservations from the Fermi Gamma-ray Space Telescope and the HAWC Observatory.In one of the most rapidly evolving $\gamma$-ray signals yet observed for anova, GeV $\gamma$ rays with a power law spectrum with index $\Gamma = 2.0 \pm0.1$ were detected over eight days following V392 Per's optical maximum. HAWCobservations constrain the TeV $\gamma$-ray signal during this time and alsobefore and after. We observe no statistically significant evidence of TeV$\gamma$-ray emission from V392 Per, but present flux limits. Tests of theextension of the Fermi/LAT spectrum to energies above 5 TeV are disfavored by 2standard deviations (95\%) or more. We fit V392 Per's GeV $\gamma$ rays withhadronic acceleration models, incorporating optical observations, and comparethe calculations with HAWC limits.<br

Galactic Gamma-Ray Diffuse Emission at TeV energies with HAWC Data

The Galactic gamma-ray diffuse emission (GDE) is emitted by cosmic rays (CRs), ultra-relativistic protons and electrons, interacting with gas and electromagnetic radiation fields in the interstellar medium. Here we present the analysis of TeV diffuse emission from a region of the Galactic Plane over the range in longitude of $l\in[43^\circ,73^\circ]$, using data collected with the High Altitude Water Cherenkov (HAWC) detector. Spectral, longitudinal and latitudinal distributions of the TeV diffuse emission are shown. The radiation spectrum is compatible with the spectrum of the emission arising from a CR population with an "index" similar to that of the observed CRs. When comparing with the \texttt{DRAGON} \textit{base model}, the HAWC GDE flux is higher by about a factor of two. Unresolved sources such as pulsar wind nebulae and TeV halos could explain the excess emission. Finally, deviations of the Galactic CR flux from the locally measured CR flux may additionally explain the difference between the predicted and measured diffuse fluxes

Searching for TeV Dark Matter in Irregular dwarf galaxies with HAWC Observatory

We present the results of dark matter (DM) searches in a sample of 31 dwarf irregular (dIrr) galaxies within the field of view of the HAWC Observatory. dIrr galaxies are DM dominated objects, which astrophysical gamma-ray emission is estimated to be negligible with respect to the secondary gamma-ray flux expected by annihilation or decay of Weakly Interacting Massive Particles (WIMPs). While we do not see any statistically significant DM signal in dIrr galaxies, we present the exclusion limits ($95\%~\text{C.L.}$) for annihilation cross-section and decay lifetime for WIMP candidates with masses between $1$ and $100~\text{TeV}$. Exclusion limits from dIrr galaxies are relevant and complementary to benchmark dwarf Spheroidal (dSph) galaxies. In fact, dIrr galaxies are targets kinematically different from benchmark dSph, preserving the footprints of different evolution histories. We compare the limits from dIrr galaxies to those from ultrafaint and classical dSph galaxies previously observed with HAWC. We find that the contraints are comparable to the limits from classical dSph galaxies and $\thicksim2$ orders of magnitude weaker than the ultrafaint dSph limits.Comment: 22 pages, 11 figures, 3 table