Spectral and Transmittance Properties of Er3+ Doped Zinc Lithium Lead Calcium Borophosphate Glasses

Zinc lithium lead calcium borophosphate glasses containing Er3+ in (40- x):P2O5:10ZnO:10Li2O:10PbO:10CaO:20B2O3:xEr2O3 (where x=1, 1.5,2 mol %) have been prepared by melt-quenching method. The amorphous nature of the glasses was confirmed by x-ray diffraction studies. Optical absorption, Excitation, fluorescence and Transmittance spectra were recorded at room temperature for all glass samples. Judd-Ofelt intensity parameters Ωλ (λ=2, 4, 6) are evaluated from the intensities of various absorption bands of optical absorption spectra. Using these intensity parameters various radiative properties like spontaneous emission probability, branching ratio, radiative life time and stimulated emission cross–section of various emission lines have been evaluated. Keywords: ZLLCBP Glasses, Optical Properties, Judd-OfeltTheory, Transmittance Properties.

An LGAD-Based Full Active Target for the PIONEER Experiment

PIONEER is a next-generation experiment to measure the charged pion branching ratios to electrons vs. muons Re/μ=Γπ+→e+ν(γ)Γπ+→μ+ν(γ) and pion beta decay (Pib) π+→π0eν. The pion to muon decay (π→μ→e) has four orders of magnitude higher probability than the pion to electron decay (π→eν). To achieve the necessary branching-ratio precision it is crucial to suppress the π→μ→e energy spectrum that overlaps with the low energy tail of π→eν. A high granularity active target (ATAR) is being designed to suppress the muon decay background sufficiently so that this tail can be directly measured. In addition, ATAR will provide detailed 4D tracking information to separate the energy deposits of the pion decay products in both position and time. This will suppress other significant systematic uncertainties (pulse pile-up, decay in flight of slow pions) to <0.01%, allowing the overall uncertainty in to be reduced to O (0.01%). The chosen technology for the ATAR is Low Gain Avalanche Detector (LGAD). These are thin silicon detectors (down to 50 μm in thickness or less) with moderate internal signal amplification and great time resolution. To achieve a 100% active region several emerging technologies are being evaluated, such as AC-LGADs and TI-LGADs. A dynamic range from MiP (positron) to several MeV (pion/muon) of deposited charge is expected, the detection and separation of close-by hits in such a wide dynamic range will be a main challenge. Furthermore, the compactness and the requirement of low inactive material of the ATAR present challenges for the readout system, forcing the amplifier chip and digitizer to be positioned away from the active region.

Vergleich von OSIRIS Natrium Nightglow D-Linien Messungen mit Ergebnissen von bodengestützten Lidar Messungen

&lt;p&gt;Die Mesopausenregion in einer H&amp;#246;he von 80-100 km ist ein Bereich der Atmosph&amp;#228;re, der schwer zu erforschen ist, da direkte Messungen kaum m&amp;#246;glich sind. Eine M&amp;#246;glichkeit bieten aber Messungen des &lt;em&gt;Airglows&lt;/em&gt;. &lt;em&gt;Airglow&lt;/em&gt; entsteht, wenn elektromagnetische Strahlung durch chemische Reaktionen ausgesendet wird. Diese kann dann mit Satelliten oder vom Boden aus gemessen werden. Eine Reaktion bei der &lt;em&gt;Airglow&lt;/em&gt; entsteht ist die Reaktion von Natrium mit Ozon. Bei dieser Reaktion, die auch &lt;em&gt;Chapman-Mechanismus &lt;/em&gt;genannt wird, entsteht angeregtes Natrium mit zwei unterschiedlichen Gesamtdrehimpulsquantenzahlen. Die Abregung in den Grundzustand f&amp;#252;hrt dann zu den zwei bekannten Natrium D-Linien (D2=589,0 nm; D1=589,6 nm). Wie hoch der Anteil des Natriums, der durch die Reaktion in den angeregten Zustand &amp;#252;bergeht ist, ist dabei noch nicht genau gekl&amp;#228;rt. Das Verh&amp;#228;ltnis von Natrium im Grundzustand und Natrium im angeregten Zustand wird durch die &lt;em&gt;branching ratio f&lt;/em&gt; beschrieben. Deren Wert wird in der aktuellen Forschung zwischen 5 und 16 % gesch&amp;#228;tzt. In dieser Arbeit soll, durch Vergleich verschiedener Messungen von unabh&amp;#228;ngigen Instrumenten, dieser Wert weiter eingegrenzt werden. Im Zentrum stehen dabei die Messungen des Instrumentes OSIRIS auf dem Satelliten ODIN und der Vergleich zu Messungen, die mit verschiedenen bodengest&amp;#252;tzten Natrium-Lidars gemacht worden sind. Das Ergebnis ist eine Sch&amp;#228;tzung der &lt;em&gt;branching ratio&lt;/em&gt; auf ca. 6 %.&lt;/p&gt;

Excellent Ultracold Molecular Candidates From Group VA Hydrides: Whether Do Nearby Electronic States Interfere?

By means of highly accurate ab initio calculations, we identify two excellent ultracold molecular candidates from group VA hydrides. We find that NH and PH are suitable for the production of ultracold molecules, and the feasibility and advantage of two laser cooling schemes are demonstrated, which involve different spin-orbit states (A3Π2 and X3Σ1− ). The internally contracted multireference configuration interaction method is applied in calculations of the six low-lying Λ-S states of NH and PH with the spin-orbit coupling effects included, and excellent agreement is achieved between the computed and experimental spectroscopic data. We find that the locations of crossing point between the A3Π and Σ−5 states of NH and PH are higher than the corresponding v′ = 2 vibrational levels of the A3Π state indicating that the crossings with higher electronic states would not affect laser cooling. Meanwhile, the extremely small vibrational branching loss ratios of the A3Π2 → a1Δ2 transition for NH and PH (NH: 1.81 × 10–8; PH: 1.08 × 10–6) indicate that the a1Δ2 intermediate electronic state will not interfere with the laser cooling. Consequently, we construct feasible laser-cooling schemes for NH and PH using three lasers based on the A3Π2 → X3Σ1− transition, which feature highly diagonal vibrational branching ratio R00 (NH: 0.9952; PH: 0.9977), the large number of scattered photons (NH: 1.04×105; PH: 8.32×106) and very short radiative lifetimes (NH: 474 ns; PH: 526 ns). Our work suggests that feasible laser-cooling schemes could be established for a molecular system with extra electronic states close to those chosen for laser-cooling.

Quantifying the Endogeneity in Online Donations

Charitable crowdfunding provides a new channel for people and families suffering from unforeseen events, such as accidents, severe illness, and so on, to seek help from the public. Thus, finding the key determinants which drive the fundraising process of crowdfunding campaigns is of great importance, especially for those suffering. With a unique data set containing 210,907 crowdfunding projects covering a period from October 2015 to June 2020, from a famous charitable crowdfunding platform, specifically Qingsong Chou, we will reveal how many online donations are due to endogeneity, referring to the positive feedback process of attracting more people to donate through broadcasting campaigns in social networks by donors. For this aim, we calibrate three different Hawkes processes to the event data of online donations for each crowdfunding campaign on each day, which allows us to estimate the branching ratio, a measure of endogeneity. It is found that the online fundraising process works in a sub-critical state and nearly 70–90% of the online donations are endogenous. Furthermore, even though the fundraising amount, number of donations, and number of donors decrease rapidly after the crowdfunding project is created, the measure of endogeneity remains stable during the entire lifetime of crowdfunding projects. Our results not only deepen our understanding of online fundraising dynamics but also provide a quantitative framework to disentangle the endogenous and exogenous dynamics in complex systems.

Study of a single line of sight gamma ray diagnostics for measurements of the absolute gamma ray emission from JET

The fusion power produced in a DT thermonuclear reactor is currently determined by measuring the absolute 14 MeV neutron yield of the D(T, α)n fusion reaction. Measurements of 17 MeV gamma rays born from the much less probable D(T, 5He)γ reaction (branching ratio of ∼10−5) have been proposed as an alternative independent method to validate the neutron counting method and also to fulfill the requests of the nuclear regulator for licensing ITER DT operations. However, the development of absolute 17 MeV gamma ray emission measurements entails a number of requirements, such as: (i) knowledge of the 17 MeV gamma ray to 14 MeV neutron emission branching ratio; (ii) the simulation of the gamma ray transport from the extended plasma source to the gamma ray detectors; (iii) a careful determination of the absolute efficiency of previously calibrated gamma ray spectrometers. In this work, we have studied the possibility to infer the global gamma ray emission rate from measurements made with a 3″ × 6″ LaBr3 spectrometer installed at the end of a collimated tangential line of sight at the JET tokamak and using the neutron emission from deuterium plasmas of the most recent experimental campaigns. Results show that 17 MeV gamma ray fluxes at the end of this tangential line of sight have a weak dependence (less than 5%) on the plasma profile and can therefore be used to infer the total emission from the plasma.

Charged and neutral $$ {\overline{B}}_{u,d,s} $$ → γ form factors from light cone sum rules at NLO

We present the first analytic $$ \mathcal{O}\left({\alpha}_s\right) $$ O α s -computation at twist-1,2 of the $$ {\overline{B}}_{u,d,s} $$ B ¯ u , d , s → γ form factors within the framework of sum rules on the light-cone. These form factors describe the charged decay $$ {\overline{B}}_u\to \gamma {\mathrm{\ell}}^{-}\overline{v} $$ B ¯ u → γ ℓ − v ¯ , contribute to the flavour changing neutral currents $$ {\overline{B}}_{d,s}\to \gamma {\mathrm{\ell}}^{+}{\mathrm{\ell}}^{-} $$ B ¯ d , s → γ ℓ + ℓ − and serve as inputs to more complicated processes. We provide a fit in terms of a z-expansion with correlation matrix and extrapolate the form factors to the kinematic endpoint by using the gBB*γ couplings as a constraint. Analytic results are available in terms of multiple polylogarithms in the supplementary material. We give binned predictions for the $$ {\overline{B}}_u\to \gamma {\mathrm{\ell}}^{-}\overline{v} $$ B ¯ u → γ ℓ − v ¯ branching ratio along with the associated correlation matrix. By comparing with three SCET-computations we extract the inverse moment B-meson distribution amplitude parameter λB = 360(110) MeV. The uncertainty thereof could be improved by a more dedicated analysis. In passing, we extend the photon distribution amplitude to include quark mass corrections with a prescription for the magnetic vacuum susceptibility, χq, compatible with the twist-expansion. The values χq = 3.21(15) GeV−2 and χs = 3.79(17) GeV−2 are obtained.

A tale of invisibility: constraints on new physics in b → sνν

The Belle II experiment will measure the rare decays B → Kνν and B → K∗νν with increased sensitivity which can hence be expected to serve as a very efficient probe of new physics. We calculate the relevant branching ratios in low-energy effective field theory (LEFT) including an arbitrary number of massive sterile neutrinos and discuss the expected sensitivity to the different operators. We also take into account the longitudinal polarisation fraction FL and the inclusive decay rate B → Xsνν. In our investigation we consider new physics dominantly contributing to one and two operators both for massless and massive (sterile) neutrinos. Our results show a powerful interplay of the exclusive decay rates B → Kνν and B → K∗νν, and a surprisingly large sensitivity of the inclusive decay mode to vector operators even under conservative assumptions about its uncertainty. Furthermore, the sensitivity of FL is competitive with the branching ratio of B → K∗νν in the search for new physics contributing to scalar operators and thus also complementary to B → Kνν and B → Xsνν.