22.—Organic Scintillators with Improved Timing Characteristics.

New fast organic scintillators using intramolecular bromine quenching

Organic liquid scintillators are used in a wide variety of applications in experimental nuclear and particle physics. Boron-loaded scintillators are particularly useful for detecting neutron captures, due to the high thermal neutron capture cross section of 10B. These scintillators are commonly used in neutron detectors, including the DarkSide-50 neutron veto, where the neutron may produce a signal when it scatters off protons in the scintillator or when it captures on 10B. Reconstructing the energy of these recoils is complicated by scintillation quenching. Understanding how nuclear recoils are quenched in these scintillators is an important and difficult problem. In this article, we present a set of measurements of neutron-induced proton recoils in a boron-loaded organic liquid scintillator at recoil energies ranging from 57–467 keV, and we compare these measurements to predictions from different quenching models. We find that a modified Birks' model whose denominator is quadratic in dE/dx best describes the measurements, with χ2/NDF=1.6. This result will help model nuclear recoil scintillation in similar detectors and can be used to improve their neutron tagging efficiency.

Ionization quenching in organic scintillators is usually corrected with methods that require careful assessment of the response relative to that of an ionization chamber. Here, we present a framework to compute ionization quenching correction factors (QCFs) from first principles for organic plastic scintillators exposed to ions. The tool solves the kinetic Blanc equation, of which the Birks model is a simplified solution, based on amorphous track structures models. As a consequence, ionization quenching correction factors can be calculated relying only on standard, tabulated scintillator material properties such as the density, light yield, and decay time.The tool is validated against experimentally obtained QCFs for two different organic plastic scintillators irradiated with protons with linear energy transfers (LETs) between 5–. The QCFs computed from amorphous track structure models and the BC-400 scintillator properties deviate less than 3% from the Birks model for LETs below and less than 5% for higher LETs. The agreement between experiments and the software for the BCF-12 scintillator is within 2% for LETs below and within 10% for LETs above, comparable to the experimental uncertainties. The framework is compiled into the open source software available for download. enables computations of QCFs in organic plastic scintillators exposed to ions independently of experimentally based quenching parameters in contrast to the Birks model. can improve the accuracy of correction factors and understanding of ionization quenching in scintillator dosimetry.

We present an alternative approach to organic scintillator detector fabrication and optical readout, in which silicon photomultipliers (SiPMs) are embedded directly into a cast-moldable organic scintillator. Organic glass scintillator formulations have properties that allow for cast-molding at temperatures below 200°C. This enables the freedom to construct arbitrary scintillator shapes, and interior photon detection is beneficial for shapes that either do not have an optimal coupling surface, or shapes with poor optical transport to a coupling surface. We provide a proof-of-principle demonstration by casting four Broadcom AFBR-S4N66P014M 6 mm × 6 mm SiPMs each into a 2.54 cm × 2.54 cm × 2.54 cm cube of organic glass scintillator. Potential performance impacts on the SiPMs due to the casting process are characterized by the noise properties before and after casting, including dark count rate, cross talk probability, and single photo-electron pulse height. We have measured small differences in noise properties resulting from the casting, none of which are expected to have a detrimental impact on overall performance. Finally, the light collection and neutron/gamma pulse shape discrimination performance for the four cubic assemblies is presented, further demonstrating functionality of the SiPMs as well as the performance of the particular organic glass scintillator formulation used.

Femtosecond laser-induced optical kerr dynamics in CS 2/alkane binary solutions

A desidratação osmótica é uma operação unitária importante para transformar os frutos perecíveis em novos produtos com valor agregado e com maior vida de prateleira. A aplicação dos modelos matemáticos confiáveis permite prever o comportamento dos diversos fenômenos que ocorrem durante o processo de secagem, o que implica na redução do custo operacional. A polpa do cupuaçu é comumente usada para preparar sucos e sorvetes, mas durante a safra é produzida em grande quantidade, que muitas vezes, é descartada devido ao custo de produção ser mais alto do que o da comercialização. O objetivo desse estudo foi investigar o efeito da solução binária e da ternária na taxa da secagem por convecção e avaliar a adequação dos modelos matemáticos na descrição das curvas da secagem do cupuaçu. No experimento, a pré-desidratação foi feita com solução binária (sacarose a 40 ºBrix) e ternária (80% de sacarose/20% de cloreto de sódio), durante três horas em temperatura ambiente, seguida pela secagem convencional na estufa (ar circulante) a 65 ºC, até peso constante. Os dados experimentais foram ajustados utilizando os modelos de Page e Midilli, Kucuk e Yapar. A solução binária usada na pré-secagem reduziu o tempo da subseqüente secagem convencional. Com variação de 99,64 a 99,77% no coeficiente de determinação (R²), o modelo de Page apresentou o melhor ajuste aos dados experimentais.

The role of the secondary fluorophore in ternary plastic scintillators aiming at discriminating fast neutrons from gamma-rays

10. Electric Arcs

A new technique for measuring the Fickian diffusion coefficient in binary liquid solutions

An essentially new design and new technology are proposed for making solar cells (SC) that combine the advantages of SC with horizontal and vertical p-n junctions. The development and study of hybrid solar batteries make it possible to significantly expand their range of practical uses in solar power generation, especially in space-borne or ground-mounted concentrator systems, laser-based power transmission systems, high-voltage electrical supply systems employed in medicine, and applications in nuclear physics, photometry, and other areas.

High precision automatic energy scanning of slit stabilized electrostatic accelerators

Isolated multi-MeV $\gamma$ -rays with attosecond duration, high collimation and beam angular momentum (BAM) may find many interesting applications in nuclear physics, astrophysics, etc. Here, we propose a scheme to generate such $\gamma$ -rays via nonlinear Thomson scattering of a rotating relativistic electron sheet driven by a few-cycle twisted laser pulse interacting with a micro-droplet target. Our model clarifies the laser intensity threshold and carrier-envelope phase effect on the generation of the isolated electron sheet. Three-dimensional numerical simulations demonstrate the $\gamma$ -ray emission with 320 attoseconds duration and peak brilliance of $9.3\times 10^{24}$ photons s ${}^{-1}$ mrad ${}^{-2}$ mm ${}^{-2}$ per 0.1 $\%$ bandwidth at 4.3 MeV. The $\gamma$ -ray beam carries a large BAM of $2.8 \times 10^{16}\mathrm{\hslash}$ , which arises from the efficient BAM transfer from the rotating electron sheet, subsequently leading to a unique angular distribution. This work should promote the experimental investigation of nonlinear Thomson scattering of rotating electron sheets in large laser facilities.

We present a framework to simulate the dynamics of hard probes such as heavy quarks or jets in a hot, strongly coupled quark-gluon plasma (QGP) on a quantum computer. Hard probes in the QGP can be treated as open quantum systems governed in the Markovian limit by the Lindblad equation. However, due to large computational costs, most current phenomenological calculations of hard probes evolving in the QGP use semiclassical approximations of the quantum evolution. Quantum computation can mitigate these costs and offers the potential for a fully quantum treatment with exponential speed-up over classical techniques. We report a simplified demonstration of our framework on IBM Q quantum devices and apply the random identity insertion method to account for cnot depolarization noise, in addition to measurement error mitigation. Our work demonstrates the feasibility of simulating open quantum systems on current and near-term quantum devices, which is of broad relevance to applications in nuclear physics, quantum information, and other fields.

Extensions of the Dyson mapping for products of any numbers of fermion and boson operators are suggested. Their general importance in obtaining the relationship between particle and subparticle quantum models and in particular between particle and subparticle nuclear models is discussed. An application in nuclear physics is demonstrated by introducing an interacting spinor model of the nucleus using a new type of supersymmetry and by showing its ability to unify and derive dynamic symmetry nuclear models. Another application is demonstrated by suggesting a quark nuclear-plasma model and by showing that it is possible to give a foundation for such system models, including the transition from quark condensate into nucleons (nucleus) in one limit and quark chaotic behaviour (plasma) in another.

High-energy vortex γ photons have significant applications in many fields. However, their generation and angular momentum manipulation are still great challenges. Here, we first investigated the generation of vortex γ photons with controllable spin and orbital angular momenta via nonlinear Compton scattering of two-color counter-rotating circularly polarized (CP) laser fields. The radiation probabilities of vortex photons are calculated using the semiclassical approach that resolves angular momenta of emitted photons. We find that the angular momenta transferred to emitted photons are determined by the dominating photon absorption channel, leading to a structured spectrum with alternations in helicity and twist directions. By tuning the relative intensity ratio of the two-color CP laser fields, the polarization and vortex charge of the emitted γ photons can be controlled, enabling the generation of CP vortex γ photons with a user-defined polarization and topological charge, which may have multiple applications in nuclear physics, astrophysics, particle physics, etc.