Features of Light Scattering by Surface Fractal Structures

The average coefficient of light scattering by surface fractal structures is calculated within the scope of the Kirchhoff’s method. Two-dimensional bandlimited Weierstrass function is used to simulate a scattering surface. On the basis of numerical calculations of average scattering coefficient, the scattering indicatrixes for various surfaces and incidence angles are calculated. The analysis of the indicatrixes leads to the following conclusions: the scattering is symmetric about the incidence plane; with the increase of surface calibration degree, the scattering pattern becomes more complicated; the greatest intensity of the scattered wave is observed along the mirror direction; there are other directions, in which the intensity bursts are observed.В рамках Кирхгоффової методи розраховано середній коефіцієнт розсіяння світла поверхневими фрактальними структурами. Для моделювання розсіювальної поверхні використовувалася двовимірна, обмежена смугою Вейєрштрассова функція. Виконано чисельні розрахунки середнього коефіцієнта розсіяння та побудовано індикатриси розсіяння для різних типів поверхонь та кутів падіння. Аналіза індикатрис розсіяння призводить до наступних висновків: розсіяння є симетричним відносно площини падіння; зі збільшенням ступеня калібрування поверхні картина розсіяння ускладнюється; найбільша інтенсивність розсіяної хвилі спостерігається в дзеркальному напрямку і, крім того, існують напрямки, в яких спостерігаються сплески інтенсивности.В рамках метода Кирхгофа рассчитан средний коэффициент рассеяния света поверхностными фрактальными структурами. Для моделирования рассеивающей поверхности использовалась двумерная, ограниченная полосой функция Вейерштрасса. Произведены численные расчеты среднего коэффициента рассеяния и построены индикатрисы рассеяния для различных поверхностей и углов падения. Анализ индикатрис рассеяния приводит к следующим заключениям: рассеяние является симметричным относительно плоскости падения; с увеличением степени калибровки поверхности картина рассеяния усложняется; наибольшая интенсивностьрассеянной волны наблюдается в зеркальном направлении и, кроме того, существуют другие направления, в которых наблюдаются всплески интенсивности

The barrel DIRC of PANDA

Cooled antiproton beams of unprecedented intensities in the momentum range of 1.5-15 GeV/c will be used for the PANDA experiment at FAIR to perform high precision experiments in the charmed quark sector. The PANDA detector will investigate antiproton annihilations with beams in the momentum range of 1.5 GeV/c to 15 GeV/c on a fixed target. An almost 4π acceptance double spectrometer is divided in a forward spectrometer and a target spectrometer. The charged particle identification in the latter is performed by ring imaging Cherenkov counters employing the DIRC principle

The barrel DIRC of PANDA

Cooled antiproton beams of unprecedented intensities in the momentum range of 1.5-15 GeV/c will be used for the PANDA experiment at FAIR to perform high precision experiments in the charmed quark sector. The PANDA detector will investigate antiproton annihilations with beams in the momentum range of 1.5 GeV/c to 15 GeV/c on a fixed target. An almost 4π acceptance double spectrometer is divided in a forward spectrometer and a target spectrometer. The charged particle identification in the latter is performed by ring imaging Cherenkov counters employing the DIRC principle

The barrel DIRC of PANDA

Cooled antiproton beams of unprecedented intensities in the momentum range of 1.5-15 GeV/c will be used for the PANDA experiment at FAIR to perform high precision experiments in the charmed quark sector. The PANDA detector will investigate antiproton annihilations with beams in the momentum range of 1.5 GeV/c to 15 GeV/c on a fixed target. An almost 4π acceptance double spectrometer is divided in a forward spectrometer and a target spectrometer. The charged particle identification in the latter is performed by ring imaging Cherenkov counters employing the DIRC principle

Status of the PANDA barrel DIRC

The PANDA experiment at the future Facility for Antiproton and Ion Research in Europe GmbH (FAIR) at GSI, Darmstadt will study fundamental questions of hadron physics and QCD using high-intensity cooled antiproton beams with momenta between 1.5 and 15 GeV/c. Hadronic PID in the barrel region of the PANDA detector will be provided by a DIRC (Detection of Internally Reflected Cherenkov light) counter. The design is based on the successful BABAR DIRC with several key improvements, such as fast photon timing and a compact imaging region. Detailed Monte Carlo simulation studies were performed for DIRC designs based on narrow bars or wide plates with a variety of focusing solutions. The performance of each design was characterized in terms of photon yield and single photon Cherenkov angle resolution and a maximum likelihood approach was used to determine the π/K separation. Selected design options were implemented in prototypes and tested with hadronic particle beams at GSI and CERN. This article describes the status of the design and R&D for the PANDA Barrel DIRC detector, with a focus on the performance of different DIRC designs in simulation and particle beams