Proof of principle of a high-spatial-resolution, resonant-response gamma-ray detector for Gamma Resonance Absorption in 14N

The development of a mm-spatial-resolution, resonant-response detector based on a micrometric glass capillary array filled with liquid scintillator is described. This detector was developed for Gamma Resonance Absorption (GRA) in 14N. GRA is an automatic-decision radiographic screening technique that combines high radiation penetration (the probe is a 9.17 MeV gamma ray) with very good sensitivity and specificity to nitrogenous explosives. Detailed simulation of the detector response to electrons and protons generated by the 9.17 MeV gamma-rays was followed by a proof-of-principle experiment, using a mixed gamma-ray and neutron source. Towards this, a prototype capillary detector was assembled, including the associated filling and readout systems. Simulations and experimental results indeed show that proton tracks are distinguishable from electron tracks at relevant energies, on the basis of a criterion that combines track length and light intensity per unit length.Comment: 18 pages, 16 figure

Cold Plasma Dispersion Relations in the Vicinity of a Schwarzschild Black Hole Horizon

We apply the ADM 3+1 formalism to derive the general relativistic magnetohydrodynamic equations for cold plasma in spatially flat Schwarzschild metric. Respective perturbed equations are linearized for non-magnetized and magnetized plasmas both in non-rotating and rotating backgrounds. These are then Fourier analyzed and the corresponding dispersion relations are obtained. These relations are discussed for the existence of waves with positive angular frequency in the region near the horizon. Our results support the fact that no information can be extracted from the Schwarzschild black hole. It is concluded that negative phase velocity propagates in the rotating background whether the black hole is rotating or non-rotating.Comment: 27 pages, 11 figures accepted for publication in Gen. Relat. & Gravi

Cold Plasma Wave Analysis in Magneto-Rotational Fluids

This paper is devoted to investigate the cold plasma wave properties. The analysis has been restricted to the neighborhood of the pair production region of the Kerr magnetosphere. The Fourier analyzed general relativistic magnetohydrodynamical equations are dealt under special circumstances and dispersion relations are obtained. We find the $x$-component of the complex wave vector numerically. The corresponding components of the propagation vector, attenuation vector, phase and group velocities are shown in graphs. The direction and dispersion of waves are investigated.Comment: 22 pages, 18 figures, accepted for publication in Astrophys. Space Sc

Isothermal Plasma Wave Properties of the Schwarzschild de-Sitter Black Hole in a Veselago Medium

In this paper, we study wave properties of isothermal plasma for the Schwarzschild de-Sitter black hole in a Veselago medium. We use ADM 3+1 formalism to formulate general relativistic magnetohydrodynamical (GRMHD) equations for the Schwarzschild de-Sitter spacetime in Rindler coordinates. Further, Fourier analysis of the linearly perturbed GRMHD equations for the rotating (non-magnetized and magnetized) background is taken whose determinant leads to a dispersion relation. We investigate wave properties by using graphical representation of the wave vector, the refractive index, change in refractive index, phase and group velocities. Also, the modes of wave dispersion are explored. The results indicate the existence of the Veselago medium.Comment: 24 pages, 12 figures, accepted for publication in Astrophys. Space Sci. arXiv admin note: text overlap with arXiv:1101.0884 and arxiv:1007.285

The present and future of QCD

This White Paper presents an overview of the current status and future perspective of QCD research, based on the community inputs and scientific conclusions from the 2022 Hot and Cold QCD Town Meeting. We present the progress made in the last decade toward a deep understanding of both the fundamental structure of the sub-atomic matter of nucleon and nucleus in cold QCD, and the hot QCD matter in heavy ion collisions. We identify key questions of QCD research and plausible paths to obtaining answers to those questions in the near future, hence defining priorities of our research over the coming decades

Aufbau eines Bleifluorid-Kalorimeters zur Messung der Paritaetsverletzung in der elastischen Elektronenstreuung

In the context of this thesis the highly transparent Cherenkov material lead fluoride (PbF_2) has been examined for its suitability as a calorimetric detector. These studies were dominated by systematic quality controls of PbF_2 monocrystals concerning their light yield and radiation resistance as well as their transmittance and its homogeneity. Besides, a simulation of the intensity and the spatial distribution of Cherenkov photons in PbF_2 as well as model parameterisations are presented. With their help the detectors were optimised for their application in a calorimeter. The homogeneous electromagnetic calorimeter has been constructed in the following years. In this thesis the design features and the completed set-up are shown. Each of the 640 detectors consists of a PbF_2 crystal wrapped in reflective material, a photomultiplier with its base and a coupled fibre. Substantial difficulties for the construction resulted from fluctuations in the mechanical dimensions of the crystals of up to #+-# 500 #mu#m. In order to be able to reject crystals with unsatisfactory geometry, all crystals were measured with a computer-controlled milling machine to an accuracy of 12 #mu#m. The determined characteristics of the crystals are presented in this thesis. In 2000 the first 511 channels of the calorimeter were taken into operation. To achieve stable pulse heights the successfully applied method of optical bleaching was implemented in the calorimeter. The mean energy resolution #DELTA#E/E of the central channels amounted to 4.27%, corresponding to a statistical term #sigma#/ E of (3.1 #+-# 0.3)% / E [GeV]. After the separation of inelastic scattering events and of pile up a raw asymmetry A (+3.0 #+-# 3.0) x 10"-"6, averaged over all central detectors, was determined from the first measurements. (orig.)Available from TIB Hannover: RA 831(3892) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman