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Unified treatment of the total angular momentum of single photons via generalized quantum observables
摘要： In this paper, we provide a consistent framework to address the notorious difficult decomposition of the single-photon total angular momentum (TAM) into a spin (SAM) and an orbital (OAM) component. We discuss the canonical decomposition into SAM and OAM components, which are the generators of internal and spatial rotations in the space of physical states. We find that those operators are mutually compatible but unsharp quantum observables, therefore POVM (Positive Operator-Valued Measures) describe their joint measurements. We present another decomposition of the TAM, which we denote as a non-canonical one. The operators resulting from this decomposition are mutually incompatible but sharp quantum observables, thus PVM (Projector-Valued Measurements). This fact reflects their consistency with the transversality condition of single-photon wavefunctions, thus explains the underlying physics from a quantum information theoretic view. Furthermore, we discuss the implementations on joint measurements for both decompositions and provide an explicit calculation of all these quantities for circularly polarized Gaussian single-photon states. The difference between the canonical and non-canonical momenta leads to observable differences in higher-order statistical moments.
关键词： spin angular momentum,total angular momentum,quantum observables,orbital angular momentum,PVM,single photons,POVM
更新于2025-09-09 09:28:46
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Stuctural, optical and radiation shielding properties of zinc boro-tellurite alumina glasses
摘要： In this work, boro-telluride glasses with additional zinc, aluminum, and alkali–alkaline modifiers have been synthesized using the melt-quenching–annealing method. Six glasses were fabricated with composition of [(60 ? x)B2O3–(10 + x)TeO2–10ZnO–10Al2O3–5Li2O–5MgO] all in mol% and x varied from 0, 10, 20, 30, 40 and 50. The aim of this work is to understand the effect of changing the main glass former from B2O3 → TeO2, to obtain new optical materials. To confirm the amorphous nature of these six glasses, X-ray diffraction was characterized for all six glasses from 10° to 80°. Optical absorption with wavelength range 200–800 nm in room temperature was measured, and the optical absorption coefficient α(λ) calculated to obtain the cutoff wavelength. In addition, gamma photons shielding features of the prepared K1–K6 glasses were evaluated by means of some essential parameters such as mass attenuation coefficients (μ/ρ) and effective atomic number (Zeff) at five energies between 0.356 and 1.33 MeV. No significant difference between the theoretical and simulation μ/ρ values was found. The effective atomic number results indiacte that as the TeO2 content increases, the photons’ attenuation increases. The number of interactions of gamma photons with K6 sample (which contains the maximum amount of TeO2) is relatively high (in comparison to the rest of the samples), which results in more attenuation and thus better shielding features for K6.
关键词： Effective atomic number,Mass attenuation coefficients,Gamma photons shielding,Boro-tellurite glasses,Optical materials
更新于2025-09-04 15:30:14
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Analysis of Secondary Photons Emergent from Combined Material Slab as a Function of Slab Thickness
摘要： Material science is very important for developing the linear accelerator. Determination and understanding of material behavior face to X-rays is a basic study for photon beam modifiers improvements. In this study, the 6 MV photon beams produced by Varian Clinac 2100 was modelled by Monte Carlo simulation using BEAMnrc code and thereafter the flattening filter was replaced by a slab of aluminum and copper separately and by slab of both materials combined together with different thickness of 2.5, 5, 7.5, and 10 mm. The purpose of this study is to investigate the scattered photons with thickness of combined material slab as a function of off-axis distance. The scattered photons increased with thickness of copper alone slab, combined aluminum-copper slab and copper-aluminum slab, but for aluminum alone slab they decreased with slab thickness. The stacking order of these two materials affects the characterization of scattered photons emergent from material slab with thickness. The combination of materials and the manner that the stacking was done affects the scattered photons production. The material combination could improve the radiotherapy efficiency in beam modifier development using more than two materials.
关键词： Monte Carlo simulation,BEAMnrc code,scattered photons,copper slab,aluminum slab,BEAMDP code
更新于2025-09-04 15:30:14
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Study of silicon photomultiplier performance in external electric fields
摘要： We report on the performance of silicon photomultiplier (SiPM) light sensors operating in electric field strength up to 30 kV/cm and at a temperature of 149 K, relative to their performance in the absence of an external electric field. The SiPM devices used in this study show stable gain, photon detection efficiency, and rates of correlated pulses, when exposed to external fields, within the estimated uncertainties. No visible damage to the surface of the devices was caused by the exposure.
关键词： Cryogenic detectors,Double-beta decay detectors,Photon detectors for UV, visible and IR photons (solid-state) (PIN diodes, APDs, Si-PMTs, G-APDs, CCDs, EBCCDs, EMCCDs etc),Noble liquid detectors (scintillation, ionization, double-phase)
更新于2025-09-04 15:30:14
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Resonant inelastic scattering of two x-ray photons by a many-electron atom
摘要： A nonrelativistic variant of the quantum theory for the resonant inelastic-scattering process of two x-ray photons in the deep 1s-shell ionization threshold energy region of a free many-electron atom is established. A quantitative estimate for the magnitude of the observed differential cross section is given.
关键词： differential cross section,quantum theory,resonant inelastic scattering,many-electron atom,x-ray photons
更新于2025-09-04 15:30:14