Photon Distribution Research Articles

Magnetic dipole moments of the hidden-charm pentaquark states: P_c(4440), P_c(4457) and P_{cs}(4459)

In this work, we employ the light-cone QCD sum rule to calculate the magnetic dipole moments of the P_c(4440), P_c(4457) and P_{cs}(4459) pentaquark states by considering them as the diquark–diquark–antiquark and molecular pictures with quantum numbers J^P = frac{3}{2}^-, J^P = frac{1}{2}^- and J^P = frac{1}{2}^-, respectively. In the analyses, we use the diquark–diquark–antiquark and molecular form of interpolating currents, and photon distribution amplitudes to obtain the magnetic dipole moment of pentaquark states. Theoretical examinations on magnetic dipole moments of the hidden-charm pentaquark states, are essential as their results can help us better figure out their substructure and the dynamics of the QCD as the theory of the strong interaction. As a by product, we extract the electric quadrupole and magnetic octupole moments of the P_c(4440) pentaquark. These values show a non-spherical charge distribution.

Laboratory-scale reproduction of lighting conditions for an outdoor vertical column photobioreactor: Theoretical fundamentals and operation of a programmable LED module

The development of tools aimed to predict the productivity of photobioreactors (PBRs) implies immense efforts in the Algae Biotechnology field. Mainly, bubble column systems are widely used for microalgae cultivation. Here, we sought to present a methodology to reproduce the solar lighting conditions of a vertical bubble column reactor located in Santa Fe, Argentina, utilising a commercial laboratory-scale reactor, with a programmable LED module attached. Based on solid, rigorous modelling of solar radiation properties and radiation transfer between surfaces, and keeping constant the effects of geometry and orientation of PBR, and those related to geography such as photoperiod and solar radiation composition (direct and diffuse), the same amount of photosynthetically active radiation (PAR) per volume unit (volumetric radiant flux) has been provided to the indoor unit.Lastly, since the deliverance of radiant energy between the indoor and outdoor units is not the same, the radiant energy field (REF) is obtained for both reactors and compared using the Monte Carlo methodology. Comparisons were made in terms of the distribution and average volumetric absorption rate of PAR photons (〈rPAR〉) for different scenarios (time, day of the year, biomass concentration and photosynthetic pigments concentration). Taken together, the 〈rPAR〉 turned out to be similar for both PBRs, highlighting the potentiality of this approach for its usage either in real or simulated units under varying outdoor conditions.

Experimental Study of Mystery of Double Slit --- Comprehensive Double Slit Experiments

Young’s double slit experiments, which represent the mystery of quantum mechanics, have been interpreted by quantum probability waves and pilot waves. In this article, to study the mystery, we introduce the “virtual box” which represents the slide of double-slit and its right-hand neighborhood. Within, and only within, the “virtual box” the standard wave interference patterns are formed. We propose and carry out “comprehensive double slit experiments” that show that, first, light travelling from a laser source towards the slides of double slit and/or cross-double slit behaves as particle (postulate-1), and second, after leaving the zone and being directed towards the detector, the light behaves as a stream of photons (postulate-2) with no further interference due to the slits. On the one hand, the interference patterns do exist in the comprehensive-double slit experiments. On the other hand, we show four novel phenomena: (1) the fringes of the interference patterns are formed independently; (2) the fringes of the interference patterns can be formed partially; (3) the longitudinal shields do not disturb the interference patterns; and (4) the range of the virtual box is less than one inch. These novel phenomena indicate that photons behave as particles, and would not be expected if photons behave as waves created by the double slit and/or cross double slit. The comprehensive-double slit experiments show the coexistence of wave distribution and particle nature of photons in the same experiment, which violates complementarity principle and thus, seems a paradox. We suggest an interpretation to address the paradox. All observations of the comprehensive-double slit experiments are consistent. Progress in studying the mystery of the double slit experiment is presented.

X-ray spectra and gamma factors from 70 to 120 kV X-ray tube voltages

The energy distribution of photons (spectrum) produced in X-ray generators, or X-ray tubes, depends on current, voltage and the target/filter combination; in turn, the dose depends on the spectrum. During the X-ray tube operation, the dose is due the direct beam or useful beam, the leaking out from the X-ray unit, and those photons scattered by the patient. The dose rate must be reduced to allowable limits using a shielding. In the shielding design an important parameter is the dose normalized to the current and the time, that in this work we named Gamma factor, as the factor used for gamma-ray sources. In this work analog Monte Carlo methods were used to calculate the photon spectra and the Gamma factors for air-Kerma and the Ambient dose equivalent for 70, 80, 90, 100 and 120 kV X-ray tubes having tungsten target and aluminum filter. The mean energies of photon spectra were calculated and the conversion coefficients for H*(10) and Ka per unit fluence were calculated and compared with the coefficients for monoenergetic photons. The glass enclosure and the filter eliminate the low-energy photons; calculated spectra show the continuous X-ray distribution due to Bremsstrahlung and the discrete distribution, due to characteristics X-rays. Photon fluences and doses depend on the X-ray unit voltage. Both gamma factors are similar to values recommended in norms while the fluence-to-dose (Ka and H*(10)) conversion coefficients in function of the mean energy are larger than the fluence-to-dose conversion coefficients for monoenergetic photons.

Graphene Plasmon Excitation with Ground-State Two-Level Quantum Emitters.

The transmission of a two-level quantum emitter in its ground state through a graphene nanosheet is investigated. The graphene plasmons (GPs) field distribution, especially the opposite orientations of the vertical electric field components on the two sides of the graphene nanosheet, produces a significant nonadiabatic process during the interaction between the emitter and the localized GPs. By taking into account the counterrotating terms, the excitation of the quantum emitter with simultaneous emission of a GP has a large probability. This happens for emitter speeds of about 10^{-4} times the speed of light. For accelerated emitters, the GPs exhibit thermal field photon distribution with a high temperature. As a consequence, this study provides a promising platform to observe the dynamical Casimir effect as well as a simulation of the Unruh effect.

An Improved Reflectance Prediction Model for Halftone Printing Dot Based on Monte Carlo Method

The improved reflectance prediction model for printing dot was established with the Monte Carlo method. Reflectance model is a useful approach to predict and control printing quality, which was widely used in color duplication field. The Monte Carlo prediction model for printing dot is a simulation model, satisfying industrial virtual reality needs, which could simulate reflectance data as well as dot shape image. This paper mainly focuses on improving the existing reflectance model for printing dot with simulation program, expanding dot simulation area from one single dot to nine dots. The results showed that the reflectance value closely approached the measured value with high dot area in particular and the correlation coefficient improved to 0.924. 100,000 times was shown to be the optimal number of simulated photon under regular printing condition. The expanding simulation area could significantly eliminate interactive influence among the dots. The photon distribution and dot shape could be sufficiently simulated through this model, providing a reference for quality control. The results indicate that the improved reflectance model increased the reflectance accuracy and could further promote optical study about color duplication.

A comparison study of photothermal effect between moxibustion therapy and laser irradiation on biological tissue

Moxibustion and laser irradiation are perceived to achieve satisfactory therapeutic effects by inducing photothermal effects on biological tissue. Understanding the photon transport and heat transfer process is an effective way to reveal their underlying mechanism. The temperature distribution of in-vitro tissue under gentle moxibustion and 808 nm laser irradiation were measured experimentally. Photon transport was simulated by Monte Carlo models. Heat transfer models on in-vitro tissue with convolved Monte Carlo results as heat sources were developed. During moxibustion, photons emitted from burning moxa stick with long-wavelength deposited in skin layer, which induced a maximum temperature on tissue surface. While for 808 nm laser irradiation, most photons penetrated through skin, which resulted in the highest temperature in fat tissue. Laser irradiation with big beam radius could induce a wide and relatively uniform thermal effect. During moxibustion and laser irradiation, the wavelength and beam radius have a significant influence on photons distribution as well as temperature profile in biological tissue. Laser irradiation with suitable parameters can be proposed as a substitution of moxibustion in terms of photothermal effect. This work would provide valuable guidance for understanding the photothermal mechanism of moxibustion and laser irradiation in the combined view of photon transport and heat transfer.

Distribution of absorbed photons in the tunneling ionization process

We describe a procedure that allows us to solve the three-dimensional time-dependent Schrödinger equation for an atom interacting with a quantized one-mode electromagnetic field. Atom-field interaction is treated in an ab initio way prescribed by quantum electrodynamics. We use the procedure to calculate probability distributions of absorbed photons in the regime of tunneling ionization. We analyze evolution of the reduced photon density matrix describing the state of the field. We show that non-diagonal density matrix elements decay quickly, as a result of the decoherence process. A stochastic model, viewing ionization as a Markovian birth-death process, reproduces the main features of the calculated photon distributions.

London-modified coherent states: statistical properties and interaction with a two-level atom

In this paper, we discuss the statistical properties of London-modified coherent states that were introduced in order to build up a resolution of the identity for London coherent states. The resolution to the identity is realized by the application of an operator to the London cohrent states. Next we find the Mandel-Q parameter that shows that there exist sub-Poissonian behaviour for a large interval of amplitudes, look at their behaviour in phase space through the Husimi-Q function and study their interaction with a two-level atom. We show that their oscillating photon distributions are responsible for the ringing revival behaviour shown by the atomic inversion.

Q-Deformed Coherent States for q-Deformed Photon by Using the Tsallis’s q-Deformed Exponential Function in the Non-Extensive Thermodynamics

In this manuscript we consider q-deformed boson algebra by using the Tsallis’s q-deformed exponential which arises in the non-extensive thermodynamics. Using this we construct q-deformed coherent states and even and odd q-deformed coherent states. We investigate non-classical properties of these q-deformed coherent states such as photon distribution, super-/sub-Poissonian structure and bunching or anti-bunching effect.

A photon-counting LiDAR bathymetric method based on adaptive variable ellipse filtering

The Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2), equipped with the advanced topographic laser altimeter system (ATLAS), is a new measurement strategy that includes a photon-counting technique. Employing such an advanced system facilitates highly accurate measurement of changes in the land surface of the Earth, as well as water depths, thereby providing a novel opportunity for nearshore bathymetry. The main problem in photon-counting bathymetry is the precise identification and separation of photons with different density distributions on the water surface and water-column. Further, automatic detection of the signal photon of the water surface and bottom from the noise photon presents a problem. To overcome such problems, we propose a novel, validated, adaptive variable ellipse filtering bathymetric method (AVEBM). This method can precisely identify and separate the photons in the above-water, water surface, and water-column regions. Filter parameters can be determined automatically by the density distribution of photons in different water environments and water depths, and the signal photons of the water surface and bottom can be detected precisely to conduct bathymetry. To ensure and improve the accuracy and reliability of the AVEBM, datasets of different photon densities were selected and employed in conducting experiments. Further, we used in situ data and remote sensing images to validate and estimate the detection accuracy of the signal photon and bathymetric accuracy. The experimental results indicated that bathymetric accuracy based on the AVEBM method reached 0.48 m of root mean square error (RMSE) when we employed three ATL03 datasets in combination for Qilianyu Islands. Moreover, the bathymetric accuracy reached 0.79 m of RMSE when comparing with the SDB result in Shanhu Island. Results showed that the proposed AVEBM method facilitated highly accurate signal photon detection and bathymetry.

Monte Carlo simulation fused with target distribution modeling via deep reinforcement learning for automatic high-efficiency photon distribution estimation

Particle distribution estimation is an important issue in medical diagnosis. In particular, photon scattering in some medical devices extremely degrades image quality and causes measurement inaccuracy. The Monte Carlo (MC) algorithm is regarded as the most accurate particle estimation approach but is still time-consuming, even with graphic processing unit (GPU) acceleration. The goal of this work is to develop an automatic scatter estimation framework for high-efficiency photon distribution estimation. Specifically, a GPU-based MC simulation initially yields a raw scatter signal with a low photon number to hasten scatter generation. In the proposed method, assume that the scatter signal follows Poisson distribution, where an optimization objective function fused with sparse feature penalty is modeled. Then, an over-relaxation algorithm is deduced mathematically to solve this objective function. For optimizing the parameters in the over-relaxation algorithm, the deep Q -network in the deep reinforcement learning scheme is built to intelligently interact with the over-relaxation algorithm to accurately and rapidly estimate a scatter signal with the large range of photon numbers. Experimental results demonstrated that our proposed framework can achieve superior performance with structural similarity > 0.94 , peak signal-to-noise ratio > 26.55 dB , and relative absolute error < 5.62 % , and the lowest computation time for one scatter image generation can be within 2 s.

Parametrization of the angular distribution of Cherenkov light in air showers

The Cherenkov light produced in air showers largely contributes to the signal observed in ground-based gamma-ray and cosmic-ray observatories. Yet, no description of this phenomenon is available covering both regions of small and large angles to the shower axis. To fill this gap, a parametrization of the angular distribution of Cherenkov photons is performed in terms of a physically-motivated parametric function. Model parameters are constrained using simulated gamma-ray and proton showers with energies in the TeV to EeV region. As a result, a new parametrization is obtained that improves the precision of previous works. Results presented here can be used in the reconstruction of showers with imaging Cherenkov telescopes as well as in the reconstruction of shower profiles with fluorescence detectors.

Effects of observer peculiar motion on the isotropic background frequency spectrum: From the monopole to higher multipoles

Context.The observer peculiar motion produces boosting effects in the anisotropy pattern of the considered background with frequency spectral behaviours related to its frequency spectrum.Aims.We study how the frequency spectrum of the background isotropic monopole emission is modified and transferred to the frequency spectra at higher multipoles,ℓ. We performed the analysis in terms of spherical harmonic expansion up to a certain value ofℓmax, for various models of background radiation, spanning the range between the radio and the far-infrared.Methods.We derived a system of linear equations to obtain the spherical harmonic coefficients and provide the explicit solutions up toℓmax = 6. These are written as linear combinations of the signals atN = ℓmax + 1 colatitudes. We take advantage of the symmetry property of the associated Legendre polynomials with respect toπ/2, which allows for the separation of the system into two subsystems: (1) forℓ = 0 and even multipoles and (2) for odd multipoles. This improves the accuracy of the solutions with respect to an arbitrary choice of the adopted colatitudes.Results.We applied the method to different types of monopole spectra represented in terms of analytical or semi-analytical functions, that is, four types of distortions of the photon distribution function of the cosmic microwave background and four types of extragalactic background signals superimposed onto the cosmic microwave background’s Planckian spectrum, along with several different combinations of these types. We present our results in terms of the spherical harmonic coefficients and of the relationships between the observed and the intrinsic monopole spectra, as well as in terms of the corresponding all-sky maps and angular power spectra. For certain representative cases, we compare the results of the proposed method with those obtained using more computationally demanding numerical integrations or map generation and inversion. The method is generalized to the case of an average map composed by accumulating data taken with sets of different observer velocities, as is necessary when including the effect of the observer motion relative to the Solar System barycentre.Conclusions.The simplicity and efficiency of the proposed method can significantly alleviate the computational effort required for accurate theoretical predictions and for the analysis of data derived by future projects across a variety of cases of interest. Finally, we discuss the superposition of the cosmic microwave background intrinsic anisotropies and of the effects induced by the observer peculiar motion, exploring the possibility of constraining the intrinsic dipole embedded in the kinematic dipole in the presence of background spectral distortions.

Quantum Hacking on an Integrated Continuous-Variable Quantum Key Distribution System via Power Analysis.

In quantum key distribution (QKD), there are some security loopholes opened by the gaps between the theoretical model and the practical system, and they may be exploited by eavesdroppers (Eve) to obtain secret key information without being detected. This is an effective quantum hacking strategy that seriously threatens the security of practical QKD systems. In this paper, we propose a new quantum hacking attack on an integrated silicon photonic continuous-variable quantum key distribution (CVQKD) system, which is known as a power analysis attack. This attack can be implemented by analyzing the power originating from the integrated electrical control circuit in state preparation with the help of machine learning, where the state preparation is assumed to be perfect in initial security proofs. Specifically, we describe a possible power model and show a complete attack based on a support vector regression (SVR) algorithm. The simulation results show that the secret key information decreases with the increase of the accuracy of the attack, especially in a situation with less excess noise. In particular, Eve does not have to intrude into the transmitter chip (Alice), and may perform a similar attack in practical chip-based discrete-variable quantum key distribution (DVQKD) systems. To resist this attack, the electrical control circuit should be improved to randomize the corresponding power. In addition, the power can be reduced by utilizing the dynamic voltage and frequency scaling (DVFS) technology.

Centrality dependence of dilepton production via γγ processes from Wigner distributions of photons in nuclei

We propose a new complete method, based on the Wigner distributions of photons, how to calculate differential distributions of dileptons created via photon-photon fusion in semicentral (b<2RA) AA collisions. The formalism is used to calculate different distributions of invariant mass, dilepton transverse momentum and acoplanarity for different regions of centrality. The results of calculation are compared with recent STAR, ALICE and ATLAS experimental data. Very good agreement with the data is achieved without free parameters and without including additional mechanisms such as a possible rescattering of leptons in the quark-gluon plasma.

Markov chains for modeling complex luminescence, absorption, and scattering in nanophotonic systems.

We developed a method to model fluorescence, absorption, and scattering in nanophotonic systems using ergodic Markov chains. Past works have used absorbing Markov chains to find the long-run angle-dependent distribution of emitted photons. In contrast, we use ergodic Markov chains to focus on the steady state distribution of photons within various media, giving additional insight into the macroscopic optical response during illumination. We show that the method reproduces Beer-Lambert's Law and Kirchhoff's Law, and can quantify deviations from these laws when their assumptions are violated. We also use the method to model luminescent solar concentrators (LSCs) based on semiconductor nanocrystals.

New approach of controlling the area affected in brain tumour treatment by LITT

There are some techniques to ablate tumours of brain, breast and liver. One of them is laser irradiation. The most important problem of this technique is to injure noncancerous tissues. It is a challenging work to control the domain of laser effects. In other words, it is hard to ablate cancerous tissue without ablating noncancerous. To gain this goal, some researchers have been proposed some ways, such as using two or three applicators or moving applicator. The objective of this paper is to present an approach to control the temperature distribution and heat affected zone in brain tumours when irradiated by shielded laser beam, 1064 nm ND-YAG. The effects of laser beam, resulting in tissue temperature increasing, follows the border of tumour by defining of a dual intensity distribution. This is included two distinct intensity distributions of laser on the applicator by shielding. Treatment of an arbitrary topology of tumour will be simulated irradiation of laser by two different distributions through numerical method. Results show when dual distribution on the tumour border is used, the pattern of photon distribution is coincident by the tumour and the affected zone and temperature increasing follows the borderline of tumour, qualitatively. It shows that the ablated volume of tumour will be 53% more than when the unique distribution is used and the treatment time is shorter, resultantly.

Numerical Study of Turbid Slab Optical Properties Reconstruction from Multiple Scattering Signals Using Time-Based Markov Chain Model

The reconstruction of optical properties for opaque mediums is highly desired for medical, atmosphere and aerosol applications. However, the modeling and reconstruction process is highly related with multiple scattering phenomena, which elevates both the complexity and computational costs for such efforts. This work introduces a time-based Markov chain method, which uses a sparse transition matrix to represent the likelihood for a photon to transit in the turbid media. The accuracy of the time-based Markov chain model was verified against the forwarding calculations of the scattering-based Markov chain model and Monte Carlo simulations. Then, reconstruction was performed with backscattered photon angular distributions. Based on the characteristics of the sparse transition matrix, the optical properties (droplet diameters) could be obtained layer by layer with transmitted photon distributions at different time durations. It is shown that the time-based Markov chain model can reconstruct the optical properties of a turbid slab with satisfactory accuracy and lower computational costs.

Nonlinearity Simulation of Digital SiPM Response for Inhomogeneous Light

Currently, we are developing a neutron scintillation detector prototype using silicon photomultipliers (SiPMs) as the photodetector. In order to reconstruct the position of single neutron events to an accuracy better than the pixel pitch of the SiPM, a very accurate photon count is required. Each pixel consists of 3200 microcells, operated in Geiger mode. A cell which is already triggered cannot detect any following photons hitting the cell, until it is recharged. This leads to a nonlinearity in the pixel’s response for a higher photon density impinging across the pixel. Previous studies provided a correction factor to estimate the saturation, by assuming a homogeneous photon distribution density and comparing it to the number of microcells. In our specific application, the photon distribution is not homogeneous, which is why we examined the influence of the homogeneity on the saturation. In this work, we present a case study for difference in nonlinearity effect for an inhomogeneous and homogeneous photon distribution density, given the light intensity is equal. The simulation results suggest that the effect could be higher for an inhomogeneous distribution. Therefore, care must be taken when using the established correction factor for saturation and an analysis of the photon distribution homogeneity is necessary.