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Effect of Gamma Irradiation on Electrical Properties of CdTe/CdS Solar Cells
摘要： The effect of Co-60 Gamma irradiation on electrical characteristics of CdTe/CdS solar cell has been analyzed using in-situ current-voltage characterization (I-V) in dark condition. The irradiation was done over a wide range of doses from 1kGy to 100 kGy. Electrical parameters such as ideality factor (n), series resistance (RS) and reverse bias leakage current (IR) for each dose have been calculated from the I-V characteristics. The ideality factor of the pristine solar cell is found to be 1.80 and it gradually increased up to 3.38 for the dose of 10 kGy, then it is around 3.38-3.61 for higher doses up to 100 kGy. The I-V characteristics showed significant increase in forward bias and drastic increase in reverse leakage current. The value of IR is 16.8 μA for pristine solar cell and it increases to 1.46 mA for 10 kGy. Further there is four times observable change in the value of IR. However the value of Rs is 0.80 ohm for pristine and continuously decreases to 0.34 ohm for 50 kGy dose. Further there is slight increase in the series resistance to 0.38 ohm for 100 kGy dose.
关键词： CdS,Radiation hardness,CdTe,Space application,Solar cells,Gamma Irradiation
更新于2025-09-12 10:27:22
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Gamma spectral analysis by artificial neural network coupled with Monte Carlo simulations
摘要： Neutron activation analysis has been widely used for quantitative analysis. It can quantify elements in parts per million or billion. Artificial neural network is an attractive technique to analyze complex gamma spectra obtained from neutron activation. This study offers an improved methodology to analyze neutron activation gamma spectra using an artificial neural network. The methodology was demonstrated by quantifying five trace elements (Br, Na, Zn, K, Au) in common kidney stones. First, Monte Carlo simulations were used to create a large training data set. Then, an artificial neural network was employed for chemical elements identification analysis. For quantitative analysis, a Levenberg–Marquardt algorithm with 5 ? 23 ? 5 structure artificial neural network was used. The artificial neural network for analysis of simulated gamma spectra resulted in estimated element concentrations. The differences between true and estimated concentrations are 1.8% for Br, 3.4% for Na, 5.4% for Zn, 2.8% for K, and 1.6% for Au. For real gamma spectral analysis, the largest difference was found to be 28.2% for Zn in a calcium oxalate monohydrate type of kidney stones.
关键词： Kidney stone,Monte Carlo,Neural network,Gamma spectroscopy
更新于2025-09-12 10:27:22
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Electromagnetic Burst Generation during Annihilation of Magnetic Field in Relativistic Laser-Plasma Interaction
摘要： We present the results of theoretical studies of formation and evolution of the current sheet in a colliosionless plasma during magnetic reconnection in relativistic limit. Relativistic magnetic reconnection is driven by parallel laser pulses interacting with underdense plasma target. Annihilation of laser created magnetic field of opposite polarity generates strong non-stationary electric field formed in between the region with opposite polarity magnetic field accelerating charged particles within the current sheet. This laser-plasma target configuration is discussed in regard with the laboratory modeling of charged particle acceleration and gamma flash generation in astrophysics. We present the results of 3-dimensional kinetic simulations and theoretical studies on the formation and evolution of the current sheet in a collisionless plasma during magnetic field annihilation in the ultra-relativistic limit. Annihilation of oppositively directed magnetic fields driven by two laser pulses interacting with underdense plasma target is accompanied by an electromagnetic burst generation. the induced strong non-stationary longitudinal electric field accelerates charged particles within the current sheet. Properties of the laser-plasma target configuration are discussed in the context of the laboratory modeling for charged particle acceleration and gamma flash generation in astrophysics.
关键词： gamma flash generation,relativistic laser-plasma interaction,electromagnetic burst,magnetic reconnection,particle acceleration
更新于2025-09-12 10:27:22
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Comparative Investigation of Gamma Radiation Effects on Long Period Gratings and Optical Power in Different Optical Fibers
摘要： This work presents a comparative study regarding the effects of gamma radiation on standard and different radiation hardened optical fibers, by means of arc-induced long period gratings (LPGs) written in these fibers. In particular, the resonance wavelength shift (Δλres) of LPG attenuation bands and the attenuation in the fiber transmitted optical power (ΔP) have been comparatively explored during irradiation. Different responses were observed depending on the fiber model. The Ge-doped fiber exhibits significant changes of both resonance wavelength and optical transmission loss, whereas the pure silica core fiber is mostly insensitive to radiation (Δλres and ΔP keep almost close to zero). Surprisingly, the radiation resistant fiber, with doped core, exhibits significant resonance shift even if with trivial power losses. In addition, by combining these results with numerical modeling of LPGs, we were able to estimate the radiation effects on the optical fibers under investigation, in terms of average refractive index change. These results can be useful for the application of such devices in radiation environments, i.e., for the development of both radiation sensitive and radiation hardened sensors.
关键词： optical fiber sensors,Gamma-ray effects,Gamma-ray detectors,optical fiber applications,Dosimetry,long period gratings
更新于2025-09-11 14:15:04
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AIP Conference Proceedings [AIP Publishing LLC EXOTIC NUCLEI AND NUCLEAR/PARTICLE ASTROPHYSICS (V). FROM NUCLEI TO STARS: Carpathian Summer School of Physics 2014 - Sinaia, Romania (13–26 July 2014)] - Perspectives for neutron and gamma spectroscopy in high power laser driven experiments at ELI-NP
摘要： The measurement of energy spectra of neutrons and gamma rays emitted by nuclei, together with charge particles spectroscopy, are the main tools for understanding nuclear phenomena occurring also in high power laser driven experiments. However, the large number of particles emitted in a very short time, in particular the strong X-rays flash produced in laser-target interaction, impose adaptation of technique currently used in nuclear physics experiment at accelerator based facilities. These aspects are discussed (Section 1) in the context of proposed studies at high power laser system of ELI-NP. Preliminary results from two experiments performed at Titan (LLNL) and ELFIE (LULI) facilities using plastic scintillators for neutron detection (Section 2) and LaBr3(Ce) scintillators for gamma detection (Section 3) are presented demonstrating the capabilities and the limitations of the employed methods. Possible improvements of these spectroscopic methods and their proposed implementation at ELI-NP will be discussed as well in the last section.
关键词： gamma spectroscopy,neutron spectroscopy,nuclear physics,ELI-NP,high power laser
更新于2025-09-11 14:15:04
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Influence of gamma radiation on microshear bond strength and nanoleakage of nanofilled restoratives in Er, Cr:YSGG laser-prepared cavities
摘要： Objective: To evaluate the effect of gamma radiation on microshear bond strength and nanoleakage of nanofilled restoratives in laser-prepared cavities. Materials and Methods: Twenty?eight flat buccal dentin surfaces were prepared for microshear bond strength test. Er, Cr:YSGG laser was used to prepare another 28 Class V cavities on the buccal surfaces of the molars. All teeth were divided into four groups; 1st group: Application of Filtek Z350 nanocomposite material, 2nd group: As the 1st group and then exposure to gamma radiation, 3rd group: Application of Ketac N100 nanoglass ionomer, and the 4th group: As the 3rd group and then gamma irradiated. The bond strength test was performed after storage in artificial saliva for 24 h. For the nanoleakage test, teeth were submerged in a solution of ammoniacal silver nitrate, sectioned, and then examined under a scanning electron microscope. The collected data were statistically analyzed. Results: Nanocomposite showed higher bond strength values than nanoglass ionomer. Despite the fact that gamma radiation did not decrease nanocomposite bond strength, it decreased nanoglass ionomer bond strength. Nanoglass ionomer-restored cavities showed higher silver ion penetration than nanocomposite in both control and gamma-irradiated groups. Conclusion: Gamma radiation has no effect on bond strength and nanoleakage of nanocomposite so that it can be placed before radiotherapy. On the other hand, the bond strength of nanoglass ionomer was adversely affected by gamma radiation.
关键词： nanoleakage,gamma radiation,Bond strength,Er, Cr:YSGG laser,nanocomposite,nanoglass ionomer
更新于2025-09-11 14:15:04
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INITIAL FOLLOW-UP OF OPTICAL TRANSIENTS WITH COLORES USING THE BOOTES NETWORK
摘要： The Burst Observer and Optical Transient Exploring System (BOOTES) is a network of telescopes that allows the continuous monitoring of transient astrophysical sources. It was originally devoted to the study of the optical emission from gamma-ray bursts (GRBs) that occur in the Universe. In this paper we show the initial results obtained using the spectrograph COLORES (mounted on BOOTES-2), when observing optical transients (OTs) of diverse nature.
关键词： stars: variables: general,gamma-ray burst: general,Telescopes
更新于2025-09-11 14:15:04
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The optical/NIR afterglow of GRB 111209A: Complex yet not unprecedented
摘要： Context. Afterglows of gamma-ray bursts (GRBs) are simple in the most basic model, but can show many complex features. The ultra-long duration GRB 111209A, one of the longest GRBs ever detected, also has the best-monitored afterglow in this rare class of GRBs. Aims. We want to address the question whether GRB 111209A was a special event beyond its extreme duration alone, and whether it is a classical GRB or another kind of high-energy transient. The afterglow may yield significant clues. Methods. We present afterglow photometry obtained in seven bands with the GROND imager as well as in further seven bands with the Ultraviolet/Optical Telescope (UVOT) on-board the Neil Gehrels Swift Observatory. The light curve is analysed by multi-band modelling and joint fitting with power-laws and broken power-laws, and we use the contemporaneous GROND data to study the evolution of the spectral energy distribution. We compare the optical afterglow to a large ensemble we have analysed in earlier works, and especially to that of another ultra-long event, GRB 130925A. We furthermore undertake a photometric study of the host galaxy. Results. We find a strong, chromatic rebrightening event at ≈0.8 days after the GRB, during which the spectral slope becomes redder. After this, the light curve decays achromatically, with evidence for a break at about 9 days after the trigger. The afterglow luminosity is found to not be exceptional. We find that a double-jet model is able to explain the chromatic rebrightening. The afterglow features have been detected in other events and are not unique. Conclusions. The duration aside, the GRB prompt emission and afterglow parameters of GRB 111209A are in agreement with the known distributions for these parameters. While the central engine of this event may differ from that of classical GRBs, there are multiple lines of evidence pointing to GRB 111209A resulting from the core-collapse of a massive star with a stripped envelope.
关键词： gamma-ray burst: general,gamma-ray burst: individual: GRB 111209A,gamma-ray burst: individual: GRB 130925A
更新于2025-09-10 09:29:36
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Simulation of the ELIGANT-GN array performances at ELI-NP for gamma beam energies larger than neutron threshold
摘要： Performance of the ELIGANT-GN array being developed at ELI-NP was evaluated using dedicated GEANT4 simulation code. The array is designed to consist of 17 LaBr3:Ce and 17 CeBr3 detectors as well as 33 BC501A and 29 6Li-glass detectors. The energy and time responses of the detectors were studied giving information on gamma and neutron absolute detection efficiencies of the array. A planned day-one experiment regarding the gamma and neutron decay from GDR in 208Pb is discussed and, based on simulations, the data analysis procedure is proposed. The detection efficiencies as well as the count rates estimations are presented.
关键词： gamma-ray detection,neutron detection,GEANT4 simulations,gamma beam
更新于2025-09-10 09:29:36
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Novel approximate and asymptotic expressions of the outage probability and BER in gamma-gamma fading FSO links with generalized pointing errors
摘要： In this paper, a novel closed-form approximate probability density function (PDF) at high signal-to-noise ratio (SNR) for the composite gamma-gamma (GG) atmospheric turbulence with a generalized pointing error model using the Beckmann distribution is derived in terms of an appropriate gamma distribution by a moment generating function (MGF) matching approach. Based on the obtained PDF, novel closed-form approximate and asymptotic expressions for the outage probability and the average bit-error rate (BER) are derived. Then, the average BER performance and the outage performance of the considered FSO system at high SNR are investigated with different turbulence conditions, receiver aperture sizes, nonzero boresight, and different jitter variances. Numerical results and Monte Carlo simulation results verify the accuracy of our derived approximate and asymptotic expressions over a wide SNR range. This work can be further extended as well to diversity links.
关键词： High SNR,Gamma-gamma distribution,Free-space optical communication,Beckmann distribution,Pointing errors,Atmospheric turbulence
更新于2025-09-10 09:29:36