Breakup Temperature of Target Spectators in Au + Au Collisions at E/A = 1000 MeV

Breakup temperatures were deduced from double ratios of isotope yields for target spectators produced in the reaction Au + Au at 1000 MeV per nucleon. Pairs of $^{3,4}$He and $^{6,7}$Li isotopes and pairs of $^{3,4}$He and H isotopes (p, d and d, t) yield consistent temperatures after feeding corrections, based on the quantum statistical model, are applied. The temperatures rise with decreasing impact parameter from 4 MeV for peripheral to about 10 MeV for the most central collisions. The good agreement with the breakup temperatures measured previously for projectile spectators at an incident energy of 600 MeV per nucleon confirms the observed universality of the spectator decay at relativistic bombarding energies. The measured temperatures also agree with the breakup temperatures predicted by the statistical multifragmentation model. For these calculations a relation between the initial excitation energy and mass was derived which gives good simultaneous agreement for the fragment charge correlations. The energy spectra of light charged particles, measured at $\theta_{lab}$ = 150$^{\circ}$, exhibit Maxwellian shapes with inverse slope parameters much higher than the breakup temperatures. The statistical multifragmentation model, because Coulomb repulsion and sequential decay processes are included, yields light-particle spectra with inverse slope parameters higher than the breakup temperatures but considerably below the measured values. The systematic behavior of the differences suggests that they are caused by light-charged-particle emission prior to the final breakup stage. PACS numbers: 25.70.Mn, 25.70.Pq, 25.75.-qComment: 29 pages, TeX with 11 included figures; Revised version accepted for publication in Z. Phys. A Two additional figure

The Study of Quantum Interference in Metallic Photonic Crystals Doped with Four-Level Quantum Dots

In this work, the absorption coefficient of a metallic photonic crystal doped with nanoparticles has been obtained using numerical simulation techniques. The effects of quantum interference and the concentration of doped particles on the absorption coefficient of the system have been investigated. The nanoparticles have been considered as semiconductor quantum dots which behave as a four-level quantum system and are driven by a single coherent laser field. The results show that changing the position of the photonic band gap about the resonant energy of the two lower levels directly affects the decay rate, and the system can be switched between transparent and opaque states if the probe laser field is tuned to the resonance frequency. These results provide an application for metallic nanostructures in the fabrication of new optical switches and photonic devices

Terahertz current noise in n+nn+ diodes

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Characterization of the In0.53Ga0.47As n+nn+ Infrared Photodetectors

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Analytical admittance characterization of high mobility channel

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Noise Calculation in nano-channel diodes for Terahertz detectors application

International audienceAn analytical calculations of the intrinsic noise and Noise Equivalent Power (NEP) in the InGaAs nanochannel diode are proposed. The model based on the one dimensional Poisson equation which is derived to obtain the current-potential relation of the diode. This relation allows to calculate the admittance/impedance elements and establish the noise spectral density according to Nyquist expression. From the complex impedance of the diode, we can extract the Responsivity generated from the power signal in proportional to the power absorbed by the nanochannel diode. The analysis combine the noise spectra and the Responsivity to determine the Equivalent Noise Power (NEP) of the diode under a high frequency signal. The discussion includes the geometrical effects, the operating temperature and proporties of the diode to optimize the generated power in terahertz frequency. The Responsivity and the Noise power schow the appearence of resonances peaks in the terahertz domain. The analysis of the resonances improves the behavior of the nanochannel diodes for high sensitive Terahertz detectors. The analytical noise results are compared with the Mont Carlo calculations in Refs. [1], [2]

Noise Calculation in nano-channel diodes for Terahertz detectors application

International audienceAn analytical calculations of the intrinsic noise and Noise Equivalent Power (NEP) in the InGaAs nanochannel diode are proposed. The model based on the one dimensional Poisson equation which is derived to obtain the current-potential relation of the diode. This relation allows to calculate the admittance/impedance elements and establish the noise spectral density according to Nyquist expression. From the complex impedance of the diode, we can extract the Responsivity generated from the power signal in proportional to the power absorbed by the nanochannel diode. The analysis combine the noise spectra and the Responsivity to determine the Equivalent Noise Power (NEP) of the diode under a high frequency signal. The discussion includes the geometrical effects, the operating temperature and proporties of the diode to optimize the generated power in terahertz frequency. The Responsivity and the Noise power schow the appearence of resonances peaks in the terahertz domain. The analysis of the resonances improves the behavior of the nanochannel diodes for high sensitive Terahertz detectors. The analytical noise results are compared with the Mont Carlo calculations in Refs. [1], [2]

Terahertz Responsivity Calculation of Unipolar Diodes Based on Transistor Channels Model

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