scholarly journals A Brewster route to Cherenkov detectors

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xiao Lin ◽  
Hao Hu ◽  
Sajan Easo ◽  
Yi Yang ◽  
Yichen Shen ◽  
...  
Keyword(s):  
Refractive Index ◽  
Incident Angle ◽  
Photon Number ◽  
Visible Spectrum ◽  
High Energy ◽  
Particle Identification ◽  
Cherenkov Detectors ◽  
Host Materials ◽  
Detection Plane ◽  
Filtering Effect

AbstractCherenkov detectors enable a valuable tool to identify high-energy particles. However, their sensitivity and momentum coverage are limited by the refractive index of host materials. Especially, identifying particles with energy above multiple gigaelectronvolts requires host materials with a near-unity refractive index, which are limited to bulky gas chambers. Overcoming this fundamental material limit is important for future particle detectors yet remains a long-standing challenge. Here, we propose a different paradigm for Cherenkov detectors that utilizes the broadband angular filter made from stacks of variable one-dimensional photonic crystals. Owing to the Brewster effect, the angular filter is transparent only to Cherenkov photons from a precise incident angle. Particle identification is achieved by mapping each Cherenkov angle to the peak-intensity position of transmitted photons in the detection plane. Such angular filtering effect, although decreases the photon number collected in the detection plane, enables the realization of a non-dispersive pseudo refractive index over the entire visible spectrum. Moreover, the pseudo refractive index can be flexibly designed to different values close to unity. Our angular-selective Brewster paradigm offers a feasible solution to implement compact and highly sensitive Cherenkov detectors especially in beam lines with a small angular divergence using regular dielectrics.

scholarly journals Adjustment of Terahertz Properties Assigned to the First Lowest Transition of (D+, X) Excitonic Complex in a Single Spherical Quantum Dot Using Temperature and Pressure

2021 ◽  
Vol 11 (13) ◽  
pp. 5969
Author(s):  
Noreddine Aghoutane ◽  
Laura M. Pérez ◽  
Anton Tiutiunnyk ◽  
David Laroze ◽  
Sotirios Baskoutas ◽  
...  
Keyword(s):  
Refractive Index ◽  
Quantum Dot ◽  
Energy Region ◽  
Practical Importance ◽  
High Energy ◽  
Spherical Quantum Dot ◽  
Terahertz Region ◽  
Mass Approximation ◽  
Optical Responses ◽  
Temperature And Pressure

This theoretical study is devoted to the effects of pressure and temperature on the optoelectronic properties assigned to the first lowest transition of the (D+,X) excitonic complex (exciton-ionized donor) inside a single AlAs/GaAs/AlAs spherical quantum dot. Calculations are performed within the effective mass approximation theory using the variational method. Optical absorption and refractive index as function of the degree of confinement, pressure, and temperature are investigated. Numerical calculation shows that the pressure favors the electron-hole and electron-ionized donor attractions which leads to an enhancement of the binding energy, while an increasing of the temperature tends to reduce it. Our investigations show also that the resonant peaks of the absorption coefficient and the refractive index are located in the terahertz region and they undergo a shift to higher (lower) therahertz frequencies when the pressure (temperature) increases. The opposite effects caused by temperature and pressure have great practical importance because they offer an alternative approach for the adjustment and the control of the optical frequencies resulting from the transition between the fundamental and the first excited state of exciton bound to an ionized dopant. The comparison of the optical properties of exciton, impurity and (D+,X) facilitates the experimental identification of these transitions which are often close. Our investigation shows that the optical responses of (D+,X) are located between the exciton (high energy region) and donor impurity (low energy region) peaks. The whole of these conclusions may lead to the novel light detector or source of terahertz range.

State-of-the-art Laser Ceramics for the Next-generation Solid-state Laser

2021 ◽  
Vol 30 (10) ◽  
pp. 22-27
Author(s):  
Ho Jin MA ◽  
Ha-Neul KIM
Keyword(s):  
Solid State ◽  
Mechanical Characteristics ◽  
High Energy ◽  
Solid State Lasers ◽  
Laser Ceramics ◽  
Host Materials ◽  
Laser Systems ◽  
Energy Laser ◽  
High Energy Laser ◽  
Gain Media

Solid-state lasers have aroused many researchers’ interests for a variety of applications in military and industrial fields. Because of the preference for increased output power, Nd:YAG single crystals, which are the most widely used gain media, should be replaced by other more suitable candidates. Polycrystalline sesquioxide ceramics show great potential for use as gain media because their thermal and mechanical characteristics are suitable for use with high-energy laser systems. Recently, novel concepts of the gain media were also introduced. Herein, while briefly looking back on the progress of polycrystalline laser ceramics, we will discuss new interests in host materials and systems.

Refractive index excursions in pulsed high energy rhodamine 6G laser solutions

1976 ◽  
Vol 15 (11) ◽  
pp. 2624
Author(s):  
M. C. Fowler ◽  
W. H. Glenn
Keyword(s):  
Refractive Index ◽  
Rhodamine 6G ◽  
High Energy

scholarly journals Vacuum laser acceleration of super-ponderomotive electrons using relativistic transparency injection

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
P. K. Singh ◽  
F.-Y. Li ◽  
C.-K. Huang ◽  
A. Moreau ◽  
R. Hollinger ◽  
...  
Keyword(s):  
Laser Field ◽  
Pulse Shaping ◽  
High Energy Physics ◽  
Incident Angle ◽  
Electron Injection ◽  
High Energy ◽  
Intense Laser ◽  
Light Sources ◽  
Very High Energy ◽  
Laser Acceleration

AbstractIntense lasers can accelerate electrons to very high energy over a short distance. Such compact accelerators have several potential applications including fast ignition, high energy physics, and radiography. Among the various schemes of laser-based electron acceleration, vacuum laser acceleration has the merits of super-high acceleration gradient and great simplicity. Yet its realization has been difficult because injecting free electrons into the fast-oscillating laser field is not trivial. Here we demonstrate free-electron injection and subsequent vacuum laser acceleration of electrons up to 20 MeV using the relativistic transparency effect. When a high-contrast intense laser drives a thin solid foil, electrons from the dense opaque plasma are first accelerated to near-light speed by the standing laser wave in front of the solid foil and subsequently injected into the transmitted laser field as the opaque plasma becomes relativistically transparent. It is possible to further optimize the electron injection/acceleration by manipulating the laser polarization, incident angle, and temporal pulse shaping. Our result also sheds light on the fundamental relativistic transparency process, crucial for producing secondary particle and light sources.

Calculation of Reflected Intensities for Medium and High Energy Electron Diffraction

1972 ◽  
Vol 27 (3) ◽  
pp. 390-395 ◽  
Author(s):  
A.R. Moon
Keyword(s):  
Electron Diffraction ◽  
Surface Structure ◽  
Incident Angle ◽  
High Energy ◽  
Numerical Calculations ◽  
High Energy Electron ◽  
Matrix Eigenvalue ◽  
High Energy Electrons ◽  
Experimental Values ◽  
Reflection Electron Diffraction

Abstract The Bethe theory of electron diffraction is used to calculate reflection electron diffraction intensities for medium and high energy electrons. A generalized Hill's determinant method is used for the numerical calculations instead of the more common but slower matrix-eigenvalue technique. Results of a "systematics" calculation of the specular intensity as a function of incident angle are compared with some experimental values for the Si (111) surface. The application of the Bethe theory to crystals where the surface structure differs from the bulk is also considered.

Electron Refraction of Amorphous Nanospheres

1997 ◽  
Vol 3 (S2) ◽  
pp. 1055-1056
Author(s):  
Y.C. Wang ◽  
T.M. Chou ◽  
M. Libera
Keyword(s):  
Refractive Index ◽  
Electron Scattering ◽  
Unit Volume ◽  
High Energy ◽  
Covalent Bonding ◽  
Electron Holography ◽  
High Energy Electron ◽  
Electron Wave ◽  
Transmission Electron ◽  
The Mean

The phase shift imparted to an incident high-energy electron wave in a TEM is related to the specimen’s electron-refractive properties. These, in turn, are related to the electrostatic potential and, by Fourier transform (1), to the electron scattering factors fei(s) for the various atom species i in the specimen and scattering vectors s. The average refractive index is determined by the mean electrostatic (inner) potential, Φo, and can be modelled as Φo = (C/Ω) Σfei(s0) [equation 1] where C = 47.878 (V-Å2) and the summation runs over all of the atoms in the unit volume Ω (2). Calculated fei(s) data are available from the literature (e.g. 3). These calculations have only been done for neutral atoms and some fully ionized cations and anions. They do not account for electron redistribution due to covalent bonding to which Φo is quite sensitive (4).This research is making Φo measurements using transmission electron holography. Holograms were collected using a 200keV Philips CM20 FEG TEM equipped with a non-rotatable biprism (5) and a Gatan 794 Multiscan camera.

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