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Teamplay
Published in Volker Knecht, AI for Physics, 2023
Specifically, it was the LHC where the “God particle” was detected in 2012, as the last particle of the Standard Model of particle physics (summarized in Chapter 3).7 This particle known as the Higgs boson was predicted in 1964 by several scientists including François Englert and Peter Higgs who both won the Nobel Prize in 2013. The Higgs boson is an elementary particle produced by the quantum excitation of the Higgs field. This field is essential as it gives mass to all fundamental constituents of matter (including electrons and quarks), except to itself.
Microscopic Theory
Published in David A. Cardwell, David C. Larbalestier, I. Braginski Aleksander, Handbook of Superconductivity, 2023
For most purposes, and in particular, when one wishes to calculate the changes that various physical properties undergo on passing from the normal to the superconducting state, it is adequate to visualize the superconducting groundstate as having all the N electrons bound into di-electronic ‘molecules’ (Cooper pairs) which are all described by the same two-particle wave function. This fundamental property, that all Cooper pairs have to occupy the same pair state, is characteristic not only of the groundstate but of all low-energy states in which a finite fraction of electrons are paired; it is tempting to think of it as a kind of ‘Bose condensation’ (the pairs have total spin zero and thus are indeed bosons!), but, irrespective of the terminology, it is the essential key to understanding the abnormal properties of superconductors such as the Meissner effect (see Chapter A2.4).
Introduction and History
Published in Volker Ziemann, ®, 2019
Note that the ISR collided protons on protons due to the unavailability of a high-quality source for anti-protons at the time. But the situation changed with the invention of stochastic cooling by van der Meer, which permitted us to greatly improve the beam quality of the anti-protons that were generated by smashing high-energy protons into a target. Once the production of high-quality anti-protons was under control, the large synchrotrons at Fermilab and CERN were replaced or converted to colliders for protons and anti-protons, leading to the discovery of the mediators of the weak-force, the Z- and W-bosons at CERN in 1983 and the top-quark in 1995 in the Tevatron at Fermilab. More recently, in operation since the year 2000, the Relativistic Heavy-Ion Collider (RHIC) in Brookhaven collides, well, heavy ions, to probe how matter behaved immediately following the big-bang. At CERN, the Large Hadron Collider (LHC), in full operation since 2010, was instrumental in the discovery of the Higgs-boson, which explains the masses of elementary particles. The FAIR-facility, based on a large synchrotron, dedicated to many aspects of nuclear physics, is under construction at GSI near Frankfurt.
Effects of quantum mechanical identity in particle scattering: experimental observations (and lack thereof)
Published in Journal of the Royal Society of New Zealand, 2021
In the quantum description of systems of particles two categories are encountered: particles with half-integer spin, called fermions, and particles with integer spin, called bosons. The quantum mechanical wave function for a system of identical bosons is required to be symmetric under the permutations of two particles. In contrast, the quantum mechanical wave function for a system of identical fermions is required to be antisymmetric under the permutations of two particles. This is the basis of the Pauli exclusion principle which forbids two identical fermions to occupy the same quantum state and for example accounts for the ordering of electrons into shells in atoms: the electron has spin 1/2 (and is consequently a fermion) with the two possible spin projections (spin-up) and (spin-down) – hence there can be exactly two in the innermost shell.
Evolution of detectors for particle physics
Published in Radiation Effects and Defects in Solids, 2022
The Large Hadron Collider (LHC) is the world's largest and highest-energy particle accelerator (37). Its construction lasted from 1998 to 2008, in the tunnel previously housing the Large Electron-Positron Collider (LEP), 27 kilometers in circumference, at depths between 100 and 175 meters. It contains six detectors, each designed for specific types of exploration. It has already achieved one of its most important goals with the discovery of the Higgs Boson, the long sought cornerstone of the Standard Model of elementary particles (Figure 8).
Structural, elastic, electronic, andoptical properties of layered TiNX (X = F, Cl, Br, I) compounds: a density functional theory study
Published in Molecular Physics, 2020
As a fundamental parameter for solids, the Debye temperature, θD, correlates with many important physical properties, such as heat capacity, bonding strengths, phonon thermal conductivity, vacancy formation energy, melting temperature, etc. It also sets the characteristic boson energy scale which takes part in electron-phonon coupling and Cooper pairing in conventional superconductors. At low temperatures the vibrational excitations arise solely from acoustic vibrations. Hence, at low temperatures the Debye temperature calculated from elastic constants is identical to that determined from the specific heat measurements. Among several methods for calculating Debye temperature, the Anderson method is simple and straightforward, which depends on average sound velocity and uses the following equation [48]: where h and kB are Planck’s and Boltzmann’s constants, respectively, NA is the Avogadro’s number, ρ refers to the mass density, M stands for the molecular weight and n is the number of atoms in a molecule. The sound wave, in a crystalline solid, propagates with an average velocity that can be determined from- where and are the longitudinal and transverse sound velocities, respectively, in a crystalline solid. Using shear and bulk moduli (G and B), these velocities can be determined using the following expressions [48]: and The calculated Debye temperature θD along with sound velocities vl, vt, and vm for the TiNX compounds are listed in Table 6. This particular method for calculating the Debye temperature from the elastic constants has been used extensively to reliably estimate θD for variety of compounds with different electronic ground states [14,16,17,30,49–51].