scholarly journals Fractional Tune Dependence of Dynamic Aperture for LHC at Collision Energy

1998 ◽  
Author(s):  
V. Ptitsin
Keyword(s):  
Collision Energy ◽  
Dynamic Aperture

scholarly journals On the scaling of fragmentation and energy dissipation in collisions of dust aggregates

2021 ◽  
Vol 23 (2) ◽  
Author(s):  
Philipp Umstätter ◽  
Herbert M. Urbassek
Keyword(s):  
Energy Dissipation ◽  
Collision Energy ◽  
Velocity Range ◽  
Collision Velocity ◽  
Granular Mechanics ◽  
Extra Factor ◽  
Cluster Fragmentation ◽  
Silica Clusters ◽  
Large Clusters ◽  
Small Clusters

Abstract Fragmentation of granular clusters may be studied by experiments and by granular mechanics simulation. When comparing results, it is often assumed that results can be compared when scaled to the same value of $$E/E_{\mathrm{sep}}$$ E / E sep , where E denotes the collision energy and $$E_{\mathrm{sep}}$$ E sep is the energy needed to break every contact in the granular clusters. The ratio $$E/E_{\mathrm{sep}}\propto v^2$$ E / E sep ∝ v 2 depends on the collision velocity v but not on the number of grains per cluster, N. We test this hypothesis using granular-mechanics simulations on silica clusters containing a few thousand grains in the velocity range where fragmentation starts. We find that a good parameter to compare different systems is given by $$E/(N^{\alpha }E_{\mathrm{sep}})$$ E / ( N α E sep ) , where $$\alpha \sim 2/3$$ α ∼ 2 / 3 . The occurrence of the extra factor $$N^{\alpha }$$ N α is caused by energy dissipation during the collision such that large clusters request a higher impact energy for reaching the same level of fragmentation than small clusters. Energy is dissipated during the collision mainly by normal and tangential (sliding) forces between grains. For large values of the viscoelastic friction parameter, we find smaller cluster fragmentation, since fragment velocities are smaller and allow for fragment recombination. Graphic abstract

scholarly journals The Little-Bang and the femto-nova in nucleus-nucleus collisions

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Nu Xu ◽  
Kenji Fukushima ◽  
Bedangadas Mohanty
Keyword(s):  
Collision Energy ◽  
Particle Production ◽  
Gluon Plasma ◽  
Baryon Density ◽  
Point Particle ◽  
Current Status ◽  
Density Region ◽  
Qcd Critical Point ◽  
Qcd Phase Diagram ◽  
Lower Collision Energy

AbstractWe make a theoretical and experimental summary of the state-of-the-art status of hot and dense QCD matter studies on selected topics. We review the Beam Energy Scan program for the QCD phase diagram and present the current status of the search for the QCD critical point, particle production in high baryon density region, hypernuclei production, and global polarization effects in nucleus-nucleus collisions. The available experimental data in the strangeness sector suggests that a grand canonical approach in the thermal model at high collision energy makes a transition to the canonical ensemble behavior at low energy. We further discuss future prospects of nuclear collisions to probe properties of baryon-rich matter. Creation of a quark-gluon plasma at high temperature and low baryon density has been called the “Little-Bang” and, analogously, a femtometer-scale explosion of baryon-rich matter at lower collision energy could be called the “femto-nova”, which could possibly sustain substantial vorticity and a magnetic field for non-head-on collisions.

Performance of the far-IR beamline of the 6 MeV tabletop synchrotron light source

2009 ◽  
Vol 16 (2) ◽  
pp. 299-306 ◽  
Author(s):  
Md. Monirul Haque ◽  
Hironari Yamada ◽  
Ahsa Moon ◽  
Mami Yamada
Keyword(s):  
Light Source ◽  
Optical System ◽  
Far Infrared ◽  
Beam Current ◽  
Small Ring ◽  
Thermal Source ◽  
Simulation Code ◽  
Dynamic Aperture ◽  
Electron Orbit ◽  
Synchrotron Light

The performance of the far-infrared (FIR) beamline of the 6 MeV tabletop synchrotron light source MIRRORCLE-6FIR dedicated to far-infrared spectroscopy is presented. MIRRORCLE-6FIR is equipped with a perfectly circular optical system (PhSR) placed around the 1 m-long circumference electron orbit. To illustrate the facility of this light source, the FIR output as well as its spectra were measured. The optimum optical system was designed by using the ray-tracing simulation code ZEMAX. The measured FIR intensity with the PhSR in place is about five times higher than that without the PhSR, which is in good agreement with the simulation results. The MIRRORCLE-6FIR spectral flux is compared with a standard thermal source and is found to be 1000 times greater than that from a typical thermal source at ∼15 cm−1. It is also observed that the MIRRORCLE-6FIR radiation has a highly coherent nature. The broadband infrared allows the facility to reach the spectral range from 10 cm−1 to 100 cm−1. MIRRORCLE-6FIR, owing to a large beam current, the PhSR mirror system, a large dynamic aperture and small ring energy, can deliver a bright flux of photons in the FIR/THz region useful for broadband spectroscopy.

THE STEREODYNAMICS STUDY OF THE C(3P) + OH (X2 Π) → CO(X1Σ+) + H(2S) REACTION

2010 ◽  
Vol 09 (05) ◽  
pp. 935-943 ◽  
Author(s):  
PENG SONG ◽  
YONG-HUA ZHU ◽  
JIAN-YONG LIU ◽  
FENG-CAI MA
Keyword(s):  
Angular Momentum ◽  
Cross Sections ◽  
Collision Energy ◽  
Energy Surface ◽  
Center Of Mass ◽  
Title Reaction ◽  
High Collision Energy ◽  
Dependency Relationship ◽  
Energy Dependency ◽  
Mass Frame

The stereodynamics of the title reaction on the ground electronic state X2A' potential energy surface (PES)1 has been studied using the quasiclassical trajectory (QCT) method. The commonly used polarization-dependent differential cross-sections (PDDCSs) of the product and the angular momentum alignment distribution, P(θr) and P(Φr), are generated in the center-of-mass frame using QCT method to gain insight of the alignment and orientation of the product molecules. Influence of collision energy on the stereodynamics is shown and discussed. The results reveal that the distribution of P(θr) and P(Φr) is sensitive to collision energy. The PDDCSs exhibit different collision energy dependency relationship at low and high collision energy ranges.

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