100 research outputs found
Notes about collision monochromatization in colliders
The manuscript describes several monochromatization schemes starting from
A.~Renieri \cite{ref:Renieri} proposal for head-on collisions based on
correlation between particles transverse position and energy deviation. We
briefly explain initial proposal and expand it for crossing angle collisions.
Then we discuss new monochromatization scheme for crossing angle collisions
based on correlation between particles longitudinal position and energy
deviation
Beam-beam effects investigation and parameters optimization for a circular e+e- collider TLEP to study the Higgs boson
Several proposals exist for future circular electron-positron colliders
designed for precise measurements of the Higgs boson characteristics and
electroweak processes. At very high energies, synchrotron radiation of the
particles in a strong electromagnetic field of the oncoming bunch
(beamstrahlung) becomes extremely important, because of degradation of the beam
lifetime and luminosity. We present theoretical calculations of beamstrahlung
(including the beam lifetime reduction and the energy spread increase) which
are benchmarked against quasi strong-strong computer simulation. Calculation
results are used to optimize TLEP project (CERN).Comment: 17 pages, 2 tables, 9 figure
Dynamic aperture limitation in colliders due to synchrotron radiation in quadrupoles
In a lepton storage ring of very high energy (e.g. in the Higgs
factory) synchrotron radiation from quadrupoles constrains transverse dynamic
aperture even in the absence of any magnetic nonlinearities. This was observed
in tracking for LEP and the Future Circular Collider (FCC-ee). Here we
describe a new mechanism of instability created by modulation of the particle
energy at the double betatron frequency by synchrotron radiation in the
quadrupoles. Energy modulation varies transverse focusing strength at the same
frequency and creates a parametric resonance of the betatron oscillations with
unusual properties. It occurs at arbitrary betatron frequency (the resonant
detuning is always zero) and the magnitude of the parameter modulation of the
betatron oscillation (strength of the resonance driving term) depends on the
oscillation amplitude. Equilibrium between the radiation damping and the
resonant excitation gives the boundary of the stable motion. Starting from 6d
equations of motion we derive and solve the relevant differential equation
describing the resonance, and show good agreement between analytical results
and numerical simulation
The FCC-ee Interaction Region Magnet Design
The design of the region close to the interaction point of the FCC-ee
experiments is especially challenging. The beams collide at an angle (+-15
mrad) in the high-field region of the detector solenoid. Moreover, the very low
vertical beta_y* of the machine necessitates that the final focusing
quadrupoles have a distance from the IP (L*) of around 2 m and therefore are
inside the main detector solenoid. The beams should be screened from the effect
of the detector magnetic field, and the emittance blow-up due to vertical
dispersion in the interaction region should be minimized, while leaving enough
space for detector components. Crosstalk between the two final focus
quadrupoles, only about 6 cm apart at the tip, should also be minimized.Comment: Poster presented at IPAC16, May 8-13, Busan, Kore
Theoretical analysis of frozen wall dynamics during transition to ice holding stage
Series of calculations for the artificial freezing of the rock mass during construction of mineshafts for the conditions of a potash mine in development was carried out. Numerical solution was obtained through the finite element method using ANSYS software package. Numerical dependencies of frozen wall thickness on time in the ice growing stage and ice holding stage are obtained for two layers of the rock mass with different thermophysical properties. External and internal ice wall boundaries were calculated in two ways: by the actual freezing temperature of pore water and by the temperature of –8 °С, at which laboratory measurements of frozen rocks' strength were carried out. Normal operation mode of the freezing station, as well as the emergency mode, associated with the failure of one of the freezing columns, are considered. Dependence of a decrease in frozen wall thickness in the ice holding stage on the duration of the ice growing stage was studied. It was determined that in emergency operation mode of the freezing system, frozen wall thickness by the –8 °C isotherm can decrease by more than 1.5 m. In this case frozen wall thickness by the isotherm of actual freezing of water almost always maintains positive dynamics. It is shown that when analyzing frozen wall thickness using the isotherm of actual freezing of pore water, it is not possible to assess the danger of emergency situations associated with the failure of freezing columns
- …