Roy Aleksan edited Luminosity and Energy.tex  almost 11 years ago

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\subsection{Luminosity and Energy}  The state-of-the-art machine parameters can be found in Ref.~\cite{cite:1305.6498}, for the four centre-of-mass energies of interest, the Z pole ($\sqrt{s} \sim m_{\rm Z}$), the WW threshold ($\sqrt{s} \sim 2 m_{\rm W}$), the HZ cross-section maximum ($\sqrt{s} \sim 240$ GeV), and the top-pair threshold ($\sqrt{s} \sim 2m_{\rm top}$). The 12 GV RF system is designed to compensate for the energy loss by synchrotron radiation at the maximum latter  centre-of-mass energy ($\sim 350$ GeV), at which an instantaneous luminosity of $1.3\times 10^{34} \cms$ can be delivered at each interaction point. At lower centre-of-mass energies, the energy losses decrease steeply like $1/E^4_{\rm beam}$, and the RF power thus made available can be used to accelerate a much larger number of ${\rm e}^\pm$ bunches. As a result, the instantaneous luminosity increases approximately like $1/E^3_{\rm beam}$ when the centre-of-mass energy decreases. (The smaller exponent is a consequence of the tighter beam-beam limit at lower energies.) The values of the instantaneous luminosities expected at each energy are displayed in Table~\ref{tab:lumi}, together with other important parameters of the machine (centre-of-mass energy, beam size, RF cavity gradient, number of bunches, total power consumption, etc.). \begin{table}  \begin{center}