Patrick Janot edited Beamstrahlung.tex  over 10 years ago

Commit id: 96b4cea506692c1186d8322873135be4c3617e1e

deletions | additions      

       

\subsection{Beamstrahlung}  Beamstrahlung is an issue for $\epem$ rings, as its effects may cause the beam lifetime to become unacceptably small. Indeed, the repeated losses of even a tiny fraction of the beam at each collision rapidly add up because of the high beam crossing rate in circular colliders. Solutions (momentum acceptance increase, flatter beams, smaller emittances, larger top-off injection frequency, beam charge compensation) to mitigate this effect are proposed in Ref.~\cite{cite:1305.6498}. For illustration, the luminosities of Fig.~\ref{fig:lumi} are obtained with a rather large vertical beam size (from 100 to 300 nm) compared to what is needed at a linear collider (from 6 to 8 nm). As a consequence, beamstrahlung effects are benign for the physics performance of TLEP since the beamstrahlung-induced beam energy spread is expected to be smaller than 0.1\%, i.e., much smaller than the spread of 2\% expected from initial state radiation (common to all $\epem$ colliders), see as shown in  Fig.~\ref{fig:beamstrahlung} for $\sqrt{s}=240$ GeV.