Exercise 57. Read and translate the text

The electron source for the ILC will use 2-nanosecond laser light pulses to eject electrons from a photocathode, a technique allowing for up to 80% of the electrons to be polarized; the electrons then will be accelerated to 5 GeV in a 250-meter linac stage. Synchrotron radiation from high energy electrons will produce electron-positron pairs on a titanium-alloy target, with as much as 60% polarization; the positrons from these collisions will be collected and accelerated to 5 GeV in a separate linac.

To compact the 5 GeV electron and positron bunches to a sufficiently small size to be usefully collided, they will circulate for 0.2 seconds in a pair of damping rings, 7 km in circumference, in which they will be reduced in size to a few mm in length and less than 100 μm diameter.

From the damping rings the particle bunches will be sent to the Superconducting RF main linacs, each 12 km long, where they will be accelerated to 250 GeV. At this energy each beam will have an average power of about 10 megawatts. Five bunch trains will be produced and accelerated per second.

To maintain a sufficient luminosity to produce results in a reasonable time frame after acceleration the bunches will be focused to a few nm in height and a few hundred nm in width. The focused bunches then will be collided inside one of two large particle detectors.