Laser source for the (gamma)-(gamma) Collider

The Next Linear Collider (NLC) offers an opportunity to use high energy photon collisions to probe basic particle structures. The production of high energy gammas from collisions between the NLC high energy electrons and low energy photons places difficult requirements on the laser low energy photon source [1]. The photon wavelength must be approximately one micron since longer wavelengths will decrease the electron utilization efficiency, and shorter wavelengths will open a loss channel for gammas through electron pair creation. The laser pulse format must match the electron generation format of the NLC. The electrons are produced in macropulses at 120 Hz. Each macro-pulse consists of around 100 subpulses separated by 2.8 nanoseconds. To interact efficiently with the electrons the laser subpulses must have approximately a 2 picosecond pulse duration. Analysis of the photon densities required for efficient utilization of the electrons and the focusing capabilities of the final photon injection optics leads to a required photon sub-pulse energy of approximately one joule. Thus the laser macro-pulse energy must be 100 joules at 120 Hz. The laser average power will be 12 kW