Design Concept of a \gamma-\gamma Collider-Based Higgs Factory Driven by   a Thin Laser Target and Energy Recovery Linacs
  A {\gamma}-{\gamma} collider has long been considered an option for a Higgs Factory. Such photon colliders usually rely on Compton back-scattering for generating high energy {\gamma} photons and further Higgs bosons through {\gamma}-{\gamma} collisions. The presently existing proposals or design concepts all have chosen a very thick laser target (i.e., high laser photon intensity) for Compton scatterings. In this paper, we present a new design concept of a {\gamma}-{\gamma} collider utilizing a thin laser target (i.e., relatively low photon density), thus leading to a low electron to {\gamma} photon conversion rate. This new concept eliminates most useless and harmful soft {\gamma} photons from multiple Compton scattering so the detector background is improved. It also greatly relaxes the requirement of the high peak power of the laser, a significant technical challenge. A high luminosity for such a {\gamma}-{\gamma} collider can be achieved through an increase of the bunch repetition rate and current of the driven electron beam. Further, a multi-pass recirculating linac could greatly reduce the linac cost and energy recovery is required to reduce the needed RF power. 
Yuhong Zhang
physics.acc-ph