Intense beams of gamma rays would find a host of uses in fundamental physics research, nuclear fusion, and medicine, but they are hard to produce. A team has now used computer simulations to show that a powerful laser hitting a plastic surface can generate intense gamma-ray emission. In the simulations, the laser light creates a plasma in the plastic and accelerates electrons enough to produce large numbers of gamma-ray photons. The researchers say that the system might work with current technology.
In extreme astrophysical environments, such as near a supermassive black hole, matter and antimatter (electrons and positrons) regularly annihilate, producing gamma rays. Researchers would like to study the reverse process by colliding beams of gamma rays, which should create electrons and positrons, a transformation of light into matter [1]. Gamma-ray beams could also enable a wide range of other fundamental experiments and might have a role in radiation therapy and radiosurgery [2]. Previous attempts to make these beams involved the interaction of a laser beam with an electron beam [3]. But to produce copious gamma-ray photons with energies in the MeV range, the laser beam would need to be more intense than any current device.
Alexey Arefiev at the University of Texas at Austin and his co-workers now propose a different method that requires somewhat less laser power. It involves shining pulses of a petawatt (10 15 W) infrared laser onto a carbon-rich, plastic target. The power density of such a pulsed laser can reach around 5x1022 W/cm2, which is about 500 times greater than would be produced by focusing all of the sunlight reaching the Earth onto a pencil tip.
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