Electrostatic is the affinity to attraction or repulsion due to electrostatic charges associated with particles.

An accelerator uses electrostatic or electromagnetic fields to increase the kinetic energy of charged particles (see alpha particle, beta particle) in order to produce ionization or a nuclear reaction in a target.
Accelerators (see cyclotron, linear accelerator) are used for the production of radionuclides (see Fluorine-18, Molybdenum, Technetium-99m) or directly for radiation therapy. Accelerator-produced radioactive material (ARM) is any radioactive substance that is produced by a particle accelerator. The accelerators used for radiation therapy generate gamma rays (also called Bremsstrahlung) with continuous energy by collision of high energy electrons on materials with high density (also referred as 'high z' - chemical elements with a high atomic number (Z)).
Electron accelerators with energies above 10 MeV can also produce neutrons induced by photons in the accelerator head material (mainly caused by photo nuclear reaction).

(R) R is a unit to express exposure to radiation (x-rays or gamma rays). 1 R corresponds to the generation of approximately 2.08 x10⁹ ion pairs (1 electrostatic unit of charge) (in 1 cm³ of dry air at 0 °C and 760 torr). 1 R, converted to SI, equals 2.58 x10^-4 coulombs per kg of air.