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An intense slow positron beam is in its early stages of operation at the 1-MW open-pool PULSTAR research reactor at North Carolina State University. The positron beam line is installed in a beam port that has a 30-cm×30-cm cross sectional view of the core. The positrons are created in a tungsten converter/moderator by pair-production using gamma rays produced in the reactor core and by neutron capture reactions in cadmium cladding surrounding the tungsten. Upon moderation, slow (∼3 eV) positrons that are emitted from the moderator are electrostatically extracted, focused and magnetically guided until they exit the reactor biological shield with 1-keV energy, approximately 3-cm beam diameter and an intensity exceeding 6×108 positrons per second. A magnetic beam switch and transport system has been installed and tested that directs the beam into one of two spectrometers. The spectrometers are designed to implement state-of-the-art PALS and DBS techniques to perform positron and positronium annihilation studies of nanophases in mater. [ABSTRACT FROM AUTHOR]

The CLIC positron source has been designed to produce non-polarized positrons for the first stage of CLIC at 380 GeV. In the CLIC positron source, the injector linac is supposed to accelerate positron beams and electron beams simultaneously from 200 MeV after the pre-injectors up to the damping ring energy of 2.86 GeV. The optics design of the injector linac has been done for the positrons since the emittance of the positron beam is much larger compared to the electron beam. This study presents new particle tracking simulations and an optimization of the CLIC injector linac for the positrons. In addition, beam offset and quadrupole misalignment errors have been investigated in the CLIC injector linac. [ABSTRACT FROM AUTHOR]