Speaker
Fabrizio Del Gaudio
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P5.2025.pdf
High current colliding beams as a potential source of energetic radiation
and relativistic pairs
F. Del Gaudio1 ,T. Grismayer1 , R. Fonseca1,2 , W. B. Mori3 , L. O. Silva1
1 GoLP/Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de
Lisboa, 1049-001 Lisbon, Portugal
2 DCTI/ISCTE Instituto Universitário de Lisboa, 1649-026 Lisboa, Portugal
3 Departments of Physics & Astronomy and of Electrical Engineering, University of California
at Los Angeles, 90095
At the interaction point of TeV particle colliders, three detrimental beam driven effects are
important: disruption [1], beamstrahlung radiation [2], and pair production [2]. Disruption is
due to the transverse motion of the beam particles which can focus (e− e+ ) or defocus (e− e− )
on the self-fields of the counter-propagating beam. In this process, photons are emitted and can
decay into new pairs by interacting with the collective field of the beams. These two effects are
more pronounced in the quantum regime which is usually avoided by using flat and long shaped
beams. Conversely, the upgrade of the linear collider at SLAC (FACET II) [3] and the next
generation of laser wakefield accelerators (LWFA) will deliver high current ultrashort round
bunches capable of reaching the quantum regime at 10s of GeV. We investigate the collision
of these beams envisaging a secondary source of collimated γ ray photons and ultrarelativistic
pairs [4]. We estimate the photon spectrum and the secondary pairs yield both analytically
and with PIC simulations, performed with QED-OSIRIS [5]. Our analytical model and the
simulations show good agreement. The collective fields topology favors the quantum effects
to take place in a distinguishing region of each beam resulting in a yield of secondary pairs
considerably higher than what previously predicted [2]. Our results encourage the exploitation
of this setup as a secondary source of radiation and of relativistic pairs. This secondary source
of photons, electron, and positrons may be of interest in reproducing astrophysical lepton jets
in the laboratory, or in delivering positron beams already at ultrarelativistic energies.
References
[1] R. Hollebeek, Nucl. Instrum. Meth. 184, 333 (1981)
[2] P. Chen, and V. Telnov, Phys. Rev. Lett. 63, 1796 (1989)
[3] C. Patrignani et al. (Particle Data Group), Chin. Phys. C, 40, 100001 (2016).
[4] F. Del Gaudio et al., to be submitted
[5] R. Fonseca et al., Lecture Notes in Comput. Sci. 2331, 342 (2002)
