beam command

Table of Contents

1. Beam Command

1. Beam Command

All OPAL commands working on a beam require the setting of various quantities related to this beam. These are entered by a BEAM command:

label:BEAM, PARTICLE=name, MASS=real, CHARGE=real,
      ENERGY=real, PC=real, GAMMA=real, BCURRENT=real,
       NPART=real, BUNCHED=logical, BFREQ=real;

The label is optional, it defaults to UNNAMED_BEAM. . The particle mass and charge are defined by:

PARTICLE: The name of particles in the machine.

OPAL knows the mass and the charge for the following particles:

POSITRON: The particles are positrons (MASS=m_e, CHARGE=1),
ELECTRON: The particles are electrons (MASS=m_e, CHARGE=-1),
PROTON: The particles are protons (default, MASS=m_p, CHARGE=1),
ANTIPROTON: The particles are anti-protons (MASS=m_p, CHARGE=-1).
HMINUS: The particles are h- protons (MASS=m_{h^{-}}, CHARGE=-1).
CARBON: The particles are carbons (MASS=m_c, CHARGE=12).
URANIUM: The particles are of type uranium (MASS=m_u, CHARGE=35).
MUON: The particles are of type muon (MASS=m_\mu, CHARGE=-1).
DEUTERON: The particles are of type deuteron (MASS=m_d, CHARGE=1).
XENON: The particles are of type xenon (MASS=m_{xe}, CHARGE=20).

For other particle names one may enter:

MASS: The particle mass in GeV.
CHARGE: The particle charge expressed in elementary charges.

The other attributes are:

BFREQ: The bunch frequency in MHz.
BCURRENT: The bunch current in A. \mathrm{BCURRENT} = Q \times \mathrm{BFREQ} with Q the total charge.
NPART: The number of macro particles for the simulations