Skip to content

The beamline

The part of 4-ID POLAR CORA models today, as areas you can jump to: the optics spine and the per-station experiment systems, plus the controls that drive them. First cut.

4-ID POLAR is a polarization and magnetic-scattering beamline with four lead-shielded stations: 4-ID-A (optics), and 4-ID-B, 4-ID-G, 4-ID-H (experiment). This cut models the operational core across all four; the Raman station and the peripheral electronics are deferred (see Model).

The modelled beamline divides into two kinds of thing. Along the beam, in order, sit the stations: the Source that delivers, polarizes, and conditions the beam, the Sample stage that places the specimen in it (and, at POLAR, applies field and temperature), and the Detector that records what scatters. Cutting across them are the Controls that drive the hardware. The stations are containment trees of apparatus (Asset.parent_id); controls relate to that apparatus sideways, by controller_id.

Stations

  • Source: the 4-ID-A optics spine and the shared front-end optics. The undulator pair feeds three diamond phase retarders that set the polarization state, the VDCM monochromator and its white-beam and mono slits, a diamond window, the toroidal and high-heat-load mirrors, the transfocator, and the per-station KB mirrors and filters.
  • Sample: the 4-ID-G Huber diffractometers, the 4-ID-B polarization analyzer, and the sample environment across the stations: superconducting magnets, temperature controllers, positioning tables, and a pump-probe laser.
  • Detector: the Eiger area detector, the beam-view flag cameras, the beam-position and intensity monitors, and the scaler counters.

Shared

  • Controls: the APS EPICS control stack. The device handles are bound from the beamline's instrument config and carried confirm (CTRL-1).
  • Resources: the continuously-available supplies a run needs (photon beam, cooling water, vacuum, and the liquid helium and nitrogen the magnet and low-temperature environments draw on); carried in the descriptor, with no operations page yet in this first cut.

Reference

The cross-cutting view that spans every area:

  • Inventory: the full planned CORA Asset model for the modelled part (every device by parent_id, with Families and pending confirmations). The hutch PSS permit signals are APS facility signals, not yet named (see Open questions).