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🌡️ Energy release 🔬 Beam spread
emittance

emittance

9.9
A number that shows how much a particle beam spreads and how well it is focused
  • noun
  • /ɪˈmɪt̬əns/
  • Specialized
translation icon : emisión
  • The lower the emittance (phase-space spread) of the antiproton beam, the higher the collider's luminosity will be.
  • high-emittance
  • emittance gun

Examples

  • Because the CEBAF beam has a small cross section and angular divergence (emittance of 2x10^-9 m-radian) and an energy spread of 10^-4, it allows high-precision measurements.

    Academic text (1993)

  • To minimize emittance, the plan is to bring the antiproton beam in the recycler into contact with a low-emittance electron beam.

    Academic text (2003)

  • One such attribute is the typically low beam emittance.

    Blog text (19)

  • To minimize emittance, the plan is to bring the antiproton beam in the recycler into contact with a low-emittance electron beam.

    Academic text (2003)

  • Therefore, the "high-emittance gun" has an emitter or cathode of several mm in diameter, quite in contrast to conventional guns typically with pointed cathodes.

    Academic text (2001)

  • The subfield illumination uniformity achieved with the high-emittance gun developed for the POC system is indicated in Figure 11.

    Academic text (2001)

  • The product of beam (or subfield) size and NA is denoted as the emittance, which is ideally conserved along the entire beam path, starting at the source.

    Academic text (2001)

  • GRAPH: Figure 11; Reticle subfield illumination uniformity achieved with high-emittance electron gun of POC system. From Reference 17, with permission.

    Academic text (2001)

  • The approach chosen was to first develop and construct a laboratory-scale system containing high-resolution, large-area reduction projection optics with beam-scanning capability and a high-emittance electron source.

    Academic text (2001)

  • Reducing the beam emittance will improve the overall quality of the particle accelerator.

Surface Forms

emittance singular
emittances plural

Morphology

emittance = emit (semi-transparent) = emit + tance + ance

Formed from 'emit' + '-ance' but used as a technical physics term meaning a specific measure of beam spread, which is not predictable from the general verb meaning for non-specialists.

Etymology

Emittance comes from the same root as emit ('to send out') and familiar words like mission and missile, all with the idea of 'sending'. So in physics emittance is a measure of how much a particle beam 'sends out' or spreads, and a low emittance means the beam stays tight and focused.