### Abstract

We present the results of a simple model calculation that highlights the effect of the finite (i.e., nonzero) angular resolution of electrostatic energy analyzers on the measurement of polarization correlation parameters in electron-photon coincidence experiments. It is demonstrated that measurements can yield drastically reduced apparent parameters in cases where the coincidence parameters vary rapidly as a function of electron scattering angle. For example, a measurement of the P1 parameter for Ar(1P) excited by 100-eV electrons which are scattered in the forward direction and detected by an analyzer with an angular resolution (full width at half maximum) of 3°will yield an apparent P1 value of 0.83 compared to the nominal value of 1.00. Since the measurement of P1 in the forward direction reveals important information about the relative contributions of direct excitation and exchange excitation, it is imperative that an experiment can distinguish a P1 value truly smaller than unity from an apparent value which is reduced merely by instrumental effects.

Original language | English (US) |
---|---|

Pages (from-to) | 4876-4879 |

Number of pages | 4 |

Journal | Physical Review A |

Volume | 38 |

Issue number | 9 |

DOIs | |

State | Published - 1988 |

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### ASJC Scopus subject areas

- Physics and Astronomy(all)
- Atomic and Molecular Physics, and Optics

### Cite this

*Physical Review A*,

*38*(9), 4876-4879. https://doi.org/10.1103/PhysRevA.38.4876

**Effect of a finite angular resolution on the measurement of polarization correlation parameters in electron heavy-noble-gas collisions.** / Martus, K. E.; Becker, K.; Madison, D. H.

Research output: Contribution to journal › Article

*Physical Review A*, vol. 38, no. 9, pp. 4876-4879. https://doi.org/10.1103/PhysRevA.38.4876

}

TY - JOUR

T1 - Effect of a finite angular resolution on the measurement of polarization correlation parameters in electron heavy-noble-gas collisions

AU - Martus, K. E.

AU - Becker, K.

AU - Madison, D. H.

PY - 1988

Y1 - 1988

N2 - We present the results of a simple model calculation that highlights the effect of the finite (i.e., nonzero) angular resolution of electrostatic energy analyzers on the measurement of polarization correlation parameters in electron-photon coincidence experiments. It is demonstrated that measurements can yield drastically reduced apparent parameters in cases where the coincidence parameters vary rapidly as a function of electron scattering angle. For example, a measurement of the P1 parameter for Ar(1P) excited by 100-eV electrons which are scattered in the forward direction and detected by an analyzer with an angular resolution (full width at half maximum) of 3°will yield an apparent P1 value of 0.83 compared to the nominal value of 1.00. Since the measurement of P1 in the forward direction reveals important information about the relative contributions of direct excitation and exchange excitation, it is imperative that an experiment can distinguish a P1 value truly smaller than unity from an apparent value which is reduced merely by instrumental effects.

AB - We present the results of a simple model calculation that highlights the effect of the finite (i.e., nonzero) angular resolution of electrostatic energy analyzers on the measurement of polarization correlation parameters in electron-photon coincidence experiments. It is demonstrated that measurements can yield drastically reduced apparent parameters in cases where the coincidence parameters vary rapidly as a function of electron scattering angle. For example, a measurement of the P1 parameter for Ar(1P) excited by 100-eV electrons which are scattered in the forward direction and detected by an analyzer with an angular resolution (full width at half maximum) of 3°will yield an apparent P1 value of 0.83 compared to the nominal value of 1.00. Since the measurement of P1 in the forward direction reveals important information about the relative contributions of direct excitation and exchange excitation, it is imperative that an experiment can distinguish a P1 value truly smaller than unity from an apparent value which is reduced merely by instrumental effects.

UR - http://www.scopus.com/inward/record.url?scp=18344380400&partnerID=8YFLogxK

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U2 - 10.1103/PhysRevA.38.4876

DO - 10.1103/PhysRevA.38.4876

M3 - Article

VL - 38

SP - 4876

EP - 4879

JO - Physical Review A

JF - Physical Review A

SN - 2469-9926

IS - 9

ER -