Aliasing errors in measurements of beam position and ellipticity

Journal Article · Thu Sep 15 04:00:00 EDT 2005 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.2038304· OSTI ID:20723149

Ekdahl, Carl ^[1]

---

1. Los Alamos National Laboratory, Mail Stop P942, PO Box 1663, Los Alamos, New Mexico 87545 (United States)

Beam position monitors (BPMs) are used in accelerators and ion experiments to measure currents, position, and azimuthal asymmetry. These usually consist of discrete arrays of electromagnetic field detectors, with detectors located at several equally spaced azimuthal positions at the beam tube wall. The discrete nature of these arrays introduces systematic errors into the data, independent of uncertainties resulting from signal noise, lack of recording dynamic range, etc. Computer simulations were used to understand and quantify these aliasing errors. If required, aliasing errors can be significantly reduced by employing more than the usual four detectors in the BPMs. These simulations show that the error in measurements of the centroid position of a large beam is indistinguishable from the error in the position of a filament. The simulations also show that aliasing errors in the measurement of beam ellipticity are very large unless the beam is accurately centered. The simulations were used to quantify the aliasing errors in beam parameter measurements during early experiments on the DARHT-II accelerator, demonstrating that they affected the measurements only slightly, if at all.

• OSTI ID: 20723149
• Journal Information: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 9 Vol. 76; ISSN 0034-6748; ISSN RSINAK
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
ASYMMETRY
BEAM POSITION
COMPUTERIZED SIMULATION
CURRENTS
ELECTROMAGNETIC FIELDS
ELECTRONS
ERRORS
IONS
LINEAR ACCELERATORS
MONITORS
PARTICLE BEAMS