Vertical beam size measurement in the CESR-TA $e^{+}{e}^{-}$ storage ring using x-rays from synchrotron radiation

Abstract

We describe the construction and operation of an x-ray beam size monitor (xBSM), a device measuring $e^{+}$ and $e^{-}$ beam sizes in the CESR-TA storage ring using synchrotron radiation. The device can measure vertical beam sizes of $10-100\mu$m on a turn-by-turn, bunch-by-bunch basis at $e^{\pm }$ beam energies of $\sim 2$GeV. At such beam energies the xBSM images x-rays of $\epsilon \approx$1-10 keV ($\lambda \approx 0.1-1$ nm) that emerge from a hard-bend magnet through a single- or multiple-slit (coded aperture) optical element onto an array of 32 InGaAs photodiodes with 50$\mu$m pitch. Beamlines and detectors are entirely in-vacuum, enabling single-shot beam size measurement down to below 0.1 mA ($2.5\times 10^9$ particles) per bunch and inter-bunch spacing of as little as 4 ns. At $E_{\mathrm{b}}=2.1$GeV, systematic precision of $\sim 1\mu$m is achieved for a beam size of $\sim 12\mu$m; this is expected to scale as $\propto 1/{\sigma }_{\mathrm{b}}$ and $\propto 1/E_{\mathrm{b}}$. Achieving this precision requires comprehensive alignment and calibration of the detector, optical elements, and x-ray beam. Data from the xBSM have been used to extract characteristics of beam oscillations on long and short timescales, and to make detailed studies of low-emittance tuning, intra-beam scattering, electron cloud effects, and multi-bunch instabilities.

35 pages, 62 figures, version published by Nuclear Instruments and Methods in Physics Research A. Nuclear Instruments & Methods in Physics Research A (2014)

References in corpus (3)

• Intrabeam Scattering Studies at CesrTA
• Low-emittance tuning at the Cornell Electron Storage Ring
• Measurement and Compensation of Horizontal Crabbing at the Cornell Electron Storage Ring Test Accelerator

Cited by in corpus (5)

• Low-emittance tuning at the Cornell Electron Storage Ring
• The Conversion of CESR to Operate as the Test Accelerator, CesrTA, Part 1: Overview
• Design and performance of coded aperture optical elements for the CESR-TA x-ray beam size monitor
• Operation of the CESR-TA vertical beam size monitor at $E_{\mathrm{b}}$=4 GeV
• Instrumentation for the Study of Low Emittance Tuning and Beam Dynamics at CESR