Storage ring lattice calibration using resonant spin depolarization

Wootton, Kent; Boland, Mark; Corbett, W.J.; Huang, Xiaobiao; Leblanc, G.; Lundin, Magnus; Panopoulos, H. P.; Safranek, J.; Tan, Yaw-Ren; Taylor, G. N.; Tian, Kai; Rassool, Roger

doi:10.1103/physrevstab.16.074001

Cited by 5 publications

(4 citation statements)

References 37 publications

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“…In order to detect the process of spin-polarization build-up, several scintillator-based beam loss monitors are installed after the first bending magnet in the 1 st and 21 st cell. For TPS, operating at high current, the beam loss is dominated by the Touschek effect and the electron loss rate (dN(t)/dt) can be written as [27] dN…”

Section: Spin Polarization Build-up and Energy Calibrationmentioning

confidence: 99%

Beam loss study and its application to the Taiwan Light Source and Taiwan Photon Source

et al. 2020

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The mechanism of beam loss and radiation hot spots at the Taiwan Light Source (TLS) and Taiwan Photon Source (TPS) are studied using various types of beam loss monitors (BLMs). The performance of readout devices and the system integration are also presented in this paper. At the TLS, the high beam loss spots downstream of the superconducting wigglers comes from the vertical aperture limit. The highest radiation is detected after the injection section and comes mainly from X-rays generated by the superconducting wavelength shifter installed between the 3rd and 4th kickers. At the Taiwan Photon Source, the high radiation spots are located before the second bending magnet and straight section because there are photon absorbers nearby to contain synchrotron radiation. In order to enhance the sensitivity to beam loss, 1-mm thick lead is used to shield synchrotron radiation to the BLM. The beam loss coming from scattering occurs downstream of the following bending magnet in a poor vacuum region for inelastic scattering and after vertical aperture limitation for elastic scattering. During routine operation in which the beam loss mainly comes from intra beam scattering during decay period, the beam loss pattern varies with the gap and phase of the insertion devices especially for the narrowest gaps. These BLMs are used to adjust skew-quads or sextupoles to minimize the beam loss for maximum beam lifetime. The precise beam energy of the TPS is also calibrated using spin-depolarization in which the beam losses are detected by scintillation detectors. The energy stability during continuous routine operation can be kept to within 10−5 by radio frequency adjustments and fast orbit feedback.

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Section: Spin Polarization Build-up and Energy Calibrationmentioning

confidence: 99%

Beam loss study and its application to the Taiwan Light Source and Taiwan Photon Source

et al. 2020

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“…where P ST and τ ST are the Sokolov-Ternov values for the equilibrium polarization level and the time constant, respectively, and τ d is the depolarization time constant. The equilibrium polarization level P ST is related with the integral of the magnetic fields B along the curvilinear trajectory of the beam s [5]:…”

Section: A Polarization Experimental Studymentioning

confidence: 99%

“…Resonant spin depolarization (RSD) is a wellestablished technique to measure the electron beam energy in synchrotrons [1][2][3][4][5]. The spin of the electrons is aligned antiparallel with the magnetic field of bending magnets due to spin-flip synchrotron radiation.…”

Section: Introductionmentioning

confidence: 99%

Continuous energy measurement of the electron beam in the storage ring of Diamond Light Source with resonant spin depolarization

Vitoratou

Karataev

Rehm

2019

Phys. Rev. Accel. Beams

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Electron spin polarization occurs naturally in an electron storage ring due to spin-flip synchrotron radiation. The equilibrium polarization level that is achieved in Diamond Light Source was studied theoretically and experimentally. A novel approach that enables measurements during user operation is presented, compatible with beams of small vertical emittance in the range of pm rad. An array of four custom-made scintillation detectors has been installed around the beam pipe downstream from the collimators to capture a significant fraction of the lost particles and witness the depolarization process in the presence of a background loss rate. A new concept for detecting the depolarization resonance even when it coincides with higher-order betatron resonances was introduced. The momentum compaction factor was measured to be in very good agreement with the storage ring numerical model. In the end, we measured a good long-term stability of the beam energy during user operation time.

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“…Panopoulos et al (2011) and subsequent experimental studies (e.g. Wootton et al, 2013) have used the technique of resonant spin depolarization to accurately determine the ring energy at the Australian Synchrotron. Variations of approximately 30 keV over an 8 h shift, and longer-term (several months) variations an order of magnitude larger were reported.…”

Section: Introductionmentioning

confidence: 99%

Quantitative characterization of the X-ray beam at the Australian Synchrotron Imaging and Medical Beamline (IMBL)

et al. 2017

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A critical early phase for any synchrotron beamline involves detailed testing, characterization and commissioning; this is especially true of a beamline as ambitious and complex as the Imaging & Medical Beamline (IMBL) at the Australian Synchrotron. IMBL staff and expert users have been performing precise experiments aimed at quantitative characterization of the primary polychromatic and monochromatic X-ray beams, with particular emphasis placed on the wiggler insertion devices (IDs), the primary-slit system and any in vacuo and ex vacuo filters. The findings from these studies will be described herein. These results will benefit IMBL and other users in the future, especially those for whom detailed knowledge of the X-ray beam spectrum (or `quality') and flux density is important. This information is critical for radiotherapy and radiobiology users, who ultimately need to know (to better than 5%) what X-ray dose or dose rate is being delivered to their samples. Various correction factors associated with ionization-chamber (IC) dosimetry have been accounted for, e.g. ion recombination, electron-loss effects. A new and innovative approach has been developed in this regard, which can provide confirmation of key parameter values such as the magnetic field in the wiggler and the effective thickness of key filters. IMBL commenced operation in December 2008 with an Advanced Photon Source (APS) wiggler as the (interim) ID. A superconducting multi-pole wiggler was installed and operational in January 2013. Results are obtained for both of these IDs and useful comparisons are made. A comprehensive model of the IMBL has been developed, embodied in a new computer program named spec.exe, which has been validated against a variety of experimental measurements. Having demonstrated the reliability and robustness of the model, it is then possible to use it in a practical and predictive manner. It is hoped that spec.exe will prove to be a useful resource for synchrotron science in general, and for hard X-ray beamlines, whether they are based on bending magnets or insertion devices, in particular. In due course, it is planned to make spec.exe freely available to other synchrotron scientists.

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Storage ring lattice calibration using resonant spin depolarization

Cited by 5 publications

References 37 publications

Beam loss study and its application to the Taiwan Light Source and Taiwan Photon Source

Beam loss study and its application to the Taiwan Light Source and Taiwan Photon Source

Continuous energy measurement of the electron beam in the storage ring of Diamond Light Source with resonant spin depolarization

Quantitative characterization of the X-ray beam at the Australian Synchrotron Imaging and Medical Beamline (IMBL)

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