IBIC2017 - List of Authors (Rehm, G.)

Paper	Title	Page
TUPWC09	Reducing Current Dependence in Position Measurements of BPM Systems by Using Pilot Tone: Quasi-Constant Power Approach	301
	G. Brajnik, S. Bassanese, G. Cautero, R. De Monte, M. Ferianis Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy G. Rehm DLS, Oxfordshire, United Kingdom
	In BPM systems, the dependence of measured position on beam current is a well-known behaviour due to many factors. Measurements were carried out at Diamond Light Source with the pilot-tone compensated RF front end developed at Elettra and they evidenced a strong link between that issue and the integral non-linearity (INL) of the ADCs. A potential way to reduce this dependence is to change the gain of the preamplifiers following the beam current variation, trying to coerce the ADC into working as close as possible to a specific level. In this paper, along with the results of the tests performed at Diamond, which confirm once again the effectiveness of the front end and of the compensation strategy, an alternative technique is proposed to mitigate the current dependence by using the pilot tone itself. The idea is to maintain constant the total amplitude at the input of the ADCs, which is composed of the signal from the beam plus the pilot tone. Our data demonstrate how, by changing the latter in a convenient way during the current variations, we can achieve a reduction of the dependence by a factor of 10 considering an equivalent current ramp from 10 to 300 mA.
	Poster TUPWC09 [1.450 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2017-TUPWC09
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TH1AB3	Beam Loss Monitors for Energy Measurements in Diamond Light Source	482
	N. Vitoratou, P. Karataev Royal Holloway, University of London, Surrey, United Kingdom P. Karataev, N. Vitoratou JAI, Egham, Surrey, United Kingdom G. Rehm, N. Vitoratou DLS, Oxfordshire, United Kingdom
	Resonant Spin Depolarization is a high precision technique for beam energy measurement employed in the Diamond Light Source storage ring. The relation between spin tune and beam energy can be used to determine the energy of a transversely polarized beam. Vertical oscillations excite the beam at frequencies that match the fractional part of the spin tune and the beam loss rate is used to monitor the beam depolarization. However, the standard procedure of these measurements is intrusive and not compatible with user operation of a light source. The Advanced Resonant Spin Depolarization (AdReSD) project aims to extend and improve the method with the goal of making the measurements compatible with the user operation, for instance by acting only on a small fraction of the stored beam. As a first step, we are investigating the beam loss monitors that will be used to detect beam depolarization. The material, location and optimal geometry of the detector to capture the largest fraction of the radiation footprint resulting from beam losses are studied. Results and designs are presented and future work is discussed.
	Slides TH1AB3 [5.521 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2017-TH1AB3
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Reducing Current Dependence in Position Measurements of BPM Systems by Using Pilot Tone: Quasi-Constant Power Approach

301

G. Brajnik, S. Bassanese, G. Cautero, R. De Monte, M. Ferianis
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
G. Rehm
DLS, Oxfordshire, United Kingdom

In BPM systems, the dependence of measured position on beam current is a well-known behaviour due to many factors. Measurements were carried out at Diamond Light Source with the pilot-tone compensated RF front end developed at Elettra and they evidenced a strong link between that issue and the integral non-linearity (INL) of the ADCs. A potential way to reduce this dependence is to change the gain of the preamplifiers following the beam current variation, trying to coerce the ADC into working as close as possible to a specific level. In this paper, along with the results of the tests performed at Diamond, which confirm once again the effectiveness of the front end and of the compensation strategy, an alternative technique is proposed to mitigate the current dependence by using the pilot tone itself. The idea is to maintain constant the total amplitude at the input of the ADCs, which is composed of the signal from the beam plus the pilot tone. Our data demonstrate how, by changing the latter in a convenient way during the current variations, we can achieve a reduction of the dependence by a factor of 10 considering an equivalent current ramp from 10 to 300 mA.

Poster TUPWC09 [1.450 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2017-TUPWC09

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TH1AB3

Beam Loss Monitors for Energy Measurements in Diamond Light Source

482

N. Vitoratou, P. Karataev
Royal Holloway, University of London, Surrey, United Kingdom
P. Karataev, N. Vitoratou
JAI, Egham, Surrey, United Kingdom
G. Rehm, N. Vitoratou
DLS, Oxfordshire, United Kingdom

Resonant Spin Depolarization is a high precision technique for beam energy measurement employed in the Diamond Light Source storage ring. The relation between spin tune and beam energy can be used to determine the energy of a transversely polarized beam. Vertical oscillations excite the beam at frequencies that match the fractional part of the spin tune and the beam loss rate is used to monitor the beam depolarization. However, the standard procedure of these measurements is intrusive and not compatible with user operation of a light source. The Advanced Resonant Spin Depolarization (AdReSD) project aims to extend and improve the method with the goal of making the measurements compatible with the user operation, for instance by acting only on a small fraction of the stored beam. As a first step, we are investigating the beam loss monitors that will be used to detect beam depolarization. The material, location and optimal geometry of the detector to capture the largest fraction of the radiation footprint resulting from beam losses are studied. Results and designs are presented and future work is discussed.

Slides TH1AB3 [5.521 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2017-TH1AB3

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)