Instrumentation & Measurement Magazine 24-9 - 31

Fig. 11. Correlation of earth tides with the LHC beam orbit during LHC Physics Run I.
on a high dynamic range for a simple, " automatic " fail-safe,
multi-purpose operation. In all cases, the BPM system performance
has improved over the years, and will continue to
improve, mainly thanks to the advances of the BPM read-out
and data acquisition electronics, in recent times driven by the
semiconductor industry on low-noise RF amplifiers, high-resolution,
multi-GS/s ADCs, low-jitter clock PLLs, faster FPGAs
and high-capacity memory chips. The latest development of
higher integration of some of these functions into a single chip,
the RFSoC, will certainly boost the BPM system performance
further ahead.
However, the BPM system of large scale, high-energy accelerators,
such as the Large Hadron Collider (LHC) at CERN,
equipped with 1100 BPM stations distributed along the two 7
TeV ring accelerators of 27 km circumference cannot always
and immediately benefit from those advances in the semiconductor
and telecommunication industry, it just takes too many
resources to always keep those large, complex BPM systems
up to date. Still, even the present " older " analog-style, and a
bit " outdated " LHC BPM system [19], [20] not only fulfills the
day-to-day requirements, also in today's view of BPM systems
it offers an impressive performance. Fig. 11 shows how the
LHC orbit feedback signal delivered by the BPM system correlates
with the earth tides during LHC physics runs.
Summary
This brief introduction to beam position monitors for
charged particle accelerators covered the basic principles and
December 2021
elementary aspects of this technique, without going into details
on technology and limiting to a very few examples on
BPM pickups and beam signals. The information presented
here is summarized from articles, tutorials and other publications
listed in the Bibliography below. More up-to-date
information, and state-of-the-art techniques and technologies
on accelerator beam instrumentation and diagnostics can
be found in the International Beam Instrumentation Conference
(IBIC) series.
References
[1] H. Schmickler, CERN-ACC-2020-0010, in Proc. 2018 Course on
Beam Instrumentation for Particle Accelerators, pp. 355-393, Jun.
2018.
[2] M. Wendt, " Overview of recent trends and developments for
BPM Systems, " MOOC01, in Proc. DIPAC 2011, pp. 18-22, 2011.
[3] F. Marcellini, M. Serio, and M. Zobov, " DAΦNE Broad-band
button electrodes, " INFN-LNF, Accelerator Division, DAΦNE
Technical Note CD-6, Frascati, Italy, Jan. 1996
[4] R. E. Shafer, " Characteristics of directional coupler beam position
monitors, " IEEE Trans. Nucl. Sci., vol. 32, pp. 1933-1937, PAC'85,
May 1985.
[5] D. P. McGinnis, " The design of beam pickup and kickers, " AIP
Conf. Proc., vol. 333, pp. 64-85, 1995.
[6] M. Gasior, " An inductive pick-up for beam position and current
measurements, " CT01, in Proc. DIPAC 2003, pp. 54-55, 2003.
[7] P. Forck et al., " Beam position monitors, " CERN-2009-005, pp.
187-228, 2008.
IEEE Instrumentation & Measurement Magazine
31
Instrumentation & Measurement Magazine 24-9

Table of Contents for the Digital Edition of Instrumentation & Measurement Magazine 24-9
