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DETERMINATION OF BEAM INTENSITY AND POSITION IN A PARTICLE ACCLERATOR
KASPROWICZ G. wydawnictwo: WYD PW , rok wydania 2011, wydanie I cena netto: 36.10 Twoja cena 34,30 zł + 5% vat - dodaj do koszyka Determination of Beam Intensity and Position in a Particle Accelerator
A subject of the thesis is conception, design, implementation, tests and deployment of
new position measurement system of particle bunch in the CERN PS circular accelerator. The
system is based on novel algorithms of particle position determination.
The Proton Synchrotron accelerator (PS), installed at CERN, although commissioned in
1959, still plays a central role in the production of beams for the Antiproton
Decelerator, Super Proton Synchrotron, various experimental areas and for the Large Hadron
Collider (LHC). The PS produces beams of different types of particles, mainly protons, but
also various species of ions. Almost all these particle beams pass through the PS. The
quality of the beams delivered to the LHC has a direct impact on the effective luminosity,
and therefore the performance of the instrumentation of the PS is of great importance.
The old trajectory and orbit measurement system of the PS is dated back to 1988 and no
longer fulfilled present day requirements. It used 40 beam position monitors (BPMs) and an
analogue signal processing chain to acquire the trajectory of one single particle bunch
out of many, over two consecutive turns at a maximum rate of once every 5ms. The BPMs were
in good condition, however the electronics was aging and increasingly difficult to
maintain.
The new measurement system digitizes the BPM signals using 125MS/s, 12 bit ADCs. The
digitized sample stream are processed on the fly into individual bunch positions, using
numerical algorithms implemented on fast programmable logic (FPGA). The system stores the
lateral positions of all bunches in the machine over the full duration of an acceleration
cycle, requiring large memories. Post processing can be applied to the data in order to
extract orbits (averaged positions over many turns), mean radial position, phase space
images or machine tune data. Client orbit display programs running on operator consoles
can then concurrently request measurements from any interesting part of the cycle.
The ADCs digitize their input signals at a constant rate, whereas the revolution frequency
of the particle bunches varies along the acceleration cycle. The increase of this
frequency depends on the increase of particle velocity, and varies over more than an
octave for heavy ions. The system is able to keep track of each individual bunch from
injection all through to ejection using tracking and synchronization algorithm.
In essence, its task is to decide which of the ADC samples belong to each particle bunch.
The new system uses an entirely numerical synchronization algorithm, implemented in the
FPGA and running at the ADC sampling rate. Synchronization is made more complicated by the
possibility of the PS accelerator to change the harmonic number of the machine (the number
of possible bunches in the machine) during the acceleration. Harmonic change requires fast
re-synchronization. These operations are used, among others, to split the bunches into two
or three bunchlets, in order to better match the beam to the properties of the subsequent
accelerators. The new measurement system is able to keep track of the beam throughout the
accelerator.
Development of the effective algorithm, which enables precise trajectory tracking of
individual particle bunches with sub-mm precision was the aim of this thesis. Moreover,
using a similar, already verified algorithm, a new absolute beam intensity measurement
system was developed as well. These two measurement systems are complementary and for the
first time give the user full information about the beam position and intensity in the
accelerator. The scope of the thesis includes measurement system conception, hardware
design and development, algorithm development and tests.
130 pages, Paperback
Po otrzymaniu zamówienia poinformujemy, czy wybrany tytuł polskojęzyczny lub
anglojęzyczny jest aktualnie na półce księgarni.
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