Excellence in Detectors and Instrumentation Technologies

INFN - Laboratori Nazionali di Frascati, Italy  October 20-29, 2015

Accelerator Laboratory

CONVENERS A. Gallo (LNF), E. Chiadroni (LNF)
TUTORS D. Alesini (LNF), M. Bellaveglia (LNF), S. Bini (LNF), F. Cardelli (INFN-RM1), F. Cioeta (LNF), S. Guiducci (LNF), F. Iungo (LNF), G. Kube (DESY), C. Ligi (LNF), A. Mostacci (LNF), L. Piersanti (LNF), L. Sabbatini (LNF), A. Vannozzi (LNF), K. Wittenburg (DESY)
LOCATION Acc. Lab. (pulsed magnet lab, Bd.2), Vacuum Lab. (Bd.5b), SPARC hall and Control room (Bds.6, 6a)

The Accelerator Laboratory aims to give to the students a practical background on the main subsystems forming a particle accelerator, i.e. Radio-Frequency accelerating structures, vacuum and magnets technology, electron beam diagnostics.
The laboratory consists of four classes in which students will be introduced to basic concepts and will acquire experimental skills through “hands on” activities on:

  1. Measurements on RF cavities
  2. Characterization of a quadrupole magnet
  3. Characterization of instrumentation for transverse and longitudinal beam diagnostics
  4. Measurements on vacuum systems and visit to the SPARC_LAB test facility
  1. Measurements on RF cavities (A. Gallo, M. Bellaveglia, A. Mostacci, L. Piersanti)

    The purpose of this class is to introduce RF acceleration concepts, focusing on standing wave (SW) cavities and travelling wave (TW) sections, with some hints on RF power sources and controls.
    A first experimental activity will concern the bench characterization of a resonant SW accelerating cavity. In particular the resonance frequency and the Q-factor of the accelerating mode, and of few high order modes, will be measured. Time domain response to an RF pulse and cavity filling time will be also measured.
    In a second experimental activity a TW accelerating section will be characterized through frequency domain measurements of the fundamental band and measurements of the attenuation coefficient in both frequency and time domains.
    Time domain response to an RF pulse, filling time and group delay will be also measured.

  2. Characterization of a quadrupole magnet (F. Iungo, S. Guiducci, C. Ligi, L. Sabbatini, A. Vannozzi)

    This class will be introduced by a theoretical excursus concerning particle accelerator magnets, lattice, transport matrices and beta functions, during which the students will also compare theoretical calculation of a particle trajectory inside a magnetic field versus a simulation of the real case. The experimental activity will concern longitudinal and transverse B-field profile measurements of a quadrupole magnet. Measurement data will be analyzed to extrapolate the magnet integral parameters used in the accelerator lattice design.

  3. Characterization of instrumentation for transverse and longitudinal beam diagnostics (G. Kube, E. Chiadroni, K. Wittenburg)

    The problem of measuring small transverse beam sizes (of the order of tens of μm and smaller) and short time duration (~ sub-ps), together with an accurate positioning, is particularly crucial for both colliders and linac-driven Free-Electron Lasers.
    The purpose of this tutorial is to provide students with a basic knowledge of the techniques used to retrieve both transverse and longitudinal beam size and become familiar with the instrumentation used.

    In the first exercise a laser beam will be set up in order to “simulate” a particle beam. The purpose of this experiment is the measurement of beam profile, in order to determine both beam size and divergence, allowing the retrieval of beam emittance.

    The second exercise concerns the characterization of a beam position monitor (BPM). A BPM test-stand, consisting of a wire scanner assembly, will be set up. An RF signal applied to the wire will simulate the beam. The position distortion will be measured for different pickup types, allowing a mapping of beam position.

    In the third exercise students will characterize and test a Michelson interferometer, used in electron beam diagnostics to retrieve the longitudinal size. The spectrum of a Globar source will be measured and discussed.

  4. Measurements on vacuum systems and visit to the SPARC_LAB test facility (D. Alesini, S. Bini, F. Cioeta, M. Bellaveglia, E. Chiadroni, A. Gallo)

    After a theoretical introduction to the basics concepts of vacuum theory and technology applied to particle accelerators, the various components of an accelerator vacuum system such as pumps, vacuum gauges, mass spectrometers and instrumentation will be described. The students will learn about the basic working principles of all types of high-vacuum and ultra-high vacuum pumps. Furthermore, students will carry out an experimental activity consisting in a complete pumping of a small vacuum chamber, including leak detection, pre-vacuum, high vacuum and residual gas characterization with a vacuum spectrometer. Practical experience of vacuum impedance, outgassing concepts and design vacuum system strategy to meet accelerator requirements will be also discussed. The lesson will conclude with a visit to the SPARC_LAB facility.


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