Intense Source of Positrons Using Channeling Effect in Crystals
Intense Source of Positrons Using Channeling Effect in Crystals

Author: Chenghai Xu

Publisher:

Published: 2012

Total Pages: 0

ISBN-13:

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The research work carried out for this PhD is concerning a special kind of positron source using channeling radiation and other crystal effects in an axially oriented crystal to generate a high number of photons which create, subsequently, a large number of pairs in an amorphous target. Photon generation and pair creation are developing in two targets separated by some distance allowing a sweeping magnet to get off the charged particles away from the amorphous converter. Such a scheme is called an hybrid positron source and has been adopted for the CLIC baseline. This kind of sources present big advantages with respect to the conventional sources where large emittance and important heat deposition are met. After some recall on the physical phenomena of interest for our study, detailed simulations are worked out using a special program dealing with crystal effects from Prof. Strakhovenko and the GEANT4 code; these tools led to a complete description of the positron source concerning the photons from one side and the positrons, from the other side, for which the main characteristics have been determined: transverse and longitudinal phase space, energy spectrum, time distribution,...Emphasis has been put on two points: first the matching devices capturing the positrons after the target which are essential for good accepted yields and the energy deposition density which is an important question for the reliability of the targets. Concerning the former point, three matching devices have been studied and their features compared: the Adiabatic Matching Device (AMD) largely used or considered for the positron sources, the Quarter Wave Transformer (QWT) and also the Lithium lens. For the latter point, related to the energy deposition and heating of the targets, we have tried to optimize the energy deposition density lowering its maximum value (PEDD); the average heat deposition has also been optimized using special converter material in granular shape, as considered for the neutrino factories. Very promising results allowed us to consider the hybrid positron source as an alternative to the difficult case of ILC; a special scheme for the transformation of the ILC beam pulses has been used, after KEK proposition. The positron beam transport has also been studied in the first part of the positron pre-accelerator including the solenoid and the first part of the quadrupole channel.

Channeling and Radiation in Periodically Bent Crystals
Channeling and Radiation in Periodically Bent Crystals

Author: Andrey V. Korol

Publisher: Springer

Published: 2014-05-13

Total Pages: 290

ISBN-13: 3642549330

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The development of coherent radiation sources for sub-angstrom wavelengths - i.e. in the hard X-ray and gamma-ray range - is a challenging goal of modern physics. The availability of such sources will have many applications in basic science, technology and medicine and in particular, they may have a revolutionary impact on nuclear and solid state physics, as well as on the life sciences. The present state-of-the-art lasers are capable of emitting electromagnetic radiation from the infrared to the ultraviolet, while free electron lasers (X-FELs) are now entering the soft X-ray region. Moving further, i.e. into the hard X and/or gamma ray band, however, is not possible without new approaches and technologies. In this book we introduce and discuss one such novel approach -the radiation formed in a Crystalline Undulator - whereby electromagnetic radiation is generated by a bunch of ultra-relativistic particles channeling through a periodically bent crystalline structure. Under certain conditions, such a device can emit intensive spontaneous monochromatic radiation and even reach the coherence of laser light sources. Readers will be presented with the underlying fundamental physics and be familiarized with the theoretical, experimental and technological advances made during the last one and a half decades in exploring the various features of investigations into crystalline undulators. This research draws upon knowledge from many research fields - such as materials science, beam physics, the physics of radiation, solid state physics and acoustics, to name but a few. Accordingly, much care has been taken by the authors to make the book as self-contained as possible in this respect, so as to also provide a useful introduction to this emerging field to a broad readership of researchers and scientist with various backgrounds. This new edition has been revised and extended to take recent developments in the field into account.

Positron Annihilation ICPA-11
Positron Annihilation ICPA-11

Author: Y. C. Jean

Publisher:

Published: 1997

Total Pages: 876

ISBN-13:

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For one and a half decades, the application of positron annihilation to condensed-matter physics concentrated on the study of the Fermi surfaces of metals and alloys. As other, often more powerful, techniques for performing this type of study were developed, it appeared that condensed-matter positron physics was going to be relegated to being a niche interest. However, the situation changed dramatically when it was found that measurements of positron annihilation in metals were sensitive to the structures of well-known defects. This discovery, and subsequent research made it a major tool in materials science.

Relativistic Channeling
Relativistic Channeling

Author: Richard A. Carrigan Jr.

Publisher: Springer Science & Business Media

Published: 2013-04-17

Total Pages: 513

ISBN-13: 1475763948

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Channeling, by its nature, involves a wide and disparate range of disciplines. Crystal preparation, material science, accelerator physics, sophisticated theoretical analysis and, of course, channeling itself all must work in concert in a research program. In spite of the gulfs separating some of these activities, researchers have drawn together over the last decade to carry out remarkable experiments in relativistic channeling and channeling radiation. Several informal workshops on high-energy channeling have been held over ~he years at Aarhus and Fermilab. However, with the vigorous progress in the field in the last several years it became clear that a more formal, comprehensive workshop was needed along with a book that covered the whole spectrum of the new developments, probed the future, and also laid out some of the foundations of the subject. This volume is the outcome of that process. The organization and preparation of both the volume and the workshop owe much to several outstanding scientific committees. The membership of these included J. Andersen (Aarhus), S. Baker (Fermilab), B. Berman (G. Washington), G. Bologna (Torino), E. Bonderup (Aarhus), S. Datz (Oak Ridge), J. Forster (Chalk River), F. Fujimoto (Tokyo), W. Gibson (Albany), I. Mitchell (Chalk River), Y. Ohtsuki (Waseda), R. Pantell (Stanford), S. Picraux (Sandia), J. Remillieux (Lyon), A. Saenz (NRL), V. Schegelsky (Gatchina), C. Sun (Albany), H. tiberall (Catholic U. ), E. Uggerh¢j (CERN), and R. Wedell (Humboldt). Others from across the spectrum of scientific disciplines agreed to serve as session chairmen.

Novel Lights Sources Beyond Free Electron Lasers
Novel Lights Sources Beyond Free Electron Lasers

Author: Andrei Korol

Publisher: Springer Nature

Published: 2022-06-09

Total Pages: 221

ISBN-13: 3031042824

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This book discusses possibilities and perspectives for designing and practical realization of novel intensive gamma-ray crystal-based light sources that can be constructed through exposure of oriented crystals—linear, bent and periodically bent, to beams of ultrarelativistic positrons and electrons. The book shows case studies like the tunable light sources based on periodically bent crystals that can be designed with the state-of-the-art beam facilities. A special focus is given to the analysis of generation of the gamma rays because the current technologies based on particle motion in the magnetic field become inefficient or incapable to achieve the desired gamma rays’ intensities. It is demonstrated that the intensity of radiation from crystal-based light sources can be made comparable to or even higher than what is achievable in conventional synchrotrons and undulators operating although in the much lower photon energy range. By exploring the coherence effects, the intensity can be boosted by orders of magnitude. The practical realization of such novel light sources will lead to the significant technological breakthroughs and societal impacts similar to those created earlier by the developments of lasers, synchrotrons and X-rays free-electron lasers. Readers learn about the underlying fundamental physics and familiarize with the theoretical, experimental and technological advances made during last two decades in exploring various features of investigations into crystal-based light sources. This research draws upon knowledge from many research fields, such as material science, beam physics, physics of radiation, solid-state physics and acoustics, to name but a few. The authors provide a useful introduction in this emerging field to a broad readership of researchers and scientists with various backgrounds and, accordingly, make the book as self-contained as possible.