Study of a positron source generated by photons from ultrarelativistic channeled particles

Chehab, R.; Couchot, F.; Nyaiesh, A. R.; Richard, F.; Artru, X.

doi:10.1109/pac.1989.73147

Cited by 24 publications

(14 citation statements)

References 2 publications

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“…The idea to use channeling effects to enhance the e + positron sources, for linear colliders, emerged in 1989 [18]. However this relies on the long term resistance of the crystal to radiation damages.…”

Section: The Hybrid Target Based On Channeling Process As E + Sourcementioning

confidence: 99%

Brilliant positron sources for CLIC and other collider projects

Rinolfi

Chehab

Dadoun³

et al. 2013

Nuclear Instruments and Methods in Physics Research Section B:

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The CLIC (Compact Linear Collider), as future linear collider, requires an intense positron source. A brief history is given up to the present baseline configuration which assumes unpolarized beams. A conventional scheme, with a single tungsten target as source of e -e + pairs, has been studied several years ago. But, in order to reduce the beam energy deposition on the e + target converter, a double-target system has been studied and proposed as baseline for CLIC. With this ''hybrid target'', the positron production scheme is based on the channeling process. A 5 GeV electron beam impinges on a thin crystal tungsten target aligned along its <111> axis, enhancing the photon production by channeling radiation. A large number of photons are sent to a thick amorphous tungsten target, generating large number of e -e + pairs, while the charged particles are bent away, reducing the deposited energy and the PEDD (Peak Energy Deposition Density). The targets parameters are optimized for the positron production. Polarized positron beams are an option for CLIC, which needs R&D. Some brilliant positron sources are briefly reviewed.

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Section: The Hybrid Target Based On Channeling Process As E + Sourcementioning

confidence: 99%

Brilliant positron sources for CLIC and other collider projects

Rinolfi

Chehab

Dadoun³

et al. 2013

Nuclear Instruments and Methods in Physics Research Section B:

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“…The qualities of such sources are depending on the photon characteristics and on the converter in which these photons are converted into e + e À pairs. Since 25 years, a proposal to use crystals as positron sources using the intense channeling radiation in axially oriented crystals [1] brought very promising results as shown in CERN and KEK experiments [2,3]. The main concern for all positron sources is not only the yield but also the energy deposition and the associated PEDD (Peak Energy Deposition Density).…”

Section: Introductionmentioning

confidence: 99%

Investigations on a hybrid positron source with a granular converter

Artru

Chaikovska

Chehab

et al. 2015

Nuclear Instruments and Methods in Physics Research Section B:

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Proceedings to appear in NIM BInternational audiencePromising results obtained with crystal targets for positron production led to the elaboration of a hybrid source made of an axially oriented tungsten crystal, as a radiator, and an amorphous tungsten converter. If the converter is granular, made of small spheres, the heat dissipation is greatly enhanced allowing the consideration of such device for the future linear colliders. A positron source of this kind is investigated. Previous simulations have shown very promising results for the yield as for the energy deposition and the PEDD (Peak Energy Deposition Density). Here, we present detailed simulations made in this granular converter with emphasis on the energy deposition density, which is a critical parameter as learned from the breakdown of the SLC target. A test on the KEKB linac is foreseen; it will allow a determination of the energy deposited in the converter through temperature measurements. Four granular converters, made of W spheres of mm radius have been built at LAL-Orsay; they will be installed at KEK and compared to compact converters. A description of the experimental lay-out at KEK is provided. Applications to future linear colliders as CLIC and ILC are considered

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“…So the target will receive less power (4), while on the other hand a crystal (but out of tungsten) might be more sensitive. The enormous effective fields which guide the particles in channels are more than three orders of mag nitude higher than the normally used fields (5) in acceler ator physics. The main characteristics are summarized in the next section and afterwards the detailed target consid erations are discussed.…”

Section: Introductionmentioning

confidence: 96%

“…The main desired features of a positron source can be characterized by the following five points: It should pro duce many positrons (1) with a low emittance (2) and also polarization (3) would be preferable. The target should stand the average and peak power (4) with the high me chanical stresses, while a capture region should provide very high guiding magnetic fields (5).…”

Section: Introductionmentioning

confidence: 99%

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Channeling crystals for positron production

Decker¹

Conference Record of the 1991 IEEE Particle Accelerator Conference

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Particles traversing at small angles along a single crystal axis experience a collective scattering force of many crystal atoms. The enormous fields can trap the particles along an axis or plane, called channeling.High energy electrons are attracted by the positive nuclei and therefore produce strongly enhanced so called coherent bremsstrahlung and pair production.These effects could be used in a positron production target: A single tungsten crystal is oriented to the incident electron beam within 1 mrad. At 28 GeV/c the effective radiation length is with 0.9 mm about one quarter of the amorphous material. So the target length can be shorter, which yields a higher conversion coefficient and a lower emittance of the positron beam. This makes single crystals very interesting for positron production targets.

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Study of a positron source generated by photons from ultrarelativistic channeled particles

Cited by 24 publications

References 2 publications

Brilliant positron sources for CLIC and other collider projects

Brilliant positron sources for CLIC and other collider projects

Investigations on a hybrid positron source with a granular converter

Channeling crystals for positron production

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