Broad and intense radiation accompanying multiple volume reflection of ultrarelativistic electrons in a bent crystal.
The radiation emitted by 120  GeV/c electrons traversing a single bent crystal under multiple volume reflection orientation is investigated. Multiple volume reflection in one crystal occurs as a charged particle impacts on a bent crystal at several axial channeling angles with respect to a crystal axis. The resulting energy-loss spectrum of electrons was very intense over the full energy range up to the nominal energy of the beam. As compared to the radiation emission by an individual volume reflection, the energy-loss spectrum is more intense and peaks at an energy 3 times greater. Experimental results are compared to a theoretical approach based on the direct integration of the quasiclassical Baier and Katkov formula. In this way, it is possible to determine the mean number of photons emitted by each electron and, thus, to extract the single-photon spectrum, which is broad and intense. The soft part of the radiation spectrum is due to the contribution of coherent interaction between electrons and several reflecting planes intersecting the same crystal axis, whereas the hard part is mainly connected to coherent bremsstrahlung induced by correlated scattering of electrons by atomic strings (string of strings scattering and radiation). The radiation generation by multiple volume reflection takes place over a broad angular range of the incident beam with respect to coherent bremsstrahlung and channeling radiation in straight crystals. Therefore, this type of radiation can be exploited for applications, such as beam dump and collimation devices for future linear colliders.
INFN Sezione di Ferrara, Dipartimento di Fisica, Università di Ferrara, Via Saragat 1, 44122 Ferrara, Italy.
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Bandiera
INFN Sezione di Ferrara, Dipartimento di Fisica, Università di Ferrara, Via Saragat 1, 44122 Ferrara, Italy.
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Bagli
INFN Sezione di Ferrara, Dipartimento di Fisica, Università di Ferrara, Via Saragat 1, 44122 Ferrara, Italy.
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Guidi
INFN Sezione di Ferrara, Dipartimento di Fisica, Università di Ferrara, Via Saragat 1, 44122 Ferrara, Italy.
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Mazzolari
Università dell'Insubria, Via Valleggio 11, 22100 Como, Italy, and INFN Sezione di Milano Bicocca, Piazza della Scienza 3, 20126 Milano, Italy.
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Berra
Università dell'Insubria, Via Valleggio 11, 22100 Como, Italy, and INFN Sezione di Milano Bicocca, Piazza della Scienza 3, 20126 Milano, Italy.
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Lietti
Università dell'Insubria, Via Valleggio 11, 22100 Como, Italy, and INFN Sezione di Milano Bicocca, Piazza della Scienza 3, 20126 Milano, Italy.
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Prest
INFN Sezione di Trieste, Via Valerio 2, 34127 Trieste, Italy.
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Vallazza
INFN Laboratori Nazionali di Legnaro, Viale dell'Università 2, 35020 Legnaro, Italy, and Dipartimento di Fisica, Università Di Padova, Via Marzolo 8, 35131 Padova, Italy.
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De Salvador
Research Institute for Nuclear Problems, Belarusian State University, Minsk, Belarus.
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Tikhomirov