Observation of Quasichanneling Oscillations

Wistisen, T. N.; Mikkelsen, R.; Uggerhøj, U. I.; Wienands, U.; Markiewicz, T.; Gessner, Spencer; Hogan, Mark; Noble, R.; Holtzapple, R.; Tucker, S.; Guidi, V.; Mazzolari, A.; Bagli, E.; Bandiera, L.; Sytov, Alexei

doi:10.1103/physrevlett.119.024801

Cited by 23 publications

(33 citation statements)

References 11 publications

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“…This simulation code is developed for ab-initio Monte Carlo simulations of charged particle trajectories in an interplanar or interaxial potential in a crystalline medium (either bent or not) with both multiple and single scattering on nuclei and electrons. The method developed by the code has already been tested vs. experimental results in [11,12,13,15,47]. The perfect alignment with bent planes, i.e., θ cr = 0, was experimentally determined by the highest intensity of the channeling peak, recorded during the angular scan.…”

Section: Experimental Results and Analysismentioning

confidence: 99%

Steering of Sub-GeV electrons by ultrashort Si and Ge bent crystals

et al. 2017

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We report the observation of the steering of 855 MeV electrons by bent silicon and germanium crystals at the MAinzer MIkrotron. Crystals with 15 µm of length, bent along (111) planes, were exploited to investigate orientational coherent effects. By using a piezo-actuated mechanical holder, which allowed to remotely change the crystal curvature, it was possible to study the steering capability of planar channeling and volume reflection vs. the curvature radius and the atomic number, Z. For silicon, the channeling efficiency exceeds 35%, a record for negatively charged particles. This was possible due to the realization of a crystal with a thickness of the order of the dechanneling length. On the other hand, for germanium the efficiency is slightly below 10% due to the stronger contribution of multiple scattering for a higher-Z material. Nevertheless this is the first evidence of negative beam steering by planar channeling in a Ge crystal. Having determined for the first time the dechanneling length, one may design a Ge crystal based on such knowledge providing nearly the same channeling efficiency of silicon. The presented results are relevant for crystal-based beam manipulation as well as for the generation of e.m. radiation in bent and periodically bent crystals.

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Section: Experimental Results and Analysismentioning

confidence: 99%

Steering of Sub-GeV electrons by ultrashort Si and Ge bent crystals

et al. 2017

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“…Such a simple dependence on k 0 disappears when the conditions (25), (29), and (33) become violated. In particular, when one considers the reflection of ultrarelativistic electrons (or positrons) from a crystal (see, e.g., [45][46][47][48][49][50][51][52][69][70][71][72]), the trajectory of the particle can be replaced by (30) in evaluating the radiation of twisted photons provided that the photon energy satisfies the estimate…”

Section: Trajectories With a Break On The Detector Axismentioning

confidence: 99%

“…Even larger K can be achieved not for the volume reflected but for the volume captured electrons in a bent crystal (see, e.g., [46,47,[49][50][51][52]). For the processes we consider, the twisted photons with large total angular momentum can be generated only when q → 1.…”

Section: Trajectories With a Break On The Detector Axismentioning

confidence: 99%

“…Of course, the coherence properties of radiation become worse in increasing the photon energy. As the particular case for application of general formulas, we shall consider the edge radiation created in the process of scattering of electrons (positrons) by crystals: the so-called volume reflection and the volume capture [44][45][46][47][48][49][50][51][52]. In this case, the electrons with the energies of the order 5 GeV produce the edge radiation with the photon energies up to 850 eV with large angular momentum.…”

Section: Introductionmentioning

confidence: 99%

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Probability of radiation of twisted photons in the infrared domain

2019

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The infrared asymptotics of probability of radiation of twisted photons in an arbitrary scattering process of quantum electrodynamics (QED) in a vacuum is investigated. This asymptotics is universal and corresponds to the radiation produced by a classical current. Such a radiation is known as the edge radiation. We represent it in terms of the twisted photons: the exact analytical formulas for the average number of radiated twisted photons are derived. We find the average projection of the total angular momentum of the edge radiation and the angular momentum per photon. It is shown that the edge radiation can be used as a source of twisted photons with large angular momentum. Moreover, this radiation can be employed as a superradiant coherent source of twisted photons in the infrared domain, in particular, in the THz part of the electromagnetic spectrum. Several general selection rules for the radiation and absorbtion of twisted photons are proved. These selection rules allow one, in particular, to modulate the one-particle radiation probability by means of scattering of charged particles on symmetrically arranged crystals. *

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“…2 an image of the YAG screen is shown for the aligned orientation where the beam hits the crystal parallel to the plane at the crystal entrance face. The almost circular light peak to the right in the image originates from the channeled particles, near which the so-called quasi-channeling oscillations can be seen [12], and to the left is seen the volume reflected particles and/or the fraction of particles that is not channeled due to the finite beam divergence and its surface transmission. After identifying the direction of the plane, we switched to the secondary beam which has a significantly higher divergence of around σ ≈ 75 μrad.…”

Section: Methodsmentioning

confidence: 99%

Photon emission by volume reflected electrons in bent crystals

Nielsen

Uggerhøj

Holtzapple

et al. 2019

Phys. Rev. Accel. Beams

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We present a quantitative experimental analysis of the radiation emission of 12.6 GeV electrons moving along and across the (111) planes of a strongly bent silicon crystal with a bending radius of 0.15 m. We have measured the radiation emitted during volume reflection, which has shown to strongly enhance the emission of low-energy photons, and a convincing agreement between simulations and experimental data is found.

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Observation of Quasichanneling Oscillations

Cited by 23 publications

References 11 publications

Steering of Sub-GeV electrons by ultrashort Si and Ge bent crystals

Steering of Sub-GeV electrons by ultrashort Si and Ge bent crystals

Probability of radiation of twisted photons in the infrared domain

Photon emission by volume reflected electrons in bent crystals

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