Paper | Title | Page |
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TUP21 | Scintillator Nonproportionality Studies at PITZ | 277 |
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A standard technique to measure beam profiles in linear accelerators are screen monitors using scintillating screens. This technique is used e.g. at the European XFEL in order to overcome coherence effects in case of OTR usage [*]. During the XFEL commissioning it was found out that screens based on LYSO:Ce as scintillating material revealed a nonproportional light output [**]. Reason for it is the high particle beam density. As consequence it was decided to exchange LYSO:Ce by GAGG:Ce scintillators because the excitation carriers can rapidly transfer their energy to excited states of gadolinium, and a rapid migration of this energy among the Gd sub-lattice is expected. Driven by the observations at XFEL a series of measurements was started to investigate the properties of various scintillator materials (LYSO:Ce, YAP:Ce, YAG:Ce, LuAG:Ce and GAGG:Ce). The last measurement campaign was carried out at PITZ which allows to operate at higher beam charge and lower electron energy compared to the XFEL. The present work summarizes the results of these measurements.
* S.Wesch and B.Schmidt, in Proc. DIPAC’11, Hamburg, WEOA01, pp. 539-543. ** G.Kube, A.Novokshonov, S.Liu, M.Scholz, in Proc. FEL’19, Hamburg, WEB01, pp. 301-306. |
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DOI • | reference for this paper ※ doi:10.18429/JACoW-IBIC2022-TUP21 | |
About • | Received ※ 11 September 2022 — Revised ※ 13 September 2022 — Accepted ※ 11 October 2022 — Issue date ※ 15 October 2022 | |
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WE1I1 |
First Observation of Quasi-Monochromatic Optical Cherenkov Radiation in a Dispersive Medium (Quartz) | |
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Spectral properties of optical Cherenkov radiation (ChR) were studied both theoretically and experimentally. This type of radiation has a continuous spectral distribution which allows to use it in different fields of physics. By exploiting the frequency dependence of the target permittivity it is possible to observe quasi-monochromatic radiation. A theoretical model based on a surface current approach is presented. In order to test the predictions, an experiment was carried out using 855 MeV electrons and a 0.2 mm thick quartz target as radiator. Quasi-monochromatic ChR was observed with a spectrometer, and tilting the radiator crystal offered the possibility to tune the radiation wavelength. The monochromatization effect is attributed to the frequency dependence of the quartz permittivity, and taking into account the refraction law it is possible to deduce a dispersion relation which connects ChR wavelength and target tilt angle for fixed observation angle. Dispersion relation and model description are confirmed in the experiment. Exploiting the ChR monochromatization mechanism might offer versatile tools which can find applications in beam diagnostics. | ||
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WEP20 | Emittance Diagnostics at PETRA IV | 430 |
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The PETRA IV project will be a Diffraction Limited Light Source designed to be the successor of PETRA III, the 6 GeV 3rd generation hard X-Ray synchrotron light source at DESY in Hamburg. It will operate at a beam energy of 6 GeV with a design emittance of 20/4 pm rad. For a precise emittance online control, two dedicated diagnostics beamlines will be built up to image the beam profile with synchrotron radiation in the X-Ray region. With two beamlines, it will be possible to extract both the transverse beam emittances and the beam energy spread. Both beamlines will be equipped with two interchangeable X-Ray optical systems: a pinhole camera system to achieve high dynamic range and a Fresnel Diffractometry system for high resolution measurements in the range 1-18 um. This paper describes the planned setup and deals with the possible limitations. | ||
DOI • | reference for this paper ※ doi:10.18429/JACoW-IBIC2022-WEP20 | |
About • | Received ※ 05 September 2022 — Revised ※ 10 September 2022 — Accepted ※ 11 September 2022 — Issue date ※ 26 September 2022 | |
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