Dataset Information

X-ray beam quality after a mirror reflection: Experimental and simulated results for a toroidal mirror in a 4 ^th generation storage-ring beamline.

ABSTRACT:

Background

The surface errors found in X-ray mirrors constitute a limiting factor for preserving beam quality. This is particularly important when the X-ray beam has low emittance and a significant coherence fraction, like in newly upgraded synchrotron storage rings.

Methods

We studied the fringes observed in the image of an undulator-produced X-ray beam reflected by a high-quality toroidal mirror. The measurements and simulations were performed using different conditions: a photon beam either monochromatic or with large bandwidth, reflected by a mirror with variable curvature.

Results

The experimental data are compared with up-to-date simulation including partial coherence.

Conclusions

The observed fringes in the unfocused beam correlate with low spatial frequency structures in mirror profiles, irrespective of beam coherence. Both classical ray tracing and partially coherent simulations through coherent mode decomposition are confirmed as accurate methods for such simulations.

SUBMITTER: Reyes-Herrera J

PROVIDER: S-EPMC10660299 | biostudies-literature | 2023

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

X-ray beam quality after a mirror reflection: Experimental and simulated results for a toroidal mirror in a 4 <sup>th</sup> generation storage-ring beamline.

Reyes-Herrera Juan J Celestre Rafael R Cammarata Marco M Barrett Raymond R Levantino Matteo M Sanchez Del Rio Manuel M

Open research Europe 20231012

<h4>Background</h4>The surface errors found in X-ray mirrors constitute a limiting factor for preserving beam quality. This is particularly important when the X-ray beam has low emittance and a significant coherence fraction, like in newly upgraded synchrotron storage rings.<h4>Methods</h4>We studied the fringes observed in the image of an undulator-produced X-ray beam reflected by a high-quality toroidal mirror. The measurements and simulations were performed using different conditions: a photo ...[more]

PMID: 37990739

Similar Datasets

Project description:Nowadays, due to the advantages of high peak power, high average power, ultra-short pulse, and fully coherent characteristics, the high-repetition-rate free-electron laser (FEL) is thriving in many countries around the world. The thermal load caused by high-repetition-rate FEL poses a great challenge to the mirror surface shape. Especially in the case of high average power, how to perfectly control the mirror shape to maintain the coherence of the beam has become a difficult problem in beamline design. In addition to multi-segment PZT, when multiple resistive heaters are used to compensate for the mirror shape, the heat flux (or power) generated by each heater must be optimized to obtain sub-nanometer height error. This article establishes MHCKF model for the mirror surface deformation under the combined effect of the mirror initial deformation, the thermal deformation caused by X-rays, and the deformation compensated by multiple heaters. By searching the perturbation term in the mathematical model, the least squares solution of the heat fluxes generated by all heaters can be obtained. This method can not only set multiple constraints on the heat fluxes but also quickly obtain their values when minimizing the mirror shape error. It overcomes the problem of time-consuming optimization processes encountered by traditional finite element analysis software, especially in the context of multi-parameter optimization. This article focuses on the offset mirror in the FEL-1 beamline at S3FEL. Using this method, the optimization of 25 heat fluxes generated by all resistive heaters was accomplished within a few seconds utilizing an ordinary laptop. The results indicate that the height error RMS decreased from 40 nm to 0.009 nm, and the slope error RMS reduced from 192.7nrad to 0.4nrad. Wave-optics simulations show that the wavefront quality has been significantly improved. In addition, some factors affecting mirror shape error, such as the number of heaters, higher repetition rate, film coefficient, and the length of copper tube, were analyzed. The results show that the MHCKF model and optimization algorithm can effectively solve the optimization problem of compensating for the mirror shape with multiple heaters.

Project description:PurposeEnergy changes in pencil beam scanning proton therapy can be a limiting factor in delivery time, hence, limiting patient throughput and the effectiveness of motion mitigation techniques requiring fast irradiation. In this study, we investigate the feasibility of performing fast and continuous energy modulation within the momentum acceptance of a clinical beamline for proton therapy.MethodsThe alternative use of a local beam degrader at the gantry coupling point has been compared with a more common upstream regulation. Focusing on clinically relevant parameters, a complete beam properties characterization has been carried out. In particular, the acquired empirical data allowed to model and parametrize the errors in range and beam current to deliver clinical treatment plans.ResultsFor both options, the local and upstream degrader, depth-dose curves measured in water for off-momentum beams were only marginally distorted (γ(1%, 1 mm) > 90%) and the errors in the spot position were within the clinical tolerance, even though increasing at the boundaries of the investigated scan range. The impact on the beam size was limited for the upstream degrader, while dedicated strategies could be required to tackle the beam broadening through the local degrader. Range correction models were investigated for the upstream regulation. The impaired beam transport required a dedicated strategy for fine range control and compensation of beam intensity losses. Our current parameterization based on empirical data allowed energy modulation within acceptance with range errors (median 0.05 mm) and transmission (median -14%) compatible with clinical operation and remarkably low average 27 ms dead time for small energy changes. The technique, tested for the delivery of a skull glioma treatment, resulted in high gamma pass rates at 1%, 1 mm compared to conventional deliveries in experimental measurements with about 45% reduction of the energy switching time when regulation could be performed within acceptance.ConclusionsFast energy modulation within beamline acceptance has potential for clinical applications and, when realized with an upstream degrader, does not require modification in the beamline hardware, therefore, being potentially applicable in any running facility. Centers with slow energy switching time can particularly profit from such a technique for reducing dead time during treatment delivery.

Dataset Information

X-ray beam quality after a mirror reflection: Experimental and simulated results for a toroidal mirror in a 4 ^th generation storage-ring beamline.

Background

Methods

Results

Conclusions

Publications

X-ray beam quality after a mirror reflection: Experimental and simulated results for a toroidal mirror in a 4 <sup>th</sup> generation storage-ring beamline.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Dataset Information

X-ray beam quality after a mirror reflection: Experimental and simulated results for a toroidal mirror in a 4 th generation storage-ring beamline.

Background

Methods

Results

Conclusions

Publications

X-ray beam quality after a mirror reflection: Experimental and simulated results for a toroidal mirror in a 4 <sup>th</sup> generation storage-ring beamline.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

X-ray beam quality after a mirror reflection: Experimental and simulated results for a toroidal mirror in a 4 ^th generation storage-ring beamline.