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| 2. |
- Glasbey, JC, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 3. |
- Brosi, Miriam, et al.
(författare)
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Time-resolved measurement and simulation of a longitudinal single-bunch instability at the MAX IV 3 GeV ring
- 2023
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Ingår i: 14th International Particle Accelerator Conference. - 9783954502318 ; , s. 2685-2688
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The study and understanding of collective effects plays a vital role for fourth-generation light sources. These effects mostly need to be mitigated and controlled to achieve the design operational parameters. However, they can also be utilized to gain insights into the properties of the machine. While the 3 GeV storage ring at the MAX IV light source is running in multi-bunch mode during user operation. Single-bunch operation is available in dedicated machine study shifts, providing the possibility to study collective effects at higher bunch currents. In such a current range an instability has been observed in the longitudinal plane. Above the threshold current of the instability a dynamic deformation of the bunch profile and a strong increase in energy spread occurs. Dedicated measurements were conducted with multiple diagnostic tools such as time-resolved bunch profile measurements. First simulations of the observed effects were performed with a Vlasov-Fokker-Planck solver. This contribution presents measurement results and draws a comparison to the simulations.
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| 4. |
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| 5. |
- Klementiev, Konstantin, et al.
(författare)
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Wiggler radiation at a low-emittance storage ring and its usage for X-ray absorption spectroscopy
- 2022
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Ingår i: Journal of Synchrotron Radiation. - 0909-0495. ; 29, s. 462-469
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Tidskriftsartikel (refereegranskat)abstract
- Awiggler is a high-power insertion device that was used in the past to produce a smooth wide-band X-ray spectrum. It is widely believed that on low-emittance synchrotrons this X-ray source loses its spatial and spectral homogeneity and therefore becomes less ideal than a scanning undulator. In this paper, we report on experimental and computational studies of an in-vacuum wiggler installed on the first fourth-generation synchrotron MAX IV. We investigate how several physical parameters affect the wiggler spectrum and propose a combination of a few of them that results in significant spectral smoothing. We also examine EXAFS spectra for possible distortions originating from the source imperfection. For this purpose, we scrutinize samples of various homogeneity. We conclude that wigglers are still an appropriate class of insertion devices, also on low-emittance synchrotrons.
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| 6. |
- Mansten, Erik, et al.
(författare)
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Cancellation of klystron-induced energy and arrival-time variations in linear accelerators with arc-type bunch compressors
- 2024
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Ingår i: Physical Review Accelerators and Beams. - 2469-9888. ; 27:4
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Tidskriftsartikel (refereegranskat)abstract
- We explain how the accelerating field amplitude and phase vary with modulator voltage in pulsed radio frequency high-power amplifiers based on klystron tubes. Changes in modulator voltage give rise to correlated changes of amplitude and phase, affecting the properties of the accelerated beam, in particular energy, arrival time, and bunch duration. We show, both theoretically and experimentally, that there exists a postcrest acceleration phase (the magic angle) where the changes of beam energy due to phase and amplitude shifts caused by modulator-voltage variations cancel out. When accelerating at the magic angle, the klystron modulator voltage jitter no longer contributes to energy and arrival-time jitter in the accelerator. Off-crest operation at the magic angle can be implemented for bunch compression schemes in accelerators with arc-type bunch compressors, which have positive momentum compaction. The experimental results, obtained at the MAX IV laboratory, show the benefit of operating close to the magic angle in arc-type bunch compressors. In a direct measurement of normalized electron-energy jitter, the energy jitter was reduced by a factor of 1.8 down to 8.2×10-5 when operating at the magic angle.
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| 7. |
- Pedro, Joana Reis, et al.
(författare)
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Transient gain of function of cannabinoid CB1 receptors in the control of frontocortical glucose consumption in a rat model of Type-1 diabetes
- 2020
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Ingår i: Brain Research Bulletin. - : Elsevier BV. - 0361-9230. ; 161, s. 106-115
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Tidskriftsartikel (refereegranskat)abstract
- Here we aimed to unify some previous controversial reports on changes in both cannabinoid CB1 receptor (CB1R) expression and glucose metabolism in the forebrain of rodent models of diabetes. We determined how glucose metabolism and its modulation by CB1R ligands evolve in the frontal cortex of young adult male Wistar rats, in the first 8 weeks of streptozotocin-induced type-1 diabetes (T1D). We report that frontocortical CB1R protein density was biphasically altered in the first month of T1D, which was accompanied with a reduction of resting glucose uptake ex vivo in acute frontocortical slices that was normalized after eight weeks in T1D. This early reduction of glucose uptake in slices was also restored by ex vivo treatment with both the non-selective CB1R agonists, WIN55212−2 (500 nM) and the CB1R-selective agonist, ACEA (3 μM) while it was exacerbated by the CB1R-selective antagonist, O-2050 (500 nM). These results suggest a gain-of-function for the cerebrocortical CB1Rs in the control of glucose uptake in diabetes. Although insulin and IGF-1 receptor protein densities remained unaffected, phosphorylated GSKα and GSKβ levels showed different profiles 2 and 8 weeks after T1D induction in the frontal cortex. Altogether, the biphasic response in frontocortical CB1R density within a month after T1D induction resolves previous controversial reports on forebrain CB1R levels in T1D rodent models. Furthermore, this study also hints that cannabinoids may be useful to alleviate impaired glucoregulation in the diabetic cortex.
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| 8. |
- Robert, Aymeric, et al.
(författare)
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MAX IV Laboratory
- 2023
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Ingår i: European Physical Journal Plus. - 2190-5444. ; 138:6
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Tidskriftsartikel (refereegranskat)abstract
- MAX IV Laboratory is a Swedish national synchrotron radiation facility that comprises three accelerators with varying characteristics. One of the accelerators, the 3 GeV storage ring, is the world’s first fourth-generation ring and pioneered the use of the multibend achromat lattice to provide access to ultrahigh brightness X-rays. MAX IV aims to stay at the forefront of the current and future research needs of its multidisciplinary user community, principally located in the Nordic and Baltic regions. Our 16 beamlines currently offer and continue to develop modern X-ray spectroscopy, scattering, diffraction, and imaging techniques to address scientific problems of importance to society.
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