| 1. |
- Sarri, Gianluca, et al.
(författare)
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A table-top laser-based source of short, collimated, ultra-relativistic positron beams
- 2013
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Ingår i: Laser Acceleration of Electrons, Protons, and Ions II; and Medical Applications of Laser-Generated Beams of Particles II; and Harnessing Relativistic Plasma Waves III. - : SPIE - International Society for Optical Engineering. - 9780819495815 - 0819495816 ; , s. 87790Z-1-87790Z-7
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Konferensbidrag (refereegranskat)abstract
- An ultra-relativistic electron beam passing through a thick, high-Z solid target triggers an electromagnetic cascade, whereby a large number of high energy photons and electron-positron pairs are produced. By exploiting this physical process, we present here the first experimental evidence of the generation of ultra-short, highly collimated and ultra-relativistic positron beams following the interaction of a laser-wakefield accelerated electron beam with high-Z solid targets. Clear evidence has also been obtained of the generation of GeV electron-positron jets with variable composition depending on the solid target material and thickness. The percentage of positrons in the overall leptonic beam has been observed to vary from a few per cent up to almost fifty per cent, implying a quasi-neutral electron-positron beam. We anticipate that these beams will be of direct relevance to the laboratory study of astrophysical leptonic jets and their interaction with the interstellar medium
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| 2. |
- Sarri, Gianluca, et al.
(författare)
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Table-Top Laser-Based Source of Femtosecond, Collimated, Ultrarelativistic Positron Beams
- 2013
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 110:25, s. 255002-1-255002-5
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Tidskriftsartikel (refereegranskat)abstract
- The generation of ultrarelativistic positron beams with short duration (τe+≃30 fs), small divergence (θe+≃3 mrad), and high density (ne+≃1014–1015 cm-3) from a fully optical setup is reported. The detected positron beam propagates with a high-density electron beam and γ rays of similar spectral shape and peak energy, thus closely resembling the structure of an astrophysical leptonic jet. It is envisaged that this experimental evidence, besides the intrinsic relevance to laser-driven particle acceleration, may open the pathway for the small-scale study of astrophysical leptonic jets in the laboratory.
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| 3. |
- Sarri, Gianluca, et al.
(författare)
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Laser-driven generation of collimated ultra-relativistic positron beams
- 2013
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Ingår i: Plasma Physics and Controlled Fusion. - London : Institute of Physics (IOP). - 0741-3335 .- 1361-6587. ; 55:12
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Tidskriftsartikel (refereegranskat)abstract
- We report on recent experimental results concerning the generation of collimated (divergence of the order of a few mrad) ultra-relativistic positron beams using a fully optical system. The positron beams are generated exploiting a quantum-electrodynamic cascade initiated by the propagation of a laser-accelerated, ultra-relativistic electron beam through high-Z solid targets. As long as the target thickness is comparable to or smaller than the radiation length of the material, the divergence of the escaping positron beam is of the order of the inverse of its Lorentz factor. For thicker solid targets the divergence is seen to gradually increase, due to the increased number of fundamental steps in the cascade, but it is still kept of the order of few tens of mrad, depending on the spectral components in the beam. This high degree of collimation will be fundamental for further injection into plasma-wakefield afterburners.
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| 4. |
- Sarri, Gianluca, et al.
(författare)
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Reply to a comment
- 2020
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 124
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 5. |
- Seeley, Stacy K, et al.
(författare)
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Metabolism of oxidized linoleic acid by glutathione transferases : peroxidase activity toward 13-hydroperoxyoctadecadienoic acid.
- 2006
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Ingår i: Biochim Biophys Acta. - 0006-3002. ; 1760:7, s. 1064-70
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Tidskriftsartikel (refereegranskat)abstract
- The oxidation of linoleic acid produces several products with biological activity including the hydroperoxy fatty acid 13-hydroperoxyoctadecadienoic acid (13-HPODE), the hydroxy fatty acid 13-hydroxyoctadecadienoic acid (13-HODE), and the 2,4-dienone 13-oxooctadecadienoic acid (13-OXO). In the present work, the peroxidase activity of glutathione transferases (GST) A1-1, M1-1, M2-2, and P1-1(Val 105) toward 13-HPODE has been examined. The alpha class enzyme is the most efficient peroxidase while the two enzymes from the mu class exhibit weak peroxidase activity toward 13-HPODE. It was also determined that the conjugated diene 13-HODE is not a substrate for GST from the alpha and mu classes but that 13-HODE does inhibit the GST-catalyzed conjugation of CDNB by enzymes from the alpha, mu, and pi classes. Finally, both 13-HODE and 13-OXO were shown to be inducers of GST activity in HT-29 and HCT-116 colon tumor cells. These data help to clarify the role of GST in the metabolic disposition of linoleic acid oxidation products.
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