| 1. |
- Barucca, G., et al.
(författare)
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The potential of Λ and Ξ- studies with PANDA at FAIR
- 2021
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Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:4
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Tidskriftsartikel (refereegranskat)abstract
- The antiproton experiment PANDA at FAIR is designed to bring hadron physics to a new level in terms of scope, precision and accuracy. In this work, its unique capability for studies of hyperons is outlined. We discuss ground-state hyperons as diagnostic tools to study non-perturbative aspects of the strong interaction, and fundamental symmetries. New simulation studies have been carried out for two benchmark hyperon-antihyperon production channels: p¯ p→ Λ¯ Λ and p¯ p→ Ξ¯ +Ξ-. The results, presented in detail in this paper, show that hyperon-antihyperon pairs from these reactions can be exclusively reconstructed with high efficiency and very low background contamination. In addition, the polarisation and spin correlations have been studied, exploiting the weak, self-analysing decay of hyperons and antihyperons. Two independent approaches to the finite efficiency have been applied and evaluated: one standard multidimensional efficiency correction approach, and one efficiency independent approach. The applicability of the latter was thoroughly evaluated for all channels, beam momenta and observables. The standard method yields good results in all cases, and shows that spin observables can be studied with high precision and accuracy already in the first phase of data taking with PANDA.
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| 2. |
- He, Y., et al.
(författare)
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A single-laser scheme for observation of linear Breit-Wheeler electron-positron pair creation
- 2021
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 23:11
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Tidskriftsartikel (refereegranskat)abstract
- We show that a single laser pulse, traveling through a dense plasma, produces a population of MeV photons of sufficient density to generate a large number of electron-positron pairs via the linear Breit-Wheeler process. While it may be expected that the photons are emitted predominantly in the forward direction, parallel to the laser propagation, we find that a longitudinal plasma electric field drives the emission of photons in the backwards direction. This enables the collision of oppositely directed, MeV-level photons necessary to overcome the mass threshold for the linear Breit-Wheeler process. Our calculations predict the production of 10(7) electron-positron pairs, per shot, by a laser with peak intensity of just 3 x 10(22) W cm(-2). By using only a single laser pulse, the scheme sidesteps the practical difficulties associated with the multiple-laser schemes previously investigated.
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| 3. |
- He, Y., et al.
(författare)
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Achieving pair creation via linear and nonlinear Breit-Wheeler processes in dense plasmas irradiated by high-intensity laser pulses
- 2022
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 29:5
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Tidskriftsartikel (refereegranskat)abstract
- It has been recently shown that over 10(9) electron-positron pairs can be produced from light alone at an experimentally accessible laser intensity of 5 x 10 (22) W / cm(2) by irradiating a target with a pre-formed channel by two counter-propagating laser pulses. Although targets of variable length and channel density have been successfully fabricated and used in recent experiments involving high-intensity lasers, the impact of these parameters on the pair yield by different pair creation processes is yet to be understood. In this paper, we explore, using two-dimensional particle-in-cell simulations, the impact of the channel density and length on pair production by the linear Breit-Wheeler process, nonlinear Breit-Wheeler process, and Bethe-Heitler process at fixed laser intensity. We find that these parameters can be successfully used to increase the linear Breit-Wheeler pair yield. More importantly, the relative contribution of each process can be adjusted by varying the same parameters. We show that this approach allows us to completely eliminate the yield from the nonlinear Breit-Wheeler process while maintaining a significant yield from the linear Breit-Wheeler process. The Bethe-Heitler process plays a secondary role in the considered system, so the majority of the positrons inside the channel are produced from light alone. Our results indicate that a structured target irradiated by two laser beams has the potential to be a versatile platform for future experimental studies of the Breit-Wheeler pair production processes, with the target parameters serving as control knobs.& nbsp;& nbsp;Published under an exclusive license by AIP Publishing.
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| 4. |
- He, Y. T., et al.
(författare)
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Dominance of gamma-gamma electron-positron pair creation in a plasma driven by high-intensity lasers
- 2021
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Ingår i: Communications Physics. - : Springer Science and Business Media LLC. - 2399-3650. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- Creation of electrons and positrons from light alone is a basic prediction of quantum electrodynamics, but yet to be observed. Our simulations show that the required conditions are achievable using a high-intensity two-beam laser facility and an advanced target design. Dual laser irradiation of a structured target produces high-density gamma rays that then create > 10(8) positrons at intensities of 2 x 10(22) Wcm(-2). The unique feature of this setup is that the pair creation is primarily driven by the linear Breit-Wheeler process (gamma gamma -> e(+)e(-)), which dominates over the nonlinear Breit-Wheeler and Bethe-Heitler processes. The favorable scaling with laser intensity of the linear process prompts reconsideration of its neglect in simulation studies and also permits positron jet formation at experimentally feasible intensities. Simulations show that the positrons, confined by a quasistatic plasma magnetic field, may be accelerated by the lasers to energies >200 MeV. Electron-positron pair generation from nonlinear quantum electrodynamics is predicted at high intensities that are, so far, beyond experimental capabilities. Here, simulations predict a high yield of positrons can be obtained from gamma-gamma photon collisions in the linear regime, using counter-propagating pulses and a microstructured target.
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