| 1. |
- Kanai, M, et al.
(författare)
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- 2023
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swepub:Mat__t
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| 2. |
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| 5. |
- 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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| 6. |
- Barucca, G., et al.
(författare)
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Study of excited Ξ baryons with the P¯ ANDA detector
- 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 study of baryon excitation spectra provides insight into the inner structure of baryons. So far, most of the world-wide efforts have been directed towards N∗ and Δ spectroscopy. Nevertheless, the study of the double and triple strange baryon spectrum provides independent information to the N∗ and Δ spectra. The future antiproton experiment P¯ANDA will provide direct access to final states containing a Ξ¯ Ξ pair, for which production cross sections up to μb are expected in p¯p reactions. With a luminosity of L= 10 31 cm- 2 s- 1 in the first phase of the experiment, the expected cross sections correspond to a production rate of ∼106events/day. With a nearly 4 π detector acceptance, P¯ANDA will thus be a hyperon factory. In this study, reactions of the type p¯p → Ξ¯ +Ξ∗ - as well as p¯p → Ξ¯ ∗ +Ξ- with various decay modes are investigated. For the exclusive reconstruction of the signal events a full decay tree fit is used, resulting in reconstruction efficiencies between 3 and 5%. This allows high statistics data to be collected within a few weeks of data taking.
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| 7. |
- Savchenkova, A. S., et al.
(författare)
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Formation of Pyridyl Radicals by Hydrogen Atom Abstraction : Theoretical Study
- 2023
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Ingår i: Combustion, Explosion and Shock Waves. - 0010-5082. ; 59:2, s. 125-128
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: Specific features of the pyridine structure make it a convenient model system to describe coal combustion; however, the main attention of researchers has been paid to the formation of the ortho-pyridyl, whereas the formation of meta- and para-pyridyls has been yet poorly studied. The rate constants of the formation of three pyridyl radicals originating from pyridine by hydrogen atom abstraction by another hydrogen atom are compared. The geometry of the reactants is optimized within the framework of the density functional theory with subsequent refinement of single-point energies by the ab initioG3(MP2,CC) hybrid method. The calculations show that the formation of ortho-pyridyl is more favorable, though the formation and further transformations of all three radicals should be taken into account for a detailed description of the coal combustion process.
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| 8. |
- Savchenkova, Anna S., et al.
(författare)
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Revisiting diacetyl and acetic acid flames : The role of the ketene + OH reaction
- 2020
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Ingår i: Combustion and Flame. - : Elsevier BV. - 0010-2180. ; 218, s. 28-41
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Tidskriftsartikel (refereegranskat)abstract
- The mechanism of the reaction of ketene with hydroxyl radical has been studied by ab initio CCSD(T)-F12/cc-pVQZ-F12//B3LYP/6-311G(d,p) calculations of the potential energy surface. Temperature- and pressure-dependent reaction rate constants have been computed using the RRKM-Master Equation and transition state theory methods in the temperature range of 300–3000 K and in the pressure range of 0.01–100 atm. Three main channels have been analyzed: through direct abstraction of H atoms or starting with OH addition to the terminal carbon and to the central carbon atoms. Major products identified agree with the recent theoretical studies, however, significant difference was found with the rate constants derived by Xu et al. [13] and Cavallotti et al. [11]. To investigate the impact of the choice of reactions between CH2CO and OH radicals on the predicted burning velocities of the flames sensitive to ketene chemistry, namely diacetyl and acetic acid flames, a detailed kinetic mechanism was updated with pertinent reactions suggested in the literature. Then the rate constants of four most important product channels of reaction CH2CO + OH forming HCCO + H2O, CH2OH + CO, CH3 + CO2 and CH2COOH from the present and from the recent theoretical studies were tested. Good agreement with the burning velocities of diacetyl + air flames was found for the present model, while the expressions from the literature underestimate them. On the contrary, any combination of the rate constants of reactions between ketene and hydroxyl radical overpredicts burning velocities of acetic acid + air flames, which strongly indicates that the kinetic model of acetic acid is most probably incomplete and requires consideration of additional reactions.
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