| 11. |
- Murin, Y, et al.
(author)
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SEE-Related Studies at CELSIUS
- 2005
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In: Proc. 6th Int. Conf. on Nuclear Physics at Storage Rings (STORI’05), Bonn. ; , s. 153-
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Conference paper (peer-reviewed)
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| 12. |
- Petrén, Henrik, et al.
(author)
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eta-meson production in proton-proton collisions at excess energies of 40 and 72 MeV
- 2010
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 82:5, s. 055206-
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Journal article (peer-reviewed)abstract
- The production of eta mesons in proton-proton collisions has been studied using the WASA detector at the CELSIUS storage ring at excess energies of Q = 40 MeV and Q = 72 MeV. The eta was detected through its 2 gamma decay in a near-4 pi electromagnetic calorimeter, whereas the protons were measured by a combination of straw chambers and plastic scintillator planes in the forward hemisphere. About 6.9 x 10(4) and 9.3 x 10(4) events were found at Q = 40 MeV and Q = 72 MeV, respectively, with background contributions of less than 5%. A simple parametrization of the production cross section in terms of low partial waves was used to evaluate the acceptance corrections. Strong evidence was found for the influence of higher partial waves. The Dalitz plots show the presence of p waves in both the pp and the eta {pp} systems and the angular distributions of the eta in the center-of-mass frame suggest the influence of d-wave eta mesons.
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| 13. |
- Schonning, K., et al.
(author)
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The pd -> He-3 eta pi(0) reaction at T-p=1450 MeV CELSIUS/WASA Collaboration
- 2010
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In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 685:1, s. 33-37
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Journal article (peer-reviewed)abstract
- The cross section for the pd -> He-3 eta pi(0) reaction has been measured at a beam energy of 1450 MeV using the WASA detector at the CELSIUS storage ring. The He-3 was detected in coincidence with four photons from the decays of the two mesons. The data indicate that the production mechanism involves the formation of the Delta(1232) isobar. Although the beam energy does not allow the full peak of this resonance to be seen, the invariant mass distributions Of all three pairs of final particles are well reproduced by a phase space Monte Carlo simulation weighted with the p-wave factor of the square of the pi(0) momentum in the He-3 pi(0) system.
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| 14. |
- Schönning, Karin, et al.
(author)
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The pd →3Heηπ0 reaction at Tp = 1450 MeV
- 2010
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In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 685:1, s. 33-37
-
Journal article (peer-reviewed)abstract
- The cross section for the pd→3Heηπ0 reaction has been measured at a beam energy of 1450 MeV using the WASA detector at the CELSIUS storage ring and detecting one 3He and four photons from the decays of the two mesons. The data indicate that the production mechanism involves the formation of the Δ(1232) isobar. Although the beam energy does not allow the full peak of this resonance to be seen, the invariant masses of all three pairs of final particles are well reproduce dby a phase space Monte Carlo simulation weighted with the p-wave factor of the square of the π0 momentum in the 3He π0 system.
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| 15. |
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| 16. |
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| 17. |
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| 18. |
- Bargholtz, Chr., et al.
(author)
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Properties of the WASA pellet target and a stored intermediate-energy beam
- 2007
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In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 587:2-3, s. 178-187
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Journal article (peer-reviewed)abstract
- Experimental data from the reaction close to threshold have been used to investigate time-dependent properties of the WASA pellet target and the stored beam of 892.8 MeV protons in the CELSIUS accelerator. The detection of 3He ions in solid-state detectors provides an excellent almost background free trigger for η production. Pellet interactions with the surrounding material and with the beam lead to evaporation of deuterium gas into the beam pipe. Approximately 30% of the registered η decay events are due to interactions in deuterium gas outside the pellets. Due to beam–target interaction the beam is transversely heated and appears to acquire a component of a slightly lower energy.
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| 19. |
- Bargholtz, Chr, et al.
(author)
-
Tagging of η mesons using the pd → 3Heη reaction near threshold
- 2006
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In: Instruments and experimental techniques (New York). - : Springer. - 0020-4412 .- 1608-3180. ; 49:4, s. 461-467
-
Journal article (peer-reviewed)abstract
- A zero-degree spectrometer for tagging η mesons on the CELSIUS/WASA facility is described, and its characteristics are presented. Tagging of η mesons is performed by detecting 3He ions produced by reaction pd → 3Heη close to the production threshold. The low background level (<2%) is in good agreement with the data obtained earlier on the SATURNE accelerator.
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| 20. |
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