Contributions to the study of the reaction pd→tπ+
Description
We have measured the excitation function of the analysing power T20 and of the cross section, at 0 deg and 180 deg, from threshold to 2.2 GeV for the antidp→3Heπ0 reaction. We have also measured the angular distributions of the analysing power Ay for the antipd→tπ+ reaction, at 1.2, 1.3 and 1.45 GeV. Having measured T20 and the cross section at 0 deg, we have extracted the experimental values of the two independent amplitudes for (polarized)d.p→3Heπ0 in colinear kinematics. At threshold, the value of T20 is near the absolute minimum, showing that the pion at rest is absorbed on an S=1 pair of nucleons in 3He. We have analysed our data with microscopic calculations in terms of two-body and three-body mechanisms. At 0 deg, only two-body mechanisms are important. At 180 deg, even in the resonance (3.3) excitation region, three-body mechanisms are necessary and become dominant around Td = 2 GeV. Nevertheless, the analysing power is not reproduced by calculations including all these mechanisms. It seems that the spin-flip amplitude is never well described
Abstract (French)
Nous avons mesure, depuis le seuil jusqu'a 2,2 GeV, la fonction d'excitation du pouvoir d'analyse T20 et de la section efficace a 0 deg et 180 deg, de la reaction antidp→3Heπ0. Nous avons egalement mesure les distributions angulaires du pouvoir d'analyse Ay de la reaction antipd→tπ+ a 1,2; 1,3 et 1,45 GeV. La mesure de T20 et de la section efficace pour la reaction d polarise →3Heπ0, ayant ete realisee a 0 deg, il a ete possible d'extraire les valeurs experimentales des modules des deux amplitudes independantes qui decrivent cette reaction en cinematique colineaire. Au seuil, la valeur mesuree de T20, proche du minimum absolu, a permis de montrer que l'absorption du pion par l'3He se fait de facon predominante sur une paire de nucleons dans l'etat S=1 (deuton). Nous avons analyse nos donnees a l'aide de calculs microscopiques prenant en compte les diagrammes ou deux nucleons participent a l'interaction, le troisieme restant spectateur, et ceux ou les trois nucleons interagissent effectivement. A 0 deg, seuls les graphes a deux nucleons sont importants. A 180 deg, meme dans la region de la resonance (3,3) (Td=1 GeV), les graphes a trois nucleons sont importants. Ils deviennent dominants vers 2 GeV, permettant d'expliquer la seconde bosse dans la section efficace. Cependant le pouvoir d'analyse n'est pas correctement reproduit par le calcul. Il semble que cela soit du, pour une bonne part, a l'incapacite de decrire correctement l'amplitude, dite de ''spin-flip''Files
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Additional details
Additional titles
- Original title (French)
- Contribution a l'etude de la reaction p+d→t+π
Publishing Information
- Imprint Pagination
- 174 p.
- Report number
- CEA-N--2539
INIS
- Country of Publication
- France
- Country of Input or Organization
- France
- INIS RN
- 19043822
- Subject category
- S73: NUCLEAR PHYSICS AND RADIATION PHYSICS;
- Resource subtype / Literary indicator
- Thesis
- Descriptors DEI
- ANGULAR DISTRIBUTION; CROSS SECTIONS; DEUTERIUM TARGET; DEUTERON REACTIONS; EXCITATION FUNCTIONS; GEV RANGE 01-10; HYDROGEN 1 TARGET; MEV RANGE 100-1000; N*BARYONS; PARTICLE PRODUCTION; PIONS; POLARIZATION-ASYMMETRY RATIO; POLARIZED BEAMS; PROTON REACTIONS
- Descriptors DEC
- BARYON REACTIONS; BARYONS; BEAMS; BOSONS; DISTRIBUTION; ELEMENTARY PARTICLES; ENERGY RANGE; FERMIONS; GEV RANGE; HADRON REACTIONS; HADRONS; MESONS; MEV RANGE; NUCLEAR REACTIONS; NUCLEON REACTIONS; PSEUDOSCALAR MESONS; TARGETS