Browsing by Author "Ernst J."

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    A precision determination of the mass of the η meson
    (2005-07-21) Abdel-Bary M.; Budzanowski A.; Chatterjee A.; Ernst J.; Hawranek P.; Jahn R.; Jha V.; Kilian K.; Kliczewski S.; Kirillov D.; Kolev D.; Kravcikova M.; Kutsarova T.; Lesiak M.; Lieb J.; Machner H.; Magiera A.; Maier R.; Martinska G.; Nedev S.; Piskunov N.; Prasuhn D.; Protić D.; Von Rossen P.; Roy B.J.; Sitnik I.; Siudak R.; Smiechowicz M.; Stein H.J.; Tsenov R.; Ulicny M.; Urban J.; Vankova G.; Wilkin C.
    Several processes of meson production in proton-deuteron collisions have been measured simultaneously using a calibrated magnetic spectrograph. Among these processes, the η meson is seen clearly as a sharp missing-mass peak on a slowly varying background in the p+d→He3+X reaction. Knowing the kinematics of the other reactions with well determined masses, it is possible to deduce a precise mass for the η meson. The final result, m(η)=547.311±0.028(stat)±0.032(syst)MeV/c2, is significantly lower than that found by the recent NA48 measurement, though it is consistent with values obtained in earlier counter experiments. © 2005 Elsevier B.V. All rights reserved.
  • No Thumbnail Available
    Item
    Detailed comparison of the pp → π+ pn and pp → π+d reactions at 951 MeV
    (2005-03-17) Abdel-Bary M.; Budzanowski A.; Chatterjee A.; Ernst J.; Hawranek P.; Hinterberger F.; Jha V.; Kilian K.; Kliczewski S.; Kirillov D.; Kolev D.; Kravcikova M.; Kutsarova T.; Lesiak M.; Lieb J.; Machner H.; Magiera A.; Maier R.; Martinska G.; Nedev S.; Niskanen J.; Piskunov N.; Prasuhn D.; Protić D.; Von Rossen P.; Roy B.J.; Sitnik I.; Siudak R.; Smiechowicz M.; Tsenov R.; Ulicny M.; Urban J.; Vankova G.; Wilkin C.
    The positively charged pions produced in proton-proton collisions at a beam momentum of 1640 MeV/c were measured in the forward direction with a high resolution magnetic spectrograph. The missing mass distribution shows the bound state (deuteron) clearly separated from the pn continuum. Despite the very good resolution, there is no evidence for any significant production of the pn system in the spin-singlet state. However, the σ(pp→π+pn)/ σ(pp→π+d) cross section ratio is about twice as large as that predicted from S-wave final-state-interaction theory and it is suggested that this is due to D-state effects in the pn system. © 2005 Published by Elsevier B.V.