Reaction π−p→ ηn in the 15 to 40 GeV/ c momentum range

• Published in: Nuclear physics. B 1979-05, Vol.152 (1), p.1-26
• Main Authors: Apel, W.D., Augenstein, K.H., Bertolucci, E., Bushnin, Yu.B., Donskov, S.V., Franceschini, R., Givoletti, M., Grachev, M.I., Inyakin, A.V., Johnson, R., Kachanov, V.A., Kittenberger, W., Krasnokutsk, R.N., Krüger, M., Leder, G., Lednev, A.A., Mannelli, I., Mikhailov, Yu.V., Müller, H., Oberparleiter, R., Pernicka, M., Pierazzini, G.M., Prokoshkin, Yu.D., Quaglia, M., Schinzel, D., Schneider, H., Scribano, A., Sergiampietri, F., Shuvalov, R.S., Sigurdsson, G., Staudenmaier, H.M., Steuer, M., Thys, A., Toropin, A.N., Vincelli, M.L.
• Format: Article
• Language: English
• ISSN: 0550-3213; 1873-1562
• DOI: 10.1016/0550-3213(79)90075-0

A high-statistics measurement of the reaction π −p→ ηn; η→2 γ has been performed at the 70 GeV Serpukhov accelerator for 15, 20, 25, 30 and 40 GeV/ c incident pion momentum using the NICE set-up with its associated 648-channel hodoscope spectrometer for γ-ray detection. It is found that the spin-flip and non-spin-flip amplitudes can be parametrized, for small | t|, as exponentials with the same slopes to within a few percent. For | t| ≳ 1 (GeV/ c) 2 there is a break in the differential cross section. In addition, the A 2 effective trajectory deviates markedly for | t| ≳ 1 GeV/ c) 2 from the linear behaviour valid for smaller | t|.