No pre-critical enhancement observed in 13C(π+, γ)13N(g.s.) at q ≅ 2mπ期刊界 All Journals 搜尽天下杂志传播学术成果专业期刊搜索期刊信息化学术搜索

No pre-critical enhancement observed in ¹³C(π⁺, γ)¹³N(g.s.) at q ≅ 2m_π

Authors:	C.J. Martoff L. Van Elmbt M. Lebrun M. Schaad U. Straumann P. Truöl K.M. Crowe C. Joseph J.P. Perroud D. Ruegger M.T. Tran J. Deutsch G. Grégoire R. Prieels W. Dahme

Affiliation:	Physik-Institut der Universität Zürich, Switzerland;University of California, Berkeley, California, USA;Institut de Physique Nucléaire, Université de Lausanne, Switzerland;Institut de Physique Corpusculaire, Université Catholique de Louvain, Louvain-la-Neuve, Belgium;Sektion Physik, Universität München, Garching, West Germany

Abstract:	The cross section and angular distribution for the reaction ¹³C(π⁺, γ)¹³N(g.s.) have been measured from 37 to 85° in the laboratory, at a pion energy of 115.5 MeV. The observed cross section ranges from 320 to 660 $nb sr$ . These results do not show the large magnitude and wide-angle peaking expected if pre-critical effects due to nascent pion condensation were present. In addition, the observed cross section is less than one-half of the predictions of available theoretical calculations which do not include the pre-critical effect. Data on the reaction ¹H(π^?, γ)n at T_π = 116.6 MeV were also obtained for calibration purposes. These data agree with expectations based on knowledge of the inverse reaction and previous measurements.

Keywords:	Nuclear reactions
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