Z. Phys. A - Atoms and Nuclei 305, 319-323 (1982) Zeitschrift Atoms fQr Physik A and Nuclei 9 Springer-Verlag 1982 Resonance Strengths of Some Light Nuclei* H.W. Becker**, W.E. Kieser***, C. Rolfs, H.P. Trautvetter, and M. Wiescher**** Institut fiir Kernphysik der Universit~it, Miinster, Federal Republic of Germany Received February 19, 1982 The strengths of the E~.m.=324 and 829 keV resonances in i9F(p, 0~7)160 have been determined relative to the Rutherford elastic scattering cross section. With these values as standards, the strengths of the E .... =259, 143 (also 1,106) and 1,259 keV resonances in l~N(p, 7)150, ~80(p, 7)19F and 14N(e, 7)18F were measured, respectively. In addition, the cross section of the direct capture process in z60(p, 7)t7F at E .... =853 keV has been obtained. All measurements were carried out by interchanging the role of pro- jectiles and target nuclei, i.e. 14N, 160, 180 and 19F ion beams of appropriate energies were guided into windowless gas target systems filled with hydrogen or helium gas. The results are compared with previous work. E Nuclear Reactions: IH(19F,~7)160, E=6.42 and 16.44 MeV, measured coy; 1H(180, 7)19F, E=2.70 and 20.88 MeV, measured 097; 1H(14N, 7)150, E=3.86 MeV, measured coy; 4He(14N, 7)18F, E=5.62 MeV, measured o~7; 1H(160, 7)17F, E= 14.40 MeV, measured a. Gas targets of the extended and jet type. Ge(Li) detectors. 1. Introduction The absolute strengths of proton- and helium- in- duced resonances in light nuclei provide detailed nuclear structure information [1]. These strengths are also of importance for the quantitative analyses of trace elements and their isotopes in matter [2, 3] as well as for the field of nuclear astrophysics [4]. The determination of absolute resonance strengths requires a precise knowledge of target stoichiometry, target thickness, absolute detection efficiency and absolute beam current integration [1]. In order to avoid in part some of these requirements, the strengths of resonances for a given reaction of in- terest were determined often relative to the reso- nance strengths of recommended standard reactions * Supported by the Deutsche Forschungsgemeinschaft(Ro 429/13) ** Supported by the Minister fOr Wissenschaftund Forschung des Landes Nordrhein-Westfalen *** Present address: Universityof Toronto, Toronto, Canada **** Present address: Ohio State University,Columbus,USA [5]. Some of these standards have been redeter- mined in recent years and discrepancies by a factor of two and more have been noted [5-12]. These discrepancies can be caused in part by the assumed target stoichiometries, which could be different from the stoichiometry of the original target material. This situation is emanent in particular for the exam- ples of nitrogen, oxygen and fluorine nuclei, which require usually a target material of chemical com- position for the production of solid state targets. The present work reports a new method in the measurement of resonance strengths for such target nuclei involving windowless gas target systems and heavy ion beams. The strong resonances in the 19F(p, 7~)160 reaction at E .... =324 and 829 keV [12] are often used for the energy calibration of accelerators [13, 14] as well as for the determination of the content and the distribution of I9F and 1H traces in material [2]. If the strengths of these resonances were better known 0340-2193/82/0305/0319/$01.00