de Boer and van Dantzig Reply: Emulsion data reported by El-Nadi and Badawy l for e + e ~ pairs from relativistic heavy-ion reactions show 2 an indication for three phenomena, consistent with production and decay of light neutral bosons. These recent observations are remarkably similar to 35-year-old emulsion data from Anand 3 obtained by exposure to cosmic rays. In his Comment, Perkins 4 objects to our interpretation of the close e + e~ pairs in both data sets, arguing that the observed numbers of such events are compatible with those expected for the Dalitz process /r°->e + e~y. In our considerations, we apply for both data sets independent criteria: the distribution in vertex distance L, in energy partition y, and in opening angle co.First, the comparison of the L distribution for close pairs with the smoothed distribution for twiceminimum-ionizing single (proton) tracks coming directly from the vertex has led Anand to conclude that these did not emerge from the collision point, with a % 2 probability of less than 0.1%. This amounts to a 3.3 6°. From the Dalitz branching ratio (0.012) for Anand's 7000 produced ;r 0, s, we expect -84 Dalitz pairs. Correction for geometric efficiency leads to -55 events spread over all angles, of which -14 (25%) would have co<6°, leaving -48 unex-

Two dedicated experiments on internal pair conversion (IPC) of isoscalar M1 transitions were carried out in order to test a 9 MeV/c 2 X-boson scenario. In the 7 Li(p, e + e − ) 8 Be reaction at 1.1 MeV proton energy to the predominantly T=0 level at 18.15 MeV, a significant deviation from IPC was observed at large pair correlation angles. In the 11 B(d, ne + e − ) 12 C reaction at 1.6 MeV, leading to the 12.71 MeV 1 + level with pure T=0 character, an anomaly was observed at 9 MeV/c 2 . The compatibility of the results with the scenario is discussed.

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Data on internal pair conversion in widely different nuclear transitions with energies above 12 MeV have an apparent excess in pairs around 9 MeV/ invariant mass. While the deviations individually may be circumstantial, in combination they appear to point to an overall anomaly.

The level structure of 87y has been studied using in-beam v-ray spectroscopic methods. Many previously unknown states have been observed. Members of the rc(gg/2)v(g9/2) -2 multiplet are identified. The results are discussed in terms of the weak-coupling model.

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In a systematic study of nucleon transfer reactions accompanied by Coulomb excitation we have bombarded 152Sm, 16~ and 232Th with 206,208pb beams at incident energies close to the Coulomb barrier. Particle-gamma coincidence techniques were used to identify excited states of reaction products populated through inelastic scattering and in nucleon transfer reactions. One-neutron stripping and pick-up reactions on 152Sm were observed leading to known states of the rotation aligned il 3/2-bands in 1538m and 15 l Sm" In the 16~ + 2o6,208pb systems no significant population of low lying states of product nuclei was found in the nucleon-transfer channels. Large cross sections were observed for one-and two-neutron pick-up from 232Th at an incident energy of 6.4 MeV/u. Around the grazing angle they are of the same order of magnitude as the cross section measured for inelastic scattering. The results are analyzed in the framework of semiclassical models. PACS: 25.70