Our previous results on the production of "giant dipole" resonance in nuclear emulsion are confirmed by an independent technique. Arguments used by Shivpuri et al. with their meager statistics at low energy, as compared with ours, do not refute our final results.Ever since we performed our first experiment' on high-energy muon-nucleon interaction in nuclear emulsion, we have been able to use the muon beam in a variety of different experimentsZ-' in our laboratory and to compare them with other experimental work on electromagnetic and hadronic interactions. The muon's heavier mass makes the energy loss by radiation negligible, and in the experiments where photons or electrons a r e generally used, one could use the muon beam perhaps more profitably. For the study of the giant-dipole resonance (GDR) in a nucleus, i t has been a common practice to use bremsstrahlung spectra at low energy. Experiments studying nuclear radiation generally require resolution of the order of 1 MeV, and among the many detectors nuclear emulsion would be better for higher-resolution work. Thus, for the primary beam we used muons and for the detector we used a nuclear emulsion for studying the giant-dipole resonance (GDR) in the heavy and the light nuclei of the emulsion a t high momenta of 10.1-GeV/c positive and 15.8-GeV/c negative muons, which had not been studied previously. Here the main objective was to s e e if the emulsion technique at high energies with the muon beam would give any reasonable answer for heavy and light elements; if it did, one could study the giant-dipole resonance in different elements which could be impregnated into the nuclear emulsion. This practice of impregnation of different elements in nuclear emulsion has been very fruitful during the past 10-15 years in the studies of hypernuclear physics. The details of our experiment were given in our preliminary r e p~r t ,~ where we emphasized that one has to be very careful to avoid personal biases in the selection of events of type (1 + 1) with "clear vertices." We shall not accept an event a s having a clear vertex if i t has (i) any Auger electron, (ii) any heavy blob or stem, or (iii) even a single extra grain attached at the vertex which can be taken very easily by mistake a s a background grain (in which case the event would be assumed to have a clear vertex). Regarding the identity of the secondary particles produced a t the vertex, we may point out that only the thickness of the track was used in separating the tracks from different Z (charge) values; however, for tracks belonging to the same Z values, i.e., Z = 1 (p, d, and t ) , i t was mentioned earlierg that we used the well-known "constant sagitta" method.'' The percentages of different particles produced by these two methods were mentioned p r e v i o~s l y .~Recently some objections1' have been raised to our experimental results in nuclear emulsion. As stated p r e v i o~s l y ,~ the emulsion i s composed of heavy elements (Ag and B r ) and light elements (C, N, and 0) with about 82% of the nucleons i...
