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unpublished). The accuracy of the coding of the amplitudes and the relevant kinematics into the fitting program was checked in a variety of ways. The isobar-model amplitudes were calculated for a set: of standard events and compared with the amplitudes calculated by other programs independently coded at Lawrenco Berkeley Laboratory, Berkeley; SLAC, Stanford; and CEN, Saelay. In addition, Monte Carlo events were used to generate a variety of mass and angular distributions fom: each wave of Table 111, and these were checked to be physically consistent with the quantum numbers. The polarization calculations were checked explicitly by hand for several events.article Data Group, 9ev. Mod. Phys. 43, S l (1971).'O~he following masses were used to calculate the mixing angle: nzN =I515 515, mx=1670 k10, mA =1690*10, mx=1832-t37, and mA=1518 *2 MeV. "R. Barloutaud (private communication).2 2~h e analysis of Ref. 5 uses an expression for this ratio which yields 3.3. We believe that the expression incorrectly normalizes the Breit-Wigner weight used to calculate an average 8(1385) momentum over the Dalitz plot. Tka normalization of this weight should be independent of the incident momentum. Zf this change i s made, their expression yields a result consistent with ours.

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The total cross sections of n* on protons in the momentum interval from 0.40 to 0.90 GeV/c have been measured with high relative precision. In this interval the statistical error varies between 1 0 and 20 pb. No new structure is observed.A number of investigations of n'p and n-i, total c r o s s sections have been made over the past seve r a l years which include the range of incident momenta measured in the present e~p e r i m e n t . ' -~ Recent experiments5" with improved statistical accuracy in the region of incident momentum from 0.4 to 0.9 GeV/c have revealed no new structure although knowledge of the heights, widths, and positions of established structure has been gradually refined. The present experiment, a subsidiary experiment to one previously r e p~r t e d ,~ was designed to cover this momentum interval with higher precision than previously obtained in order to search for possible structure and to provide data with the high relative precision necessary for an adequate check of theoretical models formulated for this region.The experiment was performed at the Lawrence Berkeley Laboratory using a secondary pion beam of the Bevatron. Incident beam pions were s elected by a counter telescope n, consisting of four scintillation counters (S,, S,, G, and S,), a Plexiglas Cerenkov counter (C,), and a high-pressure gas Cerenkov counter (C,) a s shown in Fig. 1. The 32.1 -ft flight path between S,, S,, both located downstream from C,, and S,, located at the ups t r e a m end of the hydrogen target, was used to reject protons and kaons by time-of-flight differences. C, was operated a s a threshold detector to provide further rejection of protons and kaons in the incident beam. Electrons and positrons accompanying beam pions were rejected by a factor of 50: 1 by the high-pressure Cerenkov counter C, which was operated at 65 psia of carbon dioxide. Correction for muon contamination and determination of thresholds for pions and muons was obtained from curves of counting rate versus p r e ss u r e for C, made during the tuning phase of the experiment.The beam momentum was determined by measuring the difference in time of flight for pions and protons along the 32.1-ft flight path corrected for the momentum loss of pions and protons in the remainder of the incident beam path. The e r r o r in such measurements was estimated to be *0.5%.The liquid-hydrogen target flask was 6 in. in diameter and 12 in. in length with convex Mylar end caps. Its effective length was determined by measuring the profile of these caps at liquid-nitrogen temperature and averaging its length over the measured spatial distribution of the incident pion beam. The target flask and an identical but evacuated flask could be remotely positioned on the beam axis by means of a pneumatic device in order to provide a periodic check of background during the experimental runs.The transmission counters T I , . . . , T, were placed on a movable stand downstream from the liquid-hydrogen target. These counters were used to measure the flux transmitted through t...