The results of this experiment suggest that the previously observed elastic scattering anomalies were due to the same deficiency in the procedure of the previous experiment. Unfortunately, the variation of the cross section with energy was sufficiently complicated to prevent the unambiguous determination of . The momentum of a particle following a circular path in the presence of a magnetic field is proportional to the product of the magnetic induction and the orbital radius.
The energy of the scattered particles can be calculated from the kinematics of the reaction. Then, by assuming that V at the. m center of the profile rise corresponds to the energy of particles scattered from the surface layer of' the target, Eq. 2) can be solved for k • The value of k determined from many measurements is. To relate the observed number of scattered particles and the differential scattering cross section, it is necessary to know the acceptance angle of the spectrometer.
The maximum electric field present in the depletion region is of the order of 10 volts/em. This produces a current across the junction and results in a negative voltage pulse whose height is proportional to the energy of the incident particle.
EXPERIMENTAL PROCEDURE
The direction of the incoming and outgoing particles with respect to the target normal is specified by e1 and 8. The energy spread of the particles which pass by the magnetic spectrometer is related to its resolution at. The target is placed in the target chamber by attaching the holder to the end of a rcxl which is coaxial with the center axis of the target chamber.
The background yield indicates that the ratio of the number of beryllium at The error analysis based on the quantities shown above is complicated by the possibility of a systematic error in the angular settings of the magnetic spectrometer. A value of zero for the total reaction cross-section is also an unsatisfactory result of the hard-sphere model. This is especially unrealistic in the case of Be9 + d because studies of the possible reactions indicate that a significant total reaction cross section exists. Then we relate these amplitudes to the logarithmic derivative of the wave function at the spherical surface. Furthermore, a target of said thickness would make it very difficult to determine accurate values for the energies of the deuterons when they actually experienced scattering. Judging by version c12. d,d)c12 cross section with energy, it seems unlikely that the anomaly at 1.16 Mev could also be attributed to scattering on the carbon contaminant layer. It is possible that the scattering cross section is indeed smaller than the Rutherford low. of energy due to absorption or some obscure et:fect characteristic of the structure: the deuteron. A second possible explanation of the observed sub-Rutherford cross section is that the cross section really has the Rutherford. In view of the great care Phillips took in his experiment:~ this is not considered likely. Another possibility is that some contaminant, say oxygen:~ in the surface layers of the target has increased the effective atomic stopping cross section from the pure beryllium value. This means that the thickness of the camtaminated area represents a significant proportion of the total thickness of the target layer. Although this reasoning seems to explain the sub-Rutherford scattering behavior of Li 7 (d;,d)L17;, the amount of contaminants present in it. Ford(l) measured the scattering cross section for Cu(d,d)Cu at incident energies such that the scattered deuteron energies were comparable to the lowest scattered deuteron energies in this experiment. T'nis measurement was made with the same equipment used in this experiment and the cross section was found to be within three percent of the Rutherford value. This seems to rule out gross instrumental effects and ::momalous effects due to the structure of the deuteron as possible causes of the sub-RuthP.rford cross section. After investigating possible causes ~or the observed values below Rutherford of the cross section at l~r energies, the most reasonable explanation seems to be that the true cross section is below Rutherford. An estimate of the probability of deuteron re-emission can be made by assuming that the probability of decay of a channel c is proportional to k r c c P~(k k c c r ) where k , r , and. The consequence of a small probability of emission of a deuteron during the decay of the compound nucleus is a small value of the ratio of the deuteron emission width to the total decay width, r d/r. But the small size of this anaDal, that it is present, can hardly be considered as proof of the existence of a condition in B11. Furthermore, if we get analyzable results, the zero spin of the alpha particle will greatly simplify the interpretation of the experimental data. The three horizontal lines indicate the experimental value or cross-section and the limits that lie three percent above and below it, respectively. The three horizontal lines indicate the value of the experimental cross section and the limits that lie three percent above and below it, respectively. The effect on da/daR is produced by changing the amplitude and phase 7.
DISCUSSION OF RESULTS
SUMMARY
APPENDIX I
