The polarization of protons emitted at six angles from the C12(d,p)C13 and Ca40(d,p)Ca41 ground state reactions has been measured. For the C12 reaction, the data at small angles are very close to the results of previous works, and in agreement with thesemiclassical sign rule jn=ln±1/2,P=(±). The value at θ= 115° has not been mea-sured before, we obtained P = 0.529± 0.068 at this angle. For the Ca40 reaction, the sign of polarization which we found in the region of small angles is also in agreement with the semiclassical sign rule, and is the same as those found in the work of Nemetz and of Boschitz, but is opposite to those obtained by Takeda and Bercaw. This difference may be due to the difference in the deuteron energy used, since in these experiments, the three with higher deuteron energies all gave the same positive sign of polarization while the three with lower deuteron energies all gave the same negative sign. After a survey of the polarization data now available we found that the semiclassical sign rule is still true to a certain degree, and that it may be possible to find out a modified sign rule for the use in the nuclear spectroscopy. In some cases, we found that the pattern of the polarization angular distribution is shifted towards small angles as the deuteron energy is increased, and this may be a characteristic of direct reactions. For the correspondence between the cross-section angular distribution and polarization angular distribution, we found that the position of a minimum in the cross-section curve may correspond to the position of a change in sign or of a maximum absolute value in the polarization curve, and that the position of a maximum in the cross-section curve may also correspond to the position of a change in sign in the polarization curve. We discuss these phenomena by using the distored wave theory.
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