/sup 52/Cr(p,n)/sup 52/Mn/sup g//sup ,//sup m/ and /sup 52/Cr(d,2n)/sup 52/Mn/sup g//sup ,//sup m/ excitation functions

We have irradiated natural chromium with protons and deuterons to produce /sup 52/Mn/sup g//sup ,//sup m/, primarily from the /sup 52/Cr(p,n) and /sup 52/Cr(d,2n) reactions. The excitation functions up to 27 MeV were measured by the foil activation method and were compared with results from a statistical model calculation based on the Hauser-Feshbach formalism with preequilibrium emission. For /sup 52/Cr(p,n)/sup 52/Mn/sup g//sup ,//sup m/, both the total cross section, σ(g+m), and the isomer ratio, σ(m)/σ(g), are reproduced to within 10% by the calculations. By contrast, for the /sup 52/Cr(d,2n)/sup 52/Mn/sup g//sup ,//sup m/ reaction, we find that calculations overestimate σ(g+m) by ∼50% and underestimate σ(m)/σ(g) by nearly one-half. We find that arbitrary adjustments of level density or preequilibrium parameters can yield approximate agreement for σ(g+m) but do not improve the agreement for σ(m)/σ(g). A part of this discrepancy may be due to the fact that the preequilibrium calculations do not include angular momentum. However, to fully understand this discrepancy, deuteron breakup effects in the entrance channel must be taken into account. A companion paper explores this idea