PHOTONEUTRON CROSS SECTIONS FOR V$sup 51$ AND Co$sup 5$$sup 9$

The ( gamma ,n) and ( gamma ,2n) cross sections for Co/sup 60/ and V/sup 51/ have been measured, using nearly monochromatic photons obtained from the annihilation in flight of fast positrons. The integrated cross sections up to 28 Mev for sigma ( gamma ,n) and sigma ( gamma ,2n), respectively, are 0.447 plus or minus 0.044 and 0.139 plus or minus 0.014 Mev-b for Co, and 0.451 plus or minus 0.045 and 0.106 plus or minus 0.01l Mev-b for V. The minus-second cross sections ( sigma /sup -2/) are 1.82 and 1.56 mb/Mev, respectively, for these elements. the level density parameters a were determined to be 5.49 and 6.18 Mev- 1, respectively. The quadrupole moments determined from the compound-nucleus formation cross sections, sigma ( gamma ,n) + sigma ( gamma ,2n) + sigma ( gamma ,np), were found to be 0.94 plus or minus 0.13 and 0.66 plus or minus 0.09 b, respectively, for Co and V. (auth)