Energy spectra and angular distributions have been measured for high energy gamma rays (E~& 20 MeV) from proton-nucleus reactions at 104, 145, and 195 MeV on targets of C, Zn, and Pb. Gamma rays were observed with energies up to 170 MeV. The spectra sho~ed difFerences from the typical exponential shape that is observed in gamma ray production from heavy-ion reactions. The angular distribution of the gamma ray is forward peaked in the laboratory, which is consistent with emission from a moving source. A comparison is made with previous measurements at 72, 140, 168, and 200 MeV. The experimental evidence indicates that first-chance incoherent proton-neutron bremsstrahlung is the main production mechanism.PACS number(s): 25.40. -h

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Using the ISOLDE on-line isotope separator at CERN to produce sources of 221 Fr, 221 Ra, 222 Ra, 223 Ra, and 224 Ra, and using polycarbonate track-recording films sensitive to energetic carbon nuclei but not to alpha particles, we have discovered two new cases of the rare 14 C decay mode-in 222 Ra and 224 Ra. Our results for branching ratios, B, relative to alpha decay are for 221 Fr and 221 Ra, £<4.4xl0-12 ; for 222 Ra, B = (3,7 ±0.6) x 10" 10 ; for 223 Ra, B= (6.1 ± 1.0) x 10" 10 ; for 224 Ra, £=(4.3 ±1.2)xl0-n .

Energy and angular distributions were measured for high-energy (E y > 10 MeV) gamma rays from collisions of 14 N on Pb, Zn, and C at beam energies of El A = 20, 30, and 40 MeV. The gamma-ray energy spectrum was measured to about 120 MeV at El A =40 MeV and to about 80 MeV at El A = 20 MeV. For E y > 20 MeV the spectra are roughly exponential with characteristic slope parameters ranging from 10.0 MeV for 14 N + Pb at El A = 20 MeV to 14.2 MeV at El A = 40 MeV. Reasonable agreement is obtained with a model employing bremsstrahlung from individual neutron-proton collisions in the heavy-ion collision.