RESUMO
The mass of one of the three major waiting points in the astrophysical rp process 72Kr was measured for the first time with the Penning trap mass spectrometer ISOLTRAP. The measurement yielded a relative mass uncertainty of deltam/m=1.2x10(-7) (deltam=8 keV). (73,74)Kr, also needed for astrophysical calculations, were measured with more than 1 order of magnitude improved accuracy. We use the ISOLTRAP masses of 72-74Kr to reanalyze the role of 72Kr (T(1/2)=17.2 s) in the rp process during x-ray bursts and conclude that 72Kr is a strong waiting point delaying the burst duration with at least 80% of its beta-decay half-life.
RESUMO
Masses of the short-lived radionuclides 32Ar (T(1/2)=98 ms) and 33Ar (T(1/2)=173 ms) have been determined with the Penning trap mass spectrometer ISOLTRAP. Relative uncertainties of 6.0x10(-8) (deltam=1.8 keV) and 1.4x10(-8) (deltam=0.44 keV), respectively, have been achieved. At present, these new mass data serve as the most stringent test of the quadratic form of the isobaric-multiplet mass equation. Furthermore, the improved accuracy for the mass of 32Ar will allow for a better constraint on scalar contributions to the weak interaction. New mass values have also been measured for 44Ar and 45Ar, and a 20sigma deviation for 44Ar from the literature value was found and interpreted.
RESUMO
Radiative capture of protons is investigated as a probe of clustering in nuclei far from stability. The first such measurement on a halo nucleus is reported here for the reaction 6He(p,gamma) at 40 MeV. Capture into 7Li is observed as the strongest channel. In addition, events have been recorded that may be described by quasifree capture on a halo neutron, the alpha core, and 5He. The possibility of describing such events by capture into the continuum of 7Li is also discussed.