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For the time period from 1.5 to 4 Myr before the present we found in deep ocean ferromanganese crusts a ^{53}Mn excess concentration in terms of ^{53}Mn/Mn of about 4×10^{-14} over that expected for cosmogenic production. We conclude that this ^{53}Mn is of supernova origin because it is detected in the same time window, about 2.5 Myr ago, where ^{60}Fe has been found earlier. This overabundance confirms the supernova origin of that ^{60}Fe. For the first time, supernova-formed ^{53}Mn has been detected and it is the second positively identified radioisotope from the same supernova. The ratio ^{53}Mn/^{60}Fe of about 14 is consistent with that expected for a SN with a 11-25 M_{⊙} progenitor mass and solar metallicity.

For the time period from 1.5 to 4 Myr before the present we found in deep ocean ferromanganese crusts a ^{53}Mn excess concentration in terms of ^{53}Mn/Mn of about 4×10^{-14} over that expected for cosmogenic production. We conclude that this ^{53}Mn is of supernova origin because it is detected in the same time window, about 2.5 Myr ago, where ^{60}Fe has been found earlier. This overabundance confirms the supernova origin of that ^{60}Fe. For the first time, supernova-formed ^{53}Mn has been detected and it is the second positively identified radioisotope from the same supernova. The ratio ^{53}Mn/^{60}Fe of about 14 is consistent with that expected for a SN with a 11-25 M_{⊙} progenitor mass and solar metallicity.

The $^{58}\mathrm{Ni}(n,\ensuremath{\gamma})^{59}\mathrm{Ni}$ cross section was measured with a combination of the activation technique and accelerator mass spectrometry (AMS). The neutron activations were performed at the Karlsruhe 3.7 MV Van de Graaff accelerator using the quasistellar neutron spectrum at $kT=25$ keV produced by the $^{7}\mathrm{Li}(p,n)^{7}\mathrm{Be}$ reaction. The subsequent AMS measurements were carried out at the 14 MV tandem accelerator of the Maier-Leibnitz Laboratory in Garching using the gas-filled analyzing magnet system (GAMS). Three individual samples were measured, yielding a Maxwellian-averaged cross section at $kT=30$ keV of ${\ensuremath{\langle}\ensuremath{\sigma}\ensuremath{\rangle}}_{30\phantom{\rule{0.16em}{0ex}}\text{keV}}$ = 30.4 (23)${}^{\mathrm{syst}}$(9)${}^{\mathrm{stat}}$ mbarn. This value is slightly lower than two recently published measurements using the time-of-flight (TOF) method, but agrees within the uncertainties. Our new results also resolve the large discrepancy between older TOF measurements and our previous value.