Direct Mass Measurements to Inform the Behavior of <math display="inline"><mrow><mmultiscripts><mrow><mi>Sb</mi></mrow><mprescripts/><none/><mrow><mn>128</mn><mi mathvariant="normal">m</mi></mrow></mmultiscripts></mrow></math> in Nucleosynthetic Environments

International audienceNuclear isomer effects are pivotal in understanding nuclear astrophysics, particularly in the rapid neutron-capture process where the population of metastable isomers can alter the radioactive decay paths of nuclei produced during astrophysical events. The β-decaying isomer Sb128m was identified as potentially impactful since the β-decay pathway along the A=128 isobar funnels into this state bypassing the ground state. We report the first direct mass measurements of the Sb128 isomer and ground state using the Canadian Penning Trap mass spectrometer at Argonne National Laboratory. We find mass excesses of -84564.8(25)  keV and -84608.8(21)  keV, respectively, resulting in an excitation energy for the isomer of 43.9(33) keV. These results provide the first key nuclear data input for understanding the role of Sb128m in nucleosynthesis, and we show that it will influence the flow of the rapid neutron-capture process

Interspecific divergence in foliar nutrient dynamics and stem growth in a temperate forest in response to chronic nitrogen inputs

We studied the effects of excessive nitrogen (N) fertilization on foliar nutrient dynamics and stem growth in three important tree species in a mixed-deciduous forest. Stem diameter growth, foliar N concentrations, nitrogen–phosphorus (N/P) ratios, and nutrient resorption were determined for Acer rubrum L. (ACRU), Liriodendron tulipifera L. (LITU), and Prunus serotina Ehrh. (PRSE) on two 30-year-old watersheds at the Fernow Experimental Forest, West Virginia, USA: WS3, fertilized annually with 35 kg ammonium sulfate·ha-1 since 1989, and WS7, an untreated control watershed. In an earlier (1992) study, foliar N concentrations of all three species averaged 11% higher in WS3 than in WS7. By 2000, that was no longer the case for any species; indeed N in ACRU leaves was 13% lower in WS3 that year. N/P ratios were elevated in WS3 only in PRSE in 1992 and in both ACRU and PRSE in 1997, but by 2001, mean N/P for all three species was lower in WS3. N resorption efficiencies were 30% lower in WS3 in ACRU and PRSE, but not in LITU. Stem diameter growth in WS3 was 55% lower in ACRU and 30% lower in LITU and PRSE compared with that in WS7. Results may indicate declining growth vigor in ACRU and, to a lesser extent, PRSE and LITU in the fertilized watershed. Observed interspecific differences in growth and plant nutrition responses suggest eventual changes in species composition under increasing N saturation