Prolonged production of C during the ~660 BCE solar proton event from Japanese tree rings.

Annual rings record the intensity of cosmic rays (CRs) that had entered into the Earth's atmosphere. Several rapid C increases in the past, such as the 775 CE and 994CE C spikes, have been reported to originate from extreme solar proton events (SPEs). Another rapid C increase, also known as the ca.

Discriminating the indistinguishable sapwood from heartwood in discolored ancient wood by direct molecular mapping of specific extractives using time-of-flight secondary ion mass spectrometry.

A new method that can chemically discriminate the visually indistinguishable sapwood from heartwood in discolored woods is presented in this paper. Discriminating between sapwood and heartwood, which are normally recognized by color in cross sections of stems of tress, is important in dendrochronological dating, as well as in evaluating qualities of woods such as durability. In tree-ring chronology, the felling date, which affects the construction date of architectures, can be estimated only in woods that have a recognizable sapwood/heartwood boundary.