Abstract
Abstract
Nondestructive monitoring of positron-emitting tracers in
plant bodies at multiple points, including points separated by large
distances, has been realised with the positron multiprobe system
(PMPS) to investigate graminaceous plants, whose stems and leaves
have simple shapes. Recently, the translocation of photosynthates
into fruits has been studied intensively using a 11C tracer.
The relatively complex shapes of the stems and leaves of these
plants sometimes prevent the detector heads of the PMPS from
approaching and being fixed to the target stem properly because of
its relatively large and heavy detector heads based on
photomultiplier tubes. Owing to the compactness, lightweightness
and recent advances of silicon photomultipliers (SiPMs), fabricating
compact and lightweight detector heads has become possible. In this
study, we developed a compact PMPS (CPMPS) using SiPMs and
successfully demonstrated its capability for monitoring a 11C
tracer in strawberry stems. Moreover, we found that energy-window
filtering markedly reduced noise events without radiation shielding.
The dominant ionisation events detected by the CPMPS were Compton
scattering and subsequent photoabsorption of a single 511 keV gamma
ray, suggesting that the ionisation events of single-gamma-ray
emitters, such as 42K, 43K, 54Mn, 59Fe and
65Zn, can be detected by the CPMPS. The developed CPMPS can
also be applied to study the physiology of other plants with
intricately shaped stems and leaves, such as the tomato and
eggplant.