Ron Nelson

In vivo Observation of Tree Drought Response with Low-Field NMR and Neutron Imaging

Using a simple low-field NMR system, we monitored water content in a living tree in a greenhouse over 2 months. By continuously running the system, we observed changes in tree water content on a scale of half an hour. The data showed a diurnal change in water content consistent both with previous NMR and biological observations. Neutron imaging experiments show that our NMR signal is primarily due to water being rapidly transported through the plant, and not to other sources of hydrogen, such as water in cytoplasm, or water in cell walls. After accounting for the role of temperature in the observed NMR signal, we demonstrate a change in the diurnal signal behavior due to simulated drought conditions for the tree. These results illustrate the utility of our system to perform noninvasive measurements of tree water content outside of a temperature controlled environment.

New measurement of the 238Pu(n,f) cross‐section

A new measurement of the fast neutron‐induced fission cross section of 238Pu in the 2–200 MeV domain is presented. Preliminary results confirm theoretical indications that above 6 MeV this cross section was, up to now, overestimated by 20 to 30%.

Proton-Induced Radiation Damage in Fast Crystal Scintillators

This paper reports proton-induced radiation damage in fast crystal scintillators. Large size LYSO and CeF3 crystals of 20 and 15 cm long were irradiated by 800 MeV protons at Los Alamos up to

Thin scintillators for ultrafast hard X-ray imaging

3.3\times 10^{14}

Performance of Crystal Scintillators in a Severe Radiation Environment Caused by Protons

p/cm2 with degradation and recovery of their longitudinal transmittance measured in situ . LYSO plates of

Proton-induced radiation damage in BGO, LFS, PWO and a LFS/W/Quartz capillary shashlik cell

14\times 14\times 1.5

Radiation effects in GaN devices and materials(Conference Presentation)

mm3 were irradiated by 67 MeV protons at UC Davis up to

New Physics Opportunities with GEANIE at LANSCE/WNR

9.5\times 10^{13}

Proton-Induced Radiation Damage in BaF 2 , LYSO, and PWO Crystal Scintillators

p/cm2, and by 24 GeV protons at CERN up to

Neutron Imaging Developments at LANSCE

6.9\times 10^{15}