A Millimeter-scale Single Charged Particle Dosimeter for Cancer Radiotherapy.

This paper presents a millimeter-scale CMOS 64×64 single charged particle radiation detector system for external beam cancer radiotherapy. A 1×1 m diode measures energy deposition by a single charged particle in the depletion region, and the array design provides a large detection area of 512×512 m. Instead of sensing the voltage drop caused by radiation, the proposed system measures the pulse width, i.

The surprisingly large neutron capture cross-section of Zr.

The probability that a nucleus will absorb a neutron-the neutron capture cross-section-is important to many areas of nuclear science, including stellar nucleosynthesis, reactor performance, nuclear medicine and defence applications. Although neutron capture cross-sections have been measured for most stable nuclei, fewer results exist for radioactive isotopes, and statistical-model predictions typically have large uncertainties. There are almost no nuclear data for neutron-induced reactions of the radioactive nucleus Zr, despite its importance as a diagnostic for nuclear security.

Half-lives of Rh and Ag.

Using long-term gamma-ray spectroscopy with high resolution germanium detectors and a ratio method, the half-lives of Rh and Ag have been determined to be 4.07 ± 0.05 years and 448 ± 27 years, respectively.

Observations of fallout from the Fukushima reactor accident in San Francisco Bay area rainwater.

We have observed fallout from the recent Fukushima Dai-ichi reactor accident in samples of rainwater collected in the San Francisco Bay area. Gamma ray spectra measured from these samples show clear evidence of fission products--(131,132)I, (132)Te, and (134,137)Cs. The activity levels we have measured for these isotopes are very low and pose no health risk to the public.