Measurement of the Spectral Shape of the ß-Decay of

We report on a comparison between the theoretically predicted and experimentally measured spectra of the first-forbidden nonunique ß-decay transition ^{137}Xe(7/2^{-})→^{137}Cs(7/2^{+}). The experimental data were acquired by the EXO-200 experiment during a deployment of an AmBe neutron source. The ultralow background environment of EXO-200, together with dedicated source deployment and analysis procedures, allowed for collection of a pure sample of the decays, with an estimated signal to background ratio of more than 99 to 1 in the energy range from 1075 to 4175 keV. In addition to providing a rare and accurate measurement of the first-forbidden nonunique ß-decay shape, this work constitutes a novel test of the calculated electron spectral shapes in the context of the reactor antineutrino anomaly and spectral bump.

Search for Neutrinoless Double-ß Decay with the Complete EXO-200 Dataset.

A search for neutrinoless double-ß decay (0νßß) in ^{136}Xe is performed with the full EXO-200 dataset using a deep neural network to discriminate between 0νßß and background events. Relative to previous analyses, the signal detection efficiency has been raised from 80.8% to 96.4±3.0%, and the energy resolution of the detector at the Q value of ^{136}Xe 0νßß has been improved from σ/E=1.23% to 1.15±0.02% with the upgraded detector. Accounting for the new data, the median 90% confidence level 0νßß half-life sensitivity for this analysis is 5.0×10^{25} yr with a total ^{136}Xe exposure of 234.1 kg yr. No statistically significant evidence for 0νßß is observed, leading to a lower limit on the 0νßß half-life of 3.5×10^{25} yr at the 90% confidence level.

Search for Neutrinoless Double-Beta Decay with the Upgraded EXO-200 Detector.

Results from a search for neutrinoless double-beta decay (0νßß) of ^{136}Xe are presented using the first year of data taken with the upgraded EXO-200 detector. Relative to previous searches by EXO-200, the energy resolution of the detector has been improved to σ/E=1.23%, the electric field in the drift region has been raised by 50%, and a system to suppress radon in the volume between the cryostat and lead shielding has been implemented. In addition, analysis techniques that improve topological discrimination between 0νßß and background events have been developed. Incorporating these hardware and analysis improvements, the median 90% confidence level 0νßß half-life sensitivity after combining with the full data set acquired before the upgrade has increased twofold to 3.7×10^{25} yr. No statistically significant evidence for 0νßß is observed, leading to a lower limit on the 0νßß half-life of 1.8×10^{25} yr at the 90% confidence level.

Aluminum phosphide poisoning known as rice tablet: A common toxicity in North Iran.

BACKGROUND: Aluminum phosphide (ALP) is a highly effective insecticide and rodenticide used frequently to protect stored grain. Acute poisoning with this compound is common in some countries including India and Iran, and is a serious health problem. AIM: The objective of this study was to survey ALP poisoning locally known as "Rice Tablet" and the outcome in a referral poisoning hospital in Mazandaran province, northern part of Iran. MATERIALS AND METHODS: The study was a cross-sectional study from March 2007 to February 2008. Records of all patients admitted and hospitalized to a referral teaching hospital during the 2 year period were collected. Information including gender, age, cause of toxicity, amount of AIP consumed, route of exposure, time between exposure and hospital admission, signs and symptoms of toxicity at admission, therapeutic intervention, laboratory tests, and outcome were extracted from the patients' notes. Patients who died and survived were compared using appropriate statistical tests. RESULTS: During the two-year period, 102 patients, 46 men and 56 women with mean (±SD) age 28.5 ± 12.4 year were admitted with ALP poisoning. The most common signs and symptoms at admission were nausea (79.4%), vomiting (76.5%), and abdominal pain (31.4%). 41.1% of the patients showed metabolic acidosis. Suicidal intention was the most common cause of poisoning (97%) leading to 19 (18.6%) deaths. Compared with the patients who survived, those who died had taken higher amount of ALP tablet (2.2 ± 2.4 vs. 1.4 ± 1.0, P < 0.05), had poor liver function test (P < 0.0001) and severe metabolic acidosis (pH: 7.17 ± 0.19 vs. 7.33 ± 0.08, P < 0.0001). CONCLUSION: ALP poisoning is a common toxicity in Iran causing high morality. This is a serious health problem in agricultural region where ALP is readily available. Withdrawal of ALP tablet from the market and introduction of safer products as rodenticides and insecticides is recommended.