Competition between Allowed and First-Forbidden ß Decay: The Case of

The ß decay of ^{208}Hg into the one-proton hole, one neutron-particle _{81}^{208}Tl_{127} nucleus was investigated at CERN-ISOLDE. Shell-model calculations describe well the level scheme deduced, validating the proton-neutron interactions used, with implications for the whole of the N>126, Z<82 quadrant of neutron-rich nuclei. While both negative and positive parity states with spin 0 and 1 are expected within the Q_{ß} window, only three negative parity states are populated directly in the ß decay. The data provide a unique test of the competition between allowed Gamow-Teller and Fermi, and first-forbidden ß decays, essential for the understanding of the nucleosynthesis of heavy nuclei in the rapid neutron capture process. Furthermore, the observation of the parity changing 0^{+}→0^{-}ß decay where the daughter state is core excited is unique, and can provide information on mesonic corrections of effective operators.

Large Impact of the Decay of Niobium Isomers on the Reactor ν[over ¯]_{e} Summation Calculations.

Even mass neutron-rich niobium isotopes are among the principal contributors to the reactor antineutrino energy spectrum. They are also among the most challenging to measure due to the refractory nature of niobium, and because they exhibit isomeric states lying very close in energy. The ß-intensity distributions of ^{100gs,100m}Nb and ^{102gs,102m}Nb ß decays have been determined using the total absorption γ-ray spectroscopy technique. The measurements were performed at the upgraded Ion Guide Isotope Separator On-Line facility at the University of Jyväskylä. Here, the double Penning trap system JYFLTRAP was employed to disentangle the ß decay of the isomeric states. The new data obtained in this challenging measurement have a large impact in antineutrino summation calculations. For the first time the discrepancy between the summation model and the reactor antineutrino measurements in the region of the shape distortion has been reduced.

Gamma Decay of Unbound Neutron-Hole States in

Excited states in the nucleus ^{133}Sn, with one neutron outside the double magic ^{132}Sn core, were populated following one-neutron knockout from a ^{134}Sn beam on a carbon target at relativistic energies at the Radioactive Isotope Beam Factory at RIKEN. Besides the γ rays emitted in the decay of the known neutron single-particle states in ^{133}Sn additional γ strength in the energy range 3.5-5.5 MeV was observed for the first time. Since the neutron-separation energy of ^{133}Sn is low, S_{n}=2.402(4) MeV, this observation provides direct evidence for the radiative decay of neutron-unbound states in this nucleus. The ability of electromagnetic decay to compete successfully with neutron emission at energies as high as 3 MeV above threshold is attributed to a mismatch between the wave functions of the initial and final states in the latter case. These findings suggest that in the region southeast of ^{132}Sn nuclear structure effects may play a significant role in the neutron versus γ competition in the decay of unbound states. As a consequence, the common neglect of such effects in the evaluation of the neutron-emission probabilities in calculations of global ß-decay properties for astrophysical simulations may have to be reconsidered.

Scattering of the Halo Nucleus

Angular distributions of the elastic, inelastic, and breakup cross sections of the halo nucleus ^{11}Be on ^{197}Au were measured at energies below (E_{lab}=31.9 MeV) and around (39.6 MeV) the Coulomb barrier. These three channels were unambiguously separated for the first time for reactions of ^{11}Be on a high-Z target at low energies. The experiment was performed at TRIUMF (Vancouver, Canada). The differential cross sections were compared with three different calculations: semiclassical, inert-core continuum-coupled-channels and continuum-coupled-channels ones with including core deformation. These results show conclusively that the elastic and inelastic differential cross sections can only be accounted for if core-excited admixtures are taken into account. The cross sections for these channels strongly depend on the B(E1) distribution in ^{11}Be, and the reaction mechanism is sensitive to the entanglement of core and halo degrees of freedom in ^{11}Be.

Association between exposure to household cigarette smoking behavior and cigarette smoking in Hispanic adults: Findings from the Hispanic Community Health Study/Study of Latinos.

BACKGROUND: Cigarette smoking behavior is highly determined by social influences during childhood and adolescence. This phenomenon has not been fully evaluated in the Hispanic/Latino population. PURPOSE: To examine the association between exposure to household cigarette smoking behavior (HCSB) and adult cigarette smoking among a diverse Hispanic/Latino population living in four US urban centers. The effect of acculturation on cigarette smoking was also evaluated. METHODS: Data from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) (n=13,231, ages 18-74years, collected between March 2008 and June 2011) were analyzed using logistic regression. RESULTS: HCSB exposure was an independent risk factor for adult current cigarette smoking in Hispanic/Latinos (OR 1.7; 95% CI 1.4, 2.1) after controlling for relevant confounders including socio-demographic and cultural factors. Cubans and Puerto Ricans had the highest prevalence of HCSB exposure (59% and 47% respectively) and highest prevalence of current cigarette smoking (26% and 32%) compared with other Hispanic/Latino groups, (p<.01). CONCLUSIONS: Our data suggest that exposure to HCSB in Hispanics/Latinos living in the US is an independent predictor of adult cigarette smoking, and this association appears to be strongest in Cubans and Puerto Ricans.

Reactor decay heat in 239Pu: solving the γ discrepancy in the 4-3000-s cooling period.

The ß feeding probability of (102,104,105,106,107)Tc, 105Mo, and 101Nb nuclei, which are important contributors to the decay heat in nuclear reactors, has been measured using the total absorption technique. We have coupled for the first time a total absorption spectrometer to a Penning trap in order to obtain sources of very high isobaric purity. Our results solve a significant part of a long-standing discrepancy in the γ component of the decay heat for 239Pu in the 4-3000 s range.

Observation of 54Ni: cross-conjugate symmetry in f7/2 mirror energy differences.

Gamma decays from excited states up to Jpi=6+ in the N=Z-2 nucleus 54Ni have been identified for the first time. Level energies are compared with those of the isobars 54Co and 54Fe and of the cross-conjugate nuclei of mass A=42. The good but puzzling f7/ cross-conjugate symmetry in mirror and triplet energy differences is analyzed. Shell model calculations reproduce the new data but the necessary nuclear charge-dependent phenomenology is not fully explained by modern nucleon-nucleon potentials.

Deformation of the N=Z nucleus 76Sr using beta-decay studies.

A novel method of deducing the deformation of the N=Z nucleus 76Sr is presented. It is based on the comparison of the experimental Gamow-Teller strength distribution B(GT) from its beta decay with the results of quasi-random-phase approximation calculations. This method confirms previous indications of the strong prolate deformation of this nucleus in a totally independent way. The measurement has been carried out with a large total absorption gamma spectrometer, "Lucrecia," newly installed at CERN-ISOLDE.

Relatedness of Escherichia coli colonizing women longitudinally.

PURPOSE: The longitudinal colonization patterns by Escherichia coli of the vaginal introitus and urinary tract were investigated. MATERIALS AND METHODS: Cultures of the vaginal introitus and midstream urine were collected once a week for 12 consecutive weeks from five women with (patients) and five without (controls) a history of urinary tract infection (UTI). RESULTS: A total of 63 E. coli isolates was obtained from the 10 women, 26 from controls and 37 from patients. The bacterial counts of E. coli present in control individuals were uniformly low, < or = 200 E. coli/mL. The numbers in patients were higher and more variable, reaching > 10(5)/mL in urine and vaginal specimens. In 16 instances, E. coli was present in the urine and the vaginal introitus concurrently (matched isolates). Random amplified polymorphic DNA (RAPD) fingerprinting was used to characterize all matched E. coli isolates. Concurrent vaginal and urinary tract colonization was more common in the patient population, and usually, the same E. coli strain was present at both sites; only 15% of the matched isolates represented different strains. The RAPD fingerprinting was also carried out on selected isolates recovered from four patients and three control individuals over the 12-week study period. Colonization of the vaginal introitus and urinary tract in these individuals varied over time. Generally, however, a predominant E. coli strain was present in the vaginal milieu, urinary tract, or both, either continuously (for as long as 9 consecutive weeks in one patient) or intermittently. CONCLUSION: The results support the concept that the vaginal mucosa acts as reservoir of E. coli which may enter the urinary tract.

Risk factors for coronary heart disease in men 18 to 39 years of age.

BACKGROUND: Few studies have evaluated the long-term predictive capacity of risk factors for death from coronary heart disease in men younger than 40 years of age. OBJECTIVE: To assess the predictive capacity and discriminatory ability of major coronary risk factors in predicting death from coronary heart disease in young men. DESIGN: Prospective cohort study with 20 years of follow-up. SETTING: 84 companies in the Chicago area that participated in the Chicago Heart Association Detection Project in Industry (1967-1973). PARTICIPANTS: 11 016 men 18 to 39 years of age (mean age, 29.7 years) at baseline were the primary focus of this report; 8955 men 40 to 59 years of age at baseline served as a reference group. MEASUREMENTS: The main end point was death from coronary heart disease. RESULTS: All major risk factors-age, serum cholesterol level, systolic blood pressure, and cigarette smoking-were significantly associated with death from coronary heart disease over 20 years in young men. Relative risks for the major risk factors were of generally similar magnitude in young and middle-aged men. Receiver-operating characteristic curves for the best predictive model yielded an area under the curve of 0.82, indicating that standard risk factors were highly predictive of long-term outcome in young men. CONCLUSIONS: Major coronary disease risk factors, many of which are modifiable, are strong contributors to prediction of future risk, even in young men. These data may help in formulating appropriate strategies to identify young men at heightened risk for death from coronary heart disease in later adulthood.