Simultaneous Determination of Neutron-Induced Fission and Radiative Capture Cross Sections from Decay Probabilities Obtained with a Surrogate Reaction

Reliable neutron-induced-reaction cross sections of unstable nuclei are essential for nuclear astrophysics and applications but their direct measurement is often impossible. The surrogate-reaction method is one of the most promising alternatives to access these cross sections. In this work, we successfully applied the surrogate-reaction method to infer for the first time both the neutron-induced fission and radiative capture cross sections of ^{239}Pu in a consistent manner from a single measurement. This was achieved by combining simultaneously measured fission and γ-emission probabilities for the ^{240}Pu(^{4}He,^{4}He^{'}) surrogate reaction with a calculation of the angular-momentum and parity distributions populated in this reaction. While other experiments measure the probabilities for some selected γ-ray transitions, we measure the γ-emission probability. This enlarges the applicability of the surrogate-reaction method.

0381 Association of Social Jetlag with the 2018 WCRF/AICR Cancer Prevention Score Among Parent-Adolescent Dyads in the FLASHE Study

Introduction

Social jetlag (SJL), or the mismatch between biological and social time, is a marker of circadian misalignment. SJL is linked to biological and behavioral alterations (e.g., adiposity, unhealthy food intake) which over time may increase cancer and chronic disease risk. While developmental changes exacerbate SJL among adolescents, parents may also influence adolescent behavioral patterns. This study examined associations of SJL with multiple cancer preventive behaviors among parent-adolescent dyads using the 2018 World Cancer Research Fund/American Institute of Cancer Research (WCRF/AICR) Cancer Prevention Score in the National Cancer Institute’s Family Life, Activity, Sun, Health, and Eating (FLASHE) Study.

Methods

Online cross-sectional surveys examining cancer-preventive behaviors were administered to 1,479 parent-adolescent (aged 12-17y) dyads in 2014. SJL was defined as the absolute difference between sleep midpoint on weekend and week days. The adapted 2018 WCRF/AICR Score ranged from 0-6 and was the sum of six sub-components representing adherence to specific cancer prevention recommendations concerning body weight, physical activity, and diet. Dyads with missing data on either variable were excluded. Actor-partner interdependence modeling was used to determine within-dyad correlations, actor (i.e., effect of a dyad member’s SJL on own score), and partner (i.e., effect of a dyad member’s SJL on partner’s score) effects.

Results

The analytical sample included 936 dyads. Mean SJL was 2.0 hours (SD: 1.2) for adolescents and 1.2 hours (SD: 0.9) for parents. Mean WCRF/AICR Scores were 4.1 (SD: 0.9) for adolescents and 4.0 (SD: 0.9) for parents. Within dyads, SJL (r=0.29) and the WCRF/AICR Score (r=0.41) were positively correlated (all p <0.0001). Among adolescents, greater SJL was associated with a lower WCRF/AICR Score (β= -0.077, SE: 0.03, p=0.003), but this relationship was not observed among parents. No partner effects were detected.

Conclusion

Among adolescents, SJL was associated with poorer adherence to cancer prevention recommendations. SJL may represent a modifiable risk factor with the potential to improve multiple health behaviors and decrease disease risk.

Support

FLASHE was funded with federal funds from the National Cancer Institute, National Institutes of Health (NIH), under contract number HHSN261201200039I issued to Westat, Inc

Development of a Gaseous Proton-Recoil Detector for neutron flux measurements between 0.2 and 2 MeV neutron energy

Absolute measurements of neutron fluence are an essential prerequisite of neutron-induced cross section measurements, dosimetric investigations and neutron beam lines characterisation. Independent and precise neutron flux measurements can be performed with respect to the H(n,p) elastic cross section. However, the use of silicon proton recoil detectors is not straightforward below incident neutron energy of 1 MeV, due to a high background in the detected proton spectrum. A new gaseous proton-recoil detector has been designed to answer the challenge. The detector is described in details and results of the commissioning tests are presented.

The Neutrons for Science Facility at SPIRAL-2

The neutrons for science (NFS) facility is a component of SPIRAL-2, the new superconducting linear accelerator built at GANIL in Caen (France). The proton and deuteron beams delivered by the accelerator will allow producing intense neutron fields in the 100 keV-40 MeV energy range. Continuous and quasi-mono-kinetic energy spectra, respectively, will be available at NFS, produced by the interaction of a deuteron beam on a thick Be converter and by the 7Li(p,n) reaction on thin converter. The pulsed neutron beam, with a flux up to two orders of magnitude higher than those of other existing time-of-flight facilities, will open new opportunities of experiments in fundamental research as well as in nuclear data measurements. In addition to the neutron beam, irradiation stations for neutron-, proton- and deuteron-induced reactions will be available for cross-sections measurements and for the irradiation of electronic devices or biological cells. NFS, whose first experiment is foreseen in 2018, will be a very powerful tool for physics, fundamental research as well as applications like the transmutation of nuclear waste, design of future fission and fusion reactors, nuclear medicine or test and development of new detectors.

Measurement of a complete set of nuclides, cross sections, and kinetic energies in spallation of 238U 1A GeV with protons

Spallation residues and fission fragments from 1A GeV 238U projectiles irradiating a liquid hydrogen target were investigated by using the fragment separator at GSI for magnetic selection of reaction products including ray-tracing, energy-loss and time-of-flight techniques. The longitudinal-momentum spectra of identified fragments were analyzed, and evaporation residues and fission fragments could be separated. For 1385 nuclides, production cross sections down to values of 10 microb with a mean accuracy of 15%, velocities in the uranium rest frame and kinetic energies were determined. In the reaction all elements from uranium to nitrogen were found, each with a large number of isotopes.

Two-proton radioactivity of 45Fe

In an experiment at the SISSI-LISE3 facility of GANIL, the decay of the proton drip line nucleus 45Fe has been studied. Fragment-implantation events have been correlated with radioactive decay events in a 16x16 pixel silicon-strip detector. The decay-energy spectrum of 45Fe implants shows a distinct peak at (1.14+/-0.04) MeV with a half-life of T(1/2)=(4.7(+3.4)(-1.4)) ms. None of the events in this peak is in coincidence with beta particles. For a longer correlation interval, daughter decays of the two-proton daughter 43Cr can be observed after 45Fe implantation. The decay energy for 45Fe agrees nicely with several theoretical predictions for two-proton radioactivity.

Psychosocial characteristics after acute myocardial infarction: the ENRICHD pilot study. Enhancing Recovery in Coronary Heart Disease

PURPOSE

Psychosocial factors, such as emotional distress and social isolation, have been increasingly recognized as important risk factors for patients' recovery from acute myocardial infarction (AMI). This study examined age, gender, and ethnic differences in depression and general distress, social support, and health-related quality of life after AMI.

METHODS

Data came from a series of 88 patients aged 62.1 +/- 14.2 years (46% female) who were hospitalized for AMI at eight different US clinical centers participating in the Enhancing Recovery in Coronary Heart Disease (ENRICHD) Pilot Study. Standardized psychometric measures were administered to assess three psychosocial domains: (1) depression and general distress (mental health functioning), (2) social support, and (3) health-related quality of life. Multivariate analysis of variance was used to examine the effects of age, gender, and ethnic differences in each of the three psychosocial domains.

RESULTS

Female patients reported higher levels of depression and distress compared with male patients (P = .040). Gender differences in mental health functioning differed by age (P = .046), with the greatest differences observed among younger female patients. Older patients (P = .014) and female patients (P = .025) reported lower levels of social support compared with younger and male patients, respectively. Minority patients did not differ from nonminority patients in mental health functioning or social support, and there were no significant differences in post-AMI quality of life on the basis of age, gender, or ethnicity.

CONCLUSIONS

The psychosocial risk profile after AMI may be different for male and female patients, and interventions may need to take account of each gender's specific needs.

Discovery of doubly magic 48Ni

In an experiment at the SISSI/LISE3 facility of GANIL, we used the projectile fragmentation of a primary 58Ni26+ beam at 74.5 MeV/nucleon with an average current of 3 &mgr;A on a natural nickel target to produce very neutron-deficient isotopes. In a 10-day experiment, 287 42Cr isotopes, 53 45Fe isotopes, 106 49Ni isotopes, and 4 48Ni isotopes were unambiguously identified. The doubly magic nucleus 48Ni, observed for the first time, is the most proton-rich isotope ever identified with an isospin projection T(z) = -4. It is probably the last doubly magic nucleus with "classical" shell closures accessible for present-day facilities. Its observation allows us to deduce a lower limit for the half-life of 48Ni of 0.5 &mgr;s.

A Veterans Administration Cooperative Study of biphasic calcium phosphate ceramic in periodontal osseous defects

One hundred thirty-seven V.A. patients were randomized to one of three treatment groups to evaluate the efficacy of biphasic calcium phosphate (BCP) ceramic in the treatment of periodontal osseous defects. This material was tested against both autogenous bone implant and open flap curettage procedures. Baseline probing attachment level, Navy plaque index, and gingival index were recorded for all patients. These parameters were monitored for 3 years. At the end of this period, 101 patients had completed the study. Although the plaque and gingival indices steadily increased with time, there were no statistically significant differences among the treatment groups. Patients in the ceramic group had a gain in attachment level of 1.0 mm; those in the curettage group, 0.9 mm; and 0.4 mm for those in the bone implant group. Although the BCP patients had a greater gain, the difference was not statistically significant. In this veteran population, not only did BCP patients fail to outperform those in the control groups, all three treatment groups were similarly ineffective.

First passage times as environmental safety indicators: carboxyhemoglobin from cigarette smoke

The concentration of carbon monoxide in the blood of a cigarette smoker varies in response to the frequency and dose of CO delivered by the cigarettes he smokes and by the rate at which CO washes out of his blood. Moments of first passage times or exit times above a nominal threshold can be calculated using a stochastic differential equation that takes into account certain random variations in smoking intervals. CO doses, and washout rate. Almost any additional source of variation decreases in length of time a smoker may expect to smoke until a threshold value is exceeded. In particular the methodology proposed by Gori (1976) and Gori and Lynch (1978) for constant intervals, doses and rate may greatly overestimate the length of the "low-risk" interval for carbon monoxide concentration. One possible modification that may reduce CO hazards is to smoke less from each cigarette, even when this may be partially compensated by increased frequency of smoking.