Field-testing of the revised, draft South African Paediatric Food-Based Dietary Guidelines amongst mothers/caregivers of children aged 0–12 months in the Breede Valley sub-district, Western Cape province, South Africa

Objectives: To assess the appropriateness and understanding of the revised, draft South African Paediatric Food-Based Dietary Guidelines (SA-PFBDGs) amongst mothers/caregivers of children aged 0–12 months. Exposure to guidelines with similar messages, barriers and enablers to following of the guidelines were also assessed. Design: Qualitative data were collected from 14 focus-group discussions (FGDs), conducted in isiXhosa (n = 5), English (n = 4) and Afrikaans (n = 5), totalling 73 mother/caregiver participants. Setting: Worcester, Breede Valley sub-district, Western Cape province. Subjects: The study population included mothers/caregivers who were older than 18 years. Results: The majority of participants had previous exposure to variations of messages similar to the revised, draft SA-PFBDGs. Health platforms and practitioners (community health centres, antenatal classes, nurses, doctors) and social networks and platforms (family, magazines, radio) were mentioned as primary sources of information. Barriers to following the messages included: inconsistent messages (mainly communicated by healthcare workers), contrasting beliefs and cultural/family practices, limited physical and financial access to resources, poor social support structures and the psycho-social and physical demands of raising a child. Conclusion: The revised, draft SA-PFBDGs for the age range 0–12 months have been field-tested in English, Afrikaans and isiXhosa. The messages in some of the revised, draft SA-PFBDGs were not understood by the participants, indicating that a degree of rewording should be considered to facilitate understanding of the guidelines by the public. The National Department of Health should consider the findings of this study, and use these standardised message/s to optimise infant and young child feeding

Characterization of the QUartz Photon Intensifying Detector (QUPID) for Noble Liquid Detectors

Dark Matter and Double Beta Decay experiments require extremely low radioactivity within the detector materials. For this purpose, the University of California, Los Angeles and Hamamatsu Photonics have developed the QUartz Photon Intensifying Detector (QUPID), an ultra-low background photodetector based on the Hybrid Avalanche Photo Diode (HAPD) and entirely made of ultraclean synthetic fused silica. In this work we present the basic concept of the QUPID and the testing measurements on QUPIDs from the first production line. Screening of radioactivity at the Gator facility in the Laboratori Nazionali del Gran Sasso has shown that the QUPIDs safely fulfill the low radioactive contamination requirements for the next generation zero background experiments set by Monte Carlo simulations. The quantum efficiency of the QUPID at room temperature is > 30% at the xenon scintillation wavelength. At low temperatures, the QUPID shows a leakage current less than 1 nA and a global gain of 10^5. In these conditions, the photocathode and the anode show > 95% linearity up to 1 uA for the cathode and 3 mA for the anode. The photocathode and collection efficiency are uniform to 80% over the entire surface. In parallel with single photon counting capabilities, the QUPIDs have a good timing response: 1.8 +/- 0.1 ns rise time, 2.5 +/- 0.2 ns fall time, 4.20 +/- 0.05 ns pulse width, and 160 +/- 30 ps transit time spread. The QUPIDs have also been tested in a liquid xenon environment, and scintillation light from 57Co and 210Po radioactive sources were observed.Comment: 15 pages, 22 figure

Measurement of the scintillation time spectra and pulse-shape discrimination of low-energy beta and nuclear recoils in liquid argon with DEAP-1

The DEAP-1 low-background liquid argon detector was used to measure scintillation pulse shapes of electron and nuclear recoil events and to demonstrate the feasibility of pulse-shape discrimination (PSD) down to an electron-equivalent energy of 20 keV. In the surface dataset using a triple-coincidence tag we found the fraction of beta events that are misidentified as nuclear recoils to be $<1.4\times 10^{-7}$ (90% C.L.) for energies between 43-86 keVee and for a nuclear recoil acceptance of at least 90%, with 4% systematic uncertainty on the absolute energy scale. The discrimination measurement on surface was limited by nuclear recoils induced by cosmic-ray generated neutrons. This was improved by moving the detector to the SNOLAB underground laboratory, where the reduced background rate allowed the same measurement with only a double-coincidence tag. The combined data set contains $1.23\times10^8$ events. One of those, in the underground data set, is in the nuclear-recoil region of interest. Taking into account the expected background of 0.48 events coming from random pileup, the resulting upper limit on the electronic recoil contamination is $<2.7\times10^{-8}$ (90% C.L.) between 44-89 keVee and for a nuclear recoil acceptance of at least 90%, with 6% systematic uncertainty on the absolute energy scale. We developed a general mathematical framework to describe PSD parameter distributions and used it to build an analytical model of the distributions observed in DEAP-1. Using this model, we project a misidentification fraction of approx. $10^{-10}$ for an electron-equivalent energy threshold of 15 keV for a detector with 8 PE/keVee light yield. This reduction enables a search for spin-independent scattering of WIMPs from 1000 kg of liquid argon with a WIMP-nucleon cross-section sensitivity of $10^{-46}$ cm$^2$, assuming negligible contribution from nuclear recoil backgrounds.Comment: Accepted for publication in Astroparticle Physic

Improved KL->pi e nu Form Factor and Phase Space Integral with Reduced Model Uncertainty

Using the published KTeV sample of 2 million KL-> pi e nu decays and a new form factor expansion with a rigorous bound on higher order terms, we present a new determination of the KL->pi e nu form factor and phase space integral. Compared to the previous KTeV result, the uncertainty in the new form factor expansion is negligible and results in an overall uncertainty in the phase space integral (IKe) that is a factor of two smaller: IKe = 0.15392 +- 0.00048 \.Comment: 3 pages, 2 figures, submitted to PRD Rapid Communicatio

Measurements of the Decay KL→e+e−γK_L \to e^+e^-\gamma

The E799-II (KTeV) experiment at Fermilab has collected 83262 $K_L \to e^+e^-\gamma$ events above a background of 79 events. We measure a decay width, normalized to the $K_L \to \pi^0\pi^0\pi^0_D$ (\pi^0 \to \gamma\gamma, \pi^0 to \gamma\gamma, \pi^0_D \to e^+e^-\gamma) decay width, of $\Gamma($K_L \to e^+e^-\gamma$)/\Gamma(K_L \to \pi^0\pi^0\pi^0_D) = (1.3302 \pm 0.0046_{stat} \pm 0.0102_{syst}) \times 10^{-3}$. We also measure parameters of two $K_L \gamma^{\ast}\gamma$ form factor models. In the Bergstrom, Masso, and Singer (BMS) parametrization, we find \caks = -0.517 \pm 0.030_{stat} \pm 0.022_{syst}. We separately fit for the first parameter of the D'Ambrosio, Isidori, and Portoles (DIP) model and find \adip = -1.729 \pm 0.043_{stat} \pm 0.028_{syst}.Comment: 5 pages, 3 figures, submitted to PR

Search for the Rare Decays KL->pi0pi0mu+mu- and KL->pi0pi0X0->pi0pi0mu+mu-

The KTeV E799 experiment has conducted a search for the rare decays KL->pi0pi0mu+mu- and KL->pi0pi0X0->pi0pi0mu+mu-, where the X0 is a possible new neutral boson that was reported by the HyperCP experiment with a mass of (214.3 pm 0.5) MeV/c^{2}. We find no evidence for either decay. We obtain upper limits of Br(KL->pi0pi0X0->pi0pi0mu+mu-) pi0pi0mu+mu-) < 9.2 x 10^{-11} at the 90% confidence level. This result rules out the pseudoscalar X0 as an explanation of the HyperCP result under the scenario that the \bar{d}sX0 coupling is completely real

Radon backgrounds in the DEAP-1 liquid-argon-based Dark Matter detector

The DEAP-1 \SI{7}{kg} single phase liquid argon scintillation detector was operated underground at SNOLAB in order to test the techniques and measure the backgrounds inherent to single phase detection, in support of the \mbox{DEAP-3600} Dark Matter detector. Backgrounds in DEAP are controlled through material selection, construction techniques, pulse shape discrimination and event reconstruction. This report details the analysis of background events observed in three iterations of the DEAP-1 detector, and the measures taken to reduce them. The $^{222}$Rn decay rate in the liquid argon was measured to be between 16 and \SI{26}{\micro\becquerel\per\kilogram}. We found that the background spectrum near the region of interest for Dark Matter detection in the DEAP-1 detector can be described considering events from three sources: radon daughters decaying on the surface of the active volume, the expected rate of electromagnetic events misidentified as nuclear recoils due to inefficiencies in the pulse shape discrimination, and leakage of events from outside the fiducial volume due to imperfect position reconstruction. These backgrounds statistically account for all observed events, and they will be strongly reduced in the DEAP-3600 detector due to its higher light yield and simpler geometry

Search for the Rare Decay K_{L}\to\pi^{0}\pi^{0}\gamma

The KTeV E799 experiment has conducted a search for the rare decay $K_{L}\to\pi^{0}\pi^{0}\gamma$ via the topology $K_{L}\to\pi^{0}\pi^{0}_D\gamma$ (where $\pi^0_D\to\gamma e^+e^-$). Due to Bose statistics of the $\pi^0$ pair and the real nature of the photon, the $K_{L}\to\pi^{0}\pi^{0}\gamma$ decay is restricted to proceed at lowest order by the CP conserving direct emission (DE) of an E2 electric quadrupole photon. The rate of this decay is interesting theoretically since chiral perturbation theory predicts that this process vanishes at level $O(p^4)$. Therefore, this mode probes chiral perturbation theory at $O(p^6)$. In this paper we report a determination of an upper limit of $2.43\times 10^{-7}$ (90% CL) for $K_{L}\to\pi^{0}\pi^{0}\gamma$. This is approximately a factor of 20 lower than previous results.Comment: six pages and six figures in the submission. Reformatted for Physics Review

Determination of the Parity of the Neutral Pion via the Four-Electron Decay

We present a new determination of the parity of the neutral pion via the double Dalitz decay pi^0 -> e+ e- e+ e-. Our sample, which consists of 30511 candidate decays, was collected from K_L -> pi0 pi0 pi0 decays in flight at the KTeV-E799 experiment at Fermi National Accelerator Laboratory. We confirm the negative pi^0 parity, and place a limit on scalar contributions to the pi^0 -> e+ e- e+ e- decay amplitude of less than 3.3% assuming CPT conservation. The pi^0 gamma* gamma* form factor is well described by a momentum-dependent model with a slope parameter fit to the final state phase space distribution. Additionally, we have measured the branching ratio of this mode to be B(pi^0 -> e+ e- e+ e-) = (3.26 +- 0.18) x 10^(-5).Comment: 5 pages, 4 figures. Typographical error in radiative branching ratio (Eq. 6) correcte