11Li beta decay into 9Li and deuteron within a three-body model

The beta decay process of the 11Li halo nucleus into 9Li and d is studied in a three-body model. The 11Li nucleus is described as a 9Li+n+n system in hyperspherical coordinates on a Lagrange mesh. Various 9Li+d potentials are compared involving a forbidden state, a physical bound state, and a resonance near 0.25 MeV in the s-wave. With an added surface absorption, they are compatible with elastic scattering data. The transition probability per time unit is quite sensitive to the location of the resonance. For a fixed resonance location, it does not depend much on the potential choice at variance with the 6He delayed deuteron decay. The calculated transition probability per time unit is larger than the experimental value but the difference can be explained by a slightly higher resonance location and/or by absorption from the 9Li+d final channel.Comment: 14 pages, 7 figures, 3 table

The point spread function of electrons in a magnetic field, and the decay of the free neutron

Experiments in nuclear and particle physics often use magnetic fields to guide charged reaction products to a detector. Due to their gyration in the guide field, the particles hit the detector within an area that can be considerably larger than the diameter of the source where the particles are produced. This blurring of the image of the particle source on the detector surface is described by a suitable point spread function (PSF), which is defined as the image of a point source. We derive simple analytical expressions for such magnetic PSFs, valid for any angular distribution of the emitted particles that can be developed in Legendre polynomials. We investigate this rather general problem in the context of neutron beta decay spectrometers and study the effect of limited detector size on measured neutron decay correlation parameters. To our surprise, insufficient detector size does not affect much the accuracy of such measurements, even for rather large radii of gyration. This finding can considerably simplify the layout of the respective spectrometers.Comment: 24 pages, 12 figure

Characterization of a ballistic supermirror neutron guide

We describe the beam characteristics of the first ballistic supermirror neutron guide H113 that feeds the neutron user facility for particle physics PF1B of the Institute Laue-Langevin, Grenoble (ILL). At present, the neutron capture flux density of H113 at its 20x6cm2 exit window is 1.35x10^10/cm^2/s, and will soon be raised to above 2x10^10/cm^2/s. Beam divergence is no larger than beam divergence from a conventional Ni coated guide. A model is developed that permits rapid calculation of beam profiles and absolute event rates from such a beam. We propose a procedure that permits inter-comparability of the main features of beams emitted from ballistic or conventional neutron guides.Comment: 15 pages, 11 figures, to be submitted to Nuclear Instruments and Methods

Improving maternal confidence in neonatal care through a checklist intervention

Previous qualitative studies suggest a lack of maternal confidence in care of their newborn child upon discharge into the community. This observation was supported by discussion with healthcare professionals and mothers at University College London Hospital (UCLH), highlighting specific areas of concern, in particular identifying and managing common neonatal presentations. The aim of this study was to design and introduce a checklist, addressing concerns, to increase maternal confidence in care of their newborn child. Based on market research, an 8-question checklist was designed, assessing maternal confidence in: feeding, jaundice, nappy care, rashes and dry skin, umbilical cord care, choking, bowel movements, and vomiting. Mothers were assessed as per the checklist, and received a score representative of their confidence in neonatal care. Mothers were followed up with a telephone call, and were assessed after a 7-day-period. Checklist scores before as compared to after the follow-up period were analysed. This process was repeated for three study cycles, with the placement of information posters on the ward prior to the second study cycle, and the stapling of the checklist to the mother's personal child health record (PCHR) prior to the third study cycle. A total of 99 mothers on the Maternity Care Unit at UCLH were enrolled in the study, and 92 were contactable after a 7-day period. During all study cycles, a significant increase in median checklist score was observed after, as compared to before, the 7-day follow up period (p < 0.001). The median difference in checklist score from baseline was greatest for the third cycle. These results suggest that introduction of a simple checklist can be successfully utilised to improve confidence of mothers in being able to care for their newborn child. Further investigation is indicated, but this intervention has the potential for routine application in postnatal care

A clean, bright, and versatile source of neutron decay products

We present a case study on a new type of cold neutron beam station for the investigation of angular correlations in the beta-decay of free neutrons. With this beam station, called PERC, the 'active decay volume' lies inside the neutron guide, and the charged neutron decay products are magnetically guided towards the end of the neutron guide. Hence, the guide delivers at its exit a beam of decay electrons and protons, under well-defined and precisely variable conditions, which can be well separated from the cold neutron beam. In this way a general-purpose source of neutron decay products is obtained which can be used for various different experiments in neutron decay correlation spectroscopy. A gain in phase space density of several orders of magnitude can be achieved with PERC, as compared to existing neutron decay spectrometers. Neutron beam related background is separately measurable in PERC, and magnetic mirror effects on the charged neutron decay products and edge effects in the active neutron beam volume are both strongly suppressed. Therefore the spectra and angular distributions of the emerging decay particles will be distortion-free on the level of 10^-4, more than 10 times better than achieved today.Comment: 20 pages, 6 figure

Microwave Realization of the Gaussian Symplectic Ensemble

This work was funded by the Deutsche Forschungsgemeinschaft via the individual Grants No. STO 157/16-1 and No. KU 1525/3-1. C. H. J. acknowledges the Leverhulme Trust (Grant No. ECF-2014-448) for financial support

Is the Unitarity of the quark-mixing-CKM-matrix violated in neutron β\beta-decay?

We report on a new measurement of neutron $\beta$-decay asymmetry. From the result \linebreak $A_0$ = -0.1189(7), we derive the ratio of the axial vector to the vector coupling constant $\lambda$ = ${\it g_A/g_V}$ = -1.2739(19). When included in the world average for the neutron lifetime $\tau$ = 885.7(7)s, this gives the first element of the Cabibbo-Kobayashi-Maskawa (CKM) matrix $V_{ud}$. With this value and the Particle Data Group values for $V_{us}$ and $V_{ub}$, we find a deviation from the unitarity condition for the first row of the CKM matrix of $\Delta$ = 0.0083(28), which is 3.0 times the stated error

Particle velocity in noncommutative space-time

We investigate a particle velocity in the $\kappa$-Minkowski space-time, which is one of the realization of a noncommutative space-time. We emphasize that arrival time analyses by high-energy $\gamma$-rays or neutrinos, which have been considered as powerful tools to restrict the violation of Lorentz invariance, are not effective to detect space-time noncommutativity. In contrast with these examples, we point out a possibility that {\it low-energy massive particles} play an important role to detect it.Comment: 16 pages, corrected some mistake