Low-energy electronic recoil in xenon detectors by solar neutrinos

Low-energy electronic recoil caused by solar neutrinos in multi-ton xenon detectors is an important subject not only because it is a source of the irreducible background for direct searches of weakly-interacting massive particles (WIMPs), but also because it provides a viable way to measure the solar $pp$ and $^{7}\textrm{Be}$ neutrinos at the precision level of current standard solar model predictions. In this work we perform $\textit{ab initio}$ many-body calculations for the structure, photoionization, and neutrino-ionization of xenon. It is found that the atomic binding effect yields a sizable suppression to the neutrino-electron scattering cross section at low recoil energies. Compared with the previous calculation based on the free electron picture, our calculated event rate of electronic recoil in the same detector configuration is reduced by about $25\%$. We present in this paper the electronic recoil rate spectrum in the energy window of 100 eV - 30 keV with the standard per ton per year normalization for xenon detectors, and discuss its implication for low energy solar neutrino detection (as the signal) and WIMP search (as a source of background).Comment: 12 pages, 3 figure

On The Orbital Evolution of Jupiter Mass Protoplanet Embedded in A Self-Gravity Disk

We performed a series of hydro-dynamic simulations to investigate the orbital migration of a Jovian planet embedded in a proto-stellar disk. In order to take into account of the effect of the disk's self gravity, we developed and adopted an \textbf{Antares} code which is based on a 2-D Godunov scheme to obtain the exact Reimann solution for isothermal or polytropic gas, with non-reflecting boundary conditions. Our simulations indicate that in the study of the runaway (type III) migration, it is important to carry out a fully self consistent treatment of the gravitational interaction between the disk and the embedded planet. Through a series of convergence tests, we show that adequate numerical resolution, especially within the planet's Roche lobe, critically determines the outcome of the simulations. We consider a variety of initial conditions and show that isolated, non eccentric protoplanet planets do not undergo type III migration. We attribute the difference between our and previous simulations to the contribution of a self consistent representation of the disk's self gravity. Nevertheless, type III migration cannot be completely suppressed and its onset requires finite amplitude perturbations such as that induced by planet-planet interaction. We determine the radial extent of type III migration as a function of the disk's self gravity.Comment: 19 pages, 13 figure

Optimal Eavesdropping in Quantum Cryptography. II. Quantum Circuit

It is shown that the optimum strategy of the eavesdropper, as described in the preceding paper, can be expressed in terms of a quantum circuit in a way which makes it obvious why certain parameters take on particular values, and why obtaining information in one basis gives rise to noise in the conjugate basis.Comment: 7 pages, 1 figure, Latex, the second part of quant-ph/970103

Early motherhood: A qualitative study exploring the experiences of African Australian teenage mothers in greater Melbourne, Australia

BACKGROUND: Motherhood is a significant and important aspect of life for many women around the globe. For women in communities where motherhood is highly desired, motherhood is considered crucial to the woman's identity. Teenage motherhood, occurring at a critical developmental stage of teenagers' lives, has been identified as having adverse social and health consequences. This research aimed to solicit the lived experiences of African Australian young refugee women who have experienced early motherhood in Australia. METHODS: This qualitative research used in-depth interviews. The research methods and analysis were informed by intersectionality theory, phenomenology and a cultural competency framework. Sixteen African born refugee young women who had experienced teenage pregnancy and early motherhood in Greater Melbourne, Australia took part in this research. Interviews were audio recorded, transcribed and data analysed using thematic content analysis. Ethics approval for this research was granted by Victoria University Human Research Ethics committee. RESULTS: Motherhood brings increased responsibilities, social recognition, and a sense of purpose for young mothers. Despite the positive aspects of motherhood, participants faced challenges that affected their lives. Most often, the challenges included coping with increased responsibilities following the birth of the baby, managing the competing demands of schooling, work and taking care of a baby in a site of settlement. The young mothers indicated they received good support from their mothers, siblings and close friends, but rarely from the father of their baby and the wider community. Participants felt that teenage mothers are frowned upon by their wider ethnic communities, which left them with feelings of shame and embarrassment, despite the personal perceived benefits of achieving motherhood. CONCLUSIONS: We propose that service providers and policy makers support the role of the young mothers' own mother, sisters, their grandmothers and aunts following early motherhood. Such support from significant females will help facilitate young mothers' re-engagement with education, work and other aspects of life. For young migrant mothers, this is particularly important in order to facilitate settlement in a new country and reduce the risk of subsequent mistimed pregnancies. Service providers need to expand their knowledge and awareness of the specific needs of refugee teen mothers living in 'new settings'