A study on whether the wood-saxon or the woods-saxon square parametrisation is appropriate for the phenomenological representation of different α \alpha -particle nucleus folding potentials

The Woods-Saxon (WS) and the squared Woods-Saxon (WS)$^{2}$ parametrisations for the single and double folding potentials were tested. We showed that the (WS)$^{2}$ form is appropriate for single as well as double folding approaches

On the formfactor of the imaginary part and its coupling to the real optical potential for the α\alpha-nucleus scattering

The model-independent formfactor of the absorptive cc-nucleus potential was calculated and compared with model dependent ones. The coupling between the shapes of the real and imaginary potential is discussed

Statistical analysis of excitation functions for elastic and inelastic scattering of α\alpha-particles on Mg and Si nuclei

The excitation functions for inelastic $\alpha$-scattering leading to the low lying excited states in $^{24}$Mg and $^{28}$Si were measured at $\Theta_{LAB}$ = 170°, 175° and 179° in the LAB energy range 22.75–28.40 MeV. Statistical analysis of these excitation functions and those previously measured for elastic scattering was performed. The direct interaction contribution $\mathit{y}_{D}$ to the reaction studied was obtained from probability distributions of cross sections and from correlation coefficients. Cross correlation coefficients between different reaction channels were calculated

Optimizing the growth conditions of Al mirrors for superconducting nanowire single-photon detectors

We investigate the growth conditions for thin (less than 200 nm) sputtered aluminum (Al) films. These coatings are needed for various applications, e.g. for advanced manufacturing processes in the aerospace industry or for nanostructures for quantum devices. Obtaining high-quality films, with low roughness, requires precise optimization of the deposition process. To this end, we tune various sputtering parameters such as the deposition rate, temperature, and power, which enables 50 nm thin films with a root mean square (RMS) roughness of less than 1 nm and high reflectivity. Finally, we confirm the high quality of the deposited films by realizing superconducting single-photon detectors integrated into multi-layer heterostructures consisting of an aluminum mirror and a silicon dioxide dielectric spacer. We achieve an improvement in detection efficiency at 780 nm from 40 % to 70 % by this integration approach.Comment: 11 pages, 6 figure

Charged particle densities from Au+Au collisions at sqrt{s_{NN}}=130 GeV

We present charged particle densities as a function of pseudorapidity and collision centrality for the 197Au+197Au reaction at sqrt{s_{NN}}=130 GeV. An integral charged particle multiplicity of 3860+/-300 is found for the 5% most central events within the pseudorapidity range -4.7 <= eta <= 4.7. At mid-rapidity an enhancement in the particle yields per participant nucleon pair is observed for central events. Near to the beam rapidity, a scaling of the particle yields consistent with the ``limiting fragmentation'' picture is observed. Our results are compared to other recent experimental and theoretical discussions of charged particle densities in ultra-relativistic heavy-ion collisions.Comment: 14 pages, 4 figures; to be published in Phys. Lett.

The experience of providing young people attending general practice with an online risk assessment tool to assess their own sexual health risk

<p>Abstract</p> <p>Background</p> <p>Targeted chlamydia screening has been advocated to reduce chlamydia associated reproductive sequelae. General practitioners are well positioned to play a major role in chlamydia control. The primary aim of this pilot study was to measure the effect of offering an online sexual health assessment tool, <it>Youth Check Your Risk</it>, on chlamydia testing rates among young people attending general practices. The secondary aim was to test the acceptability of the tool among general practitioners and young people.</p> <p>Methods</p> <p>General practitioners at three practices in Melbourne, Australia, referred patients aged 16 to 24 years to <it>Youth Check Your Risk </it><url>http://www.checkyourrisk.org.au</url> for use post-consultation between March to October 2007. The proportion of young people tested for chlamydia before and during the implementation of the tool was compared. Acceptability was assessed through a structured interviewer-administered questionnaire with general practitioners, and anonymous online data provided by <it>Youth Check Your Risk </it>users.</p> <p>Results</p> <p>The intervention did not result in any significant increases in the proportion of 16 to 24 year old males (2.7% to 3.0%) or females (6.3% to 6.4%) tested for chlamydia. A small increase in the proportion of 16 to 19 year old females tested was seen (4.1% to 7.2%). Of the 2997 patients seen during the intervention phase, 871 (29.1%) were referred to <it>Youth Check Your Risk </it>and 120 used it (13.8%). Major reasons for low referral rates reported by practitioners included lack of time, discomfort with raising the issue of testing, and difficulty in remembering to refer patients.</p> <p>Conclusion</p> <p>Offering an online sexual risk assessment tool in general practice did not significantly increase the proportion of young people tested for chlamydia, with GPs identifying a number of barriers to referring young people to <it>Youth Check Your Risk</it>. Future interventions aimed at increasing chlamydia screening in general practice with the aid of an online risk assessment tool need to identify and overcome barriers to testing.</p

Rapidity dependence of antiproton to proton ratios in Au+Au collisions at sqrt{s_{NN}}=130 GeV

Measurements, with the BRAHMS detector, of the antiproton to proton ratio at central and forward rapidities are presented for Au+Au reactions at sqrt{s_{NN}}=130 GeV, and for three different collision centralities. For collisions in the 0-40% centrality range we find $N(\bar{{\rm p}})/N({\rm p}) = 0.64 +- 0.04 (stat.) +- 0.06 (syst.) at y ~0, 0.66 +- 0.03 +- 0.06 at y ~ 0.7, and 0.41 +- 0.04 +- 0.06 at y ~ 2. The ratios are found to be nearly independent of collision centrality and transverse momentum. The measurements demonstrate that the antiproton and proton rapidity densities vary differently with rapidity, and indicate that a net-baryon free midrapidity plateau (Bjorken limit) is not reached at this RHIC energy.Comment: 8 pages, 3 figure

La polarisation des neutrons de la réaction de stripping 12C(d,n) 13N

The polarization of neutrons emitted from the stripping reaction 12C(d, n) 13CN has been investigated at the reaction angle θ lab = 15° and deuteron energy Ed = 12.9 MeV. The polarization of neutrons connected with the 3.56 MeV energy level in 13N nucleus was found to be — (0.39 ± 0.11). Also some general remarks concerning the preliminary results of the polarization of neutrons at the reaction angles 30°, 45° and 60° are given.On a étudié la polarisation des neutrons provenant de la réaction de stripping 12C(d, n) 13N pour l'angle θlab = 15° et l'énergie des deutérons Ed = 12,9 MeV. La valeur de la polarisation des neutrons liés avec le niveau énergétique 3,56 MeV du noyau résultant 13N fut déterminée : — (0,39 ± 0,11). On donne aussi quelques remarques générales sur les résultats préliminaires de la polarisation des neutrons pour les angles θ lab égaux à 30°, 45° et 60°