A search for the decay B+→K+ννˉB^+ \to K^+ \nu \bar{\nu}

We search for the rare flavor-changing neutral-current decay $B^+ \to K^+ \nu \bar{\nu}$ in a data sample of 82 fb$^{-1}$ collected with the {\sl BABAR} detector at the PEP-II B-factory. Signal events are selected by examining the properties of the system recoiling against either a reconstructed hadronic or semileptonic charged-B decay. Using these two independent samples we obtain a combined limit of ${\mathcal B}(B^+ \to K^+ \nu \bar{\nu})<5.2 \times 10^{-5}$ at the 90% confidence level. In addition, by selecting for pions rather than kaons, we obtain a limit of ${\mathcal B}(B^+ \to \pi^+ \nu \bar{\nu})<1.0 \times 10^{-4}$ using only the hadronic B reconstruction method.Comment: 7 pages, 8 postscript figures, submitted to Phys. Rev. Let

High-reflectivity broadband distributed Bragg reflector lattice matched to ZnTe

We report on the realization of a high quality distributed Bragg reflector with both high and low refractive index layers lattice matched to ZnTe. Our structure is grown by molecular beam epitaxy and is based on binary compounds only. The high refractive index layer is made of ZnTe, while the low index material is made of a short period triple superlattice containing MgSe, MgTe, and ZnTe. The high refractive index step of Delta_n=0.5 in the structure results in a broad stopband and the reflectivity coefficient exceeding 99% for only 15 Bragg pairs.Comment: 4 pages, 3 figure

EuFe2_2As2_2 under high pressure: an antiferromagnetic bulk superconductor

We report the ac magnetic susceptibility $\chi_{ac}$ and resistivity $\rho$ measurements of EuFe$_2$As$_2$ under high pressure $P$. By observing nearly 100% superconducting shielding and zero resistivity at $P$ = 28 kbar, we establish that $P$-induced superconductivity occurs at $T_c \sim$~30 K in EuFe$_2$As$_2$. $\rho$ shows an anomalous nearly linear temperature dependence from room temperature down to $T_c$ at the same $P$. $\chi_{ac}$ indicates that an antiferromagnetic order of Eu$^{2+}$ moments with $T_N \sim$~20 K persists in the superconducting phase. The temperature dependence of the upper critical field is also determined.Comment: To appear in J. Phys. Soc. Jpn., Vol. 78 No.

Measurement of the electron energy spectrum and its moments in inclusive B -> Xe nu decays

We report a measurement of the inclusive electron energy spectrum for semileptonic decays of B mesons in a data sample of 52 million Y(4S)-->B(B) over bar decays collected with the BABAR detector at the PEP-II asymmetric-energy B-meson factory at SLAC. We determine the branching fraction, first, second, and third moments of the spectrum for lower cutoffs on the electron energy between 0.6 and 1.5 GeV. We measure the partial branching fraction to be B(B-->Xenu,E-e>0.6 GeV)=[10.36+/-0.06(stat.)+/-0.23(sys.)]%

Improved measurement of CP asymmetries in B-0 ->(c(c)over-bar)K0((*)) decays

We present results on time-dependent CP asymmetries in neutral B decays to several CP eigenstates. The measurements use a data sample of about 227x10(6) Upsilon(4S)-> B (B) over bar decays collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. The amplitude of the CPasymmetry, sin2 beta in the standard model, is derived from decay-time distributions from events in which one neutral B meson is fully reconstructed in a final state containing a charmonium meson and the other B meson is determined to be either a B-0 or (0) from its decay products. We measure sin2 beta=0.722 +/- 0.040(stat)+/- 0.023(syst) in agreement with the standard model expectation

Reflectance Spectroscopy of Ferric Sulfate-Bearing Montmorillonites as Mars Soil Analog Materials

Spectroscopic analyses have shown that smecthites enhanced in the laboratory with additionalferric species exhibitimportant similarities to those of the soils on MArs. Ferrihydrite in these chemically treated smectites has features in the visible to near- infrared region that resemble the energies and band strengths of features in reflectance spectra observed for several bright regions on Mars. New samples have been prepared with sulfate as well, becauseS was found by Viking to be a major component in the surface materialon MArs. A suite of ferrihydrite-bearing and ferric sulfate-bearing montmorillonites, prepared with variable Fe3+ and S concentrations and variable pH conditions, has been analyzed using reflectance spectroscopy in the visible and infrared regions, Moessbauer spectroscopy at room temperature and 4 K, differential thermal analysis, and X-ray diffraction. These analyses support the formationof ferrihydrite of variable crystallinity in the ferrihydrite-bearingmontmorillonites and a combination of schwertmannite and ferrihydritein the ferric sulfate-bearing montmorillonites. Small quantities of poorly chrystalline and nanophase forms of other ferric materials mayalso be present in these samples. The chemical formation conditions of the ferrihydrite-bearing and ferric sulfate-bearing montmorillonites influence the character of the low temperature moessbauer sextets and the visible reflectance spectra. An absorptionminimum is observed at 0.88-0.89 muem in spectra of the ferric sulfate-bearing samples, and at 0.89-0.92 muem in spectra of the ferrihydrite-bearing montmorillonites. Moessbauer spectra of the ferric sulfate-bearing montmorillonites indicate variable concentrations of ferrihydrite and schwertmannite in the interlaminarspaces and along grain surfaces

Current status of the BIOFILMS ISS experiment: testing functionalized antimicrobial surfaces in space

Microbial biofilms are universally present in our environment. However, biofilms can be problematic since they can damage materials and pose a health risk. Especially during space travel, where crew health is top priority and failure of equipment is detrimental, methods for preventing biofilm formation are vital. Antimicrobial active metals, such as copper, have already shown their potential on Earth [1]. Furthermore, additional surface functionalization of copper surfaces through direct laser interference patterning using ultra short pulses (USP-DLIP) can increase the antimicrobial efficiency and biofilm inhibition for certain types of bacteria [2]. The spaceflight project “BIOFILMS” investigates the antimicrobial effect of these functionalized copper surfaces in microgravity by using a unique experimental setup on board the ISS. For this, three bacterial species Staphylococcus capitis subsp. capitis, Cupriavidus metallidurans and Acinetobacter radioresistens were selected. Copper and brass were selected as antimicrobial metals and steel is used as an inert reference. All three metals are tested with and without surface functionalization. For the experiment, specific hardware was developed that allows bacterial biofilm formation in liquid medium in immediate contact to the different surfaces. The first results from the Science Verification Test and Experiment Sequence test showed that the hardware is biocompatible with the selected bacterial species and is suitable for the scientific requirements and proposed experimental sequence. The first launch for BIOFILMS was in August 2021 with SpX 23 with the first set of samples. Aboard the ISS, the hardware was integrated into the KUBIK incubator inside the Columbus laboratory. In this incubator, the experiment was incubating at 20 °C for 14 days in microgravity (Space), 0.4 x g (Mars) and 1 x g (Earth) as control. The second and third set of samples will be launched in 2022. Preliminary experiments on Earth indicated that the functionalized copper surfaces have altered antimicrobial effects on the selected bacteria