New limits on the β+\beta^{+}EC and ECEC processes in 120^{120}Te

New limits on the double beta processes for $^{120}$Te have been obtained using a 400 cm$^3$ HPGe detector and a source consisting of natural Te0$_2$ powder. At a confidence level of 90% the limits are $0.19\times 10^{18}$ y for the $\beta^+$EC$(0\nu + 2\nu)$ transition to the ground state, $0.75\times 10^{18}$ y for the ECEC$(0\nu + 2\nu)$ transition to the first 2$^+$ excited state of $^{120}$Sn (1171.26 keV) and $(0.19-0.6)\times 10^{18}$ y for different ECEC($0\nu$) captures to the ground state of $^{120}$Sn.Comment: 9 pages, 4 figures; v2: minor change

Anomalous oxygen isotope effect on the in-plane FIR conductivity of detwinned YBa2Cu316,18^{16,18}O6.9_{6.9}

We observe an anomalous oxygen isotope effect on the a-axis component of the far-infrared electronic response of detwinned YBa2Cu3$^{16,18}$O$_{6.9}$. For $^{18}$O a pronounced low-energy electronic mode (LEM) appears around 240 cm$^{-1}$. This a-axis LEM exhibits a clear aging effect, after one year it is shifted to 190 cm$^{-1}$. For $^{16}$O we cannot resolve a corresponding a-axis LEM above 120 cm$^{-1}$. We interpret the LEM in terms of a collective electronic mode that is pinned by `isotopic defects', i.e. by the residual $^{16}$O in the matrix of $^{18}$O.Comment: 10 pages, 2 figure

New Results from the X-ray and Optical Survey of the Chandra Deep Field South: The 300ks Exposure

We present results from 300 ks of X-ray observations of the Chandra Deep Field South. The field of the four combined exposures is now 0.1035 deg^2 and we reach a flux limit of 10^{-16} erg s^{-1} cm^{-2} in the 0.5-2 keV soft band and 10^{-15} erg s^{-1} cm^{-2} in the 2-10 keV hard band, thus a factor 2 fainter than the previous 120 ks exposure. The total catalogue is composed of 197 sources including 22 sources detected only in the hard band, 51 only in the soft band, and 124 detected in both bands. We have now the optical spectra for 86 optical counterparts. We compute the total contribution to the X-ray background in the 2-10 keV band, which now amounts to (1.45\pm 0.15)*10^{-11} erg cm^{-2} s^{-1} deg^{-2} (after the inclusion of the ASCA sources to account for the bright end) to a flux limit of 10^{-15} erg s^{-1} cm^{-2}. This corresponds to 60-90% of the unresolved hard X-ray background (XRB), given the uncertainties on its actual value.[ABRIDGED]Comment: 26 pages including 10 figures, ApJ accepted (scheduled for v560, Oct 10, 2001). Figure 10 replace

Infrared Hall effect in high Tc superconductors: Evidence for non-Fermi liquid Hall scattering

Infrared (20-120 cm-1 and 900-1100 cm-1) Faraday rotation and circular dichroism are measured in high Tc superconductors using sensitive polarization modulation techniques. Optimally doped YBCO thin films are studied at temperatures down to 15 K and magnetic fields up to 8 T. At 1000 cm-1 the Hall conductivity varies strongly with temperature in contrast to the longitudinal conductivity which is nearly independent of temperature. The Hall scattering rate has a T^2 temperature dependence but, unlike a Fermi liquid, depends only weakly on frequency. The experiment puts severe constraints on theories of transport in the normal state of high Tc superconductors.Comment: 8 pages, 3 figure

Perbandingan penggunaan grid dan teknik celah udara serta pengaruhnya terhadap pengurangan radiasi hambur

Telah dilakukan penelitian perbandingan penggunaan grid dan teknik celah udara serta pengaruhnya terhadap pengurangan radiasi hambur. Penelitian dilakukan dengan menggunakan grid linear yang berbeda rasio, terdiri dari. rasio 6 : 1, 10 : 1 dan 12 :1. Celah udara dibuat dengan mengatur jarak antara obyek dengan film sejauh 30 cm dan dilakukan penyinaran setiap interval 5 cm. Obyek penelitian berupa dua buah koin timbal masing-masing berdiameter 3 cm dan ketebalan 2 mm yang diletakkan dalarn wadah berukuran 22 cm x 16 cm x 18 cm dengan ketinggian air 16 cm. Faktor paparan yang digunakan adalah variasi tegangan tabung dan 50 kV sampai 120 kV dengan kenaikan interval tiap 10 kV, anus tabung 100 mA dan waktu penyinaran 0,40 detik serta jarak fokus ke film 90 cm. Penyinaran dilakukan tanpa grid terlebih dahulu dan hasilnya dibandingkan dengan penyinaran menggunakan grid serta variasi celah udara untuk diketahui tingkat perbaikan kontrasnya. Hasil penelitian menunjukkan bahwa diperoleh kesetaraan densitas dan kontras radiograf antara pemakaian grid rasio 6 1 dengan celah udara 20 cm pada faktor paparan 90 kV 40 mAs dan teknik celah udara 30 cm setara dengan grid rasio 10 : 1 dan 12 : 1 pada faktor paparan 100 kV 40 mAs. It have been done the comparitions experiment of using the grid and the air gap tecnique and the influence to the scatter radiation reducing. This experiment was done with using various linear grid with different ratio, such as 6 : 1, 10 : 1 and 12 : 1 ratio. Using air gap was done with drive the distance between object with interval 5 cm. The experimental object are two Pb coins. They have diameter 3 cm and the thickness 2 mm that put in the plastic box with size 12 cm X 16 cm X 18 cm with water high 16 cm. Exposure factor that using is tube. voltage Variation begin 50 kV till 120 kV, with interval increasing each 10 kV, tube current 100 mA and the exposure time 0,40 second. So, the focus distance to the film 90 cm. Exposure was done without grid first and the result was compare with sliding use grid with air gab variation to know the rate contrast make up. The experiment results show that get the density equelibrium and radiograph density between using grid with ratio 10 : 1 and 12 : 1 with air gap 30 cm at 100 kV 40 mAs and ratio grid 6 : 1 equivalen with air gap 20 cm at 90 kV 40 mAs. The rate magnification image is 1,3 % at the air gap 20 cm and 1,5 % at air gab 30 cm

PENGARUH DIAMETER PIPA KELUAR DAN DIMENSI BAK PENAMPUNG PADA ALIRAN AIR SISTEM VACUM

Vakum merupakan suatu kondisi dari udara / gas sekitar lingkungan tertentu dimana tekanan udara dibawah tekanan atmosfir,  dimana proses sistem vakum pengambilan sumber air dari permukaan yang rendah ke tempat yang lebih tinggi dapat memberikan alternatif yang lebih efisien kepada masyarakat. Penelitian ini mempelajari pengaruh diameter pipa keluar dan dimensi bak penampung pada sistem vacum. Pembuatan sistem vacum  dilakukan pada beberapa variasi yaitu variasi diameter pipa keluar dengan ukuran ½”, ¾”, dan 1”.  Dan variasi dimensi bak penampung dengan volume 30/40 cm, 36/40 cm, 50/80 cm, 80/120 cm, 100/120 cm,dan 120/120 cm. Dari hasil penelitian maka dapat disimpulkan bahwa diameter pipa keluar harus sama atau lebih kecil dari diameter pipa masuk agar debit yang dialirkan akan terus-menerus. Semakin besar diameter pipa keluar, semakin kecil debit air yang dihasilkan. Leher angsa berfungsi untuk mencegah udara dari luar tidak masuk ke dalam tabung yang dapat menyebabkan kekosongan di dalam tabung. Untuk mengalirkan air pada beda tinggi 2 m, maka ukuran bak penampung adalah 120/120cm, dengan pipa masuk ½”; pipa keluar ½”

The Neutral Hydrogen Bridge between M31 and M33

The Green Bank Telescope has been used to search for 21cm HI emission over a large area between the galaxies M31 and M33 in an attempt to confirm at 9.1 arcmin angular resolution the detection by Braun and Thilker (2004) of a very extensive neutral gas "bridge" between the two systems at the level NHI approximately 10^{17} cm^{-2}. We detect HI emission at several locations up to 120 kpc in projected distance from M31, at least half the distance to M33, with velocities similar to that of the galaxies, confirming the essence of the Braun and Thilker discovery. The HI does not appear to be associated with the extraplanar high-velocity clouds of either galaxy. In two places we measure NHI > 3 x 10^{18} cm^{-2}, indicative of concentrations of HI with ~10^5 solar masses on scales <2 kpc, but over most of the field we have only 5sigma upper limits of NHI <= 1.4 x 10^{18} cm^{-2}. In very deep measurements in two directions HI lines were detected at a few 10^{17} cm^{-2}. The absence of emission at another location to a 5sigma limit NHI <= 1.5 x 10^{17} cm^{-2} suggests that the HI bridge is either patchy or confined to within ~125 kpc of M31. The measurements also cover two of M31's dwarf galaxies, And II and And XV, but in neither case is there evidence for associated HI at the 5sigma level of 1.4 x 10^4 solar masses of HI for And II, and 9.3 x 10^3 solar masses for And XV.Comment: Submitted to the Astronomical Journa