119493694
H alpha equivalent width variations across the face of a microlensed K giant in the galactic bulge
We present Very Large Telescope FORS1 spectroscopy that temporally resolves the second caustic crossing of the Galactic bulge K giant source of microlensing event EROS 2000-BLG-5, the first time this has been accomplished for several phases of a caustic transit. The similar to1 Angstrom H alpha equivalent width of the source star increases slightly as the center of the star egresses the caustic and then plummets by 30% during the final limb crossing. These changes are not seen in contemporaneous spectra of control stars in the FORS1 slit but are qualitatively consistent with expectations from stellar atmosphere models as the caustic differentially magnifies different portions of the stellar face of the target. Observations such as these in a variety of stellar lines are equivalent to atmospheric tomography and are expected to provide a direct test of stellar models.
118468268
The PLANET microlensing campaign: Implications for planets around galactic disk and bulge stars
With round-the-clock monitoring of galactic bulge microlensing events, the PLANET experiment constrains the abundance and can yield the discovery of planets down to the mass of earth around galactic disk and bulge stars. Data taken until 1999 imply that less than 1/3 of bulge M-dwarfs are surrounded by jupiter-mass companions at orbital radii between 1 and 4 AU. The current rate of microlensing alerts allows 15-25 jupiters and 1-3 earths to be probed per year.
15769177
Limits on Stellar and Planetary Companions in Microlensing Event OGLE-1998-BUL-14
We present the PLANET photometric data set for OGLE-1998-BUL-14, a high-magnification (A(max) similar to 16) event alerted by the OGLE collaboration toward the Galactic bulge in 1998. The PLANET data set consists a total of 461 I-band and 139 V-band points, the majority of which was taken over a 3 month period. The median sampling interval during this period is about 1 hr,and the I sigma scatter over the peak of the event is 1.5%. The excellent data quality and high maximum magnification of this event make it a prime candidate to search for the short-duration, low-amplitude perturbations that are signatures of a planetary companion orbiting the primary lens. The observed light curve for OGLE-1998-BUL-14 is consistent with a single lens (no companion) within photometric uncertainties. We calculate the detection efficiency of the light curve to lensing companions as a function of the mass ratio and angular separation of the two components. We find that companions of mass ratio greater than or equal to 0.01 are ruled out at the 95% significance level for projected separations between 0.4 and 2.4r(E), where r(E) is the Einstein ring radius of the primary lens. Assuming that the primary is a G dwarf with r(E) similar to 3 AU, our detection efficiency for this event is similar to 60% for a companion with the mass and separation of Jupiter and similar to 5% for a companion with the mass and separation of Saturn. Our efficiencies for planets like those around nu And and 14 Her are >75%.
15485017
The Spatially Resolved Mass Function of the Globular Cluster M22
Hubble Space Telescope imaging of M22 has allowed, for the first time, a detailed and uniform mapping of mass segregation in a globular cluster. Luminosity and mass functions from the turnoff down to the mid to lower main sequence are presented for M22 in annular bins from the center of the cluster out to five core radii. Within the core, a significant enhancement is seen in the proportion of 0.5-0.8 M☉ stars compared with their numbers outside the core. Numerical modeling of the spatial mass spectrum of M22 shows that the observed degree of mass segregation can be accounted for by relaxation processes within the cluster. The global cluster mass function for M22 is flatter than the Salpeter initial mass function and cannot be represented by a single power law.
54000022
Waveform digitization for high resolution timing detectors with silicon photomultipliers
Abstract The results of time resolution studies with silicon photomultipliers (SiPMs) read out with high bandwidth constant fraction discrimination electronics were presented earlier [1–3] . Here we describe the application of fast waveform digitization readout based on the DRS4 chip [4] , a switched capacitor array (SCA) produced by the Paul Scherrer Institute, to further our goal of developing high time resolution detectors based on SiPMs. The influence of the SiPM signal shape on the time resolution was investigated. Different algorithms to obtain the best time resolution are described, and test beam results are presented.
56225334
Double Pomeron Exchange: the early years
I review the early experimental searches for double pomeron exchange, the first observations at the CERN Intersecting Storage Rings (ISR) and further studies at the SPS and Tevatron (fixed target). I only have space for a superficial coverage of some highlights, and will not cover later colliders with s>100 GeV.
126196482
ELASTIC SCATTERING OF POSITIVE KAONS ON POLARIZED PROTONS BETWEEN 0.87 AND 2.74 GeV/c. RESULTS AND PHASE-SHIFT ANALYSIS.
Abstract Polarization and differential cross-section data at 16 momenta between 0.86 and 2.74 GeV/ c are presented. (Preliminary data on some of the momenta have been published earlier.) In an energy-independent phase-shift analysis from threshold up to 2.5 GeV/ c , resonant-like as well as non-resonant solutions are found for the P 3 wave. An helicity flip-non-flip decomposition of the partial waves partly supports the indications found in the analyses of other reactions that the pomeron is built up mainly from s -channel helicity non-flip contributions.
54863271
QCD in hadron hadron collisions
Quantum Chromodynamics provides a good description of many aspects of high energy hadron-hadron collisions, and this will be described, along with some aspects that are not yet understood in QCD. Topics include high ET jet production, direct photon, W , Z and heavy avor production, rapidity gaps and hard di raction. Supported by DOE Contract through Fermilab Contracts
82550552
Search for stable particles of charge 1 and mass deuteron mass
In a search for stable massive particles of charge q ⩾ 1 at the CERN ISR (√s = 53 GeV) no new particle in the mass range q × 2.4 GeV < m ≲ 30 GeV has been found among 3.1 × 107 recorded secondaries. At x = 2pL/√s = 0.21 and pT = 0.21 GeV/c the deuteron to π+ ratio is (1.3±0.2) × 10−4 and the antideuteron to π− ratio is (7.6±2.3) × 10−6. for (anti)tritons upper limits of (t/π+) < 5 × 10−7and (t/π−7) < 5 × 10−7 have been obtained.