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.
15316082
Microlensing Constraints on the Frequency of Jupiter Mass Planets
Microlensing is the only technique likely, within the next 5 years, to constrain the frequency of Jupiter-analogs. The PLANET collaboration has monitored nearly 100 microlensing events of which more than 20 have sensitivity to the perturbations that would be caused by a Jovian-mass companion to the primary lens. No clear signatures of such planets have been detected. These null results indicate that Jupiter mass planets with separations of 1.5-3 AU occur in less than 1/3 of systems. A similar limit applies to planets of 3 Jupiter masses between 1-4 AU.
73625238
1318 new variable stars in a 0.25 square degree region of the Galactic plane
We conducted a deep photometric survey of a 0.5 ◦ × 0.5 ◦ area of the Galactic plane using the WFI instrument on the 2.2-m ESO telescope on La Silla, Chile. The dataset comprises a total of 267 R-band images, 204 from a 16 day observation run in 2005, supplemented by 63 images from a six week period in 2002. Our reduction employed the new numerical kernel difference image analysis method as implemented in the pysis3 code and resulted in more than 500 000 lightcurves of stars down to a magnitude limit of R ∼ 24.5. A search for variable stars resulted in the detection of 1318 variables of different types. 1011 of these are eclipsing or contact binary stars. A number of the contact binaries have low mass-ratios and several of the detached binaries appear to have low-mass components. Three candidate contact binaries have periods at the known cut off including two with periods lower than any previously published. Also identified are 3 possible pre-main sequence detached eclipsing binaries.
7459273
Limits on the Abundance of Galactic Planets From 5 Years of PLANET Observations
We search for signatures of planets in 43 intensively monitored microlensing events that were observed between 1995 and 1999. Planets would be expected to cause a short-duration (∼1 day) deviation on the smooth, symmetric light curve produced by a single lens. We find no such anomalies and infer that less than one-third of the ∼0.3 stars that typically comprise the lens population have Jupiter mass companions with semimajor axes in M, the range of . Since orbital periods of planets at these radii are 3–15 yr, the outer portion of 1.5 AU ! a ! 4A U this region is currently difficult to probe with any other technique. Subject headings: gravitational lensing — planetary systems — stars: late-type — stars: low-mass, brown dwarfs — techniques: photometric On-line material: color figure
119441536
Early estimation of microlensing event magnifications
Gravitational microlensing events with high peak magnifications provide a much-enhanced sensitivity to the detection of planets around the lens star. However, estimates of peak magnification during the early stages of an event by means of χ2 minimization frequently involve an overprediction, making observing campaigns with strategies that rely on these predictions inefficient. I show that a rudimentary Bayesian formulation, incorporating the known statistical characteristics of a detection system, produces much more accurate predictions of peak magnification than χ2 minimization. Implementation of this system will allow efficient follow-up observing programs that focus solely on events that contribute to planetary abundance statistics.
16391684
A short, nonplanetary, microlensing anomaly: Observations and light-curve analysis of MACHO 99-BLG-47
We analyze PLANET and MACHO observations of MACHO 99-BLG-47, the first nearly normal microlensing event for which high signal-to-noise ratio data reveal a well-covered, short-duration anomaly. This anomaly occurs near the peak of the event. Short-duration anomalies near the peak of otherwise normal events are expected to arise both from extreme-separation (either very close or very wide), roughly equalmass binary lenses and from planetary systems. We show that the lens of MACHO 99-BLG-47 is in fact an extreme-separation binary, not a planetary system, thus demonstrating for the first time that these two important classes of events can be distinguished in practice. However, we find that the wide-binary and closebinary lens solutions fit the data equally well and cannot be distinguished even at D� 2 ¼ 1. This degeneracy is qualitatively much more severe than the one identified for MACHO 98-SMC-1 because the present degeneracy spans two rather than one dimension in the magnification field and does not require significantly different blending fractions. In the Appendix, we explore this result and show that it is related to the symmetry in the lens equation. Subject headings: binaries: general — gravitational lensing — planetary systems
37640204
Future of the CERN intersecting storage rings
124894753
Forward physics with the 'pipetron'
56270364
Central exclusive production of hadrons in CDF
At the Fermilab Tevatron with s = 900 and 1960 GeV, we have studied exclusive double pomeron exchange in the Collider Detector at Fermilab, CDF. With ∼300,000 events we present the mass spectrum of two hadrons, h+h−, assumed to be pions, with |η(π)| 4.6. The mass spectrum shows resonance structures, including f0(980), f2(1270), and f0(1370). The cross section ratio 1960 GeV/900 GeV and the mean pT (pair) show massdependent structures, even above M = 2 GeV where there are no established π+π− resonances. The data extend above M = 5 GeV. We place an upper limit on exclusive χc0 →π+π− and K+K−.
122746097
Performance of a uranium/tetramethylpentane electromagnetic calorimeter
Abstract A calorimeter, consisting of uranium plates and thin liquid ionization chambers filled with tetramethylpentane (TMP) at room temperature, has been tested using electrons between 10 and 70 GeV. The essential characteristics of the liquid are discussed, including measurements of the free electron lifetime. Results on uniformity, linearity and energy resolution are described and some information on the response to hadrons has been obtained. A single TMP box containing four electrodes and a TMP position detector for electromagnetic showers have also been tested.
119986660
Missing mass spectra in pp inelastic scattering at total energies of 23 GeV and 31 GeV
Abstract Results are reported of measurements of the momentum spectra of protons emitted at small angles in inelastic reactions at the CERN ISR. The data are for total energies s 1 2 of 23 GeV and 31 GeV. The structure of the peak at low values of the missing mass M (of the system recoiling against the observed proton) is studied. The missing mass distributions have the form ( M 2 ) − B ( t ) where t is the four-momentum transfer squared. B ( t ) drops from 0.98±0.06 at t =−0.15 GeV 2 to 0.20±0.15 at t =−1.65 GeV 2 . The results are compared with a simple triple-Regge formula.