208859927
Search for Radiative B-Hadron Decays in $p\bar{p}$ Collisions at $\sqrt{s}$ = 1.8 TeV
We have performed a search for radiative b-hadron decays using events produced in p (p) over bar collisions at roots=1.8 TeV and collected by the Collider Detector at Fermilab. The decays we considered were (B) over bar (0)(d)→(K) over bar*(0)(→K(-)pi(+))gamma, (B) over bar (0)(s)→phi(→K+K-)gamma, Lambda(b)(0)→Lambda(→ppi(-))gamma, and their charge conjugates. Two independent methods to identify photons from such decays were employed. In the first method, the photon was detected in the electromagnetic calorimeter. In the second method, the photon was identified by an electron-positron pair produced through the external photon conversion before the tracking detector volume. By combining the two methods we obtain upper limits on the branching fractions for the (B) over bar (0)(d), (B) over bar (0)(s), and Lambda(b)(0) radiative decays which, at the 95% confidence level, are found to be B((B) over bar (0)(d)→(K) over bar*(0)gamma) lt 1.4x10(-4), B((B) over bar (0)(s)→phigamma) lt 1.6x10(-4), and B(Λ(0)(b)→Lambdagamma) lt 1.9x10(-3).
208261990
Precision measurement of the top quark mass from dilepton events at CDF II
We report a measurement of the top quark mass, M{sub t}, in the dilepton decay channel of t{bar t} {yields} b{ell}{prime}{sup +} {nu}{sub {ell}}, {bar b}{ell}{sup -}{bar {nu}}{sub {ell}} using an integrated luminosity of 1.0 fb{sup -1} of p{bar p} collisions collected with the CDF II detector. We apply a method that convolutes a leading-order matrix element with detector resolution functions to form event-by-event likelihoods; we have enhanced the leading-order description to describe the effects of initial-state radiation. The joint likelihood is the product of the likelihoods from 78 candidate events in this sample, which yields a measurement of M{sub t} = 164.5 {+-} 3.9(stat.) {+-} 3.9(syst.) GeV/c{sup 2}, the most precise measurement of M{sub t} in the dilepton channel.
15082169
Search for Neutral Charmless B-Decays at Lep
Abstract A search for rare charmless decays of B d 0 and B s 0 mesons has been performed in the exclusive channels B d(s) 0 → ηη , B d(s) 0 → ηπ 0 and B d(s) 0 → π 0 π 0 . The data sample consisted of three million hadronic Z decays collected by the L3 experiment at LEP from 1991 through 1994. No candidate event has been observed and the following upper limits at 90% confidence level on the branching ratios have been set: Br ( B () d → ηη ) x 10 −4 , Br ( B () s → ηη ) x 10 −3 , Br ( B () d → ηφ () ) x 10 −4 , Br ( B () s → ηphi ; () ) x 10 −3 , Br ( B () d → phi ; () phi ; () ) x 10 −5 , Br ( B () s → phi ; () phi ; () ) x 10 −4 . These are the first experimental limits on B d 0 →ηη and on the B s 0 neutral charmless modes.
209835030
Alignment of the CMS Silicon Tracker during Commissioning with Cosmic Rays
This is the Pre-print version of the Article. The official published version of the Paper can be accessed from the link below - Copyright @ 2010 IOP
121196052
First results of the ISIS1 beam test
Abstract The in situ storage image sensor (ISIS) is a monolithic active pixel sensor with memory cells in each pixel. The memory cells are implemented as a CCD register. This and other features of the sensor make the ISIS an excellent device for detectors that will be used at the International linear collider (ILC), an electron-positron accelerator with a proposed centre-of-mass energy of around 500 GeV. The sensor can be made very thin while retaining a high signal-to-noise ratio. The memory cells can be read out between bunch trains at a relatively low clock speed, hence limiting power consumption. The actual signal charge is stored in potential wells and not on capacitors, minimizing the sensitivity to electromagnetic interference. This paper presents the results of the first beam test of the first ISIS prototype. The measurements made include the signal-to-noise ratio, position resolution and efficiency.
125107038
The effect of dead-timeless silicon strip readout at CDF II
The Run IIa CDF Silicon Upgrade has recently finished installation. The detector uses revision D of the SVX3 readout IC. This final revision incorporated new features in order to improve the potential of dead-timeless operation. This paper describes measurements of dead-timeless effects on silicon strip readout on the test bench. This paper also describes tests of the dynamic pedestal subtraction circuitry, which is shown to improve greatly the dead-timeless performance of the silicon systems.
18539160
First results from the arcminute cosmology bolometer array receiver
Abstract We review the first science results from the Arcminute Cosmology Bolometer Array Receiver (ACBAR); a multi-frequency millimeter-wave receiver optimized for observations of the Cosmic Microwave Background (CMB) and the Sunyaev–Zel’dovich (SZ) effect in clusters of galaxies. ACBAR was installed on the 2 m Viper telescope at the South Pole in January 2001 and the results presented here incorporate data through July 2002. We present the power spectrum of the CMB at 150 GHz over the range l=150–3000 measured by ACBAR as well as estimates for the values of the cosmological parameters within the context of ΛCDM models. We find that the inclusion of Ω Λ greatly improves the fit to the power spectrum. We also observe a slight excess of small-scale anisotropy at 150 GHz; if interpreted as power from the SZ effect of unresolved clusters, the measured signal is consistent with CBI and BIMA within the context of the SZ power spectrum models tested.
16229687
Sunyaev-Zeldovich Observations of Massive Clusters of Galaxies
We present detections of the Sunyaev‐Zeldovich Effect (SZE) at 150GHz and 275GHz for the X‐ray luminous z=0.299 cluster 1E0657‐67. These observations were obtained as part of an X‐ray, weak lensing, and SZE survey of nearby X‐ray bright clusters. The SZE maps were made with the ACBAR (150, 210, 275 GHz) bolometer array installed at the Viper telescope located at the South Pole. We also present preliminary results from a blind SZE cluster survey.