CLEO-c and CESR-c: A New Frontier in Weak and Strong Interactions

We report on the physics potential of a proposed conversion of the CESR machine and the CLEO detector to a charm and QCD factory: CLEO-c and CESR-c that will make crucial contributions to flavor physics in this decade and offers our best hope for mastering non-perturbative QCD which is essential if we are to understand strongly coupled sectors in the new physics that lies beyond the Standard Model.Comment: 11 pages, 8 figures, submitted to the proceedings of the 9th International Symposium on Heavy Flavor Physics, September 10-13, 2001, Caltech, Pasadena, US

Towards Coherent Neutrino Detection Using Low-Background Micropattern Gas Detectors

The detection of low energy neutrinos ($<$ few tens of MeV) via coherent nuclear scattering remains a holy grail of sorts in neutrino physics. This uncontroversial mode of interaction is expected to profit from a sizeable increase in cross section proportional to neutron number squared in the target nucleus, an advantageous feature in view of the small probability of interaction via all other channels in this energy region. A coherent neutrino detector would open the door to many new applications, ranging from the study of fundamental neutrino properties to true "neutrino technology". Unfortunately, present-day radiation detectors of sufficiently large mass ($>$ 1 kg) are not sensitive to sub-keV nuclear recoils like those expected from this channel. The advent of Micropattern Gas Detectors (MPGDs), new technologies originally intended for use in High Energy Physics, may soon put an end to this impasse. We present first tests of MPGDs fabricated with radioclean materials and discuss the approach to assessing their sensitivity to these faint signals. Applications are reviewed, in particular their use as a safeguard against illegitimate operation of nuclear reactors. A first industrial mass production of Gas Electron Multipliers (GEMs) is succinctly described.Comment: Presented at the 2002 IEEE Nuclear Science Symposium and Medical Imaging Conference, Norfolk VA, November 10-16. Submitted to IEEE Tran. Nucl. Sci. Five pages, eight figure

Medipix3 Demonstration and understanding of near ideal detector performance for 60 & 80 keV electrons

In our article we report first quantitative measurements of imaging performance for the current generation of hybrid pixel detector, Medipix3, as direct electron detector. Utilising beam energies of 60 & 80 keV, measurements of modulation transfer function (MTF) and detective quantum efficiency (DQE) have revealed that, in single pixel mode (SPM), energy threshold values can be chosen to maximize either the MTF or DQE, obtaining values near to, or even exceeding, those for an ideal detector. We have demonstrated that the Medipix3 charge summing mode (CSM) can deliver simultaneous, near ideal values of both MTF and DQE. To understand direct detection performance further we have characterized the detector response to single electron events, building an empirical model which can predict detector MTF and DQE performance based on energy threshold. Exemplifying our findings we demonstrate the Medipix3 imaging performance, recording a fully exposed electron diffraction pattern at 24-bit depth and images in SPM and CSM modes. Taken together our findings highlight that for transmission electron microscopy performed at low energies (energies <100 keV) thick hybrid pixel detectors provide an advantageous and alternative architecture for direct electron imagin

GEM Operation in Negative Ion Drift Gas Mixtures

The first operation of GEM gas gain elements in negative ion gas mixtures is reported. Gains up to several thousand were obtained from single-stage GEMs in carbon disulfide vapor at low pressure, and in mixtures of carbon disulfide with Argon and Helium, some near 1 bar total pressure.Comment: 7 pages, 3 figure

Measurement of the Neutron Lifetime by Counting Trapped Protons in a Cold Neutron Beam

A measurement of the neutron lifetime $\tau_{n}$ performed by the absolute counting of in-beam neutrons and their decay protons has been completed. Protons confined in a quasi-Penning trap were accelerated onto a silicon detector held at a high potential and counted with nearly unit efficiency. The neutrons were counted by a device with an efficiency inversely proportional to neutron velocity, which cancels the dwell time of the neutron beam in the trap. The result is $\tau_{n} = (886.6\pm1.2{\rm [stat]}\pm3.2{\rm [sys]})$ s, which is the most precise measurement of the lifetime using an in-beam method. The systematic uncertainty is dominated by neutron counting, in particular the mass of the deposit and the $^{6}$Li({\it{n,t}}) cross section. The measurement technique and apparatus, data analysis, and investigation of systematic uncertainties are discussed in detail.Comment: 71 pages, 20 figures, 9 tables; submitted to PR

Determination of the D0 -> K+pi- Relative Strong Phase Using Quantum-Correlated Measurements in e+e- -> D0 D0bar at CLEO

We exploit the quantum coherence between pair-produced D0 and D0bar in psi(3770) decays to study charm mixing, which is characterized by the parameters x and y, and to make a first determination of the relative strong phase \delta between doubly Cabibbo-suppressed D0 -> K+pi- and Cabibbo-favored D0bar -> K+pi-. We analyze a sample of 1.0 million D0D0bar pairs from 281 pb^-1 of e+e- collision data collected with the CLEO-c detector at E_cm = 3.77 GeV. By combining CLEO-c measurements with branching fraction input and time-integrated measurements of R_M = (x^2+y^2)/2 and R_{WS} = Gamma(D0 -> K+pi-)/Gamma(D0bar -> K+pi-) from other experiments, we find \cos\delta = 1.03 +0.31-0.17 +- 0.06, where the uncertainties are statistical and systematic, respectively. In addition, by further including external measurements of charm mixing parameters, we obtain an alternate measurement of \cos\delta = 1.10 +- 0.35 +- 0.07, as well as x\sin\delta = (4.4 +2.7-1.8 +- 2.9) x 10^-3 and \delta = 22 +11-12 +9-11 degrees.Comment: 37 pages, also available through http://www.lns.cornell.edu/public/CLNS/2007/. Incorporated referee's comment

New Measurements of Cabibbo-Suppressed Decays of D Mesons in CLEO-c

Using 281 pb^-1 of data collected with the CLEO-c detector, we report on first observations and new measurements of Cabibbo-suppressed decays of D mesons to 2, 3, 4, and 5 pions. Branching fractions of previously unobserved modes are measured to be: B(D^0\to pi^+pi^-pi^0pi^0)=(9.9\pm0.6\pm0.7\pm0.2\pm0.1)x10^-3, B(D^0\to\pi^+\pi^+\pi^-\pi^-\pi^0)=(4.1\pm0.5\pm0.2\pm0.1\pm0.0)x10^-3, B(D^+\to\pi^+\pi^0\pi^0)=(4.8\pm0.3\pm0.3\pm0.2)x10^-3, B(D^+\to\pi^+\pi^+\pi^-\pi^0)=(11.6\pm0.4\pm0.6\pm0.4)x10^-3, B(D^0\to\eta\pi^0)=(0.62\pm0.14\pm0.05\pm0.01\pm0.01)x10^-3, and B(D^0\to\omega\pi^+\pi^-)=(1.7\pm0.5\pm0.2\pm0.0\pm0.0)x10^-3. The uncertainties are from statistics, experimental systematics, normalization and CP correlations (for D^0 modes only). Improvements in other multi-pion decay modes are also presented. The D-->pi pi rates allow us to extract the ratio of isospin amplitudes A(Delta I=3/2)/A(\Delta I=1/2)=0.420\pm0.014(stat)\pm0.016(syst) and the strong phase shift of delta_I=(86.4+-2.8+-3.3) degrees, which is quite large and now more precisely determined.Comment: 9 pages postscript also available through http://www.lns.cornell.edu/public/CLNS/2005/, submitted to PR

Observation of the Hadronic Transitions Chi_{b 1,2}(2P) -> omega Upsilon(1S)

The CLEO Collaboration has observed the first hadronic transition among bottomonium (b bbar) states other than the dipion transitions among vector states, Upsilon(nS) -> pi pi Upsilon(mS). In our study of Upsilon(3S) decays, we find a significant signal for Upsilon(3S) -> gamma omega Upsilon(1S) that is consistent with radiative decays Upsilon(3S) -> gamma chi_{b 1,2}(2P), followed by chi_{b 1,2} -> omega Upsilon(1S). The branching ratios we obtain are Br(chi_{b1} -> omega Upsilon(1S) = 1.63 (+0.35 -0.31) (+0.16 -0.15) % and Br(chi_{b2} -> omega Upsilon(1S) = 1.10 (+0.32 -0.28) (+0.11 - 0.10)%, in which the first error is statistical and the second is systematic.Comment: submitted to XXI Intern'l Symp on Lepton and Photon Interact'ns at High Energies, August 2003, Fermila