N. Menaa

Front end electronics and readout system for a gas radiator ring imaging Cherenkov detector using multi-anode photomultiplier tubes

We describe the design and performance of a novel custom made front end ASICs and their associated data acquisition (DAQ) system that we developed to process charge signals from an array of 53 Hamamatsu multi-anode photomultiplier tubes (MAPMTs) used as photon detectors for a ring imaging Cherenkov (RICH) detector. This system was tested as part of a gas radiator RICH prototype in the test beam facility at Fermilab. The VA MAPMT ASIC has 64 readout channels with built-in discriminator and parallel binary readout; features low noise, high dynamic range and is suitable for data driven architecture. We characterized a second iteration of this design that features higher dynamic range and optimum performance for large signals in our electronics laboratory test-setup

Comparison of D{yields}K{sub S}{sup 0}{pi} and D{yields}K{sub L}{sup 0}{pi} Decay Rates

We present measurements of D{yields}K{sub S}{sup 0}{pi} and D{yields}K{sub L}{sup 0}{pi} branching fractions using 281 pb{sup -1} of {psi}(3770) data at the CLEO-c experiment. We find that B(D{sup 0}{yields}K{sub S}{sup 0}{pi}{sup 0}) is larger than B(D{sup 0}{yields}K{sub L}{sup 0}{pi}{sup 0}), with an asymmetry of R(D{sup 0})=0.108{+-}0.025{+-}0.024. For B(D{sup +}{yields}K{sub S}{sup 0}{pi}{sup +}) and B(D{sup +}{yields}K{sub L}{sup 0}{pi}{sup +}), we observe no measurable difference; the asymmetry is R(D{sup +})=0.022{+-}0.016{+-}0.018. The D{sup 0} asymmetry is consistent with the value based on the U-spin prediction A(D{sup 0}{yields}K{sup 0}{pi}{sup 0})/A(D{sup 0}{yields}K{sup 0}{pi}{sup 0})=-tan{sup 2}{theta}{sub C}, where {theta}{sub C} is the Cabibbo angle.

Measurement of the Decay Constant f{sub D{sub s}{sup +}} Using D{sub s}{sup +}{yields}l{sup +}{nu}

We measure the decay constant f{sub D{sub s}{sup +}} using the D{sub s}{sup +}{yields}l{sup +}{nu} channel, where the l{sup +} designates either a {mu}{sup +} or a {tau}{sup +}, when the {tau}{sup +}{yields}{pi}{sup +}{nu}. Using both measurements we find f{sub D{sub s}{sup +}}=274{+-}13{+-}7 MeV. Combining with our previous determination of f{sub D{sup +}}, we compute the ratio f{sub D{sub s}{sup +}}/f{sub D{sup +}}=1.23{+-}0.11{+-}0.04. We compare with theoretical estimates.

Evidence for the Decay D{sup 0}{yields}K{sup -}{pi}{sup +}{pi}{sup -}e{sup +}{nu}{sub e}

Using a 281 pb{sup -1} data sample collected at the {psi}(3770) with the CLEO-c detector, we present the first absolute branching fraction measurement of the decay D{sup 0}{yields}K{sup -}{pi}{sup +}{pi}{sup -}e{sup +}{nu}{sub e} at a statistical significance of about 4.0 standard deviations. We find 10 candidates consistent with the decay D{sup 0}{yields}K{sup -}{pi}{sup +}{pi}{sup -}e{sup +}{nu}{sub e}. The probability that a background fluctuation accounts for this signal is less than 4.1x10{sup -5}. We find B(D{sup 0}{yields}K{sup -}{pi}{sup +}{pi}{sup -}e{sup +}{nu}{sub e})=[2.8{sub -1.1}{sup +1.4}(stat){+-}0.3(syst)]x10 = {sup -4}. By restricting the invariant mass of the hadronic system to be consistent with K{sub 1}(1270), we obtain the product of branching fractions B(D{sup 0}{yields}K{sub 1}{sup -}(1270)e{sup +}{nu}{sub e})xB(K{sub 1}{sup -}(1270){yields}K{sup -}{pi}{sup +}{pi}{sup -})=[2.5{sub -1.0} = {sup +1.3}(stat){+-}0.2(syst)]x10{sup -4}. Using B(K{sub 1}{sup -}(1270){yields}K{sup -}{pi}{sup +}{pi}{sup -})=(33{+-}3)%, we obtain B(D{sup 0}{yields}K{sub 1}{sup -}(1270)e{sup +}{nu}{sub e})=[7.6{sub -3.0}{sup +4.1}(stat){+-}0.6(syst){+-}0.7] = x10{sup -4}. The last error accounts for the uncertainties in the measured K{sub 1}{sup -}(1270){yields}K{sup -}{pi}{sup +}{pi}{sup -} branching fractions.

Observation of {psi}(3770){yields}{gamma}{chi}{sub c1}{yields}{gamma}{gamma}J/{psi}

From e(+)e(-) collision data acquired with the CLEO detector at the Cornell Electron Storage Ring, we observe the non-DD(_) decay Psi(3770))-->gammachi(c1) with a statistical significance of 6.6 standard deviations, using the two-photon cascades to J/Psi and J/Psi-->l(+)l(-). We determine sigma(e(=)e(-)-->Psi(3770))xBeta(Psi(3770)-->gammachi(c1))=(18.0 +/- 3.3 +/- 2.5) pb and branching fraction Beta(Psi(3770)-->gammachi(c1)=(2.8 +/- 0.5+/-0.4) x 10(-3). We set 90% C.L. upper limits for the transition to chi(c2) (chi(c0)): sigma x Beta<5.7 pb (<282 pb) and Beta<0.9 x 10(-3) (<44 x 10(-3)). We also determine Gamma(Psi(3770)gammachi(c1))/Gamma(Psi(3770)-->pi(+)pi(-)J/Psi)=1.5 +/- 0.3 +/- 0.3 (>1.0 at 90% C.L.), which bears upon the interpretation of X(3872).

Measurement of {gamma}{sub ee}(J/{psi}), {gamma}{sub tot}(J/{psi}), and {gamma}{sub ee}[{psi}(2S)]/{gamma}{sub ee}(J/{psi})

Using data acquired with the CLEO detector at the CESR e+e- collider at sqrt{s} = 3.773 GeV, we measure the cross section for the radiative return process e+e- --> gamma J/psi, J/psi --> mu+mu-, resulting in B(J/psi --> mu+mu-) x Gamma_ee(J/psi) = 0.3384 +- 0.0058 +- 0.0071 keV, Gamma_ee(J/psi) = 5.68 +- 0.11 +- 0.13 keV, and Gamma_tot(J/psi) = 95.5 +- 2.4 +- 2.4 keV, in which the errors are statistical and systematic, respectively. We also determine the ratio Gamma_ee[psi(2S)] / Gamma_ee(J/psi) = 0.45 +- 0.01 +- 0.02.

Beam test results of a C/sub 4/F/sub 8/O gas radiator Cherenkov detector using multi-anode photomultiplier tubes

We present the main results from a beam test done at Fermilab of a novel gaseous RICH detector that uses Hamamatsu multi-anode photomultiplier tubes (MAPMT) as photon detectors and a new gas C/sub 4/F/sub 8/O as a Cherenkov radiator. A novel front end electronics ASIC has been developed geared towards reading out the charge signals from the photon detectors. The ASIC features low noise and high dynamic range and is suitable for data driven architecture. The data acquisition system was developed to read 52 MAPMTs. An external trigger was used and the events were built using the time stamp information provided by the readout chips. We report the number of detected photons, the angular resolution per photon and the resolution per track after averaging over the photons. We also compare our measurements with simulations.

Evidence for B{sub s}{sup (*)}B{sub s}{sup (*)} Production at the {upsilon}(5S) Resonance

We use data collected by the CLEO III detector at the Cornell Electron Storage Ring to measure the inclusive yields of D{sub s} mesons as B({upsilon}(5S){yields}D{sub s}X)=(44.7{+-}4.2{+-}9.9)% and B({upsilon}(4S){yields}D{sub s}X)=(18.1{+-}0.5{+-}2.8)%. From these measurements, we make a model dependent estimate of the ratio of B{sub s}{sup (*)}B{sub s}{sup (*)} to the total bb quark pair production of (16.0{+-}2.6{+-}5.8)% at the {upsilon}(5S) energy.We use data collected by the CLEO III detector at CESR on the Upsilon(5S) resonance to measure the inclusive yield of Ds mesons. Comparing with data taken on the Upsilon(4S), which decays into lighter B mesons, we make a model dependent estimate of the ratio of Bs(*)anti-Bs(*) to the total b anti-b quark pair production at the Upsilon(5S) energy of (16.0+/-2.6+/-5.8)%.Using data collected by the CLEO III detector at CESR, we started a series of investigations on the Upsilon(5S) resonance decay properties. The data sample used for this analysis consists of 0.42 fb-1 of data taken on the Upsilon(5S) resonance, 6.34 fb-1 of data collected on the Upsilon(4S) and 2.32 fb-1 of data taken in the continuum below the Upsilon(4S). B_s mesons are expected to decay predominantly into D_s meson, while the lighter B mesons decay into D_s only about 10% of the time. We exploit this difference to make a preliminary model dependent estimate of the ratio of B_s(*) anti-B_s(*) to the total b anti-b quark pair production at the Upsilon(5S) energy to be (21 +- 3 +- 9)%.

Measurement of Absolute Hadronic Branching Fractions of D Mesons and e{sup +}e{sup -}{yields}DD Cross Sections at E{sub c.m.}=3773 MeV

Using 55.8 pb(-1) of e+e- collisions recorded at the psi(3770) resonance with the CLEO-c detector at CESR, we determine absolute hadronic branching fractions of charged and neutral D mesons using a double tag technique. Among measurements for three D0 and six D+ modes, we obtain reference branching fractions B(D0-->K-pi+)=(3.91+/-0.08+/-0.09)% and B(D+-->K-pi+pi+)=(9.5+/-0.2+/-0.3)%, where the uncertainties are statistical and systematic, respectively. Final state radiation is included in these branching fractions by allowing for additional, unobserved, photons in the final state. Using a determination of the integrated luminosity, we also extract the cross sections sigma(e+e- -->D0D0)=(3.60+/-0.07(+0.07)(-0.05)) nb and sigma(e+e- -->D+D-)=(2.79+/-0.07(+0.10)(-0.04)) nb.

Search for Rare and Forbidden Decays D{sup +}{yields}h{sup {+-}}e{sup {+-}}e{sup +}

Using 0.8 x 10(6) D+ D- pairs collected with the CLEO-c detector at the psi(3770) resonance, we have searched for flavor-changing neutral current and lepton-number-violating decays of D+ mesons to final states with dielectrons. We find no indication of either, obtaining 90% confidence level upper limits of B(D+ --> pi+ e+ e-) < 7.4 x 10(-6), B(D+ --> pi- e+ d+) < 3.6 x 10(-6), B(D+ --> K+ e+ e-) < 6.2 x 10(-6), and B(D+ --> K- e+ e+) < 4.5 x 10(-6).Using 0.8x10{sup 6} D{sup +}D{sup -} pairs collected with the CLEO-c detector at the {psi}(3770) resonance, we have searched for flavor-changing neutral current and lepton-number-violating decays of D{sup +} mesons to final states with dielectrons. We find no indication of either, obtaining 90% confidence level upper limits of B(D{sup +}{yields}{pi}{sup +}e{sup +}e{sup -})<7.4x10{sup -6}, B(D{sup +}{yields}{pi}{sup -}e{sup +}e{sup +})<3.6x10{sup -6}, B(D{sup +}{yields}K{sup +}e{sup +}e{sup -})<6.2x10{sup -6}, and B(D{sup +}{yields}K{sup -}e{sup +}e{sup +})<4.5x10{sup -6}.