A field-programmable gate array (FPGA) TDC for Fermilab SeaQuest (E906) experiment and its tests with a novel external wave union launcher
We developed a field-programmable gate array (FPGA) TDC module for the tracking devices of Fermilab SeaQuest (E906) experiment, including drift chamber, proportional tube and hodoscope. The requirement of time resolution is better than 4 ns. This 64-channel TDC is made of a 6U VMEbus unit equipped with a Microsemi ProASIC3 Flash based FPGA of low power and high radiation tolerance. The new FPGA firmware (Run2-TDC) is designed to reduce the data volume and data acquisition (DAQ) deadtime. The firmware digitizes multiple input hits of both polarities while allowing users to turn on a multiple-hit elimination logic to remove after-pulses in the wire chambers and proportional tubes. A scaler is fitted into the firmware of each channel to allow for recording the number of hits in its respective channel. The TDC resolution is determined by internal cell of 450 ps, and a measurement precision of 200 ps has been achieved. As a demonstration of constructing the Wave Union TDC using an existing multi-hit TDC without modifying its firmware, external wave union launchers are utilized in our test to improve the TDC's measurement precision. Measurement precision is nearly halved (108 ps) in data based on a four-edge wave union. An even larger improvement of measurement precision (69 ps) has been reached by combining the approaches of Wave Union TDC and multiple-channel ganging.

title: A Field-Programmable Gate Array (FPGA) TDC for the Fermilab SeaQuest (E906) Experiment and Its Test with a Novel External Wave Union Launcher
abstract: We developed a field-programmable gate array (FPGA) TDC module for the tracking detectors of the Fermilab SeaQuest (E906) experiment, including drift chambers, proportional tubes, and hodoscopes. This 64-channel TDC module had a 6U VMEbus form factor and was equipped with a low-power, radiation-hardened Microsemi ProASIC3 Flash-based FPGA. The design of the new FPGA firmware (Run2-TDC) aimed to reduce the data volume and data acquisition (DAQ) deadtime. The firmware digitized multiple input hits of both polarities while allowing users to turn on a multiple-hit elimination logic to remove after-pulses in the wire chambers and proportional tubes. A scaler was implemented in the firmware to allow for recording the number of hits in each channel. The TDC resolution was determined by an internal cell delay of 450 ps. A measurement precision of 200 ps was achieved. We used five kinds of tests to ensure the qualification of 93 TDCs in mass production. We utilized the external wave union launcher in our test to improve the TDC's measurement precision and also to illustrate how to construct the Wave Union TDC using an existing multi-hit TDC without modifying its firmware. Measurement precision was improved by a factor of about two (108 ps) based on the four-edge wave union. Better measurement precision (69 ps) was achieved by combining the approaches of Wave Union TDC and multiple-channel ganging.

title: Direct photon cross section with conversions at CDF
abstract: We present a measurement of the isolated direct photon cross section in pp collisions at {radical}(s)=1.8 TeV and |{eta}|<0.9 using data collected between 1994 and 1995 by the Collider Detector at Fermilab (CDF). The measurement is based on events where the photon converts into an electron-positron pair in the material of the inner detector, resulting in a two track event signature. To remove {pi}{sup 0}{yields}{gamma}{gamma} and {eta}{yields}{gamma}{gamma} events from the data we use a new background subtraction technique which takes advantage of the tracking information available in a photon conversion event. We find that the shape of the cross section as a function of photon p{sub T} is poorly described by next-to-leading-order QCD predictions, but agrees with previous CDF measurements.

title: RESEARCH ON THE TRANSVERSE STABILITY OF THE CENTRAL BEAM IN A WAKE FIELD ACCELERATOR

title: Measurement of the bottom-strange meson mixing phase in the full CDF data set.
abstract: We report a measurement of the bottom-strange meson mixing phase β(s) using the time evolution of B(s)(0)→J/ψ(→μ(+)μ(-))φ(→K(+)K(-)) decays in which the quark-flavor content of the bottom-strange meson is identified at production. This measurement uses the full data set of proton-antiproton collisions at √s=1.96 TeV collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.6 fb(-1) of integrated luminosity. We report confidence regions in the two-dimensional space of β(s) and the B(s)(0) decay-width difference ΔΓ(s) and measure β(s)∈[-π/2,-1.51]∪[-0.06,0.30]∪[1.26,π/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of β(s), we also determine ΔΓ(s)=0.068±0.026(stat)±0.009(syst) ps(-1) and the mean B(s)(0) lifetime τ(s)=1.528±0.019(stat)±0.009(syst) ps, which are consistent and competitive with determinations by other experiments.

title: Measurement of $\chi_{cJ}$ decaying into $p\bar{n}\pi^{-}$ and $p\bar{n}\pi^{-}\pi^{0}$
abstract: Using a data sample of $1.06 \times 10^{8}$ $\psip$ events collected with the BESIII detector in 2009, the branching fractions of $\chi_{cJ}\to p\bar{n}\pi^{-}$ and $ p\bar{n}\pi^{-}\pi^{0}$ ($J$=0,1,2) are measured{Throughout the text, inclusion of charge conjugate modes is implied if not stated otherwise.}. The results for $\chi_{c0}\to p\bar{n}\pi^{-}$ and $\chi_{c2}\to p\bar{n}\pi^{-}$ are consistent with, but much more precise than those of previous measurements. The decays of $\chi_{c1}\to p\bar{n}\pi^{-}$ and $ p\bar{n}\pi^{-}\pi^{0}$ are observed for the first time.

title: Search for anomalous production of multiple leptons in association with $W$ and $Z$ bosons at CDF
abstract: This paper presents a search for anomalous production of multiple low-energy leptons in association with a W or Z boson using events collected at the CDF experiment corresponding to 5.1 fb{sup -1} of integrated luminosity. This search is sensitive to a wide range of topologies with low-momentum leptons, including those with the leptons near one another. The observed rates of production of additional electrons and muons are compared with the standard model predictions. No indications of phenomena beyond the standard model are found. A 95% confidence level limit is presented on the production cross section for a benchmark model of supersymmetric hidden-valley Higgs production. Particle identification efficiencies are also provided to enable the calculation of limits on additional models.