J. Incandela

The Intermediate Silicon Layers (ISL) detector is currently being built as part of the CDF II detector upgrade project. The ISL detector will significantly improve tracking in the central region and, together with the Silicon Vertex detector, provide stand-alone 3D track information in the forward/backward regions. In this article, we present the quality of the production sensors manufactured by Hamamatsu Photonics, which account for roughly half of the silicon sensors used in the ISL detector.

A study of events containing at least four high transverse momentum jets and a search for double parton scattering (DPS) have been performed using data collected with the UA2 detector at the CERN pp Collider (√s=630 GeV). The results are in good agreement with leading order QCD calculations. A value of σDPS<0.82 nb at 95% confidence level (CL) is obtained for the DPS cross section.

The two-jet invariant mass spectrum as measured in the UA2 experiment is used to search for additional heavy vector bosons decaying to two-jets. The mass of an additional W boson that couples to fermions with a V+A form is constrained to be greater than 261 GeV to the 90% confidence level. A limit on the production cross section of additional W and Z bosons is given as a function of the boson mass. A limit on the production of excited quarks is also given as a function of the excited quark mass.

The W and Z bosons masses, mw and mz, are measured using saing samples of W→ev and Z→e+e− decays observed in pp collisions at √s=630 GeV. The ration is found to be mwmz=0.8813±0.0036 ± 0.0019. This gives a value sin2 θw = 0.2234 ± 0.0064 ± 0.0033, and in combination with precise mz measurements from LEP yields mw=80.35±0.33±0.17 GeV. This result is in good agreement with other experiments, and with the standard model for a top quark mass lighter than 250 GeV.

A search has been made with the upgraded UA2 experiment at the CERN pp Collider at s=630 GeV for multi-jet events with large transverse momentum imbalance in a data sample corresponding to an integrated luminosity of 7.4 pb−1. Under the assumption that the photino is the lightest stable supersymmetric (SUSY) particle, the data have been used to deduce lower limits in a minimal SUSY model for the squark (mq) and the gluino (mg) masses. The 90% CL bounds are mg> 74 GeV independent of mg, mg> 79 GeV independent of mg, and and m> 106 GeV for mq=mq=m.

The UA2 experiment has collected large samples of W and Z events during recent runs at the CERN pp Collider at s = 630 GeV. These samples have been used to perform precise measurements of the masses of the W and Z bosons. After a careful analysis of systematic errors, an improved result is obtained for the mass ratio mwmz. This provides a new value for the weak mixing parameter sin2θw. Furthermore, it can be combined with recent measurements of the Z mass from e+e− colliders to give an absolute measurement of the W mass, leading to the result mw=80.49±0.43 (stat) ± 0.24 (syst) GeV.

A study of the two-jet mass spectrum measured with the UA 2 calorimeter has revealed a signal from hadronic decays ofW andZ bosons above a large background. Production and decay properties of the signal have been measured. The combined production cross-section σ·B(W, Z → two jets) is 9.6±2.3 (stat.)±1.1 (syst.) nb, compared with an expectation of 5.8 nb calculated to order α s 2 . A limit on the production cross-section of additional heavy vector bosons decaying into two jets is given as a function of the boson mass.

The process pp→evγ+X is studied as √s=630 GeV. The observed signal is used to extract a direct measurement of the parameters κ and λ which define the magnetic dipole and electric quadrupole moments of the W boson and therefore the WWγ coupling. We find κ=1+2.6−2.2 and λ=0+1.7−1.8 and their 95% confidence limits −3.5<κ<5.9 and −3.6<λ<3.5. The results are model indepedent and in good agreement with the standard model values, κ=1 and λ=0.

The inclusive jet cross-section has been measured at the CERN pp Collider (s = 630 GeV) as a function of the jet transverse momentum (pT) and pseudorapidity (η) for pT values up to 180 GeV and for−2<η<2. The results are consistent with leading order QCD calculations, and a lower limit Λc>825 GeV (95% CL) is set on the quark compositeness scale Λc.

The large sample of W→eν events collected by the UA2 experiment at the CERN pp̄ collider between 1988 and 1990 has been used to determine the strong coupling constant αs. From a measurement of the ratio of the production rate of W events with one jet to that with no jets, αs has been extracted to second order in the MS̄ scheme: αs(M2w)=0.123±0.0.18(stat.)±0.017 (syst.).

The decays W → ev and Z → e+e− are studied in [ovbar|p]p collisions at √s=630 GeV. The products of production cross section and branching ratio are measured as σew=682±12±40 pb and σew=65.6±4.0±3.8 pb. The results are in good agreement with O(α2s) calculations of the production cross sections. Many systematic effects cancel in the ratio, R=10.4±0.70.6±0.3, which can be used to give an indirect measurement of the total width of the W boson: Γw=2.10±0.13±0.09 GeV. The width gives a limit on the top quark mass, mtop>53 GeV (95% CL), which is independent of the top decay mode.

The High Luminosity phase of the Large Hadron Collider will deliver 10 times more integrated luminosity than the existing collider, posing significant challenges for radiation tolerance and event pileup on detectors, especially for forward calorimetry. As part of its upgrade program, the Compact Muon Solenoid collaboration is designing a high-granularity calorimeter (HGCAL) to replace the existing endcap calorimeters. It will feature unprecedented transverse and longitudinal readout and triggering segmentation for both electromagnetic and hadronic sections. The electromagnetic section and a large fraction of the hadronic section will be based on hexagonal silicon sensors of 0.5–1 cm2 cell size, with the remainder of the hadronic section being based on highly-segmented scintillators with silicon photomultiplier readout. The intrinsic high-precision timing capabilities of the silicon sensors will add an extra dimension to event reconstruction, especially in terms of pileup rejection. First hexagonal silicon modules, using the existing Skiroc2 front-end ASIC developed for CALICE, have been tested in beams at Fermilab and CERN in 2016. We present results from these tests, in terms of system stability, calibration with minimum-ionizing particles and resolution (energy, position and timing) for electrons, and the comparisons of these quantities with GEANT4-based simulation.

The Collider Detector at Fermilab (CDF) pursues a broad physics program at Fermilab's Tevatron collider. Between Run II commissioning in early 2001 and the end of operations in September 2011, the Tevatron delivered 12 fb-1 of integrated luminosity of p-pbar collisions at sqrt(s)=1.96 TeV. Many physics analyses undertaken by CDF require heavy flavor tagging with large charged particle tracking acceptance. To realize these goals, in 2001 CDF installed eight layers of silicon microstrip detectors around its interaction region. These detectors were designed for 2--5 years of operation, radiation doses up to 2 Mrad (0.02 Gy), and were expected to be replaced in 2004. The sensors were not replaced, and the Tevatron run was extended for several years beyond its design, exposing the sensors and electronics to much higher radiation doses than anticipated. In this paper we describe the operational challenges encountered over the past 10 years of running the CDF silicon detectors, the preventive measures undertaken, and the improvements made along the way to ensure their optimal performance for collecting high quality physics data. In addition, we describe the quantities and methods used to monitor radiation damage in the sensors for optimal performance and summarize the detector performance quantities important to CDF's physics program, including vertex resolution, heavy flavor tagging, and silicon vertex trigger performance.

Results on the production cross sections ofW andZ bosons detected in the UA2 experiment are given based on a large sample ofW→eν andZ→e + e − decays. The measured cross sections are σ = 660±15(stat)±37(syst)pb, σ = 70.4±5.5(stat)±4.0(syst)pb and their ratioR=9.38 −0.72 +0.82 (stat)±0.25(syst). In the framework of the Standard Model, the measured value ofR is used to determine the total width of theW, Γ(W)=2.30±0.19(stat)±0.06(syst) GeV.

A measurement of the cross-sections for single and double prompt photon production in pp interactions at s = 630GeV is presented. The data sample corresponds to an integrated luminosity of 13.2 pb−1. The results are in good agreement with the predictions of perturbative QCD. The signal from double prompt photon production has a statistical significance of 4.3 standard deviations.

The upgraded UA 2 detector has collected data corresponding to a total integrated luminosity of 7.5 pb−1 from $$\bar pp$$ collisions at a centre of mass energy of 630 GeV during 1988 and 1989. A search has been performed for the production and decay of the top quark (t) or a member of a hypothetical fourth family (b′). No evidence has been found for such processes. Using the expected rates for production and decay branching ratios from the Standard Model, this implies that the top quark mass is greater than 69(71) GeV/c2, and that theb′ mass is greater than 54(57) GeV/c2, at 95(90)% confidence.

Data from high-energy physics (HEP) experiments are collected with significant financial and human effort and are mostly unique. An inter-experimental study group on HEP data preservation and long-term analysis was convened as a panel of the International Committee for Future Accelerators (ICFA). The group was formed by large collider-based experiments and investigated the technical and organisational aspects of HEP data preservation. An intermediate report was released in November 2009 addressing the general issues of data preservation in HEP. This paper includes and extends the intermediate report. It provides an analysis of the research case for data preservation and a detailed description of the various projects at experiment, laboratory and international levels. In addition, the paper provides a concrete proposal for an international organisation in charge of the data management and policies in high-energy physics.

We present a new method for the experimental determination of the top quark mass that is based upon the mean distance of travel of b hadrons in top quark events. The dominant systematic uncertainties of this method are not correlated with those of other methods, but alarge number of events is required to achieve small statistical uncertainty. Large ttbar event samples are expected from Run II of the Fermilab Tevatron and the CERN Large Hadron Collider (LHC). We show that by the end of Run II, a single experiment at the Tevatron could achieve a top quark mass uncertainty of ~5 GeV/c^2 by this method alone. At the CERN LHC, this method could be comparable to all others methods, which are expected to achieve an uncertainty of ~1.5 GeV/c^2 per experiment. This new method would provide a useful cross-check to other methods, and could be combined with them to obtain a substantially reduced overall uncertainty.

The process t→H+b, H+→τ+v, τ+→hadrons+v and its charge conjugate are investigated by seeking an excess in number of observed τ's beyond that expected from the standard model under the assumption of e-τ universality. No such excess is found and new regions of the mH−mt plane are excluded for B(H+→τv) = 0.5 and 1.0. In addition, the ratio of couplings of the τ and e to the W is precisely measured as gwτ/gwe = 1.02 ± 0.04(stat.)±0.04(syst.).

The transverse momentum distributions ofW andZ bosons produced in $$\bar pp$$ collisions at $$\sqrt s = 630 GeV$$ are examined. Comparisons are made with QCD predictions, and good agreement is found. The fraction ofW bosons produced withp T >25 GeV is found to be 3.8±0.6(stat) −1.3 +0.9 (syst)%.

The decay, , is dominant for a Standard Model Higgs boson in the mass range just above the exclusion limit of 114.4 GeV/c2 reported by the LEP experiments. Unfortunately, an overwhelming abundance of events arising from more mundane sources, together with the lack of precision inherent in the reconstruction of the Higgs mass, renders this decay mode a priori undetectable in the case of direct Higgs production at the LHC. It is therefore of no small interest to investigate whether can be observed in those cases where the Higgs is produced in association with other massive particles. In this note, the results of a study of Higgs bosons produced in association with top quarks and decaying via are presented. The study was performed as realistically as possible by employing a full and detailed Monte Carlo simulation of the CMS detector followed by the application of trigger and reconstruction algorithms that were developed for use with real data. Important systematic effects resulting from such sources as the uncertainties in the jet energy scale and the estimated rates for correctly tagging b jets or mistagging non-b jets have been taken into account. The impact of large theoretical uncertainties in the cross sections for plus N jets processes due to an absence of next-to-leading order calculations is also considered.

A search has been made for scalar leptoquark pair production with the upgraded UA2 detector at the CERN pp Collider at √s = 630 GeV, investigating decays of the leptoquark into a quark and either an electron or an electron neutrino. From an event sample corresponding to an integrated luminosity of 13 pb−1 a lower limit has been determined for the mass of first generation leptoquarks, yielding 67 GeV (95% CL) for a scalar leptoquark decaying with a 50% branching ratio into a quark and an electron.

The new FF-LYNX communication protocol, aiming at the fulfillment of non-homogeneous latency and bandwidth requirements of future High Energy Physics experiments, as well as its implementation into IP Cores available for ASICs development, are described in this paper. The first test-chip implementing FF-LYNX IP-Cores has been designed in the IBM 130 nm CMOS technology, adopting radiation hardening techniques. Transmitter and Receiver interfaces, designed in three different speed options, 4 × F, 8 × F and 16 × F (F=reference clock frequency), as well as different rad-hard FIFOs, constitute the overall architecture of the testchip. A detailed analysis of the area, power consumption and speed has been performed besides the functional characterization, by means of a configurable test-bed. X-ray irradiation tests have been carried out at CERN facilities to verify the Total Ionization Dose hardness of the interfaces, with their full functionality up to 40 Mrad(SiO2).

Abstract We report results of a study to determine how the performance of photomultipliers is affected by exposure to He. In our tests we monitor two 5 in. diameter EMI hemispherical photomultipliers while they are operated in He environments. Initially we observed He + afterpulses, at an approximately constant delay relative to the primary anode pulse. As the He gas pressure in the tubes increases however, strings of pulses typical of Townsend discharges occur. For the glass composition and geometry of the photomultipliers used in our tests, the internal gas concentration as a function of exposure to He is calculated using Fick's law for the permeation of solids by gases. The He permeation constant for the photomultiplier glass is obtained from a semiempirical formula developed by Altemose. We calculate the internal He concentration resulting from the He exposure which is observed to cause the regular occurrence of discharges and find that it is consistent with that required for production of discharges in the Townsend model. Guidelines are presented for using our results to estimate lifetimes of photomultiplier's of different geometries and glass types when operated in He environments.

A measurement of the gluon structure fusion using direct photon events observed with the UA2 detector in pp collisions at √s=630 GeV is presented. The x-range covered by this analysis is between 0.049 and 0.207 and the Q2 range is between 280 GeV2 and 3670 GeV2. The data sample corresponds to an integrated luminosity of 7.14 pb−1. The results are found to be in good agreement with the gluon distributions measured in deep inelastic scattering experiments extrapolated to the UA2 Q2 values.

In many research fields as high energy physics (HEP), astrophysics, nuclear medicine or space engineering with harsh operating conditions, the use of fast and flexible digital communication protocols is becoming more and more important. The possibility to have a smart and tested top-down design flow for the design of a new protocol for control/readout of front-end electronics is very useful. To this aim, and to reduce development time, costs and risks, this paper describes an innovative design/verification flow applied as example case study to a new communication protocol called FF-LYNX. After the description of the main FF-LYNX features, the paper presents: the definition of a parametric SystemC-based Integrated Simulation Environment (ISE) for high-level protocol definition and validation; the set up of figure of merits to drive the design space exploration; the use of ISE for early analysis of the achievable performances when adopting the new communication protocol and its interfaces for a new (or upgraded) physics experiment; the design of VHDL IP cores for the TX and RX protocol interfaces; their implementation on a FPGA-based emulator for functional verification and finally the modification of the FPGA-based emulator for testing the ASIC chipset which implements the rad-tolerant protocol interfaces. For every step, significant results will be shown to underline the usefulness of this design and verification approach that can be applied to any new digital protocol development for smart detectors in physics experiments.

Only one-sixth of the matter in our universe is made of the fundamental particles we understand. Understanding what the remaining "dark" matter is made of is one of the most important fundamental goals in modern science. It connects such disparate scientific areas as the formation of stars and galaxies, the earliest moments of our universe, and the constituents of matter at the smallest length scales. Astronomical evidence for dark matter has built steadily for eight decades, though the elementary particles or waves that constitute dark matter remain a mystery. Recent theoretical developments have highlighted the importance of searching for dark matter particles in the range from as heavy as a single hydrogen atom to the lightest mass consistent with galactic structure (30 orders of magnitude lighter). Remarkably, small projects at the $5M–$15M scale can explore key milestones throughout this range. By seizing these opportunities, we are now in a position to finally discover the nature of dark matter. The Particle Physics Project Prioritization Panel (P5) identified the search for dark matter as one of the five priority science drivers for the High-Energy Physics Program. The 2014 P5 report further recommended a portfolio of small projects to enable an uninterrupted flow of high-priority results. This Basic Research Needs (BRN) Report presents a program of small projects to lead to the discovery of the nature of dark matter. The program makes use of Department of Energy (DOE) facilities and infrastructure and is complementary to the ongoing Generation-2 (G2) dark matter program.

The top search in the dilepton and lepton plus jets channels with the Collider Detector at Fermilab is presented. The analysis uses a 67 pb{sup {minus}1} sample of p{bar p} collisions at 1.8 TeV. A 4.8{sigma} excess of candidate events establishes the existence of the top quark. The t{bar t} production cross section is measured to be {sigma}{sub t{bar t}} = 7.6{sub {minus}2.0}{sup +2.4} pb with branching Br(t {yields} Wb) = 0.87{sub {minus}0.30}{sup +0.13}(stat) {sub {minus}0.11}{sup +0.13}(syst). The measured mass is M{sub top} = 176{plus_minus}8{plus_minus}10 GeV.

In future HEP experiments the increased luminosity and the need of higher detector performance will push toward severe requirements on radiation hardness and power dissipation of hardware components. The use of “standard” and flexible protocols, modular architectures and IP-cores available to ASIC and FPGA designers will contribute to meet these requirements, while keeping development and production costs under control. The goal of the FF-LYNX project is the definition of a flexible protocol that allows the use of the same physical serial links and interfaces for the transmission of Timing, Trigger and Control (TTC) signals and Data Acquisition (DAQ). The protocol has been implemented in TX and RX interfaces based on serial electrical links designed as IP Cores. A test chip has been fabricated in the IBM 130nm CMOS technology. The architecture of the test interface and of the test chip will be presented together with preliminary results on area, speed and power consumption. Also the performance in terms of total ionization dose rad-tolerance will be reported.

The ratio of branching fractions of theW decaying to τ ande leptons is measured using $$\bar pp$$ collisions at $$\sqrt s = 630$$ GeV. The ratio of the electroweak charged current couplings to theW is then determined to beg /g =0.997±0.056 (stat.)±0.042 (syst.). The decay modeZ→τ+→τ+ is observed and also found to be consistent withe-τ universality.

The Intermediate Silicon Layers detector (ISL) is a large radius silicon tracker, installed in the CDF detector for the RUN II of the Tevatron Collider. With almost 4 m2 of double-sided silicon sensors and 300,000 electronic channels it represents the biggest system of this kind ever built. The construction and installation phases, the performed quality assurance tests as well as the problems encountered are reviewed. RUN II of the Tevatron officially started on March 1st, 2001. Although the CDF silicon system is still being commissioned, results on the performance of the ISL detector obtained using the first data are presented.

The innermost layer (L00) of the Run IIa silicon detector of CDF was planned to be replaced for the high luminosity Tevatron upgrade of Run IIb. This new silicon layer (L0) is designed to be a radiation tolerant replacement for the otherwise very similar L00 from Run IIa. The data are read out via long, fine-pitch, low-mass cables allowing the hybrids with the chips to sit at higher z(/spl sim/70 cm), outside of the tracking volume. The design and first results from the prototyping phase are presented. Special focus is placed on the amount and the structure of induced noise as well as signal-to-noise values.

We describe the characteristics of silicon microstrip sensors fabricated by Hamamatsu Photonics for the CDF Run 2b silicon detector. A total of 953 sensors, including 117 prototype sensors, have been produced and tested. Five sensors were irradiated with neutrons up to 1.4 /spl times/10/sup 14/ n/cm/sup 2/ as a part of the sensor quality assurance program. The electrical and mechanical characteristics are found to be superior in all aspects and fulfill our specifications. We comment on charge-up susceptibility of the sensors that employ a <100> crystal structure.

The various generations of Silicon Vertex Detectors (SVX, SVX', SVXII) for Collider Detector at Fermilab (CDF) at the Fermilab Tevatron have been fundamental tools for heavy-flavor tagging via secondary vertex detection. The CDF Run IIb Silicon Vertex Detector (SVXIIb) has been designed to be a radiation-tolerant replacement for the currently installed SVXII because SVXII was not expected to survive the Tevatron luminosity anticipated for Run IIb. One major change in the new design is the use of a single mechanical and electrical element throughout the array. This element, called a stave, carries six single-sided silicon sensors on each side and is built using carbon fiber skins with a high thermal conductivity on a foam core with a built-in cooling channel. A Kapton bus cable carries power, data and control signals underneath the silicon sensors on each side of the stave. Sensors are read out in pairs via a ceramic hybrid glued on one of the sensors and equipped with four SVX4 readout chips. This new design concept leads to a very compact mechanical and electrical unit, allowing streamlined production and ease of testing and installation. A description of the design and mechanical performance of the stave is given. Results on the electrical performance obtained using prototype staves are also presented.

The main building block and readout unit of the planned CDF Run IIb silicon detector is a "stave," a highly integrated mechanical, thermal, and electrical structure. One of its characteristic features is a copper-on-Kapton flexible cable for power, high voltage, data transmission, and control signals that is placed directly below the silicon microstrip sensors. The dense packaging makes deadtime-less operation of the stave a challenge since coupling of bus cable activity into the silicon sensors must be suppressed efficiently. The stave design features relevant for deadtime-less operation are discussed. The electrical performance achieved with stave prototypes is presented.

Results on the cross section for the production of electron pairs in pp collisions at √s = 630 GeV are presented. The measured value is σ = 405 ± 51 (syst.) ± 84 (syst.) pb, in the invariant mass interval 10 < m< 70 GeV. The results are compared to recent theoretical calculations which include O(αs2) QCD contributions. The comparison of these data with those of lower energy experiments show approximate scaling as a function of the variable √τ =m√s.

A search for supersymmetric decays of the Z boson into a pair of scalar electrons or winos (partners of the electron and W boson) has been made with the upgraded UA2 experiment at the CERN pp collider at s= 630GeV. The analysis of the sample of electron pairs, corresponding to an integrated luminosity of 7.4 pb−1, shows no evidence for such exotic decays. The 90% confidence level lower mass limits obtained exclude selectron masses up to e40 GeV/c2 in the case of a light photino, and wino masses up to 45 GeV/c2 in the case of a light scalar neutrino.

We present three measurements of the top quark mass in the lepton plus jets channel with 1.9 fb-1 of data using quantities with minimal dependence on the jet energy scale in the lepton plus jets channel at CDF. One measurement uses the mean transverse decay length of b-tagged jets (L2d) to determine the top mass, another uses the transverse momentum of the lepton (LepPt) to determine the top mass, and a third measurement uses both variables simultaneously. Using the L2d variable we measure a top mass of 176.7 (+10.0) (-8.9) (stat) +/- 3.4 (syst) GeV/c^2, using the LepPt variable we measure a top mass of 173.5 (+8.9) (-9.1) (stat) +/- 4.2 (syst) GeV/c^2, and doing the combined measurement using both variables we arrive at a top mass result of 175.3 +/- 6.2 (stat) +/- 3.0 (syst) GeV/c^2. Since some of the systematic uncertainties are statistically limited, these results are expected to improve significantly if more data is added at the Tevatron in the future, or if the measurement is done at the LHC.

Results are given on a search for the decay W±→π±γ with the UA2 detector in pp collisions at √s=630 GeV. No signal for such a process is observed and upper limits on the ration R=Γ(W±→π±γ)/Γ(W±→e±v)<4.9×10−3 and on the branching ratio BR(W±→π±γ)<5.4×10−4 are derived at 95% confidence level.

Abstract The Intermediate Silicon Layers Detector is presently being built as part of the CDF upgrades to prepare for the next Tevatron data taking run, scheduled to start in the year 2000. The ISL will be located in the radial region between the Silicon Vertex Detector and the Central Outer Tracker. It will add tracking in the forward region and significantly improve tracking in the central region. Together with the SVX II, the ISL forms a standalone, 3D silicon tracker. In this article we present the design of the ISL and the current status of its construction.

We propose the construction and installation of a layer of silicon microstrips at very small radius. The additional layer would improve track purity and result in more precise and uniform track impact parameter measurements by CDF II with corresponding improvements in high pT b tagging and overall pattern recognition that would result in greater sensitivity to a low mass higgs. It would also improve performance of CDF II for B physics and SUSY searches. The basic readout element would be individual, single sided, axial strip sensors ~10 cm long. A readout pitch of 50 μm is considered along with the possibility of alternating strips for an overall 25 μm pitch to provide hit position resolution of order ‐6 μm. The sensors take advantage of recent LHC designs for high bias voltages that enable good signal-to-noise ratios after extreme radiation doses. Layer 00 would be expected to significantly outlive the innermost layer of SVX II despite a two-fold greater radiation exposure rate. It would thus allow the possibility of extended high pT data taking. It would also provide CDF experience with new radiation hard microstrip detectors that could lead to a straightforward upgrade of the inner layers of SVX II for Run III with minimal downtime. Thus, Layer 00 is the first step toward maximizing CDF II data taking with a commensurate enhancement of the ability of CDF II to detect a low mass higgs or SUSY signal in the pre-LHC era. The overall costs, manpower, and schedule for the construction of Layer 00 are reasonable and achievable within the CDF II upgrade schedule.

We present three measurements of the top quark mass in the lepton plus jets channel with 1.9fb 1 of data using quantities with minimal dependence on the jet energy scale in the lepton plus jets channel at CDF. One measurement uses the mean transverse decay length of b-tagged jets (L2d) to determine the top mass, another uses the transverse momentum of the lepton (LepPt) to determine the top mass, and a third measurement uses both variables simultaneously. Using the L2d variable we measure a top mass of (176.7 +10.0 8.9 (stat)± 3.4(syst)) GeV/c 2 , using the LepPt variable we measure a top mass of (173.5 +8.9 9.1 (stat)± 4.2(syst)) GeV/c 2 , and doing the combined measurement using both variables we arrive at a top mass result of (175.3 ± 6.2(stat) ± 3.0(syst)) GeV/c2. Since some of the systematic uncertainties are statistically limited, these results are expected to improve significantly if more data is added at the Tevatron in the future, or if the measurement is done at the LHC.

This note details the infrastructure deployed and developed at the University of California at Santa Barbara (UCSB) to handle the construction of CMS Silicon Tracker modules for the outer barrel and endcap. Capacity has been developed to assemble and wirebond 15 modules per day and in addition to wirebond 30 hybrids. Early results and experiences of production are also given. In the £rst substantial module build, 5.3% of 150 modules were slightly outside of the mechanical speci£cations. Based on the data obtained during that build, it was possible to introduce correction factors which resulted in the 58 subsequent modules constructed being all within speci£cations. For module bonding a very low introduced failure rate of only 0.005% is observed. A higher corresponding rate for hybrid bonding of 0.022%, is attributable to one particular batch of problematic hybrids.

We present the results of a search for third generation leptoquark (LQ) pairs in 110{plus_minus}8pb{sup -1} of {bar p}p collisions at {radical}(s)=1.8TeV recorded by the Collider Detector at Fermilab. We assume third generation leptoquarks decay to a {tau} lepton and a b quark with branching ratio {beta}. We observe one candidate event, consistent with standard model background expectations. We place upper limits on {sigma}({bar p} p{r_arrow}LQ{ovr LQ}){center_dot}{beta}{sup 2} as a function of the leptoquark mass M{sub LQ}. We exclude at 95{percent} confidence level scalar leptoquarks with M{sub LQ}{lt}99GeV/c{sup 2}, gauge vector leptoquarks with M{sub LQ}{lt}225GeV/c{sup 2}, and nongauge vector leptoquarks with M{sub LQ}{lt}170GeV/c{sup 2} for {beta}=1. {copyright} {ital 1997} {ital The American Physical Society}

We have searched for anomalous production of missing E{sub T}thinsp(E/ {sub T}) , jets, leptons (e,thinsp{mu},thinsp{tau}) , b quarks , or additional photons in events containing two isolated, central ({vert_bar}{eta}{vert_bar}{lt}1.0) photons with E{sub T}{gt}12 GeV . The results are consistent with standard model expectations, with the possible exception of one event that has in addition to the two photons a central electron, a high-E{sub T} electromagnetic cluster, and large E/{sub T} . We set limits using two specific supersymmetry scenarios for production of diphoton events with E/{sub T} . {copyright} {ital 1998} {ital The American Physical Society}

A new technique to measure the ratio of [ital b] quark fragmentation fractions in p[bar p] collisions is described. Using a 70-pb[sup [minus]1] sample of low-mass dimuon trigger data recorded with the Collider Detector at Fermilab, we identify [ital B] mesons by observing the double semileptonic decays b[r arrow]c[mu]X with c[r arrow]s[mu]X. By counting the numbers of K[sup [asterisk]](892)[sup 0], K[sup [asterisk]](892)[sup +], and [phi](1020) mesons produced in association with these muon pairs, we measure the ratio of strange to nonstrange [ital B] meson production to be f[sub s]/(f[sub u]+f[sub d])=[21.0[plus minus]3.6(stat)[sub [minus]3.0][sup +3.8](syst)][percent]. This measurement is the most precise available from hadron collisions to date. Limits on the branching fractions of semileptonic charm meson decays with K[sub 1](1270), K[sub 1][sup [asterisk]](1410), and K[sub 2][sup [asterisk]](1430) mesons in the final state are also obtained. [copyright] [ital 1999] [ital The American Physical Society]

We report a measurement of the fraction of dijet events with a rapidity gap between jets produced by color-singlet exchange in {ovr p}p collisions at {radical} (s) =630 GeV at the Fermilab Tevatron. In events with two jets of transverse energy E{sup jet}{sub T}{gt}8 GeV , pseudorapidity in the range 1.8{lt}{vert_bar}{eta}{sup jet}{vert_bar}{lt}3.5 and {eta}{sub 1}{eta}{sub 2}{lt}0 , the color-singlet exchange fraction is found to be R=[2.7{plus_minus}0.7(stat){plus_minus}0 .6(syst)]{percent} . Comparisons are made with results obtained at {radical} (s) =1800 GeV and with theoretical expectations. {copyright} {ital 1998} {ital The American Physical Society }

We present a study of J/{psi} and {psi}(2S) production in p{bar p} collisions, at {radical}(s)=1.8 TeV with the CDF detector at Fermilab. The J/{psi} and {psi}(2S) mesons are reconstructed using their {mu}{sup +}{mu}{sup {minus}} decay modes. We have measured the inclusive production cross section for both mesons as a function of their transverse momentum in the central region, {vert_bar}{eta}{vert_bar}{lt}0.6 . We also measure the fraction of these events originating from b hadrons. We thus extract individual cross sections for J/{psi} and {psi}(2S) mesons from b -quark decays and prompt production. We find a large excess (approximately a factor of 50) of direct {psi}(2S) production compared with predictions from the color singlet model. {copyright} {ital 1997} {ital The American Physical Society}

A strong signal for double parton (DP) scattering is observed in a 16pb{sup {minus}1} sample of {bar p}p{r_arrow}{gamma}/{pi}{sup 0}+3jets+X data from the CDF experiment at the Fermilab Tevatron. In DP events, two separate hard scatterings take place in a single {bar p}p collision. We isolate a large sample of data ({approximately}14000 events) of which 53{percent} are found to be DP. The process-independent parameter of double parton scattering, {sigma}{sub eff}, is obtained without reference to theoretical calculations by comparing observed DP events to events with hard scatterings in separate {bar p}p collisions. The result {sigma}{sub eff}=(14.5{plus_minus}1.7{sub {minus}2.3}{sup +1.7})mb represents a significant improvement over previous measurements, and is used to constrain simple models of parton spatial density. The Feynman x dependence of {sigma}{sub eff} is investigated and none is apparent. Further, no evidence is found for kinematic correlations between the two scatterings in DP events. {copyright} {ital 1997} {ital The American Physical Society}

We present results of a search for W{sup +}W{sup -} production through the leptonic decay channel W{sup +}W{sup -}{r_arrow}l{sup +}l{sup -}{nu}{ovr {nu}} in {ovr p}p collisions at {radical}(s)=1.8TeV. In a 108pb{sup -1} data sample recorded with the Collider Detector at Fermilab, five W{sup +}W{sup -} candidates are found with an expected standard model background of 1.2{plus_minus}0.3 events. The W{sup +}W{sup -} production cross section is measured to be {sigma}({ovr p}p{r_arrow} W{sup +}W{sup -})=10.2{sup +6.3}{sub -5.1}(stat){plus_minus}1.6(syst)pb, in agreement with the standard model prediction. Limits on WW{gamma} and WWZ anomalous couplings are presented. {copyright} {ital 1997} {ital The American Physical Society}

We present measurements of correlated b{bar b} cross sections, {mu}-{mu} correlations, the average B{sup 0}{bar B}{sup 0} mixing parameter {bar {chi}}, and a limit on the {ital CP}-violating parameter {epsilon}{sub B}. For these measurements, we use muon pairs from b{bar b} double semileptonic decays. The data used in this analysis were taken with the Collider Detector at Fermilab and represent an integrated luminosity of 17.4{plus_minus}0.6 pb{sup {minus}1}. The results concerning b{bar b} production correlations are compared to predictions of next-to-leading order QCD computations. {copyright} {ital 1997} {ital The American Physical Society}

We have searched for heavy neutral gauge bosons (Z{sup {prime}}) in dielectron and dimuon decay modes using 110 pb{sup {minus}1} of {ital {bar p}}{ital p} collisions at {radical}(s)=1.8 TeV collected with the Collider Detector at Fermilab. We present a limit on the production cross section times branching ratio of a Z{sup {prime}} boson decaying into dileptons as a function of Z{sup {prime}} mass. For mass M{sub Z{sup {prime}}}{gt}600 GeV /c{sup 2}, the upper limit is 40fb at 95% confidence level. We set the lower mass limits of 690, 590, 620, 595, 565, 630, and 600 GeV/c{sup 2} for Z{sup {prime}}{sub SM}, Z{sub {psi}}, Z{sub {eta}}, Z{sub {chi}}, Z{sub I}, Z{sub LR}, and Z{sub ALRM}, respectively. {copyright} {ital 1997} {ital The American Physical Society}

The decay {Lambda}{sub b}{sup 0}{r_arrow}J/{psi}{Lambda} is observed in 110 pb{sup {minus}1} of p{bar p} collisions taken at {radical}(s)=1.8 TeV. These data are used to measure a {Lambda}{sub b}{sup 0} mass of 5621{plus_minus}4(stat){plus_minus}3(syst) MeV/c{sup 2}, and a mass difference between the {Lambda}{sub b}{sup 0} and the B{sup 0} of 340{plus_minus}5(stat){plus_minus}1(syst) MeV/c{sup 2}. The production cross-section times branching fraction for the decay {Lambda}{sub b}{sup 0}{r_arrow}J/{psi}{Lambda} relative to that for the decay B{sup 0}{r_arrow}J/{psi}K{sub S}{sup 0} has been measured to be 0.27{plus_minus}0.12(stat){plus_minus}0.05(syst). {copyright} {ital 1997} {ital The American Physical Society}

We search for new particles that decay into b{ovr b} and are produced with W bosons in p{ovr p} collisions at {radical}(s)=1.8 TeV . The search uses 109{plus_minus}7 pb{sup {minus}1} accumulated by the CDF experiment at Fermilab. We select events with an e{nu} or {mu}{nu} , and two jets, one of them b tagged. The number of events and the two-jet mass distribution are consistent with expectations. Using W+Higgs production as a model for the acceptance, we set an upper limit on the production cross section times branching ratio for the new particle ranging from 14 to 19pb (95{percent} C.L.) as the particle mass varies from 70 to 120 GeV/c{sup 2} . {copyright} {ital 1997} {ital The American Physical Society}

We present a measurement of the t{bar t} production cross section in p{bar p} collisions at {radical}(s)=1.8 TeV using an integrated luminosity of 109 pb{sup {minus}1} collected with the Collider Detector at Fermilab. The measurement uses t{bar t} decays into final states which contain one or two high transverse momentum leptons and multiple jets, and final states which contain only jets. Using acceptances appropriate for a top quark mass of 175 GeV/c{sup 2} , we find {sigma}{sub t{bar t}}=7.6{sup +1 .8}{sub {minus}1.5} pb . {copyright} {ital 1998} {ital The American Physical Society}

We present the first measurement of the jet pseudorapidity distribution in direct photon events from a sample of p{bar p} collisions at {radical} (s) =1.8TeV, recorded with the Collider Detector at Fermilab. Quantum chromodynamics (QCD) predicts that these events are primarily from hard quark-gluon Compton scattering, qg{r_arrow}q{gamma}, with the final state quark producing the jet of hadrons. The jet pseudorapidity distribution in this model is sensitive to parton momentum fractions between 0.015 and 0.15. We find that the shape of the measured pseudorapidity distribution agrees well with next-to-leading order QCD calculations. {copyright} {ital 1997} {ital The American Physical Society}

The top search in the lepton plus jets channel with the Collider Detector at Fermilab (CDF) is presented. The analysis uses a 67 pb−1 data sample of pp̄ collisions at √s=1.8 TeV. Soft lepton tagging (SLT) and secondary vertex tagging (SVX) of b jets are used to reduce backgrounds. A significant excess of events over expected backgrounds is seen, and together with the excess of observed events in the dilepton (DIL) channel, firmly establish the existence of the top quark. Combining all channels, the tt̄ production cross section is measured to be σtt̄=7.6−2.0+2.4 pb. The Branching of top to Wb is measured to be Br(t→Wb)=0.87+0.13−0.30(stat)+0.13−0.11(syst).

The top search in the lepton plus jets channel with the Collider Detector at Fermilab (CDF) is presented. The analysis uses a 67 pb{sup {minus}1} data sample of p{bar p} collisions at {radical}s = 1.8 TeV. Soft lepton tagging (SLT) and secondary vertex tagging (SVX) of b jets are used to reduce backgrounds. A significant excess of events over expected backgrounds is seen, and together with the excess of observed events in the dilepton (DIL) channel, firmly establish the existence of the top quark. Combining all channels, the t{bar t} production cross section is measured to be {sigma} {sub t{bar t}} = 7.6{sub -2.0}{sup +2.4} pb. The Branching of top to Wb is measured to be Br(t {yields} Wb) = 0.87{sub -0.30}{sup +0.13}(stat) {sub -0.11}{sup +0.13}(syst).