CDF level 2 trigger upgrade Anikeev, K.; Bogdan, M.; Demaat, R. ...
IEEE transactions on nuclear science,
04/2006, Letnik:
53, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We describe the new CDF Level 2 Trigger, which was commissioned during Spring 2005. The upgrade was necessitated by several factors that included increased bandwidth requirements, in view of the ...growing instantaneous luminosity of the Tevatron, and the need for a more robust system, since the older system was reaching the limits of maintainability. The challenges in designing the new system were interfacing with many different upstream detector subsystems, processing larger volumes of data at higher speed, and minimizing the impact on running the CDF experiment during the system commissioning phase. To meet these challenges, the new system was designed around a general purpose motherboard, the PULSAR, which is instrumented with powerful FPGAs and modern SRAMs, and which uses mezzanine cards to interface with upstream detector components and an industry standard data link (S-LINK) within the system.
The Event Builder and Level 3 trigger systems of the CDF experiment at Fermilab are required to process about 300 events per second, with an average event size of ∼200 KB. In the event building ...process the event is assembled from 15 sources supplying event fragments with roughly equal sizes of 12–16 KB. In the subsequent commercial processor-based Level 3 trigger, the events are reconstructed and trigger algorithms are applied. The CPU power required for filtering such a high data throughput rate exceeds 45
000 MIPS. To meet these requirements a distributed and scalable architecture has been chosen. It is based on commodity components: VME-based CPU's for the data read out, an ATM switch for the event building and Pentium-based personal computers running the Linux operating system for the event processing. Event flow through ATM is controlled by a reflective memory ring. The roughly homogeneous distribution of the expected load allows the use of 100 Mbps Ethernet for event distribution and collection within the Level 3 system. Preliminary results from a test system obtained during the last year are presented.
Design and performance tests of the CDF time-of-flight system Paus, Ch; Grozis, C.; Kephart, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2001, Letnik:
461, Številka:
1
Journal Article
Recenzirano
The CDF
II detector contains a time-of-flight detector consisting of 216 scintillator bars of 279
cm length and 4×4
cm
2 cross-section located at a radius of 138
cm from the beam axis. The bars are ...installed on the inner surface of the CDF solenoid, which produces an axial field of 1.4
T. Nineteen-stage fine-mesh photomultiplier tubes are attached at both ends of the scintillator bars. Photostatistics limit the time-of-flight resolution, which is expected to be 100
ps. The primary physics motivation is K
± identification for improved neutral B meson flavor determination.
In the technical design report the event building process at Fermilab's CDF experiment is required to function at an event rate of 300 events/sec. The events are expected to have an average size of ...150 kBytes (kB) and are assembled from fragments of 16 readout locations. The fragment size from the different locations varies between 12 kB and 16 kB. Once the events are assembled they are fed into the Level-3 trigger which is based on processors running programs to filter events using the full event information. Computing power on the order of a second on a Pentium II processor is required per event. The architecture design is driven by the cost and is therefore based on commodity components: VME processor modules running VxWorks for the readout, an ATM switch for the event building, and Pentium PCs running Linux as an operation system for the Level-3 event processing. Pentium PCs are also used to receive events from the ATM switch and further distribute them to the processing nodes over multiple 100 Mbps Ethernets. Studies with a prototype of up to 10 VME readout modules and up to 4 receiving PCs are presented. This system is also a candidate for the CMS experiment at CERN.
We search for Z{sup '} bosons in dielectron events produced in pp collisions at {radical}(s)=1.96 TeV, using 0.45 fb{sup -1} of data accumulated with the Collider Detector at Fermilab II detector at ...the Fermilab Tevatron. To identify the Z{sup '}{yields}e{sup +}e{sup -} signal, both the dielectron invariant mass distribution and the angular distribution of the electron pair are used. No evidence of a signal is found, and 95% confidence level lower limits are set on the Z{sup '} mass for several models. Limits are also placed on the mass and gauge coupling of a generic Z{sup '}, as well as on the contact-interaction mass scales for different helicity structure scenarios.
A Time-of-Flight detector in CDF-II Acosta, D.; Ahn, M.; Anikeev, K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2004, Letnik:
518, Številka:
1
Journal Article
Recenzirano
A Time-of-Flight (TOF) detector, based on plastic scintillators and fine-mesh photomultipliers, has been added to the Collider Detector at Fermilab (CDF)-II experiment at the Tevatron
p
p
̄
collider. ...The primary physics motivation is to provide charged kaon identification to improve neutral B meson flavor determination. Besides that, the TOF detector found application in the CDF trigger system in implementation of highly ionizing particle, high multiplicity and cosmic rays triggers.
We present a measurement of the t{bar t} production cross section in p{bar p} collisions at {radical}(s)=1.96 TeV which uses events with an inclusive signature of significant missing transverse ...energy and jets. This is the first measurement which makes no explicit lepton identification requirements, so that sensitivity to W{yields}{tau}{nu} decays is maintained. Heavy flavor jets from top quark decay are identified with a secondary vertex tagging algorithm. From 311 pb{sup -1} of data collected by the Collider Detector at Fermilab, we measure a production cross section of 5.8{+-}1.2(stat){sub -0.7}{sup +0.9}(syst) pb for a top quark mass of 178 GeV/c2, in agreement with previous determinations and standard model predictions.
The authors report a search for the anomalous production of events with multiple charged leptons in p{bar p} collisions at {radical}s = 1.96 TeV using a data sample corresponding to an integrated ...luminosity of 346 pb{sup -1} collected by the CDF II detector at the Fermilab Tevatron. The search is divided into three-lepton and four-or-more-lepton data samples. They observe six events in the three-lepton sample and zero events in the {ge}4-lepton sample. Both numbers of events are consistent with standard model background expectations. Within the framework of an R-parity violating supergravity model, the results are interpreted as mass limits on the lightest neutralino ({bar {chi}}{sub 1}{sup 0}) and chargino ({bar {chi}}{sub 1}{sup {+-}}) particles. For one particular choice of model parameters, the limits are M({bar {chi}}{sub 1}{sup 0}) > 110 GeV/c{sup 2} and M({bar {chi}}{sub 1}{sup {+-}}) > 203 GeV/c{sup 2} at 95% confidence level; the variation of these mass limits with model parameters is presented.
The authors report the observation of B{sub s}{sup 0}-{bar B}{sub s}{sup 0} oscillations from a time-dependent measurement of the B{sub s}{sup 0}-{bar B}{sub s}{sup 0} oscillation frequency ...{Delta}m{sub s}. Using a data sample of 1 fb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron, they find signals of 5600 fully reconstructed hadronic B{sub s} decays, 3100 partially reconstructed hadronic B{sub s} decays, and 61,500 partially reconstructed semileptonic B{sub s} decays. They measure the probability as a function of proper decay time that the B{sub s} decays with the same, or opposite, flavor as the flavor at production, and they find a signal for B{sub s}{sup 0}-{bar B}{sub s}{sup 0} oscillations. The probability that random fluctuations could produce a comparable signal is 8 x 10{sup -8}, which exceeds 5{sigma} significance. They measure {Delta}m{sub s} = 17.77 {+-} 0.10(stat) {+-} 0.07(syst) ps{sup -1} and extract |V{sub td}/V{sub ts}| = 0.2050 {+-} 0.0007(exp{sub -0.0060}{sup +0.0081})(theor).
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