Fermilab Collider Detector Research Articles

Tevatron Wij Anomaly for a Model with Two Different Mechanisms for Mass Generation of Gauge Fields

The latest Fermilab Collider Detector (CDF) anomaly, namely the excess of dijet events in the invariant-mass window 120–160 GeV in associated production with a W boson, is explained by a baryonic new neutral vector C-boson, of mass (145 GeV), predicted by the Wu mechanisms for mass generation of gauge field. The Standard Model (SM) W, Z-bosons normally get their masses through the coupling with the SM Higgs particle of mass 114–200 GeV. Here, the baryonic C-boson has negligible couplings with leptons and, thus, is unaffected by the dilepton C constraints.

The top quark, others new phenomena observed at the CDF in {ie359-1} collisions at √s = 1.96 TeV (Review)

Upgraded Tevatron luminosity in Run-II (started 2001) has opened a new level of modern heavy-quark studies compared to that one of Run-I. Now top event samples contain hundreds of event statistics for investigation. This review mainly covers the mass measurements of the top quark produced at √s = 1.96 TeV in {ie359-2} collisions at the Collider Detector of Fermilab with the integrated luminosity samples up to 1 fb−1. As an example of the top quark mass measurements we consider so-called Matrix Element method in “lepton + jets” and “dilepton” channels of the top-quark decay. The CDF top quark mass obtained in lepton +jets mode is the world most precise single measurement of this important physics parameter. The review summarizes the essential results of the CDF top-quark mass measurement achieved and published for the recent 2003–2008 period. We consider also b-quark baryon discoveries like Σb, Σb*, Θb as well as first observation of {ie359-3} oscillations. Let us mention here that a CDF/JINR-group created significant contribution to the new CDF complex and physics investigation.

Fermilab Tevatron Collider Group Goes Over the Top—Cautiously

The evidence from Fermilab's Collider Detector Facility group for a 174‐GeV/c2 top quark (see PHYSICS TODAY, May, page 20) has been received with cautious enthusiasm by the particle physics community. Since most physicists still have not seen the 153‐page preprint submitted on 22 April to Physical Review D, the demand for speakers on the result exceeds even CDF's abundant supply of experimenters. Still, it is unlikely that new developments will suppant CDF's present results before we've had time to digest them. the low top‐production rate, the large backgrounds—events that mimic top decay—and the complicated topologies of t‐quark decays all but ensure that the discovery of the t quark will be a protracted process rather than a single dramatic event. While awaiting new results from CDF and DO (the other detector at Fermilab's 1.8‐TeV pp̄ collider), it is appropriate to evaluate CDF's present evidence and to anticipate possible future developments.

Radial wire drift chambers for CDF forward tracking

We describe the design, construction, and operating experience of unique drift chambers with radially strung wires for the Collider Detector of Fermilab (CDF) [1] which cover forward and backward cone angles between 2° and 10°, and 170° and 178°. The chambers are capable of operating in our high rate and high track multiplicity environment with excellent multitrack resolution of 2–3 mm and high tracking accuracy of 140 μm per wire. Results from the recent running experience will be presented.

Construction and performance of silicon detectors for the small angle spectrometers of the collider detector of fermilab

The manufacturing process of a series of position sensitive silicon detectors is described together with the tests performed to optimize the performance of the detectors. The detectors are Schottky diodes with strips on the ohmic contract which allow to determine the position of the incoming ionizing particles by charge partition. Four detectors were assembled in a telescope and tested inside the vacuum pipe of the Tevatron Collider at Fermilab. The system is a prototype of the Small Angle Silicon Spectrometer, designed primarily to study p- p elastic and diffractive cross sections, and is a part of the Collider Detector of Fermilab (CDF). Several tests were performed to check the efficiency and the linearity of response of various regions of the detectors. Scans of the beam halo were also done both in high and low β optics to check how close to the beam the detectors could be operated. Finally, the dependence of the detector response on temperature and integrated radiation dose was investigated.

Radial Wire Drift Chambers for CDF Forward Tracking

Radial wire drift chambers have been built for the Collider Detector of Fermilab (CDF) to cover forward and backward cone angles between 20 and 100 and 170° and 178°. The chambers are built to provide good azimuthal track resolution, good multi-track resolutions, and high rate capability. Tests done using cosmic-rays and nitrogen UV-laser beam show that single wire resolution of 110 ?m and 68 ?m are obtainable, respectively. Construction details and test results are presented.

A Large Dynamic Range Charge Amplifier ADC for the Fermilab Collider Detector Facillity

A multi-channel charge amplifier ADC system for use with electromagnetic and hadronic calorimetry has been built with Xl and X16 amplifier channels which extend the range of the single 16 bit ADC to the equivalent of a 20 bit system having 0.7 fC least significant resolution. Two on-board calibration schemes, a fast analog trigger output, and redundant readout are also included. The point-wise error in linearity (expressed as the maximum error as a percentage of the full charge scale) is less than 0.02% for the Xl channels, and less than 0.002% for the X16 channels. Other features include a Before/After signal differencing scheme which provides low frequency noise rejection and compensation for baseline drifting, and temperature stability on the order of 30 ppm/C.

Software for Initializing Multi-Segment FASTBUS Systems

Before becoming fully operational, a FASTBUS system must be initialized; each segment interconnect (SI) must be downloaded with the correct route table, group address (GP) assignments must be made to each segment, etc. Furthermore, each system component must be initialized in the correct order; a given segment cannot be accessed until all SIs on the path to that segment have been initialized. It is desirable that the initialization procedure be automatic (i.e., requires no. human intervention), be driven from a database containing the system topology and information of all devices in the system, and assure that the system is placed in a completely specified state regardless of the initial state. This paper presents an algorithm for doing this whicn nas been successfully implemented at the Fermilab Collider Detector Facility (CDF).

Construction and testing of a 3 m diameter × 5 m superconducting solenoid for the fermilab collider detector facility (CDF)

A thin 3 m diameter × 5 m, 1.5 T superconducting solenoid for the Fermilab collider detector facility (CDF solenoid) was constructed. Cool-down and excitation tests of the solenoid were carried out. The design current is 5000 A and the stored magnetic energy is 30 × 10 6 J. The solenoid utilizes the forced flow cooling method of two-phase helium and does not have a permanent inner bobbin. The material thickness of the solenoid is 0.85 radiation length in the radial direction. An aluminum-stabilized NbTi/Cu superconductor fabricated with the EFT method was used. Radially outward magnetic forces must be supported with an outer support cylinder shrink-fitted outside the coil. The helium cooling tube of 20 mm in inner diameter and about 140 m in length was welded to the outer support cylinder. The maximum excitation current was limited to 2800 A in the present tests without an iron return yoke. Thermal response of the solenoid during the cool-down and excitation tests was very steady. A series of heater quench tests was attempted by using a heater installed at the outer support cylinder. The solenoid did not quench even for a heater input of about 10 kJ. In a warm-up test the liquid helium supply was shut off. The coil stayed superconducting for about 90 min and then the entire coil became normal very uniformly. This result is consistent with the measured heat load of the solenoid of about 35 W. The results of the present tests indicate the excellent thermal stability of the solenoid.

Fabrication and testing of the 3-m diameter superconducting solenoid and refrigeration system for the Fermilab Collider Detector

A large, 1.5-T conduction cooled superconducting solenoid for the Collider Detector at Fermilab was designed and built as part of a US-Japan international high-energy physics collaboration. Initial tests of the coil without its iron return yoke indicated that the coil performed as designed and should operate in a very stable manner when installed in the flux return iron at Fermilab. The refrigeration system for the solenoid has been installed and operated with a dummy load. The nominal 600-W capacity of the system was achieved in the initial test.

Radial Drift Chambers Fop CDF Forward Tracking

Radial wire drift chambers are built for the Collider Detector of Fermilab to cover forward and backward regions between 2° and 10° cones which will provide good azimuthal position information of tracks, good multi-track, and high rate capability. Results obtained from a prototype chamber show ? resolution of ?rms ? 130 ?m and a charge division accuracy of 0.7 percent along the wire (?,r) running in the saturated avalanche mode.

Design of an indirectly cooled 3-m diameter superconducting solenoid with external support cylinder for the Fermilab collider detector facility

A 3-m diameter, 5 m long superconducting thin solenoid with indirect cooling and an external support cylinder has been designed for the Fermilab Collider Detector Facility. An aluminum stabilized Nb-Ti superconductor produced by the extrusion with front tension (EFT) method is used. Radiation length for the solenoid is .831, and absorption length is .186.

Central shower counter prototype for the fermilab collider detector facility

The construction of a full scale prototype shower counter for the FNAL Collider Detector Facility central calorimetry is described in detail. Beam tests provide results on performance parameters.