R.S. Moore

Overview of the Tevatron collider complex: goals, operations and performance

For more than two decades the Tevatron proton-antiproton collider was the centerpiece of the worlds high energy physics program. The collider was arguably one of the most complex research instruments ever to reach the operation stage and is widely recognized for numerous physics discoveries and for many technological breakthroughs. In this article we outline the historical background that led to the construction of the Tevatron Collider, the strategy applied to evolution of performance goals over the Tevatrons operational history, and briefly describe operations of each accelerator in the chain and achieved performance.

Beam instrumentation for the Tevatron collider

The Tevatron in Collider Run II (2001-present) is operating with six times more bunches and many times higher beam intensities and luminosities than in Run I (1992-1995). Beam diagnostics were crucial for the machine start-up and the never-ending luminosity upgrade campaign. We present the overall picture of the Tevatron diagnostics development for Run II, outline machine needs for new instrumentation, present several notable examples that led to Tevatron performance improvements, and discuss the lessons for future colliders.

Beam test of a 12-layer scintillating-fiber charged-particle tracking system

Abstract A 96-channel, 3-superlayer, scintillating-fiber tracking system has been tested in a 5 GeV/ cπ − beam. The scintillating fibers were 830 μm in diameter, spaced 850 μm apart, and 4.3 m in length. They were coupled to 6 m long, clear fiber waveguides and finally to visible light photon counters. A spatial resolution of ∼ 150 μm for a double-layered ribbon was achieved with this tracking system. This first prototype of a charged-particle tracking system configured for the Solenoidal Detector Collaboration at the Superconducting Super Collider is a benchmark in verifying the expected number of photoelectrons from the fibers.

Correction of second order chromaticity at Tevatron

Correction of the second order betatron tune chromatic - ity is essential for operation at the working point near half integer resonance which is proposed as one of the ways to improve performance of the Tevatron. In this report the new chromaticity correction scheme with split sextupole families is described. Details of implementation and commissioning at the present working point are discussed.

Effects of hadron irradiation on scintillating fibers

Trackers based on scintillating-fiber technology are being considered by the Solenoidal Detector Collaboration at SSC and the DO collaboration at Fermilab. Some 600 fibers in the Fermilab Tevatron CO area were irradiated, thereby obtaining a hadronic irradiation at realistic rates. Four-meter-long samples of ten Bicron polystyrene-based fibre types, maintained in air, dry nitrogen, argon, and vacuum atmospheres within stainless-steel tubes, were irradiated for seven weeks at various distances from the accelerator beam pipes. Maximum doses, measured by thermoluminescence detectors, were about 80 krad. Fiber properties, particularly light yield and attenuation length, were measured over a one-year period. A description of the work together with the results is presented. At the doses achieved, corresponding to a few years of actual fiber-tracking detector operation, little degradation was observed. Recovery after several days exposure to air was noted. Properties of unirradiated samples kept in darkness show no changes after one year. >

Scintillating fibers and waveguides for tracking applications

A test facility to study the light-transmission properties of scintillating fiber waveguides for tracking applications in high-energy physics is being developed. A light-tight box 2 m in length has been built, and data acquisition hardware and software is in place for testing various aspects of scintillating fibers and waveguides. Scintillating fibers have been excited with radioactive sources, ultraviolet light sources, and light-emitting diodes. Various photodetectors such as photomultiplier tubes, photodiodes, charge-coupled devices and solid-state photomultipliers have been utilized to detect the transmitted light. Studies of attenuation length and transmission through splices are presented. >

Longitudinal dynamics and tomography in the Tevatron

Motivated by the desire to understand the longitudinal effects of beam-beam forces, we study the longitudinal dynamics of protons and anti-protons at injection energy and top energy in the Tevatron. Multi-turn data of the longitudinal profiles are captured to reveal information about frequencies of oscillation, and changes in the bunch distributions. Tomographic reconstruction is used to create phase space maps which are subsequently used to find the momentum distributions. Changes in these distributions for both proton and anti-proton beams are also followed through the operational cycle. We report on the details of interesting dynamics during injection, acceleration and collisions.

Tevatron Instrumentation: Boosting Collider Performance

The Tevatron in Collider Run II (2001‐present) is operating with six times more bunches and many times higher beam intensities and luminosities than in Run I (1992–1995). Beam diagnostics were crucial for the machine start‐up and the never‐ending luminosity upgrade campaign. We present the overall picture of the Tevatron diagnostics development for Run II, outline machine needs for new instrumentation, present several notable examples that led to Tevatron performance improvements, and discuss the lessons for the next big machines — LHC and ILC.

Simulation studies of a scintillating fiber tracker for the SDC detector

Abstract Six design options for a scintillating fiber inner tracker for the SDC detector operating at the Superconducting Super Collider (SSC) are simulated. Concentric cylindrical configurations of axial fiber superlayers, ranging from four to six in number, are considered. Tracks from events generated by Pythia 4.8 at rates up to ten times design luminosity are swum through the tracker. Algorithms for reconstructing tracks of physics interest with p T > 10 GeV/ c among a background of low p T tracks are described. The optimum configuration found permits level 1 triggering up to η = 2.3 at ten times design luminosity. Inclusion of additional stereo fibers in this configuration permits level 2 stereo reconstruction up to eight times design luminosity.

Studies of visible light photon counters with fast preamplifiers

Scintillating fiber tracking detectors are being developed for the SDC experiment at Superconducting Super Collider (SSC) and the upgrade of the D0 detector at the Fermilab Tevatron. The many attractive features of a fiber tracker include good position resolution, low occupancy, low mass in the active volume, and excellent resistance to radiation damage. An additional important feature, especially at the SSC, is the intrinsically prompt response time of a scintillating fiber. The photodetector of choice is the visible light phonon counter (VLPC), a device which combines high rate capability with high quantum efficiency at visible wavelengths. To realize the high rate capability of the VLPC requires the implementation of a suitable, fast preamplifier. Until recently, studies of fibers and VLPCs with radioactive sources and cosmic rays have been performed under low rate conditions using transimpedance amplifiers (TIAs). The authors report on the response characteristics of a fiber-VLPC system coupled to a variety of fast preamplifiers, including QPA02, VTX, and TVC devices. Their performance is compared with that of a transimpedance amplifier.<<ETX>>