A. Baumbaugh

Performance of multiclad scintillating and clear waveguide fibers read out with visible light photon counters

Abstract Measurements have been made of the performance of scintillating fibers read out with visible light photon counters (VLPCs). The light yields of single-clad and multiclad scintillating fibers have been compared. The experiment consisted of 3 m long scintillating fibers of 830 μm diameter optically coupled to 8 m long waveguide fibers of 965 μm diameter read out with HISTE-IV VLPCs. For the case of multiclad scintillating fiber and waveguide, an average of 6.2 photoelectrons was detected from the far end of the scintillating fiber if the fiber end was unmirrored, and 10.2 photoelectrons if the fiber end was mirrored. With this substantial photoelectron yield, minimum-ionizing tracks can be easily detected in fiber arrays, and excellent performance characteristics are expected for the fiber trackers designed for the D0 experiment at the Fermilab Tevatron Collider and the SDC experiment at the SSC Laboratory.

A scintillating fiber-optic active target (SFT) for studies of high energy photoproduction

A description is given of a high-resolution, gateable scintillating fiber target that has been developed for Fermilab Experiment E687 to study charm and beauty particle production and decay in high-energy photon interactions. The detector consists of a scintillating target of either GS1 cerium glass fibers or polystyrene fibers of 29- mu m cross section, a multistage image intensifier, and an intensified CCD or SIT/VIDICON camera system used in conjunction with a custom-built video data acquisition system. >

Development of new scintillating fiber detectors for high energy physics applications

The development of novel scintillating fiber detectors for colliding-beam and fixed target applications is considered. The authors present initial results from a developmental study of high-refractive-index liquid scintillators and the incorporation of these liquids in glass capillaries. Advantages of liquid-in-capillary fiber detectors include high efficiency and fast decay; the potential for high-resolution tracking, as light emission is expected to be local to the deposited ionization in liquids containing single solutes; the potential for good radiation resistance; and replaceability. >

A Scintillating Glass Fiber-Optic Active Target for Vertex Detection and Tracking Applications in High Energy Physics Experiments

A high resolution, fast gateable active target has been developed for Fermilab experiment E687 in order to study charm and beauty particle production and decay in high energy photon and hadron induced processes. The detector consists of a GS1 Cerium scintillating glass fiber-optic target, a multi-stage image intensifier and CCD camera system used in conjunction with a custom-built video data acquisition system. We currently detect ¿ 4 photoelectrons per mm with a resolution per photoelectron of ¿pe < 25¿m.

Radioactive source calibration technique for the CMS hadron calorimeter

Abstract Relative calibration of the scintillator tiles used in the hadronic calorimeter for the Compact Muon Solenoid detector at the CERN Large Hadron Collider is established and maintained using a radioactive source technique. A movable source can be positioned remotely to illuminate each scintillator tile individually, and the resulting photo-detector current is measured to provide the relative calibration. The unique measurement technique described here makes use of the normal high-speed data acquisition system required for signal digitization at the 40 MHz collider frequency. The data paths for collider measurements and source measurements are then identical, and systematic uncertainties associated with having different signal paths are avoided. In this high-speed mode, the source signal is observed as a Poisson photo-electron distribution with a mean that is smaller than the width of the electronics noise (pedestal) distribution. We report demonstration of the technique using prototype electronics for the complete readout chain and show the typical response observed with a 144 channel test beam system. The electronics noise has a root-mean-square of 1.6 least counts, and a 1 mCi source produces a shift of the mean value of 0.1 least counts. Because of the speed of the data acquisition system, this shift can be measured to a statistical precision better than a fraction of a percent on a millisecond time scale. The result is reproducible to better than 2% over a time scale of 1 month.

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.

Front end readout electronics for the CMS Hadron Calorimeter

The front-end electronics for the CMS Hadron Calorimeter provides digitized data at the beam interaction rate of 40 MHz. Analog signals provided by hybrid photodiodes (HPDs) or photomultiplier tubes (PMTs) are digitized and the data is sent off board through serialized fiber optic links running at 1600 Mbps. In order to maximize the input signal, the front-end electronics are housed on the detector in close proximity to the scintillating fibers or phototubes. To fit the electronics into available space, custom crates, backplanes and cooling methods have had to be developed. During the expected ten-year lifetime, the front-end readout electronics will exist in an environment where radiation levels approach 330 rads and the neutron fluence will be 1.3E11 n/cm/sup 2/. For this reason, the design approach relies heavily upon custom radiation tolerant ASICs. This paper will present the system architecture of the front-end readout crates and describe our results with early prototypes.

High Speed Video Data Acquisition System (VDAS) for H.E.P., Including Reference Frame Subtractor, Data Compactor and 16 Megabyte FIFO

A Video-Data-Acquisition-System (VDAS) has been developed to record image data from a scintillating glass fiber-optic target developed for High Energy Physics[ l],[2]. VDAS consists of a combination flash ADC, reference frame subtractor, high speed data compactor, an N megabyte First-In-First-Out (FIFO) memory (where N is a multiple of 4), and a single board computer as a control processor. System data rates are in excess of 30 megabytes/second. The reference frame subtractor, in conjunction with the data compactor, records only the differences from a standard frame. This greatly reduces the amount of data needed to record an image. Typical image sizes are reduced by as much as a factor of 20. With the exception of the ECL ADC board, the system uses standard TTL components to minimize power consumption and cost. VDAS operation as well as enhancements to the original system are discussed.

Liquid capillary scintillation detectors

Liquid-in-capillary detectors for tracking applications in high-energy physics experiments are discussed. The detectors consist of glass capillaries of low refractive index filled with liquids of sufficiently high refractive index to produce an efficient waveguides. The preparation of scintillating core liquids from the solvent 1-phenylnaphthalene and single solutes of selected fluorescent dyes is described. >

Observations of the coma of comet P/Halley and the outburst of 1986 March 24–25 (UT)

Observations using a fast CCD and custom built Video Data Acquisition System at the Nasmyth focus of the 2.3 meter telescope at Siding Spring Observatory, Australia produced digitized spectra and images of comet Halley. On March 25 (UT), an overall brightening and anti-sunward jet was recorded continuously over several hours and is shown to be consistent with the enhanced spectral activity recorded on March 24 (UT). The outburst and is consistent with the Giotto measurements. Preliminary analysis of the spectral enhancement of March 24 is presented. The time resolution system allowed a spectral range from 3800A to 7000A to be analyzed every 1/2 s. Indications of unexplained rapid variations in several molecular emmission band persist and are noted.