B. 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.

Scintillating Glass, Fiber-Optic Plate Detectors for Active Target and Tracking Applications in High Energy Physics Experiments

We have been developing a scintillating glass fiber-optic imaging system for active target and tracking applications in high energy physics experiments, Extensive measurements have been performed on several scintillating-glass compositions, one of which is a silicate-glass containing 0. 6 mole % of Ce2O3 known commercially as NRL glass. For this material, fabricated into coherent fiber-optic plates of 10 ¿m and 25 ¿m diameter cladded-glass fibers, we have observed: (1) clear particle tracks and interactions; and (2) a yield of ~ 2 photoelectrons per millimeter of path length for minimum ionizing particles, Additionally, for the bulk NRL glass formed in disks of 1 diameter and 4 mm thickness, we have observed a ~80% retention of optical transmission through 4 mm of material at 395 nm (the peak of the fluorescence spectrum) for a radiation dose in excess of 107 rads acquired over several days. Results of these tests and others suggest that Ce2O3 based scintillating glasses constitute very promising materials for the fabrication of high resolution tracking detectors for fixed target and colliding beam applications.

A Real Time Data Compactor (Sparsifier) and 8 Megabyte High Speed Fifo for Hep.

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.[1],[2] The major components of the VDAS are a flash ADC, a real time high speed data compactor, and high speed 8 megabyte FIFO memory. The data rates through the system are in excess of 30 megabytes/second. The compactor is capable of reducing the amount of data needed to reconstruct typical images by as much as a factor of 20. The FIFO uses only standard NMOS DRAMS and TTL components to achieve its large size and high speed at relatively low power and cost.

Cosmic ray test results of the DO prototype scintillating fiber tracker

The performance of a large scale scintillating fiber tracker with VLPC readout has been studied in a cosmic-ray test. Approximately 9.6 photoelectrons per single layer per trigger were detected at a VLPC bias voltage of 6.5V. The doublet efficiency was nearly 100% at a 0.1% noise level and a position resolution of about 140{mu}m was measured. The authors also studied the relationship between VLPC performance and VLPC bias voltage by measuring single fiber efficiency as a function of VLPC bias in the range 6.2V to 7.0V at a fixed temperature of 6.5{degrees}K. They observed no significant variation in VLPC performance within this bias range.

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.

A Scintillating Glass, Fiber-Optic Plate Imaging System for Active Target and Tracking Applications in High Energy Physics Experiments

We have studied the performance of a scintillating glass fiber-optic plate with minimum ionizing particles. The target is composed of terbium activated cladded-glass cores in a matrix of 25 ¿m spacing. The plate was viewed by a three-stage, electrostatically focussed image intensifier. Particle tracks were observed with a width consistent with the resolution of the device. Details of the detection system and future developments are discussed.

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.

Studies of wavelength-shifting liquid filled quartz capillaries for use in a proposed CMS calorimeter

Studies have been done and continue on the design and construction of a Shashlik detector using Radiation hard quartz capillaries filled with wavelength shifting liquid to collect the scintillation light from LYSO crystals for use as a calorimeter in the Phase II CMS upgrade at CERN. The work presented here focuses on the studies of the capillaries and liquids that would best suit the purpose of the detector. Comparisons are made of various liquids, concentrations, and capillary construction techniques will be discussed.

Studies of SiPM and Scintillation Plates with waveshifter fiber and SiPM readout

We have been studying the performance of SiPM devices and Scintillation Plates read out with SiPM. Applications are for the detection of ionizing radiation, for example in particle and nuclear physics experiments. Results are presented on performance of the SiPM using pulsed LEDs and scintillating tiles excited by radioactive sources, and for SiPM devices that have been used to transduce waveshifted scintillation signals from scintillation tiles with embedded waveshifter fiber.

Small cryostem for operation of Visible Light Photon Counters (VLPC)

We have designed, constructed, and operated a small cryostem which supports the operation of 32 channels of visible light photon counters (HISTE-IV VLPCs). The VLPCs are situated within a small enclosure which can be lowered into a 30-100 liter dewar. The enthalpy of the boil-off helium keeps the VLPCs cold, and allows the system to be operated with stability for many days within the desired temperature range of 6.0 K-7.5 K. The cryostem is instrumented with clear fiber waveguides which transport the light from an optical connector situated at the top of the cryostem and outside of the dewar to the photosensors at cryogenic temperatures within the dewar. Electrical signals from the VLPCs are amplified at room temperature using QPA02 preamplifiers. Details of design and performance are reviewed.