摘要:

A number of original proton-transfer fluors were prepared as shifters for green-emitting scintillating fibers of multi-meter lengths. Quantum efficiencies up to 0.52 are reported for the new fluors which showed emission maxima between 478 and 612 nm. None proved clearly superior to 3HF, the standard fluor for scintillating fibers whose light is measured with PM tubes. For the current goal of half-meter length waveshifting fibers with blue-green emission for use with blue-violet-emitting polystyrene tiles, a number of fluors related to TPBD and Bis-MSB were prepared bearing dialkylamino auxofluors. Some of these failed to fluoresce, and those that did were photochemically unstable. A proposal was made on some original conjugated polyenes for waveshifting fibers. In general, accurate predictions could be made on excitation and emission wavelengths, while light output, decay time, photochemical stability and radiation hardness are more difficult targets. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.56948

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The possibilities, problems and limitations for the use of various semiempirical molecular orbital methods to predict absorption and emission spectra of various types of organic dyes (laser dyes, e.g. coumarines and carbostyriles, probes for analytical and/or biochemical measurements, e.g., fluoresceins, and dyes for the D2T2 (dye diffusion by thermal transfer photocopying process, donor-substituted aromatics with dimeric malononitrile as acceptor) will be discussed. Although, especially for polycyclic (hetero)aromatic systems, the semiempirical methods give quite encouraging results, several pitfalls requiring a critical assessment of the reliability of any computational method will be presented. Finally, some examples of the effect of a proper treatment of environmental (solvent) effects on the quality of the calculated transition energies will be given. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.56933

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Scintillating crystals in future high energy physics experiments face a new challenge to maintain its performance in a hostile radiation environment. This paper discusses the effects of radiation damage in scintillating crystals. The importance of maintaining crystal’s light response uniformity and the feasibility to build a precision crystal calorimeter under radiation are elaborated. The mechanism of radiation damage in scintillating crystals is also discussed. While the damage in alkali halides is found to be caused by the oxygen/hydroxyl contamination, it is the structure defects, such as oxygen vacancies, cause damage in oxides. Material analysis used to reach these conclusions are presented in details. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.56940

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

In x-ray imaging, many combinations of scintillators and detectors are used for a variety of reasons. This paper reviews several scintillators currently used in x-ray imaging systems in medical and non-destructive testing (NDT) applications. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.56947

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Effects of strong magnetic fields on scintillators and sampling calorimeter have been studied. Light yield in scintillators increased with increasing magnetic field until saturation at about 2 tesla. The maximum increase was between 6&percent; and 8&percent;, depending on the plastic composition. The sampling calorimeter saw an additional effect due to changes in shower particle path in the magnetic field. An additional 20&percent; (8&percent;) increase was observed in the energy measurement for electrons (pions) in 3 tesla. This additional effect strongly depends on geometry of the sampling calorimeter and orientation of the field. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.56954

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Optical fibers are used extensively in high energy physics, as well as in communication. Fibers in medium and high radiation environments show considerable damage. This damage can be quantified as a reduction in the transmission length, which is a function of the transmitted wavelength. The primary observed damage in a fiber is due to the cladding material. Damage is observed even at low levels of irradiation. Quartz fibers damage less than plastic fibers. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.56958

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Several types of WLS fibers, candidates to be used in the TILECAL/ATLAS detector, were irradiated in a60Co&hthinsp;&ggr;source. Bicron, Kuraray and Pol.Hi.Tech fibers were exposed to a total dose of ∼150 Krad. The degradation of light output was measured just after irradiation and followed during several days. The results are presented. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.56965

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The use of scintillating fibers to collect the scintillation light produced by electrons drifting in a noble gas is discussed. The imaging of photons in the 10 to 150 keV range is discussed and light yield produced by photons in this range is estimated. Results are presented from an experimental setup to measure the change in light yield of scintillating fibers as a function of time while in a 20 atmosphere Noble gas environment. An upper limit of less than5⋅10−5per day was obtained on the change in fiber brightness as a function of time. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.56966

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

This paper documents the fiber R and D for the CMS hadron barrel calorimeter (HCAL). The R and D includes measurements of fiber flexibility, splicing, mirror reflectivity, relative light yield, attenuation length, radiation effects, absolute light yield, and transverse tile uniformity. Schematics of the hardware for each measurement are shown. These studies are done for different diameters and kinds of multiclad fiber. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.56967

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A decade of research into plastic scintillation materials at Fermilab is reviewed. Early work with plastic optical fiber fabrication is revisited and recent experiments with large-scale commercial methods for production of bulk scintillator are discussed. Costs for various forms of scintillator are examined and new development goals including cost reduction methods and quality improvement techniques are suggested. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.56927

出版商:AIP    

年代:1998

数据来源: AIP