Development of NaI(Tl) scintillating films for imaging soft x-rays

Miscellaneous · Fri Jan 01 00:00:00 EST 1993

OSTI ID:6978854

Shepherd, J A

Thin film NaI(Tl) scintillators, of areas of up to 130 cm[sup 2], have been fabricated and characterized for use on soft x-ray imaging photomultiplier tubes. Relevant parameters of photon-counting imaging detectors are defined and used to predict the performance of several materials, including CsI(Na), CsI(Tl), CaF[sub 2](Eu), Lu[sub 2](SiO[sub 4])O:Ce, and NaI(Tl), as thin film scintillators on fiber optic substrates. Also, x-ray imaging methodologies are compared. The NaI(Tl) films were vapor-deposited onto quartz and fiber optic substrates using a powder flash deposition technique. When compared to single crystal NaI(Tl), the films were found to have equally high light yield but lower energy resolution. Light yield optimization was studied in detail including the effects of substrate temperature, activator concentration in the evaporant, and boat temperature. Spatial resolution as well as parallax errors are discussed and measured for film thicknesses up to 61 [mu]m. A technique is described that can substantially increase the light collection of high index films on fiber optic disks. The light collection was improved by 20% by coating the disk with potassium silicate before the NaI(Tl) deposition. Large area films, up to 130 cm[sup 2], had a spatial uniformity of response within [+-]1.5% for count rate and [+-]3.5% for light yield, and their spatial resolution exceeded 16.6 lp mm[sup [minus]1] when deposited onto fiber optic substrates. The 8-keV x-ray detection efficiency of the microchannel plate imaging photomultiplier tube coupled to a NaI(Tl) film scintillator is predicted to be 88%. Other uses for the films are also described.

• Research Organization: Virginia Univ., Charlottesville, VA (United States)
• OSTI ID: 6978854
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
36 MATERIALS SCIENCE
SODIUM IODIDES
DEPOSITION
OPTICAL PROPERTIES
SOFT X RADIATION
SCINTILLATION COUNTING
FILMS
PHOTOMULTIPLIERS
SOLID SCINTILLATION DETECTORS
ALKALI METAL COMPOUNDS
COUNTING TECHNIQUES
ELECTROMAGNETIC RADIATION
HALIDES
HALOGEN COMPOUNDS
INORGANIC PHOSPHORS
IODIDES
IODINE COMPOUNDS
IONIZING RADIATIONS
MEASURING INSTRUMENTS
PHOSPHORS
PHOTOTUBES
PHYSICAL PROPERTIES
RADIATION DETECTORS
RADIATIONS
SCINTILLATION COUNTERS
SODIUM COMPOUNDS
X RADIATION
440103* - Radiation Instrumentation- Nuclear Spectroscopic Instrumentation
360606 - Other Materials- Physical Properties- (1992-)
360601 - Other Materials- Preparation & Manufacture