Skip to main content
OSTI.GOVU.S. Department of Energy Office of Scientific and Technical Information
U.S. Department of Energy
Office of Scientific and Technical Information
 

Measurement of positron reemission from thin single-crystal W(100) films

Journal Article · · Phys. Rev. B: Condens. Matter; (United States)
; ; ;

Epitaxial thin single-crystal (100) tungsten films 1000, 2500, and 5000 A thick have been fabricated by high-vacuum electron-beam evaporation. These films were subsequently used as thin-film moderators for the study of the positron-transmission-reemission process with a variable-energy (0--80 keV) monoenergetic positron beam in an ultrahigh-vacuum system. The films were shown to be routinely cleanable by heating first in oxygen (10/sup -6/ Torr) and then in vacuum (10/sup -9/ Torr). Transmission and back reemission of slow positrons from these surfaces was observed. The positron work function, phi/sub +/ has been determined to be approx. =3.0 eV ( +- 0.3 eV). The transmission slow positrons were emitted in a narrow cone with a full width at half maximum of approx. =30/sup 0/ consistent with the angular distribution of back-reemission positrons. The reemitted yields as a function of incident positron energy were found to be very different between forward reemission and back reemission. The maximum forward-reemission yields were 18% for 1000-A-thick W film and 12% for 2500-A-thick W film at 5 and 10 keV optimum incident positron energies, respectively. These results show that one can use thin single-crystal tungsten films as positron moderators or remoderators.

Research Organization:
Physics Department, Brookhaven National Laboratory, Upton, New York 11973
OSTI ID:
5884590
Journal Information:
Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 31:7; ISSN PRBMD
Country of Publication:
United States
Language:
English

Similar Records

The effect of laser annealing of thin W(100) films on positron transmission reemission properties
Journal Article · Sun Dec 31 23:00:00 EST 1989 · Journal of Applied Physics; (USA) · OSTI ID:7243185
Transmitted positron reemission from a thin single-crystal Ni(100) foil
Journal Article · Tue Jul 01 00:00:00 EDT 1986 · Phys. Rev. B: Condens. Matter; (United States) · OSTI ID:5567806
Submicron-resolution study of a thin Ni crystal using a brightness-enhanced positron reemission microscope
Journal Article · Mon Aug 01 00:00:00 EDT 1988 · Phys. Rev. Lett.; (United States) · OSTI ID:6852671

Related Subjects

654001* -- Radiation & Shielding Physics-- Radiation Physics
Shielding Calculations & Experiments
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ANGULAR DISTRIBUTION
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
BACKSCATTERING
CHARGED-PARTICLE TRANSPORT
CONVERSION RATIO
CRYSTALS
DISTRIBUTION
ELEMENTARY PARTICLES
ELEMENTS
ENERGY LOSSES
ENERGY RANGE
FERMIONS
FILMS
FUNCTIONS
KEV RANGE
KEV RANGE 10-100
LEPTONS
LOSSES
METALS
MODERATORS
MONOCRYSTALS
POSITRONS
RADIATION TRANSPORT
SCATTERING
SMALL ANGLE SCATTERING
THIN FILMS
TRANSITION ELEMENTS
TRANSMISSION
TUNGSTEN
WORK FUNCTIONS