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Author Yovanovitch, D. D.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword PHYSICS ♦ ABSORPTION- ALUMINUM- BINDING ENERGY- BOUND STATE- CADMIUM- DECAY- DISTRIBUTION- ELECTRIC CHARGES- ELECTRONS- IRON- LAYERS- LEAD- MOLYBDENUM- MUONS- MUONS-MINUS- NUCLEI- PARTICLE MODELS- TARGETS- TUNGSTEN- ZINC ♦ ABSORPTION- ATOMIC MODELS- BINDING ENERGY- BOUND STATE- CALCIUM- CARBON- COBALT- DECAY- EFFICIENCY- ELECTRIC CHARGES- ELECTRONS- ERRORS- IODINE- IRON- LEAD- MANGANESE- MUONS- MUONS-MINUS- MUONS-PLUS- NICKEL- NUCLEI- POSITRONS- TARGETS- TITANIUM- VANADIUM- ZINC
Abstract The decay rate of negative muons bound to nuclei of atomic number Z, LAMBDA /sub d/(Z), was investigated experimentally by two independent methods: (a) the "sandwich" method, and (b) the "calibrated efficiency" method. Both methods are based on the fact that the negatron yield per muon, y/sup -/(Z), is proportional to LAMBDA /sub d/(Z)/ LAMBDA /sub t/(Z), where LAMBDA /sub t/(Z) is the total disappearance rate of negative muons for element Z, and are designed to avoid absolute measurements of y/sup -/(Z). In method (a), mu /sup -/ are stopped in a multilayer "sandwich" target made by alternately stacking sheets of two elements Z, Z', and the resultant e/sup -/ time distribution is decomposed into components due to Z and Z'. The ratio of muon stops in Z and Z' is established empirically; knowing LAMBDA /sub d/(Z'), LAMBDA /sub d/(Z) can be computed. This method was applied to Al, Fe, Zn, Cd, Mo, W, and Pb. In method (b), mu /sup -/ and mu /sup +/ of identical range distributions are stopped in a given target, and the e/sup +/ yield, y/sup +/, is used as a calibration of the e/sup -/ counting efficiency. This method was applied to C, Ca, Ti, V, Mn, Fe, Co, Ni, Zn, I, and Pb. The sources of error of either method are discussed in detail. The results indicate: (1) In the range 20 < Z < 30, LAMBDA /sub d/(Z)> LAMBDA /sub d/(O), i.e., the bound decay rate exceeds the vacuum (i.e., mu /sup +/) decay rate; LAMBDA /sub d/(Z) presents a sharp peak near Z = 26. (2) For Z> 30, one finds LAMBDA /sub d/(Z) < LAMBDA /sub d/(0), i.e., the decay is inhibited by binding. The effect is very marked for the heaviest elements, e.g., LAMBDA /sub d/(82)/ LAMBDA /sub d/O) = 0.34 plus or minus 0.04. These results are compared with the predictions of simplified theoretical models. The peak near Z = 26 is tentatively attributed to the Coulomb enhancement of the outgoing electron ways function at the point of decay. (auth)
ISSN 0031899X
Educational Use Research
Learning Resource Type Article
Publisher Date 1960-03-15
Publisher Department Univ. of Chicago
Journal Physical Review
Volume Number 117
Organization Univ. of Chicago


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