title: Limits on asymmetric orthopositronium formation in high Z optically active molecules.
abstract: The proposed connection between the parity violating handedness of beta particles in radioactive decay and the sign (L) of biological chirality (the Vester-Ulbricht [V-U] hypothesis) is experimentally tested. The theoretically predicted asymmetry in triplet positronium formation (Aps) is measured in several high Z optically active molecules using low energy positrons with a net helicity. We find Aps less than 3 X 10(-4) in selenocystine (Z = 34) and thyroxine (Z = 53), excluding part of the theoretically predicted range of 4 X 10(-3) greater than Aps greater than 2 X 10(-6) in these molecules. The connection between these limits and limits on asymmetric radiolysis (AR) is made, with a new limit of AR greater than 10(-9) being placed. This limit on AR, which is thirty times lower than a previous measurement in the amino acid leucine (Z = 6), is still not small enough to rule out the V-U hypothesis. rule out the V-U hypothesis.
mesh_terms: D003553:Cystine / Q000031:analogs & derivatives; D004583:Electrons; D007930:Leucine; D008968:Molecular Conformation; D016566:Organoselenium Compounds; D012643:Selenium; D013237:Stereoisomerism; D013974:Thyroxine
chemical_list: D016566:Organoselenium Compounds; C009226:selenocystine; D003553:Cystine; D007930:Leucine; D012643:Selenium; D013974:Thyroxine