A MEASUREMENT OF THE LONGITUDINAL POLARISATION OF NEON-19 POSITRONS (thesis). Technical Report No. 1

Technical Report · Mon May 01 04:00:00 EDT 1961

OSTI ID:4841440

Jovanovic, J V

An experiment to measure the energy dependence of helicity of positrons emitted from Ne'9 is described. The positron helicity was measured indirectly by transferring it to the annihilation-in-flight photons, whose transmission through a magnetized iron cylinder was dependent on their polarization. The positron helicity therefore resulted in a difference of the counting rates for opposed directions of the magnetic field. The measured dependence of this asymmetry with pulse height was compared with a computation which assumes the validity of the two-component neutrino theory of beta decay and neglects the depolarization of positrons. A good fit of theoretical curve to the experimental points was obtained for pulse heights larger than about 1.3 Mev. A strong disagreement was found in the pulse height range between 0.75 and 1.0 Mev, where the experimental asymmetries were much lower than the prediction. Although the influence of the induced pseudoscalar interaction cannot be excluded, it is likely that this discrepancy was produced by the depolarization of positrons due to multiple Coulomb scattering. The measurement of the asymmetry of bremsstrahlung produced in copper by electrons from a Sr/sup 90/-Y/sup 90/ source was used in order to measure the effective number of aligned electrons in the magnetized iron cylinder. It was assumed, in agreement with measurements performed previously, that the polarization of Y/sup 90/ electrons is equal to --(v/c). By comparison with the bremsstrahlung asymmetries at the higher energy part of the spectrum, the helicity of the Ne/sup 1>/ positrons was determined to be H = (0.97 plus or minus 0.10)(v/c) for positron energies greater than about 1.2 Mev. No conclusion about the positron helicities at lower energies can be obtained until the effect of the depolarization is carefully acccunted for. (auth)

• Research Organization: Washington Univ., St. Louis
• NSA Number: NSA-15-028453
• OSTI ID: 4841440
• Report Number(s): NP-10611; AFOSR-TN-1099
• Country of Publication: United States
• Language: English

Related Subjects

ANNIHILATION
BETA DECAY
BREMSSTRAHLUNG
COPPER
CYLINDERS
ELECTRIC POTENTIAL
ELECTRONS
ENERGY
ENERGY RANGE
HELICITY
INTERACTIONS
IRON
MAGNETIC FIELDS
MEASURED VALUES
MEV RANGE
MOMENTUM
NEON 19
NEUTRINOS
PARTICLE MODELS
PHOTONS
PHYSICS
POLARIZATION
POSITRONS
PSEUDOSCALAR
SCATTERING
SPIN
STRONTIUM 90
VECTORS
YTTRIUM 90