Experimental investigations of neutrino oscillations at a fission reactor
To investigate the possibility of neutrino oscillations, the positron kinetic energy spectrum was measured using the inverse beta decay of the neutron (anti v/sup -//sub e/ + p ..-->.. e/sup +/ n) as a detector reaction. The experiment was carried out at the fission reactor of the Institut Laue Langevin at Grenoble, France. The well shielded detector was set up at 8.76 meters from the point-like reactor core in an antineutrino flux of 9.8 x 10/sup 11/ cm/sup -2/sec/sup -1/. The target protons were provided by a liquid scintillator (total volume of 377 liters) which also served as a positron detector. The product neutrons were moderated in the scintillator and detected by /sup 3/He wire counters via the /sup 3/He(n,p)/sup 3/H reaction. A delayed coincidence was required between the prompt positron and the delayed neutron events. The positron energy resolution was 18% FWHM at 1 MeV. The signal to background ratio was better than one to one between 2 MeV and 6 MeV positron energy. With a counting rate of 1.56 counts per hours, 2919 + 131 neutrino induced events were detected. The shape of the measured positron spectrum was analyzed in terms of parameters for neutrino oscillations. The experimental data are consistent with no oscillations. An upper limit of 0.2 eV/sup 2/ (90% c.l.) for the mass-squared differences of the neutrinos was achieved, assuming maximum mixing of two neutrino states. The ratio of the measured to the expected integral yield of positrons was determined to be integral Y/sub exp// integral Y/sub th/ = 0.89 +- 0.04 (statistical) +- 0.13 (systematic).
- Research Organization:
- California Inst. of Tech., Pasadena (USA)
- OSTI ID:
- 5445439
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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ANTINEUTRINO-PROTON INTERACTIONS
NEUTRINOS
OSCILLATIONS
BETA DECAY
POSITRONS
REACTORS
ANTILEPTON-PROTON INTERACTIONS
ANTILEPTONS
ANTIMATTER
ANTINEUTRINO-NUCLEON INTERACTIONS
ANTIPARTICLES
DECAY
ELEMENTARY PARTICLES
FERMIONS
INTERACTIONS
LEPTON-BARYON INTERACTIONS
LEPTON-HADRON INTERACTIONS
LEPTON-NUCLEON INTERACTIONS
LEPTON-PROTON INTERACTIONS
LEPTONS
MASSLESS PARTICLES
NEUTRINO-NUCLEON INTERACTIONS
NEUTRINO-PROTON INTERACTIONS
PARTICLE INTERACTIONS
645102* - High Energy Physics- Particle Interactions & Properties-Experimental- Weak Interactions & Properties