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Title: THE FREE ANTINEUTRINO ABSORPTION CROSS SECTION. PART I. MEASUREMENT OF THE FREE ANTINEUTRINO ABSORPTION CROSS SECTION. PART II. EXPECTED CROSS SECTION FROM MEASUREMENTS OF FISSION FRAGMENT ELECTRON SPECTRUM

Abstract

Part I. The cross section for the reactioa, v/sub -/+ p yields BETA / sup +/ + n, was measured using reactor antineutrinos (v/sub -/). Target protons were provided by a 370 gallon liquid scintiliation detector in which the scintillator solution (triethylbenzene, terphenyl, and POPOP) was loaded with a cadmlum compound (cadmium octoate) to allow the detection of the reaction by means of the delayed coincidence techaique. The first pulse of thae pair was caused by the slowing down and annihilation of the positron ( BETA /sup +/ the second by the capture of the neutron (n) in cadmium following its moderation by the scintillator protons. A second scintillation detector witbout cadmium loaing was used above tue first to provide an anticoincidence signal against cosmic ray induced events. The antineutrino signal was related to the reactor by means of runs taken while thae reactor was on and off. Reactor radiations other than antineutrinos were ruled out as the cause of the signal by a differential shielding experiment. The signal rate was 44 events/ hour and the signal to noise was 1/8, where half the noise was correlated and cosmic ray associated and about half was due to non-reactor associated accidentalmore » coincideuees. The cross section pcr fission nu /sub -/(assuming 6.1 nu /sup -/ per fission) for the inverse beta decay of the proton was measured to be 4 plus or minus 1 x 10/sup - 44/ cm/sup 2/. Part II. The cross section expected for the reaction nu /sup -/ plus or minus p yields BETA /sup +/ + n using nu /sup -/ from fission fragments is a function of the nu /sup -/ spectrum as well as the particular neutrino theory employed. The cross section for the two componeat theory is a factor of two greater than that predicted by the four-component neutrino theory. In an attempt to test neutrino theories, experiments are being performed to enable the inference of the antineutrino spectrum from the fission fragments via a measurement of the electron spectrum from these fragments. In these experiments a foil of U/sup 235/ is irradiated by thermal neutrons, and the emitted electron spectrum is studied by means of small plastic scintillators placed in a collimator shield set off to one side of the ueutron beam. Backgrounds due to gamma rays reduced to less than 1/10 the electron signal by means of a transmission proportional counter placed in front of the scintillation detector. Details and results of these experiments are reported. (auth)« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Los Alamos Scientific Lab., N. Mex.
OSTI Identifier:
4326484
Report Number(s):
A/CONF.15/P/1026
NSA Number:
NSA-12-014961
Resource Type:
Technical Report
Resource Relation:
Other Information: Prepared for the Second U.N. International Conference on the Peaceful Uses of Atomic Energy, 1958. Orig. Receipt Date: 31-DEC-58
Country of Publication:
Country unknown/Code not available
Language:
English
Subject:
PHYSICS; ABSORPTION; ANNIHILATION; ANTINEUTRINOS; BACKGROUND; BACKGROUND- - BENZENE; BETA DECAY; BETA PARTICLES; CADMIUM COMPOUNDS; CAPTURE; COINCIDENCE METHODS; COSMIC RADIATION; CROSS SECTIONS; ETHYL RADICALS; FISSION; FISSION PRODUCTS; FOILS; GAMMA RADIATION; IRRADIATION; LIQUIDS; MEASURED VALUES; MODERATORS; NEUTRON BEAMS; NEUTRONS; NUCLEAR REACTIONS; NUCLEAR THEORY; NUMERICALS; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; PHENYL RADICALS; PHOSPHORS; POLYMERS; POLYPHENYLS; POPOP; POSITRONS; PROPORTIONAL COUNTERS; PROTONS; PULSES; RADIATION DETECTORS; RADIATIONS; REACTORS; SCINTILLATION COUNTERS; SHIELDING; SOLUTIONS; SPECTRA; TARGETS

Citation Formats

Reines, F., Cowan, C.L. Jr., Carter, R.E., Reines, F., Wagner, J.J., and Wyman, M.E. THE FREE ANTINEUTRINO ABSORPTION CROSS SECTION. PART I. MEASUREMENT OF THE FREE ANTINEUTRINO ABSORPTION CROSS SECTION. PART II. EXPECTED CROSS SECTION FROM MEASUREMENTS OF FISSION FRAGMENT ELECTRON SPECTRUM. Country unknown/Code not available: N. p., 1958. Web.
Reines, F., Cowan, C.L. Jr., Carter, R.E., Reines, F., Wagner, J.J., & Wyman, M.E. THE FREE ANTINEUTRINO ABSORPTION CROSS SECTION. PART I. MEASUREMENT OF THE FREE ANTINEUTRINO ABSORPTION CROSS SECTION. PART II. EXPECTED CROSS SECTION FROM MEASUREMENTS OF FISSION FRAGMENT ELECTRON SPECTRUM. Country unknown/Code not available.
Reines, F., Cowan, C.L. Jr., Carter, R.E., Reines, F., Wagner, J.J., and Wyman, M.E. Fri . "THE FREE ANTINEUTRINO ABSORPTION CROSS SECTION. PART I. MEASUREMENT OF THE FREE ANTINEUTRINO ABSORPTION CROSS SECTION. PART II. EXPECTED CROSS SECTION FROM MEASUREMENTS OF FISSION FRAGMENT ELECTRON SPECTRUM". Country unknown/Code not available. doi:.
@article{osti_4326484,
title = {THE FREE ANTINEUTRINO ABSORPTION CROSS SECTION. PART I. MEASUREMENT OF THE FREE ANTINEUTRINO ABSORPTION CROSS SECTION. PART II. EXPECTED CROSS SECTION FROM MEASUREMENTS OF FISSION FRAGMENT ELECTRON SPECTRUM},
author = {Reines, F. and Cowan, C.L. Jr. and Carter, R.E. and Reines, F. and Wagner, J.J. and Wyman, M.E.},
abstractNote = {Part I. The cross section for the reactioa, v/sub -/+ p yields BETA / sup +/ + n, was measured using reactor antineutrinos (v/sub -/). Target protons were provided by a 370 gallon liquid scintiliation detector in which the scintillator solution (triethylbenzene, terphenyl, and POPOP) was loaded with a cadmlum compound (cadmium octoate) to allow the detection of the reaction by means of the delayed coincidence techaique. The first pulse of thae pair was caused by the slowing down and annihilation of the positron ( BETA /sup +/ the second by the capture of the neutron (n) in cadmium following its moderation by the scintillator protons. A second scintillation detector witbout cadmium loaing was used above tue first to provide an anticoincidence signal against cosmic ray induced events. The antineutrino signal was related to the reactor by means of runs taken while thae reactor was on and off. Reactor radiations other than antineutrinos were ruled out as the cause of the signal by a differential shielding experiment. The signal rate was 44 events/ hour and the signal to noise was 1/8, where half the noise was correlated and cosmic ray associated and about half was due to non-reactor associated accidental coincideuees. The cross section pcr fission nu /sub -/(assuming 6.1 nu /sup -/ per fission) for the inverse beta decay of the proton was measured to be 4 plus or minus 1 x 10/sup - 44/ cm/sup 2/. Part II. The cross section expected for the reaction nu /sup -/ plus or minus p yields BETA /sup +/ + n using nu /sup -/ from fission fragments is a function of the nu /sup -/ spectrum as well as the particular neutrino theory employed. The cross section for the two componeat theory is a factor of two greater than that predicted by the four-component neutrino theory. In an attempt to test neutrino theories, experiments are being performed to enable the inference of the antineutrino spectrum from the fission fragments via a measurement of the electron spectrum from these fragments. In these experiments a foil of U/sup 235/ is irradiated by thermal neutrons, and the emitted electron spectrum is studied by means of small plastic scintillators placed in a collimator shield set off to one side of the ueutron beam. Backgrounds due to gamma rays reduced to less than 1/10 the electron signal by means of a transmission proportional counter placed in front of the scintillation detector. Details and results of these experiments are reported. (auth)},
doi = {},
journal = {},
number = ,
volume = ,
place = {Country unknown/Code not available},
year = {Fri Oct 31 00:00:00 EST 1958},
month = {Fri Oct 31 00:00:00 EST 1958}
}

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