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Title: Time reversal invariance in polarized neutron decay

Abstract

An experiment to measure the time reversal invariance violating (T-violating) triple correlation (D) in the decay of free polarized neutrons has been developed. The detector design incorporates a detector geometry that provides a significant improvement in the sensitivity over that used in the most sensitive of previous experiments. A prototype detector was tested in measurements with a cold neutron beam. Data resulting from the tests are presented. A detailed calculation of systematic effects has been performed and new diagnostic techniques that allow these effects to be measured have been developed. As the result of this work, a new experiment is under way that will improve the sensitivity to D to 3 x 10 -4 or better. With higher neutron flux a statistical sensitivity of the order 3 x 10 -5 is ultimately expected. The decay of free polarized neutrons (n → p + e + $$\bar{v}$$ e) is used to search for T-violation by measuring the triple correlation of the neutron spin polarization, and the electron and proton momenta (σ n • p p x p e). This correlation changes sign under reversal of the motion. Since final state effects in neutron decay are small, a nonzero coefficient, D, of this correlation indicates the violation of time reversal invariance. D is measured by comparing the numbers of coincidences in electron and proton detectors arranged symmetrically about a longitudinally polarized neutron beam. Particular care must be taken to eliminate residual asymmetries in the detectors or beam as these can lead to significant false effects. The Standard Model predicts negligible T-violating effects in neutron decay. Extensions to the Standard Model include new interactions some of which include CP-violating components. Some of these make first order contributions to D.

Authors:
 [1]
  1. Harvard Univ., Cambridge, MA (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
10137967
Report Number(s):
LA-12735-T
ON: DE94009225; TRN: 94:006651
DOE Contract Number:  
W-7405-ENG-36
Resource Type:
Thesis/Dissertation
Resource Relation:
Other Information: DN: Thesis submitted to the Harvard University, Department of Physics, Cambridge, Massachusetts; TH: Thesis (Ph.D.); PBD: Mar 1994
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; T INVARIANCE; SYMMETRY BREAKING; NEUTRONS; BETA DECAY; CP INVARIANCE; NEUTRON SOURCES; DETECTION; 662360; 662120; DECAYS OF BARYONS; SYMMETRY, CONSERVATION LAWS, CURRENTS AND THEIR PROPERTIES

Citation Formats

Wasserman, Eric G. Time reversal invariance in polarized neutron decay. United States: N. p., 1994. Web. doi:10.2172/10137967.
Wasserman, Eric G. Time reversal invariance in polarized neutron decay. United States. doi:10.2172/10137967.
Wasserman, Eric G. Tue . "Time reversal invariance in polarized neutron decay". United States. doi:10.2172/10137967. https://www.osti.gov/servlets/purl/10137967.
@article{osti_10137967,
title = {Time reversal invariance in polarized neutron decay},
author = {Wasserman, Eric G.},
abstractNote = {An experiment to measure the time reversal invariance violating (T-violating) triple correlation (D) in the decay of free polarized neutrons has been developed. The detector design incorporates a detector geometry that provides a significant improvement in the sensitivity over that used in the most sensitive of previous experiments. A prototype detector was tested in measurements with a cold neutron beam. Data resulting from the tests are presented. A detailed calculation of systematic effects has been performed and new diagnostic techniques that allow these effects to be measured have been developed. As the result of this work, a new experiment is under way that will improve the sensitivity to D to 3 x 10-4 or better. With higher neutron flux a statistical sensitivity of the order 3 x 10-5 is ultimately expected. The decay of free polarized neutrons (n → p + e + $\bar{v}$e) is used to search for T-violation by measuring the triple correlation of the neutron spin polarization, and the electron and proton momenta (σn • pp x pe). This correlation changes sign under reversal of the motion. Since final state effects in neutron decay are small, a nonzero coefficient, D, of this correlation indicates the violation of time reversal invariance. D is measured by comparing the numbers of coincidences in electron and proton detectors arranged symmetrically about a longitudinally polarized neutron beam. Particular care must be taken to eliminate residual asymmetries in the detectors or beam as these can lead to significant false effects. The Standard Model predicts negligible T-violating effects in neutron decay. Extensions to the Standard Model include new interactions some of which include CP-violating components. Some of these make first order contributions to D.},
doi = {10.2172/10137967},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1994},
month = {3}
}

Thesis/Dissertation:
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