Determination of the Gamma-ray Asymmetry in the Capture of Polarized Neutrons on Hydrogen and Deuterium

Determination of the Gamma-ray Asymmetry in the Capture of Polarized Neutrons on Hydrogen and Deuterium

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Published: 2001

Total Pages: 4

ISBN-13:

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The n+p→d+[gamma] experiment measures the parity-violating directional gamma-ray asymmetry, A[gamma], with uncertainties of 0.5x10−8 when cold polarized neutrons are captured by para-hydrogen. This precision measurement will determine the long-range pion-nucleon weak coupling constant, H{sub {pi}}1, with a precision of 10% of its predicted value, and thus will help to clarify our understanding of the weak interaction between nucleons. The n+p→d+[gamma] experiment on the SNS beamline 14B is designed to take advantage of the high intensity of the source and its pulsed nature. The experiment requires a 30-Hz pulsed beam for optimal performance. In three months of run time the experiment will achieve a statistical uncertainty of 0.5x10−8.


A Measurement of the Parity-violating Gamma-ray Asymmetry in the Neutron-proton Capture

A Measurement of the Parity-violating Gamma-ray Asymmetry in the Neutron-proton Capture

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Published: 2002

Total Pages: 11

ISBN-13:

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The {rvec n} + p → d + [gamma] experiment under construction at LANSCE studies the weak interaction between neutrons and protons. The experiments will measure the directional dependence of the parity-violating [gamma]-ray asymmetry, A{sub {gamma}}, in the polarized cold neutron capture by para-hydrogen. The goal is to measure A{sub {gamma}} with uncertainty of 0.5 x 10−8, 10% of its predicted value. A{sub {gamma}} primarily isolates the [Delta]I = 1 component of the hadronic weak interaction and thus will determine the long-range weak pion-nucleon coupling constant H{sub {pi}}1. The experiment is carefully designed for the LANSCE pulsed spallation neutron source to achieve the proposed statistical precision and to control systematic errors. We discuss the experiment and its status.


Polarimetry Studies for the NPDGamma Experiment at the SNS

Polarimetry Studies for the NPDGamma Experiment at the SNS

Author: Mostafa Jon Dadras

Publisher:

Published: 2009

Total Pages: 72

ISBN-13:

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The NPDGamma collaboration aims to measure a parity_violating directional gamma-ray asymmetry from the capture of polarized cold neutrons on protons. The asymmetry, predicted to be on the order of 50 ppb, is a result of the weak interaction between mesons and nucleons during the neutron capture reaction. The experiment is designed to make a statistics limited measurement of the asymmetry at the level of about 20%. The experiment will be carried out at the Fundamental neutron Physics Beamline (FnPB) at the Spallation Neutron Source (SNS). The neutron beam is polarized by a super_mirror polarizer. A 9.5 G magnetic field guides the neutron spin to a liquid para-hydrogen target, where the neutrons capture forming a deuteron and a 2.2 MeV gamma-ray. The gamma_rays will be detected by a cylindrical array of CsI scintillating crystals. The beam polarization is reversed with the aid of a resonant RF Spin Rotator (RFSR). This thesis considers different methods for determining the beam polarization and efficiency of the RFSR.


Neutron Capture Gamma-Ray Spectroscopy

Neutron Capture Gamma-Ray Spectroscopy

Author: R. E. Chrien

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 875

ISBN-13: 146132940X

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The post World War II era witnessed a tremendous growth in the research carried out in neutron-induced reactions and especially in neutron capture y-ray studies. This growth was stimulated by the availability of neutron sources, such as reactors and accelerators, and by the development of high resolution y-ray and conversion electron detectors. Today the combination of high flux reactors and precise instrumentation has produced spectral data of exceptional quality, as the pages of these proceedings illustrate. The world-wide community of the practioners of the art of cap ture y-ray spectroscopy has met three times in the last decade: the first international symposium on this subject was held at Studsvik, Sweden in 1969, and the second at Petten, The Netherlands in 1974. A smaller meeting, of mostly u. S. and some European parti cipation, was held at Argonne National Laboratory in 1966. A perusal of the proceedings of these meetings shows the striking ad vances in this now mature field of physics over the last dozen years. Each meeting has seen a small but perceptible increase in the number of papers presented and the number of laboratories repre sented. More importantly, each meeting has documented the increasing impact of (n,y) reasearch, not only on other areas of basic physics, but also on commercial and medical applications of this technology. A total of 29 invited papers and 97 contributed papers were presented at this symposium.


Precision Measurement of Parity Violation in Polarized Cold Neutron Capture on the Proton: the NPDGamma Experiment

Precision Measurement of Parity Violation in Polarized Cold Neutron Capture on the Proton: the NPDGamma Experiment

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Published: 2006

Total Pages:

ISBN-13:

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The NPDGamma experiment at the Los Alamos Neutron Science Center (LANSCE) is dedicated to measure with high precision the parity violating asymmetry in the $\gamma$ emission after capture of spin polarized cold neutrons in para-hydrogen. The measurement will determine unambiguously the weak pion-nucleon-nucleon ($\pi NN$) coupling constant [\it f$1̂-[\pi]$].