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Title: Angular distribution of neutron inverse beta decay, {bar {nu}}{sub e}+p{r_arrow}e{sup +}+n

Abstract

The reaction {bar {nu}}{sub e}+p{r_arrow}e{sup +}+n is very important for low-energy (E{sub {nu}}{approx_lt}60 MeV) antineutrino experiments. In this paper we calculate the positron angular distribution, which at low energies is slightly backward. We show that weak magnetism and recoil corrections have a large effect on the angular distribution, making it isotropic at about 15 MeV and slightly forward at higher energies. We also show that the behavior of the cross section and the angular distribution can be well understood analytically for E{sub {nu}}{approx_lt}60 MeV by calculating to O(1/M), where {ital M} is the nucleon mass. The correct angular distribution is useful for separating {bar {nu}}{sub e}+p{r_arrow}e{sup +}+n events from other reactions and detector backgrounds, as well as for possible localization of the source (e.g., a supernova) direction. We comment on how similar corrections appear for the lepton angular distributions in the deuteron breakup reactions {bar {nu}}{sub e}+d{r_arrow}e{sup +}+n+n and {nu}{sub e}+d{r_arrow}e{sup {minus}}+p+p. Finally, in the reaction {bar {nu}}{sub e}+p{r_arrow}e{sup +}+n, the angular distribution of the outgoing neutrons is strongly forward peaked, leading to a measurable separation in positron and neutron detection points, also potentially useful for rejecting backgrounds or locating the source direction. {copyright} {ital 1999} {ital The American Physicalmore » Society}« less

Authors:
;  [1]
  1. Physics Department 161-33, California Institute of Technology, Pasadena, California 91125 (United States)
Publication Date:
OSTI Identifier:
362721
Resource Type:
Journal Article
Journal Name:
Physical Review, D
Additional Journal Information:
Journal Volume: 60; Journal Issue: 5; Other Information: PBD: Sep 1999
Country of Publication:
United States
Language:
English
Subject:
66 PHYSICS; NEUTRINO-PROTON INTERACTIONS; NEUTRINO-NEUTRON INTERACTIONS; ANTINEUTRINO-PROTON INTERACTIONS; ANGULAR DISTRIBUTION; POSITRONS; NEUTRONS; CROSS SECTIONS

Citation Formats

Vogel, P., and Beacom, J.F. Angular distribution of neutron inverse beta decay, {bar {nu}}{sub e}+p{r_arrow}e{sup +}+n. United States: N. p., 1999. Web. doi:10.1103/PhysRevD.60.053003.
Vogel, P., & Beacom, J.F. Angular distribution of neutron inverse beta decay, {bar {nu}}{sub e}+p{r_arrow}e{sup +}+n. United States. doi:10.1103/PhysRevD.60.053003.
Vogel, P., and Beacom, J.F. Wed . "Angular distribution of neutron inverse beta decay, {bar {nu}}{sub e}+p{r_arrow}e{sup +}+n". United States. doi:10.1103/PhysRevD.60.053003.
@article{osti_362721,
title = {Angular distribution of neutron inverse beta decay, {bar {nu}}{sub e}+p{r_arrow}e{sup +}+n},
author = {Vogel, P. and Beacom, J.F.},
abstractNote = {The reaction {bar {nu}}{sub e}+p{r_arrow}e{sup +}+n is very important for low-energy (E{sub {nu}}{approx_lt}60 MeV) antineutrino experiments. In this paper we calculate the positron angular distribution, which at low energies is slightly backward. We show that weak magnetism and recoil corrections have a large effect on the angular distribution, making it isotropic at about 15 MeV and slightly forward at higher energies. We also show that the behavior of the cross section and the angular distribution can be well understood analytically for E{sub {nu}}{approx_lt}60 MeV by calculating to O(1/M), where {ital M} is the nucleon mass. The correct angular distribution is useful for separating {bar {nu}}{sub e}+p{r_arrow}e{sup +}+n events from other reactions and detector backgrounds, as well as for possible localization of the source (e.g., a supernova) direction. We comment on how similar corrections appear for the lepton angular distributions in the deuteron breakup reactions {bar {nu}}{sub e}+d{r_arrow}e{sup +}+n+n and {nu}{sub e}+d{r_arrow}e{sup {minus}}+p+p. Finally, in the reaction {bar {nu}}{sub e}+p{r_arrow}e{sup +}+n, the angular distribution of the outgoing neutrons is strongly forward peaked, leading to a measurable separation in positron and neutron detection points, also potentially useful for rejecting backgrounds or locating the source direction. {copyright} {ital 1999} {ital The American Physical Society}},
doi = {10.1103/PhysRevD.60.053003},
journal = {Physical Review, D},
number = 5,
volume = 60,
place = {United States},
year = {1999},
month = {9}
}