# Rapid HeII-\>HeI recombination and radiation concerned with this process

Source: [Rapid HeII-\>HeI recombination and radiation concerned with this process](<https://www.sota2.com/research/paper/68fa28052c2a3760193c64ea>)

Collection index: [llms.txt](<https://www.sota2.com/research/llms.txt>)

Data updated: 2025-10-24T12:13:23.877Z

Authors: E.E. Kholupenko, A.V. Ivanchik, D.A. Varshalovich

Published: 2007-03-16T12:44:44.000Z

## Abstract

Recombination of the primordial helium plasma (HeII-\>HeI, $z \\simeq 1500 - 3000$) is considered. This process has an effect on the CMBR anisotropy and CMBR spectrum distortion. In this work an influence of neutral hydrogen on kinetics of HeII-\>HeI recombination is investigated in the frame of the standard cosmological model. It is shown that small amount of neutral hydrogen ($10^{-5} - 10^{-2}$ of total number of hydrogen ions and atoms) leads to acceleration of HeII-\>HeI recombination at $z\\lesssim 2000$ and at $z\\lesssim 1600$ quasi-equilibrium HeII-\>HeI recombination (according to the Saha formula) becomes valid.

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## Original sources and implementation

[Original paper](<https://arxiv.org/abs/astro-ph/0703438>)

[PDF](<https://arxiv.org/pdf/astro-ph/0703438.pdf>)