Deuterium and lithium for precision cosmology

用于精密宇宙学的氘和锂

• 批准号: 329701419
• 负责人: Professor Dr. Daniel Bemmerer
• 金额: --
• 依托单位: Institut für Kern- und Teilchenphysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/329701419?language=en
• 关键词: Deuterium; lithium; precision; cosmology

The aims of the proposed project are:1. Improve the best Big Bang Nucleosynthesis (BBN) observable, to make it competitive to the cosmic microwave background (CMB):The precision of the predicted 2H abundance as a function of the baryon-to-photon ratio shall be improved to approach the precision of the 2H observation. Thus, the precision of the currently most precise BBN tool, 2H, shall be further sharpened so that it becomes competitive in its impact on the baryon-to-photon ratio to the CMB constraint.2. Sharpen the discrepancy for the worst BBN observable, in order to enable it as a tool for new physics:The precision of the predicted 7Li abundance as a function of the baryon-to-photon ratio shall be improved, not in a hope to resolve the cosmic 7Li problem, but instead in order to enable the use of the discrepancy between CMB-predicted and observed 7Li abundances to explore new physics in the first 1000 seconds of the universe.3. Improve the precision of the predicted fluxes of solar 7Be and 8B neutrinos:The precision of the worst-known nuclear input for the solar 7Be neutrino flux shall be improved, in order to enable a precision of better than 5% for the predicted 7Be neutrino flux, and to improve the precision of the predicted 8B neutrino flux.These three aims shall be reached with new cross section measurements on the nuclear reactions dominating the error bars for Big Bang 2H, 2H(p,gamma)3He (aim 1), and for Big Bang 7Li and solar 7Be and 8B neutrinos, 3He(alpha,gamma)7Be (aims 2 and 3).WP 1: At the LUNA 400 kV underground accelerator, the 2H(p,gamma)3He cross section shall be measured with a systematic precision of 3% or better, in 10 keV energy steps from 50-400 keV proton beam energy.WP 2: In Dresden, at the 3 MV Tandetron accelerator the angular distribution of the 3He(alpha,gamma)7Be reaction shall be measured at 1 MeV center-of-mass energy with 2% precision. In addition, the 3He(alpha,gamma)7Be cross section shall be measured by activation, using the new Felsenkeller 150% ultra-low background germanium detector, at eight points in the center-of-mass energy range between 0.25 and 1.1 MeV.

建议项目的目标是：1。提高大爆炸核合成（BBN）观测的最佳性，使其与宇宙微波背景（CMB）竞争：预测的2 H丰度作为重子-光子比的函数的精度应提高到接近2 H观测的精度。因此，目前最精确的BBN工具2 H的精度应该进一步提高，以便它在对CMB约束的重子-光子比的影响方面具有竞争力。使最坏的BBN观测到的差异更加尖锐，以便使其成为新物理学的工具：预测的7 Li丰度作为重子与光子比的函数的精度将得到提高，不是希望解决宇宙7 Li问题，而是为了能够使用CMB预测和观测到的7 Li丰度之间的差异来探索宇宙前1000秒的新物理学。提高太阳7 Be和8B中微子通量的预测精度：提高太阳7 Be中微子通量的已知最差核输入的精度，使7 Be中微子通量的预测精度优于5%，提高8B中微子通量的预测精度，这三个目标将通过对大爆炸2 H，2 H（p，γ）3 He（目标1）和大爆炸7 Li和太阳7 Be和8B中微子3 He的核反应的新截面测量来实现（α，γ）7Be（目标2和3）.WP 1：在LUNA 400 kV地下加速器上，应以3%或更高的系统精度测量2 H（p，gamma）3 He截面，WP 2：在德累斯顿，在3 MV Tandetron加速器上，应在1 MeV质心能量下以2%的精度测量3 He（α，γ）7 Be反应的角分布。此外，3 He（α，γ）7 Be横截面应通过激活测量，使用新的Felsenkeller 150%超低本底锗探测器，在质心能量范围0.25和1.1 MeV之间的八个点。