Deuterium and lithium for precision cosmology

拟建项目的目标是：1。改进最佳的大爆炸核合成（BBN）观测结果，使其与宇宙微波背景（CMB）相竞争：预测的2H丰度作为重子光子比的函数的精度应提高到接近2H观测的精度。因此，目前最精确的BBN工具2H的精度将进一步提高，使其在对CMB约束的重子光子比的影响方面具有竞争力。提高最坏的BBN观测值的差异，以便使其成为新物理的工具：预测7Li丰度作为重子光子比的函数的精度应该得到提高，不是希望解决宇宙7Li问题，而是为了能够利用cmb预测和观测到的7Li丰度之间的差异在宇宙的前1000秒探索新的物理。提高太阳7Be和8B中微子通量的预测精度：提高太阳7Be中微子通量已知最差核输入的精度，使预测7Be中微子通量的精度达到5%以上，提高预测8B中微子通量的精度。这三个目标将通过对大爆炸2H、2H(p, γ)3He（目标1）和大爆炸7Li、太阳7Be和8B中微子3He(α, γ)7Be（目标2和3）主导误差条的核反应进行新的截面测量来实现。WP 1：在LUNA 400 kV地下加速器上，2H(p,gamma)3He横截面应以3%或更高的系统精度进行测量，从50-400 keV质子束能量中分10 keV能量步进行测量。WP 2：在德累斯顿，在3mv Tandetron加速器上，3He(alpha,gamma)7Be反应的角分布应以1mev质心能量测量，精度为2%。此外，3He(alpha,gamma)7Be的截面将通过活化测量，使用新的Felsenkeller 150%超低本底锗探测器，在质心能量范围在0.25 - 1.1 MeV之间的8个点。

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.