Model-independent form factors for spin-independent neutralino–nucleon scattering from elastic electron scattering data
Model-independent form factors for spin-independent neutralino–nucleon scattering from elastic electron scattering data
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DOI：
10.1088/1475-7516/2007/04/012
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发表时间：
2006-08
影响因子：
6.4
通讯作者：
G. Dūda;Ann Kemper;P. Gondolo
中科院分区：
文献类型：
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作者：
G. Dūda;Ann Kemper;P. Gondolo
中性子-核子与各种原子核相互作用速率的理论计算对于指导暗物质研究如CDMS、EDELWEISS、ZEPLIN和其他实验具有重要意义，因为它们被用来建立WIMP-质子截面的上界。这些相互作用率和截面通常用标准的、单参数或双参数模型依赖的核形状因子来计算，这可能不完全反映所讨论的特定核的实际形状因子。众所周知，弹性电子散射可以非常精确地确定球形或近球形核的核形状因子，从而确定核电荷密度。我们使用来自弹性电子散射数据的电荷密度来计算模型无关的，分析的形状因子的各种目标核重要的暗物质搜索，如Si，Ge，S，Ca等。我们发现，对于1-100 keV范围内的核反冲，当使用与模型无关的形状因子时，截面和速率存在显着差异：在30 keV核反冲下，形状因子的平方相差1.06倍（28 Si），1.11倍（40 Ca），1.27倍（70 Ge）和1.92倍（129 Xe）。我们示出了不同的形状因子上的上限上的WIMP质子横截面的效果与一个假设的70 Ge探测器在一个50千克-天的有效曝光。具有各种参数选择的头盔形状因子与最佳（傅立叶-贝塞尔）形状因子最多相差10-20%，并且如果选择参数来模拟实际核密度，则可以接近它超过1%。
Theoretical calculations of neutralino–nucleon interaction rates with various nuclei are of great interest to direct dark matter searches such as CDMS, EDELWEISS, ZEPLIN and other experiments since they are used to establish upper bounds on the WIMP–proton cross section. These interaction rates and cross sections are generally computed with standard, one- or two-parameter model-dependent nuclear form factors, which may not exactly mirror the actual form factor for the particular nucleus in question. As is well known, elastic electron scattering can allow for very precise determinations of nuclear form factors and hence nuclear charge densities for spherical or near-spherical nuclei. We use charge densities derived from elastic electron scattering data to calculate model-independent, analytic form factors for various target nuclei important in dark matter searches, such as Si, Ge, S, Ca and others. We have found that for nuclear recoils in the range of 1–100 keV significant differences in cross sections and rates exist when the model-independent form factors are used: at 30 keV nuclear recoil the form factors squared differ by a factor of 1.06 for 28Si, 1.11 for 40Ca, 1.27 for 70Ge and 1.92 for 129Xe. We show the effect of different form factors on the upper limit on the WIMP–proton cross section obtained with a hypothetical 70Ge detector during a 50 kg-d effective exposure. Helm form factors with various parameter choices differ at most by 10–20% from the best (Fourier–Bessel) form factor, and can approach it to better than 1% if the parameters are chosen to mimic the actual nuclear density.