Experimental comparison of performances of ultracold neutron gravity spectrometers

我们研制的超冷中子下落聚焦重力谱仪的特点是能量转移和动量转移的分辨率都很高，分别约为10^<-8>eV和10^<-3>A^<o-1>。这种高分辨率是任何一台中子能谱仪都达不到的，但最近一种新型的自旋回波能谱仪正在研制中，它采用小角排列的方法，其性能与现有的装置相当。我们研制的落聚焦能谱仪使同时测量各种散射角成为可能。这对于传统的到达聚焦重力分光计是不可能的。散射角分析的这一性质对于研究扩散样品的动力学等非常有用。接下来，研究了该谱仪与新型小角自旋回波谱仪的性能比较，结果表明，由于超冷中子在散射样品中的中子光学过程，超冷中子重力谱仪在散射样品中应给出不同的动力学信息，这对研究超冷中子重力谱仪的性能具有指导意义作为本研究结果导出的指示将有效地应用于目前正在制备的几个实际散射样品的未来应用实验中。

The characteristic performances of the fall focusing gravity spectrometer with ultracold neutrons developed in our Institute were investigated to be the high resolutions for both of the energy transfer and of the momentum transfer, about 10^<-8> eV and about 10^<-3> A^<o-1>, respectively. These very high resolutions are not attained with any other single machine of neutron spectrometers, but recently a new type of spin echo spectrometer is going to be developed applied with the method of small angle arrangements which should also show similar performances with the present device.Our fall focusing spectrometer gives the possibility of measurements of various scattering angles simultaneously, which was not possible with the conventional reach focusing gravity spectrometer. This property of scattering angle analyses is very much useful for studying, for example, dynamics of diffusing samples. In the next place, the Characteristic performances of our spectrometer compared to the new type of the small angle spin echo spectrometer were studied in the present investigation and the result was indicated that the gravity spectrometer with ultracold neutrons should give much different dynamical information on the scattering sample due to the neutron optical processes of ultracold neutrons in the scattering processes in the sample.These much instructive indications derived as the results of the present studies would be effectively applied in the coming applied experiments for several actual scattering samples now under preparation.