Development of compact emulsion spectrometer using a permanent magnet

我们研制了一种紧凑型乳化液光谱仪，可以在没有电子探测器和电磁铁的地方使用。(1)我们与公司的工程师合作，设计并建造了紧凑型乳化液光谱仪的永磁路。通过计算产生的磁场，考察了两种类型的磁路。选择了三层结构的Halbach结构，因为它会在内部产生均匀的磁场。(2)我们测量了磁路内部的磁场，证实其与设计值几乎相同。(3)通过插入由乳胶膜和间隔物组成的乳胶室，制作了紧凑型乳胶谱仪。(4)将紧凑型乳胶谱仪暴露在美国国家放射科学研究所HIMAC的180 MeV/u碳束中，以研究其性能。从最上游和最下游薄膜的径迹角之差，成功地测量了碳束的动量(p/z)，分辨率为12%。(5)为了考察它在高能核-核相互作用中产生的介子和介子的动量测量上的性能，它还被暴露在SPS，CERN的158GeV/N铟束流中。分析目前正在进行中。

We have developed a compact emulsion spectrometer which can be used in places where neither electronic detectors nor electromagnets are available.(1)We designed and constructed a permanent magnetic circuit for the compact emulsion spec-trometer in cooperation with company engineers. Two types of magnetic circuits were examined by calculating magnetic field to be produced. Three-layer-structure Halbach configuration was chosen because it would produce uniform magnetic field inside it.(2)We measured magnetic field inside the magnetic circuit and confirmed that it was almost the same as the designed value.(3)We made a compact emulsion spectrometer by inserting an emulsion chamber which consists of emulsion films and spacers.(4)The compact emulsion spectrometer was exposed to a 180 MeV/u Carbon beam of HIMAC, the National Institute of Radiological Sciences in order to study its performance. The momentum (p/z) of the Carbon beam was successfully measured with a resolution of 12% from the difference between track angles in the most upstream and the most downstream films.(5)It was also exposed to a 158GeV/N Indium beam of SPS, CERN in order to examine its performance on the momentum measurements of pions and Kaons produced in high energy nucleus-nucleus interactions. The analysis is now in progress.