The Study of optical specification for the near backscattering Si crystal analyzer spectrometer

Shibata, Kaoru  ; Takahashi, Nobuaki; Nakajima, Kenji  ; Kawakita, Yukinobu*; Sato, Taku*; Tsukushi, Itaru*; Nakagawa, Hiroshi   ; Fujiwara, Satoru; Mezei, F.*; Mutka, H.*; Neumann, D.*; Tregenna-Piggott, P.*; Arai, Masatoshi

We are planning and partially beginning the construction of the near backscattering Si crystal analyzer spectrometer DNA at the Material and Life Science Facility (MLF), J-PARC. The optical specification of DNA is as follows. In the center of the vacuum chamber, a sample position is located at 42 m away form the coupled moderator. The analyzer banks of Si(111) and Si(311) single crystal wafers which are pasted on the spherical surface, are mounted at the right and left side each in the vacuum chamber. The Bragg angle of those analyzer crystals are about 87.5 deg and the distance between the sample position and the analyzer crystal is about 2.3 m. The analyzed neutron beams are detected by the Hee gas position sensitive detector located at around the sample position. Then the expected energy resolution and the dynamic range of the Si(111) crystal analyzer are about 1 micro-eV and 40 micro-eV, respectively. We will report the optical principle and specification of DNA spectrometer.