Repetition rate multiplication capability for a high energy resolution mode of DIANA at J-PARC

DIANA is an indirect geometry TOF spectrometer which will be installed at Materials and Life science experimental Facility (MLF), Japan Proton Accelerator Research Complex (J-PARC). We are especially aiming at high energy resolution of about 2µeV by using perfect crystal Si(111) analyzer together with high speed counter-rotating pulse-shaping choppers with each rotation frequency of 300 Hz as optional equipments. Although such a high energy resolution is attained, it is considerably inefficient to chop a very narrow incident energy band from one pulse period of a source. Therefore, we have varied the number of slits and have performed Monte Carlo simulations to study repetition rate multiplication (RRM) capabilities. By using the optimum 8-slit pulse-shaping choppers, 23 incident energy bands are simultaneously available from one pulse period of a source. It will give us better measurement efficiency when investigating between quasi-elastic and low energy inelastic regions of about 3meV with high energy resolution of about 0.1%.