Studies on the development of a curved superconducting solenoid magnet for the very intense ultra slow muon beam with high luminosity

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We are designing one super omega muon channel with a large acceptance of 400mSr for the study of thin film magnetism or negative muon physics in the MLF experimental hall No.～2. In the case of the super omega beam channel, we are going to install a large acceptance solenoid made of mineral insulation cables (MIC) and a superconducting curved transport solenoid. We can collect either surface or cloud muons with a large acceptance of 400mSr. Finally, we are expecting 4 $\times$ $10^{8}$ surface $\mu^{+}$/s and $10^{7}$ cloud $\mu^{-}$/s in the MLF experimental hall No.～2. Although many of these studies can be performed using either surface or decay muons, at the super omega channel we are aiming to create a new type of muon source : an intense ultra-slow muon source. Slow muons are generated through resonant ionization of muonium (Mu). Mu is formed by stopping an intense surface muon beam on the rear surface of a hot W foil. At the RIKEN/RAL muon facility, 20 slow $\mu^{+}$/s are obtained out of 1.2 $\times$ $10^{6}$ surface muons/s \cite{Pavel2008}. Taking into account the repetition rate of the pulsed laser system and the proton beam, as well as the surface muon ratio between RIKEN-RAL and J-PARC MUSE, we can expect 1.3 $\times$ $10^{4}$ slow $\mu^{+}$/s without any additional laser development. A rate of 1.3 $\times$ $10^{6}$ slow $\mu^{+}$/s can be achieved with additional laser development, such as the tripling of 366nm photons with pico second pulse width to match the Doppler broadening of the Mu at 2000K. By obtaining the budget of Kakenhi(Grants-in-Aid for scientific research) (A), we have completed a design for the curved superconducting magnet, which enables us to generate an very intense ultra slow muons.