Scintillation property in helium mixed with xenon

We have studied a possibility to exchange a luminescence origin from helium to xenon by adding a small amount of xenon to helium. Luminescence spectra in the mixture were measured using an X-ray generator and a VUV monochromator. The scintillation yields and time profiles in the mixture were also measured using alpha particles. From the measurements of luminescence spectra, it became clear that the scintillation photons in He/Xe mixture were emitted in the wavelength region of 150-200 nm with a peak around 173 nm. The scintillation yields were measured using a PMT sensitive to photons with wavelength of 115-300 nm. The scintillation yields increases with increasing the ratio of xenon. When the partial pressure of xenon is 0.01 MPa in He/Xe mixture of 1.0 MPa, the scintillation yield is almost equal to that in pure xenon of 1.0 MPa.