Application of scintillation in helium mixed with xenon to a position-sensitive detector

We have been studying scintillation properties of He/Xe, such as luminescence spectra, time profile and scintillation yield. Furthermore we have been measuring ionization yields and studying the scintillation mechanism. 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. The time profiles depend on not only the xenon pressure but also the helium pressure and decay times of scintillation in He/Xe are shorter than decay time of He₂. Scintillation yields in He/Xe are large as compared with the estimated yields assuming that the energy transfer from helium to xenon does not exist. 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.