@article{oai:repo.qst.go.jp:00080496,
 author = {Yamawaki, Masato and Uesugi, Naoya and Oka, Toshitaka and Nagasawa, Naotsugu and Ando, Hirokazu and Brain, E. O' Rourke and Kobayashi, Yoshinori and Naotsugu, Nagasawa},
 issue = {11},
 journal = {Japanese Journal of Applied Physics},
 month = {Nov},
 note = {Positron annihilation lifetime measurements were performed on polyethylene films [Low Density Polyethylene (LDPE) and Ultra High Molecular Weight Polyethylene (UHMWPE)] with thickness of 15 m – 2,000 m using a Na-22 positron source enclosed in a Kapton film. For thin films, some positrons will pass through the film and annihilate behind it. Using a single film in a commercial anti-coincidence system, by placing an annealed stainless steel (SUS304) cover behind the sample, it is possible to sufficiently measure the long lifetime ortho-positronium (o-Ps) component even in thin films. Additionally, calculated intensities of the o-Ps component determined from the estimated film transmittance agreed well with the measured values. Furthermore, by applying this method to uniaxially stretched UHMWPE, we were able to observe structural changes owing to the stretching consistent with shorter measured o-Ps lifetime and increased o-Ps intensity.},
 title = {Development of a method for positron annihilation lifetime measurement in thin polyethylene films using a Na-22 source},
 volume = {59},
 year = {2020}
}