Oct 16 – 20, 2016
Europe/Zurich timezone

Neutron Lifetime Measurement at J-PARC/MLF/BL05

Oct 18, 2016, 12:20 PM
Oral Fundamental physics and precision experiments with muons, pions, neutrons, antiprotons, and other particles Tu - 2


Tatsuhiko Tomita (Kyushu University)


The neutron lifetime (880.3 ± 1.1 [sec] [Particle Data Group]) is one of the most important parameters for the Big Bang Nucleosynthesis, which predicts nucleosynthesis in the early universe. So far it has been measured by two different methods, penning trap and UCN bottle, and they got recent value 888.0 ± 2.1 [sec] and 879.6 ± 0.8 [sec] respectively. Although both methods decide the lifetime at Ο(0.1)% precision independently, there is a 3.8 sigma(8.4 [sec]) discrepancy. Therefore we need new approaches which can resolve this problem. Our method, “Electron Counting”, is one of such approaches. In this method, we count the number of electrons which emitted by neutron beta decay using Time Projection Chamber (TPC). Not only counting electrons, we count the number of 3He(n,p)3H reactions to determine neutron flux using same detector at the same time. Our method has different kinds of systematic uncertainties from previous two methods, thus our results directly contribute to resolve current discrepancy. We acquired the first physics data set at J-PARC/MLF/BL05 in 2016 spring. The statistical uncertainty is about O(10)% precision on neutron lifetime. This talk will report the recent results of obtained data set.

Primary author

Tatsuhiko Tomita (Kyushu University)


Aya Morishita (Kyushu University) Hidetoshi Otono (RCAPP, Kyushu University) Hideyuki Oide (CERN) Hirochika Sumino (The University of Tokyo) Hirohiko Shimizu (Nagoya University) Kaoru Taketani (KEK) Katsuya Hirota (Nagoya University) Kenji Mishima (KEK) Mami Yokohashi (Nagoya University) Masaaki Kitaguchi (KMI, Nagoya University) Naoki Nagakura (The University of Tokyo) Naoyuki Sumi (Kyushu University) Ryunosuke Kitahara (Kyoto University) Satoru Yamashita (ICEPP, The University of Tokyo) Sei Ieki (The University of Tokyo) Takahito Yamada (The University of Tokyo) Takashi Ino (KEK) Tamaki Yoshioka (RCAPP, Kyushu University) Tatsushi Shima (RCNP, Osaka University) Yoshichika Seki (JAEA) Yoshihisa Iwashita (ICR, Kyoto University)

Presentation materials