EPJ Web of Conferences (Jan 2019)
New project for precise neutron lifetime measurement at J-PARC
- Nagakura Naoki,
- Hirota Katsuya,
- Ieki Sei,
- Ino Takashi,
- Iwashita Yoshihisa,
- Kitaguchi Masaaki,
- Kitahara Ryunosuke,
- Koga Jun,
- Mishima Kenji,
- Morishita Aya,
- Nakano Yusuke,
- Oide Hideyuki,
- Okabe Hiroki,
- Otono Hidetoshi,
- Seki Yoshichika,
- Sekiba Daiichiro,
- Shima Tatsushi,
- Shimizu Hirohiko,
- Sumi Naoyuki,
- Sumino Hirochika,
- Taketani Kaoru,
- Tomita Tatsuhiko,
- Uehara Hideaki,
- Yamada Takahito,
- Yamashita Satoru,
- Yokohashi Mami,
- Yoshioka Tamaki
Affiliations
- Nagakura Naoki
- Department of Physics, Graduate School of Science
- Hirota Katsuya
- Department of Physics, Graduate School of Science
- Ieki Sei
- Department of Physics, Graduate School of Science
- Ino Takashi
- KEK
- Iwashita Yoshihisa
- Institute for Chemical Research
- Kitaguchi Masaaki
- Kobayashi-Maskawa Institute for the Origin of Particles and the Universe (KMI)
- Kitahara Ryunosuke
- Department of Physics, Graduate School of Science
- Koga Jun
- Department of Physics, Graduate School of Science
- Mishima Kenji
- KEK
- Morishita Aya
- Department of Physics, Graduate School of Science
- Nakano Yusuke
- Department of Physics, Graduate School of Science
- Oide Hideyuki
- Istituto Nazionale di Fisica Nucleare (INFN-Genova)
- Okabe Hiroki
- Department of Physics, Graduate School of Science
- Otono Hidetoshi
- Research Center for Advanced Particle Physics (RCAPP), Kyushu University
- Seki Yoshichika
- J-PARC Center, Japan Atomic Energy Agency
- Sekiba Daiichiro
- Institute of Applied Physics, University of Tsukuba
- Shima Tatsushi
- Research Center for Nuclear Physics (RCNP), Osaka University
- Shimizu Hirohiko
- Department of Physics, Graduate School of Science
- Sumi Naoyuki
- Department of Physics, Graduate School of Science
- Sumino Hirochika
- Department of Basic Science, Graduate School of Arts and Sciences
- Taketani Kaoru
- KEK
- Tomita Tatsuhiko
- Department of Physics, Graduate School of Science
- Uehara Hideaki
- Department of Physics, Graduate School of Science
- Yamada Takahito
- Department of Physics, Graduate School of Science
- Yamashita Satoru
- International Center for the Elementary Particle Physics (ICEPP)
- Yokohashi Mami
- Department of Physics, Graduate School of Science
- Yoshioka Tamaki
- Research Center for Advanced Particle Physics (RCAPP), Kyushu University
- DOI
- https://doi.org/10.1051/epjconf/201921903003
- Journal volume & issue
-
Vol. 219
p. 03003
Abstract
The decay lifetime of free neutrons (∼880 s) is an important parameter of the weak interaction and for Big Bang Nucleosynthesis. However, results of measurements currently show discrepancies depending on the method used. As most experiments nowadays employ ultra cold neutrons, we have developed a new cold-beam experiment which we perform at the Japan Proton Accelerator Research Complex. As a special feature, a polarized neutron beam is bunched by a spin flip chopper. A time projection chamber operated with He and CO2 gas, including a well-controlled amount of 3He, is used for detection of the beta-decays and simultaneous determination of the beam intensity. Using the data between 2014 and 2016, we evaluated our first, preliminary result of the neutron lifetime as 896 ± 10(stat.) −10+14(sys.) s. We plan several upgrades to achieve our precision goal of 1 s.
