TY - JOUR
T1 - Search for invisible decay of orthopositronium
AU - Mitsui, T.
AU - Fujimoto, R.
AU - Ishisaki, Y.
AU - Ueda, Y.
AU - Yamazaki, Y.
AU - Asai, S.
AU - Orito, S.
PY - 1993
Y1 - 1993
N2 - Orthopositronium (o-Ps) decay or conversion into ''invisible'' final states is searched for by measuring the energy deposited in a hermetic photon detector for each positron produced from β+ decay of Na22 and stopped by an aerogel target. No invisible event is detected for a total of 108 stopping positrons, thereby giving an upper limit of 2.8×10-6 on the o-Ps branching ratio, which is 200 times more stringent than previous limits. This experiment excludes an invisible decay as the origin of the reported discrepancy on o-Ps lifetime, provides a limit of ε<1.5×10-8 on the photon-mirror-photon mixing, and rules out millicharged particles lighter than 500 keV.
AB - Orthopositronium (o-Ps) decay or conversion into ''invisible'' final states is searched for by measuring the energy deposited in a hermetic photon detector for each positron produced from β+ decay of Na22 and stopped by an aerogel target. No invisible event is detected for a total of 108 stopping positrons, thereby giving an upper limit of 2.8×10-6 on the o-Ps branching ratio, which is 200 times more stringent than previous limits. This experiment excludes an invisible decay as the origin of the reported discrepancy on o-Ps lifetime, provides a limit of ε<1.5×10-8 on the photon-mirror-photon mixing, and rules out millicharged particles lighter than 500 keV.
UR - http://www.scopus.com/inward/record.url?scp=0001628110&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0001628110&partnerID=8YFLogxK
U2 - 10.1103/PhysRevLett.70.2265
DO - 10.1103/PhysRevLett.70.2265
M3 - Article
AN - SCOPUS:0001628110
SN - 0031-9007
VL - 70
SP - 2265
EP - 2268
JO - Physical Review Letters
JF - Physical Review Letters
IS - 15
ER -