TY - JOUR
T1 - Negative-pion trapping by a metastable state in liquid helium
AU - Nakamura, S. N.
AU - Iwasaki, M.
AU - Outa, H.
AU - Hayano, R. S.
AU - Watanabe, Y.
AU - Nagae, T.
AU - Yamazaki, T.
AU - Tada, H.
AU - Numao, T.
AU - Kuno, Y.
AU - Kadono, R.
PY - 1992/1/1
Y1 - 1992/1/1
N2 - We have found a long-lived metastable state of stopped - in liquid helium by measuring the time spectra of two different delayed products: (i) protons emitted after - absorption by He4 nuclei and (ii) 70-MeV electrons originating from free -'e-e» decay. The lifetime and fraction of delayed - absorption obtained by using the emitted protons are 7.26"0.12 nsec and 1.66"0.05%, respectively. The free-decay fraction of a pion in liquid helium was obtained to be 0.64"0.03% from this result, which is consistent with the observed free-- decay fraction. These results imply that 2.30"0.07% of stopped - are trapped in the metastable state which have an overall lifetime of 10.1"0.2 nsec. The same experimental and analysis were performed for stopped - in liquid neon, where no evidence for trapping was found.
AB - We have found a long-lived metastable state of stopped - in liquid helium by measuring the time spectra of two different delayed products: (i) protons emitted after - absorption by He4 nuclei and (ii) 70-MeV electrons originating from free -'e-e» decay. The lifetime and fraction of delayed - absorption obtained by using the emitted protons are 7.26"0.12 nsec and 1.66"0.05%, respectively. The free-decay fraction of a pion in liquid helium was obtained to be 0.64"0.03% from this result, which is consistent with the observed free-- decay fraction. These results imply that 2.30"0.07% of stopped - are trapped in the metastable state which have an overall lifetime of 10.1"0.2 nsec. The same experimental and analysis were performed for stopped - in liquid neon, where no evidence for trapping was found.
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U2 - 10.1103/PhysRevA.45.6202
DO - 10.1103/PhysRevA.45.6202
M3 - Article
AN - SCOPUS:0000800902
VL - 45
SP - 6202
EP - 6208
JO - Physical Review A - Atomic, Molecular, and Optical Physics
JF - Physical Review A - Atomic, Molecular, and Optical Physics
SN - 1050-2947
IS - 9
ER -