NEGATIVE-PION TRAPPING BY A METASTABLE STATE IN LIQUID-HELIUM

被引：40

作者：

NAKAMURA, SN

IWASAKI, M

OUTA, H

HAYANO, RS

WATANABE, Y

NAGAE, T

YAMAZAKI, T

TADA, H

NUMAO, T

KUNO, Y

KADONO, R

机构：

[1] UNIV TOKYO, FAC SCI, MESON SCI LAB, TOKYO 113, JAPAN

[2] UNIV TOKYO, INST NUCL STUDY, TANASHI, TOKYO 188, JAPAN

[3] UNIV TOKYO, COLL GEN EDUC, DEPT NAT SCI, MEGURO KU, TOKYO 153, JAPAN

[4] TRIUMF, VANCOUVER V6T 2A3, BC, CANADA

来源：

PHYSICAL REVIEW A | 1992年 / 45卷 / 09期

关键词：

D O I：

10.1103/PhysRevA.45.6202

中图分类号：

O43 [光学];

学科分类号：

070207 ; 0803 ;

摘要：

We have found a long-lived metastable state of stopped-pi- in liquid helium by measuring the time spectra of two different delayed products: (i) protons emitted after pi--absorption by He-4 nuclei and (ii) 70-MeV electrons originating from free pi- --> e--nu(e)BAR decay. The lifetime and fraction of delayed pi--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-pi- decay fraction. These results imply that 2.30 +/- 0.07% of stopped-pi-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-pi- in liquid neon, where no evidence for trapping was found.

引用

页码：6202 / 6208

页数：7

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