奇异粒子的性质及其产生和衰变

用一架30厘米×30厘米×10厘米磁场为6200高斯的云室,在海拔3185米的云南落雪高山实验室拍摄了30000对照片,获得105个V⁰,而可以进行分类的有43个。其中有26个θ₁⁰,16个Λ⁰和一个θ₂⁰。本文对θ₁⁰,Λ⁰和一个θ₂⁰进行了研究,其结果如下:1)Q值,Q_(Λ⁰)=(36.2±2.5)Mev,Q_(θ1⁰)=(233±11)Mev;2)平均寿命,τ_(Λ⁰)=(3.19_-0.92^+2.42)×10^-10秒,τ_(θ1⁰)=(1.14_-0.27^+0.49)×10^-10秒;3)动量分布与以前的工作没有显著差别;4)N(Λ⁰)/N(θ₁⁰)=0.51±0.22(权衡数);5)Λ⁰和θ₁⁰在质心系的衰变角分布没有明显的不对称性;6)一个θ₂⁰在静止坐标系寿命为～10^-9秒,衰变类型可能为θ₂⁰→π^-+π⁺+π⁰或者θ₂⁰→π^±+μ^?+ν。

THE PROPERTIES, PRODUCTION AND DECAY OF STRANGE PARTICLE

The cloud-chamber has a volume 30×30×10 cm³ in a maguetic field of 6200 gauss, which is operated at a 3185m mountain altitude. In a set of 30000 pairs of photographs taken, 105 events of the decay of neutral V particles and 21 of the decay of charged particles wore observed. It is seen that 16 events have been classified as due to the decay of ∧⁰ particles, 26 as due to the decay of θ₁⁰ particles, one as decay of a θ₂⁰ particle and 62 as nonclassified. We have studied the following properties of the ∧⁰ and θ⁰ particles, the results of which are summamed as follows: 1) Q values Q_(Λ⁰)=(36.2±2.5)Mev, Q_(θ1⁰)=(233±11)Mev; 2)mean lifotimes τ_(Λ⁰)=(3.19_-0.92^+2.42)×10^-10sec,τ_(θ1⁰)=(1.14_-0.27^+0.49)×10^-10sec; 3) The Momentum distributions found for ∧⁰ and θ⁰ particles have no appreciable difference with earlier results;4) N(∧0)/N(θ₁⁰)=0.51±0.22 (corrected number in lead);5) The angular distributions of the decay products of the ∧⁰ and θ⁰ particles in the rest system have no marked asymmetry;6) The lifetime of one θ₂⁰ particle is estimated to be :10^-9 sec. in the rest system. The decay mode of this θ₂⁰ particle is probably θ₂⁰→π^-+π⁺+π⁰ or θ₂⁰→π^±+μ^?+ν.