6.8GeV/cπ-N非弹性作用下π0介子的产生

利用联合原子核研究所24立升丙烷气泡室照片,对动量为6.8GeV/cπ^-介子与核子非弹性作用产生π⁰介子的问题进行了研究。扫描了约2700对立体照片。在宽度为29.3厘米的有效范围内得到了1275个π^--N非弹性作用事例。在936个π^--p事例和339个π^--n事例中,观察到正电子、负电子对数目分别为240和89。考虑了气泡室对γ光子的探测效率,我们得到每个事例产生的平均π⁰介子数n_(π⁰)=1.00±0.06。γ光子的平均横动量为p_⊥γ=173MeV/c。此外,着重研究了γ光子的能量分布。在γ光子全部是由π⁰介子衰变产生以及π⁰介子和π^±介子具有相同能谱的假设下,利用在相同入射粒子能量的π^--N作用中所产生的次级π^±介子能量分布变换成γ光子的能量分布;将本实验所得的γ光子能量分布和变换得到的分布进行比较,这两个分布在实验误差范围内完全符合。

π0-MESON PRODUCTION IN π--N INELASTIC INTERACTIONS AT 6.8 GeV/c

Using the 24-litre propane chamber, photographs from JINR π⁰-meson production in inelastic interactions of π^--mesons of momentum 6.8 GeV/c with nucleons are examined. About 2700 pairs of stereoscopic pictures have been scanned and 1275 events of π^--N inelastic interactions have been found in an effective region 29.3 cm wide. In these events, 936 π^--p and 339 π^--n events, 240 and 89 electron-positron pairs have been observed respectively. After taking account of the efficiency of the bubble chamber for detection of γ-photons, it is found that the mean number of π⁰ mesons produced per event is n_(π⁰)=1.00±0.06 and the mean transverse momentum of the γ-photons is P_γ⊥ = 173 MeV/c. In addition, the energy distribution of the γ-photons is especially examined. Under the assumptions that the γ-photons are entirely due to π⁰ decays and that the energy spectrum of the π⁰ mesons is the same as that of the π^± -mesons', an energy distribution of γ-photons can be deduced from the energy distribution of the secondary π^±-mesons produced in π^--N interactions at the same incident energy; the γ-photon energy distribution obtained in the present experiment is in agreement with this deduced distribution within experimental error.