海拔3220米动量大于4 GeV/c的μ子垂直积分动量谱

我们在云南海拔3220米高山上,利用G-M计数管磁谱仪,测量了动量大于4 GeV/c的宇宙线μ子垂直积分动量谱.实验给出的谱可用一指数函数表示:I（>P）=Q（p+4）^1.86±0.06(cm^-2·sr^-1·s^-1),其中动量P以GeV/c为单位,Q为常数.同时测量了动量在4—23 GeV/c范围μ子的荷电比为N_μ⁺/N_μ^-=1.26±0.11.另外对本谱仪的动量误差问题作了讨论和计算.     

海平面宇宙线μ子垂直绝对强度及积分动量谱测量

利用两个大面积塑料闪烁计数器和两个液体闪烁计数器组成的望远镜系统与铅吸收体组成射程谱仪, 并用一个灵敏体积为70×50×30cm³的流光室作为剔除簇射装置, 1981年冬季, 对北京地区海平面宇宙线μ子垂直通量及其积分动量谱进行了测量. 动量测量范围为0.2 GeV/c至1.3 GeV/c μ子的垂直通量为9.2×10^－3sr^－1cm^－2s^－1. 在3.5×10⁴张照片进行了扫描判别, 可得簇射比例约占30%. 文中并对若干修正进行了讨论.     

高山宇宙线荷电强子流强的负正比

在海拔3220米的实验室里,用磁谱仪动量予选装置和多板云室,对落在0.23m²面积上的单根荷电强子进行了观测.考虑到各种可能的修正以后,得出在10—20 GeV/c之间,荷电强子的负正比为:N^-/N⁺=0.53±0.05.当认为N⁺只包含有P和π⁺,N^-是π^-,而且N_π+/N_π-=1时,推算出N_π-/N_p=0.9±0.1.若π^-积分谱的形式为j（>p）=Kp^-r,估算出在5—20 GeV/c的动量范围,r（?）2.3.本文也对荷电强子的积分流强作了粗略的估计,其结果是:j_⊥^p+π（>12 GeV/c）=（7.4±0.7）×10^-5cm^-2·st^-1·s^-1.     

Luminosity determination for the pd reaction at 2.14 GeV with WASA-at-COSY

The luminosity for a WASA-at-COSY experiment involving the pd reaction at 2.14 GeV proton-beam energy is determined by the forward pd elastic scattering, which yields an average beam-on-target value of [5.2 ± 0.3(stat) ± 0.3syst] × 10³⁰s^-1cm^-2. In addition, the forward pd elastic-scattering angular distribution is obtained with four-momentum transfer squared -t between 0.16 (GeV/c)² and 0.78 (GeV/c)² at this beam energy, which is compared with other experimental data and the pd double scattering model.     

水平宇宙线穿透粒子的鉴别

本文描述一个用大型磁云室在水平方向宇宙线穿透粒子中寻找新粒子的实验,结果表明β<0.7、m>1GeV/c²的单电荷粒子或相对论性分数电荷粒子的流强小于3×10^-8cm^-2·sr^-1·sec^-1。     

BES主漂移室模型性能的束流测试

本文描述了北京谱仪BES主漂移室一个多层多单元模型的结构, 给出在日本KEK12GeV质子同步加速器K2试验束上, 利用动量0.5～1.5GeV/c的e⁺,π⁺和p束测量模型性能的主要结果. 在3.1cm的单元半宽内, 室的单丝空间分辨率σ_x=170～210μm. 相当四十次dE/dx取样的能量分辨率σ_E/E约为15%, 提供了北京谱仪工作能区鉴别粒子的一种有效方法, 可同飞行时间(TOF)计数器和簇射计数器相互补充.     

宇宙线μ子天顶角分布在线测量

本文给出了用闪烁计数器描迹仪构成的望远镜阵列测量宇宙线μ子天顶角分布的初步结果. 天顶角的范围为0°到17.7°十种不同的角度值. 实验结果表明, 宇宙线μ子强度对天顶角θ的依赖关系服从cos^2.6θ分布规律. 用描迹仪望远镜阵列测量天顶角分布的优点是: 角度分辨率好, 而且还可以同时获取多个角度的数据.     

关于高能p+N→μ(?)+X中μ对的横动量分布

本文讨论了高能p+N→μμ+X中μ对横动量Q_T,谱和〈Q_T²〉随Q²的变化。指出如果在α_s阶QCD的计算结果上再考虑价夸克-价夸克子过程中双夸克态的贡献,并假定初态部分子有通常估计的固有横动量〈P_T〉～0.3GeV/c后,利用核子深度非弹实验得到的部分子分布函数,能使计算结果与实验数据有较好的符合。     

Applying Bayesian neural networks to identify pion, kaon and proton in BESⅡ

The Monte-Carlo samples of pion, kaon and proton generated from 0.3GeV/c to 1.2GeV/c by the `tester' generator from SIMBES which are used to simulate the detector of BESⅡ are identified with the Bayesian neural networks (BNN). The pion identification and misidentification efficiencies are obviously better at high momentum region using BNN than the methods of χ² analysis of dE/dX and TOF information. The kaon identification and misidentification efficiencies are obviously better from 0.3GeV/c to 1.2GeV/c using BNN than the methods of χ² analysis. The proton identification and misidentification efficiencies using BNN are basically consistent with the ones of χ² analysis. The anti-proton identification and misidentification efficiencies are better below 0.6GeV/c using BNN than the methods of χ² analysis.     

Study of charmonium(-like) states via ISR at Belle

The cross sections for e⁺e－→π⁺π^－J/ψ, π⁺π^－ψ(2S), K⁺K^－J/ψ, DD, D⁰D^－+π⁺+c.c., D^*D+c.c., and D^*D^* are measured using data sample collected on or near the Υ(4S) resonance with the Belle detector at KEKB. A peak near 4.25GeV/c², corresponding to the so called Y(4260), is observed in π⁺π^－J/ψ final state. In addition, there is another cluster of events at around 4.05GeV/c². Two resonant structures are observed in the π⁺π^－ψ(2S) invariant mass distribution, one at 4361±9±9MeV/c² with a width of 74±15±10MeV/c², and another at 4664±11±5MeV/c² with a width of 48±15± 3MeV/c². The rich structures observed in all these final states indicate that our understanding of the vector charmonium states above the open charm threshold is still poor, let alone the other possible dynamics such as charmonium hybrids or final state re-scattering and so on.     

2M阈式气体契仑科夫探测器

本文描述了为鉴别5—10GeV/c的π—K、K—P而研制的阈式气体契仑科夫探测器.速度分辨率达3.5×10^-5,对粒子的探测效率为99.99％,对阈能以下的粒子的排斥比为1.6×10^-5。     

Effect of Annealing Temperature on Electrical Properties of Ferroelectric Bi3.25La0.75Ti3O12 Capacitors

Lanthanum-modified bismuth titanate (Bi_3.25La_0.75Ti₃O₁₂, BLT) thin films arefabricated on platinized Si wafers by the sol-gel method, and the effect of annealing temperatures ranging from 650°C to 800°C on the electrical properties of Pt/BLT/Pt capacitors are investigated. It is found that polarization and leakage current of BLT capacitors strongly depend on the annealing temperature although all the capacitors demonstrate very similar characteristics, except the value of polarization, in pulse-width dependence, retention, and fatigue. Remanent polarization increases with the increase of annealing temperature, and annealing temperature of 700°C can yield thelargest remanent polarization, and then polarization decreases with increasing annealing temperature. For the 700°C annealed Pt/BLT/Pt capacitor, the remanent polarization 2P_r and the coercive field 2E_c, at an electric field of 226kV/cm, are 23.8μC/cm² and 130kV/cm, respectively. Dielectric breakdown voltages of BLT films annealed at 750°C and 800°C are much lower than those annealed at 650°C and 700°C. At 100kV/cm, the leakage currents of BLT films prepared at 650°C and 700°C are only1.5×10^-6A/cm² and 8.9×10-7A/cm², espectively. Moreover, all the Pt/BLT/Pt capacitors exhibit excellent retention properties after a cumulative time of 1× m 10⁴s and do not show any significant fatigue up to 1×10¹⁰ switching cyclesat frequency of 1MHz.     

BEPC-LINAC试验束上1GeV/c多粒子磁谱仪的设计和性能测量

试验束上2Q2D结构的磁谱仪系统由2块二极磁铁和2块四极磁铁以及位置灵敏探测器组成.该磁谱仪的接收立体角5×10^–4sr,动量范围0.2—1.3GeV/c.测量了聚焦面上的束流截面和动量谱.介绍了一种测量电子与质子飞行时间差的动量测量方法.     

15C的中子晕结构研究

实验测量了83A MeV ^14,15C的核反应总截面(σ_R)及¹⁵C产生^14,15C和¹⁴C产生¹³C的动量分布(P_//). 分析得到了¹⁵C产生¹⁴C和¹³C的动量分布半高宽(FWHM)分别为71±9MeV/c和223±28MeV/c, 而¹⁴C产生¹³C的FWHM为195±21MeV/c. 从¹⁵C和¹⁴C产生¹³C的FWHM与Goldhaber模型的预言基本一致. 而¹⁵C产生¹⁴C的FWHM却要比该模型计算小得多. 同时观测到¹⁵C的σ_R比相邻核有反常增加. 在Glauber模型框架中, 对实验测得的P_//和σ_R进行了探讨. P_//和σ_R的分析结果同时显示¹⁵C的最后一个中主要处于s_1/2态, 具有中子晕结构.     

对带电轻子质量公式的一些猜测

本文建议轻子电磁自能通过（（δm）/m）=（1/（2π））n^-b 与量子数 n 联系起来,其中 b 为待定常数.并建议动量截断值 M 与引力常数 k 和精细结构常数α的联系为 M=（?）.得到了带电轻子质量公式（?）.利用 e^-和μ^-质量的实验值和α值作输入,给出计算值 k=（6.67231±0.00026）×10^-8 cm³g^-lsec^-2和m_τ=（1782.306±0.078）MeV,与观察值 k=（6.6720±0.0041）×10^-8cm³ g^-1sec^-2和 m_τ=(1782_-4⁺³)MeV 很好符合.公式预言第四个带电轻子质量应为 m=（11725.47±0.51）MeV 可以在最近的实验中检验。本文还对所建议的质量公式和结果进行了讨论.     

THE NEGATIVE-POSITIVE RATIO OF CHARGED COSMIC RAY HADRONS AT THE 3220 m ABOVE SEA-LEVEL

Single tracks of unaccompanÏed charged hadrons, within a horigontal area of 0.23m² have been measured with a magnetic spectrometer, a pre-selector of momentum in combination with a multiplate cloud chamber in a laboratory at 3220m above sea level. Taking various possible corrections into account, the negative-positive ratio of charged hadrons was obtained as N^-/N⁺=0.53±0.05 in the momentum range of 10-20 GeV/c. If we considered N⁺ contained only P and π⁺, N^-were π^-and that N_π+/N_π-=1, we deduced the result N_π-/N_p=0.9±0.1. Taking the form of the π^-integral spectrum as j（>p）=Kp^-γ, it was estimated that γ（?）2.3 in the momentum range 5—20 GeV/c. In this paper the integral verticel flux intensity of all charged hadrons was also estimated roughly, the result is:j_⊥^p+π（>12 GeV/c）=（7.4±0.7）×10^-5/cm²·sг·s_^.     

Fourth generation effects in Bs→π^-K^＋ decay

We study the effects of the fourth quark generation model in B_s → π^-K⁺ decay. Combining with the up-to-date experimental measurement for B(B_s → π^-K⁺) and A_cp^dir(B_s → π^-K⁺) by the CDF Collaboration, we derive the new bound of weak phase ø_bd, which are 0°< ø_bd <44°, 321°< ø_bd < 360° and 0°< ø_bd < 26°, 342°< ø_bd < 360° for m_t'=400 and 600 GeV respectively. In these regions, B(B_s → π^-K⁺) and A_cp^dir(B_s → π^-K⁺) consist with the current experimental data within errors.     

海拔3200米的μ子垂直微分动量谱

在海拔3200米的云南高山实验室(地磁刚度14GeV), 利用改进了的G-M计数管磁谱仪和吸收谱仪, 测量了动量在(0.4—250GeV/c)范围的宇宙线μ子垂直微分动量谱和μ子荷电比, 并与相同高度的μ谱比较基本相符. 实验给出的谱在动量大于150GeV/c以上与O.C.Allkofer等人的海平面μ谱也符合得很好. μ子荷电比在5—100GeV/c动量范围几乎是常数, 其值为1.30±0.06.     

在海平面宇宙线中寻找小电荷粒子

用符合计数器望远镜测量电离损失的方法,在海平面宇宙线中寻找相对论性的小电荷粒子。实验中用厚碘化钠（铊）计数器测量粒子的很小电离损失,来确定粒子电荷。用反符合环形计数器排除侧面进入的粒子本底,实验测量了电荷范围从1/12到1/4电子电荷的小电荷区域。测量的初步结果给出:海平面宇宙线中的（非大气簇射中心区的）小电荷粒子通量的上限,在电荷0.08到0.19电子电荷范围内及0.19到0.25电子电荷范围内,分别小于4×10^-5粒子/平方厘米·秒·立体孤度及2×10^-5粒子/平方厘来·秒·立体弧度（置信水平90％）。     

非定域位势e-μr/r·e-μr′/r′·e-αR/R及e-μr/r·e-μr′/r′·e(-(β(r+r′))1/2·R))/R的Regge渐近行为

本文证明了两个物理上有兴趣的非定域位势e^-μr/r·e^-μr′/r′·e^-αR/R及e^-μr/r·e^-μr′/r′·e^{(-(β(r+r′))1/2·R)})/R的分波S矩阵元对动量变数k在除沿虚轴的割线(-∞i,0),(μi,∞i)的全平面,对角动量变数λ在右半平面Reλ>-1/2的半纯性和当k,λ分别趋于无穷大时的渐近性质。最后得到了Regge渐近行为。