63Cu(n,α)60Co反应截面测量

本文报告了E_n=13.6—14.8MeV中子能区用活化法以²⁷Al(n,α)²⁴Na截面为中子注量标准得的⁶³Cu(n,α)⁶⁰Co的反应截面.在中子能量为13.64,13.79,14.03,14.33,14.60和14.80MeV的截面值分别为58.3±3.1,56.3±2.4,53.4±2.0,50.8±1.9,48.4±1.7和47.4±1.7mb.在文中还列举了一些作者的数据以作比较.中子能量是用铌锆截面比法测定的.     

14MeV钕的同位素反应截面的测量

报道了在13.5—14.6MeV中子能区用活化法以⁹³Nb(n,2n)^92mNb反应截面为中子注量标准测得的¹⁵⁰Nd(n,2n)¹⁴⁹Nd,¹⁴⁸Nd(n,2n)¹⁴⁷Nd和¹⁴²Nd(n,2n)¹⁴¹Nd的反应截面值.由13.5±0.2,14.1±0.1和14.6±0.2MeV中子引起的¹⁵⁰Nd(n,2n)¹⁴⁹Nd反应截面值分别为2037±85,1737±68,1657±65mb,¹⁴⁸Nd(n,2n)¹⁴⁷Nd反应截面值分别为1394±58,1416±54,1956±76mb,^{142Nd(n,2n)141Nd反应截面值分别为1501±59,1623±62,1764±111mb.单能中子由T(d,n)4He反应获得.文中还收集了已发表的数据以作比较.}     

13.5—14.6MeV中子能区镓的同位素反应截面的测量

报道了在13.5—14.6MeV中子能区用活化法以⁹³Nb(n,2n)^92mNb反应截面为中子注量标准测得的⁶⁹Ga(n,2n)⁶⁸Ga,⁶⁹Ga(n,p)^69mZn,⁷¹Ga(n,p)^71mZn和⁷¹Ga(n,n′α)⁶⁷Cu的反应截面值.由(13.5±0.2),(14.1±0.1)和(14.6±0.2)MeV中子引起的⁶⁹Ga(n,2n)68Ga反应截面值分别为(794±31),(869±35)和(986±39)mb,⁷¹Ga(n,n′α)⁶⁷Cu反应截面值分别为(1.3±0.1),(1.7±0.1)和(2.5±0.1)mb.在中子能量为(14.1±0.1)MeV能量点,⁶⁹Ga(n,p)^69mZn反应截面值为(21.5±1.0)mb,⁷¹Ga(n,p)^71mZn反应截面值为(12.4±0.7)mb.单能中子由T(d,n)⁴He反应获得.文中还列举了尽可能收集到的数据以作比较.     

160Gd(n,2n)159Gd和158Gd(n,p)158Eu反应截面测量

报道了在13.5—14.6MeV中子能区用活化法测得的¹⁶⁰Gd(n,2n)¹⁵⁹Gd和¹⁵⁸Gd(n,p)¹⁵⁸Eu的 反应截面值. 中子注量用⁹³Nb(n, 2n)⁹²m Nb反应截面得到. 由(13.5±0.2)MeV,(14.1±0.1)MeV和(14.6±0.2)MeV中子引起的¹⁶⁰Gd(n, 2n) ¹⁵⁹Gd反应截面值分别为(1940±83)mb, (2324±92)mb和(1983±77)mb, ¹⁵⁸Gd(n, p) ¹⁵⁸Eu反应截面值分别为(1.9±0.1)mb, (2.1±0.1)mb和(3.5±0.1)mb. 单能中子由T(d, n)⁴He反应获得.文中还列举了已收集到的数据以作比较.     

14MeV中子引起的185Re(n,2n)184g,mRe和191Ir(n,2n)190Ir的核反应截面测量

利用活化方法测量了1?4MeV中子引起的¹⁸⁵Re(n,2n)^184gRe,¹⁸⁵Re(n,2n)^184mRe和¹⁹¹Ir(n,2n)¹⁹⁰Ir核反应的截面.中子能量E_n=(14.7±0.2)MeV时的实验结果分别为:(1817±85)mb,(390±18)mb和(2038±82)mb.并利用HFTT程序计算了中子能量在7—18MeV范围内的截面值,给出了其中两个核反应的激发函数曲线.     

28Si+12C中的两体反应与全熔合反应

利用ΔE-E望远镜系统测量了156.3MeV ²⁸Si+¹²C反应(近对称系统)中出射的Z=4—14的产物元素的能谱和角分布,并由此给出了这些产物的胁变截面图.从理论上计算了Z=4—11产物的实验室系最可几动能分布E₁(θ)和各元素的质心系的总动能分布Et(Z),指出了这些产物主要来自系统的两体反应过程.还给出了该反应系统的全熔合截面值为(980±68)mb,并指出从低能数据外推到此能量下的全熔合截面值与实验值之差主要归因于两体过程.     

用基态特征γ射线计算同质异能态反应截面的公式及其应用

根据人工放射性的生长与衰变规律, 推导出一个在特殊情况下用基态特征γ射线计算同质异能态反应截面的公式, 并据此公式用活化法以⁹³Nb(n,2n)^92mNb反应截面为中子注量标准对¹²⁸Te(n,2n)^127mTe反应截面进行了测量. 由能量为(14.1±0.2)和(14.6±0.3)MeV的中子引发的¹²⁸Te(n,2n)^127mTe反应截面值分别为(737±69)和(853±82)mb. 单能中子用T(d,n)⁴He反应获得, 其能量用铌锆截面比法测定. 为减小热中子的(n, γ)反应的影响, 在辐照过程中对样品进行了包镉处理.     

用高纯锗γ-谱仪借助滑动比较方法精密测量放射性核的γ-射线能量

以¹⁹²Ir γ-射线能量准确值为标准对高纯锗γ-谱仪进行滑动扫描刻度,通过比较测定放射性核γ-射线能量,得到:477603.18±0.44eV(⁷Be)、5.11852.70±0.58eV(¹⁰⁶Ru)、514004.87±0.52eV(⁸⁵Sr)、520399.01±0.63eV(⁸³Rb)、529594.48±0.69eV(⁸³Rb)和552551.14±0.68eV(⁸³Rb).用这一结果校正以往的实验,得到电子质量值510998.6±1.1eV,它与电子质量的近期调节值良好符合.     

62Ni(n,α)59Fe反应截面测量

本文报告了在E_n=13.6—14.8MeV中子能区用活化法以²⁷Al(n,α)²⁴Na截面为中子注量标准测得的⁶²Ni(n,α)⁵⁹Fe的反应截面.在E_n为 13.64,13.79,14.00,14.05,14.33,14.60和14.80MeV处的截面分别为17.4±1.1,19.5±1.5,21.9±1.9,22.4±1.6,25.4±1.4,26.1±1.1和26.0±1.1mb.在文章中还列举了所能收集到的一些作者的数据以作比较.中子能量是用铌锆截面比法测定的.     

J/ψ共振参数的测定

利用北京正负电子对撞机(BEPC)和北京谱仪(BES),测量了e+e－对撞束在J/ψ共振峰附近能区内末态为强子、e⁺e^－和μ⁺μ^－的实验观测截面,对这些截面的拟合得到J/ψ衰变宽度和分支比的新的实验测定值:Γ=84.4±8.9keV,Γh =74.1±8.1keV,Γe=5.14±0.39keV,Γμ=5.13±0.52keV, /=(87.8±0.5)%,Γe/Γ=(6.09±0.33)%,Γh/Γ=(6.08±0.33)%.     

Direct pair production by positive and negative electrons in a hydrogen bubble chamber

The production of electron pairs by negative and positive electrons in the energy region 0.65 – 5.8 GeV has been investigated in the DESY 81-cm hydrogen bubble chamber. The effective cross section σ = 0.62 ± 0.04 mb averaged over the energy spectrum of incident electrons is found to be in good agreement with the predictions of quantum electrodynamics. The energy distribution of created pairs as well as the dependence of the total cross section on energy are best represented by the expression of Murota, Ueda and Tanaka with the constant c = 0.66 ± _0.17^0.24 and by Bhabhá's formula with the constants c₁ = 1 and c₂ = 2.8 ± _0.7^0.9. The contribution of the interference term between space-like and time-like Feynman diagrams to the cross section is estimated to be less than about 10% and to fall off with an increase of the incident energy.     

Chiral recognition in electron scattering by S- and R-2-butanol

Experiments are described involving the low-energy scattering of electrons from the two optical enantiomers S- and R-2-butanol. Using a synchrotron radiation photoionisation source on the ASTRID storage ring, scattering spectra are reported between a few meV and 140 meV at an electron energy resolution of 1.6 meV. These data show electron dichroism at 35 meV, for scattering into the backward hemisphere, with a cross-section of 202.1 ± 8.0 Ų (4σ) and 182.8 ± 9.0 Ų (4σ) for S- and R-, respectively, with the racemic mixture lying at the average value. No dichroic effect could be detected in the integral cross-section within the accuracy of the experiment. A brief qualitative discussion is given of a possible electron dissociative attachment mechanism for the creation of homochirality in space, including a new feature involving feedback through enhancement of electron polarisation through scattering from non-racemic mixtures of enantiomers.     

Internal ionization in 41Ca

The internal ionization accompanying the first-forbidden unique electron-capture decay of ⁴¹Ca was investigated. The integrated probability of electron ejection with energy greater than 38keV was found to be (0.17 ± 0.02) × 10⁻⁵ per K-capture. In this energy range, the measured spectrum of ejected electrons is fairly close to predictions of the simple theory of Primakoff and Porter, and of the relativistic theory of Mukoyama et al. By a model-dependent extrapolation of this spectrum toward low energies, the total probability of internal ionization in ⁴¹Ca was estimated and compared with relevant experimental results for other isotopes.     

Multihadron production in e+e− collisions up to 3 GeV total C.M. energy

New results on the multihadron production by electron and positron beams colliding with a total energy of up to 3 GeV are reported. Disregarding possible kaon final states, the ratio σ_mh/σ_μμ of the total multihadron cross-section to the point-like cross section for process e⁺e^?→μ⁺μ^? has an average value of 1.58 ± 0.25 in the energy interval 2.6–3.0 GeV. The average charged multiplicity over this energy range is 〈n_c〉 = 2.9 ± 0.3.     

电子迥旋加热等离子体及热电子环特性的实验研究

在简单磁镜MM-2中,采用15GHZ大功率迴旋管进行了电子迴旋共振加热(ECRH)实验。结果表明,随充气压强的提高,预电离时间迅速变短。在高气压“C-模式”运行区,等离子体径向密度分布呈马鞍形。在迴旋管输出30kW功率的条件下,适于建立热电子环的气体压力窗为(0.4—1.2)×10^-5Torr。利用一个可移动Laugmuir探针配合反磁测量的简便方法,在中心场为2.95kG时,确定了电子环半径为7cm,环厚约4cm,环的轴向边界由z=±10cm一直延伸到z=±20cm。热电子温度为140—170keV,热电环平均β值为(4—5)％。观测到了由热电子环不稳定性引起的迸发式径向电子逃逸,并同时发生反磁信号跌落。     

Messung derK-Fluoreszenzausbeute von Silber und Antimon

Atoms of thin Ag- and Sb-targets have been ionized by electron impact and the followingK-X-rays andK-Auger-electrons were measured simultaneously. A scintillation counter was used for the X-rays and an electrostatic mirror spectrometer with a Si-Li-detector for the electrons. From these measurements we obtained for the fluorescence yields for Ag and Sb ω _K (Ag) = 0.834±0.017; ω _K (Sb) = 0.868±0.014. These results are in agreement with the measurements of Foin et al. [2] for Ag, of Hribar et al. [3] for Sb and with the theories of McGuire [10] and Kostroun et al. [11].     

Three-photon absorption and subsequent excited-state absorption in CdS

The nonlinear absorption of single picosecond light pulses (λ = 1.06 μm) in CdS is investigated at very high light intensities. Three-photon absorption and subsequent excited-state absorption of the generated electrons and holes explain the rapid decrease of transmission with increasing intensity. A three-photon absorption cross-section of σ⁽³⁾ = (2±0.5) × 10^-80 cm⁶ s² and an average excited state absorption cross-section of σ_ex = (7 ± 3) × 10^-18 cm² was determined.     

Elektronenpolarisation im Energiebereich unterhalb 50 eV durch Streuung an freien Hg-Atomen

The angular dependence of spin polarizationP(Θ) of electrons elastically scattered by a beam of mercury atoms is measured in a double scattering experiment for electron energies of 45±1 eV; 23±1 eV; 7±1 eV; and 3,5±1 eV. Maximum degree of polarization obtained isP(100°)=0,39±0,07; electron energy 7±1 eV; electron current 10^?12–10^?11 A.     

Derivation of Absolute Depth-Intensity Spectrum under Standard Rock from the Recently Estimated Primary Cosmic Ray Spectrum

Using the recently derived primary cosmic ray nucleon spectrum from JACEE and GSFC balloon flight data and Fermilab results for pp → π^± + X anything inclusive reaction data in the light of Feynman scaling the depth-intensity spectrum under standard rock has been estimated. A precisely constructed range-energy relation has been applied in this analysis. The derived spectrum when corrected for range fluctuation agrees approximately with the experimental data under standard rocks measured by MIYAZAKI , BARTON , CASTAGNOLI et al., MEYER et al., BERGAMASCO et al., SHELDON et al. and BASCHIERA et al.     

Improved non-empirical absorption potential for electron scattering at intermediate and high energies: 30–10000 eV

The non-empirical model proposed by Staszewka et al. in 1983 for the imaginary part of the electron scattering optical potential is revised, improving the treatment used for the e⁻ −e⁻ dispersion. New cross-section calculations employing the revised potential are in agreement with available experimental data for elastic and inelastic processes.