共查询到20条相似文献,搜索用时 31 毫秒
1.
Polarization analyzing power of 3He3He and 3He4He elastic scattering is reported for bombarding energies between 7.5 and 17.9 MeV. A phase-shift analysis for 3He4He elastic scattering incorporating this and other polarization data is presented. The analyzing power of 3He3He elastic scattering is consistent with zero at θc.m. = 66°. 相似文献
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Susanne Friedreich D��niel Barna Andreas Dax Ryu Hayano Dezs? Horv��th Masaki Hori Bertalan Juh��sz Oswald Massiczek Anna S��t��r Thomas Pask Eberhard Widmann 《Hyperfine Interactions》2011,199(1-3):337-346
The spin magnetic moment $\mu^{\overline{p}}_{s}$ of the antiproton can be determined by comparing the measured transition frequencies in $\overline{p}^4$ He?+? with three-body QED calculations. A comparison between the proton and antiproton can then be used as a test of CPT invariance. The highest measurement precision of the difference between the proton and the antiproton spin magnetic moments to date is 0.3%. A new experimental value of the spin magnetic moment of the antiproton was obtained as $\mu^{\overline{p}}_{s} = -2.7862(83)\mu_{N}$ , slightly better than the previously best measurement. This agrees with $\mu^{p}_{s}$ within 0.24%. In 2009, a new measurement with antiprotonic 3He has been started. A comparison between the theoretical calculations and experimental results would lead to a stronger test of the theory and address systematic errors therein. A measurement of this state will be the first HF measurement on $\overline{p}^3$ He?+?. We report here on the new experimental setup and the first tests. 相似文献
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《Physics letters. [Part B]》1986,167(2):150-152
Group theoretically the hidden colour components of the multibaryonic 9- and 12-quark systems are determined to be 97.6% and 99.8%, respectively. Arguments based on QCD show that the hole in the centre of 3He and 4He arises due to the presence of these large hidden colour components. 相似文献
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Forward dispersion relations for nucleon-4He scattering have been analyzed for 0 < Elab < 600 MeV with the help of new experimental data. Improving over a previous analysis restricted to E < 50 MeV the 4He3He n coupling constant is determined unambiguously as r = 3.2 ± 0.4 in agreement with information from stripping reactions. Moreover the strength of uncorrelated three nucleon exchange and the summed strength of mesonic exchange is determined. 相似文献
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The asymmetric 3He4He2 three-atomic system is studied on the basis of a hard-core version of the Faddeev differential equations. Binding energy and scattering observables for this system are compared to previous results for the symmetric 4He3 problem. 相似文献
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The equilibrium geometries, potential energy curves, spectroscopic dissociation energies of the ground and low-lying electronic states of He2, He2+ and He2++ are calculated using symmetry adapted cluster/symmetry adapted cluster-configuration interaction (SAC/SAC-CI) method with the basis sets CC-PV5Z. The corresponding dissociation limits for all states are derived based on atomic and molecular reaction statics. The analytical potential energy functions of these states are fitted with Murrell--Sorbie potential energy function from our calculation results. The spectroscopic constants Be, α e, ω e, and ω e χ e of these states are calculated through the relationship between spectroscopic data and analytical energy function, which are in well agreement with the experimental data. In addition, the origin of the energy barrier in the ground state X1Σg+ of He2++ energy curve are explained using the avoided crossing rules of valence bond model. 相似文献
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采用Tang-Toennies势模型,通过坐标变换,得到了氦原子与氢分子的非对称同位素替代体系HD,HT,DT在质心坐标系中的势能函数,在此基础上计算了He-HD,HT,DT碰的角分布。 相似文献
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We have studied the stability of mixed 3He/4He clusters in L = 0 and L = 1 states by the diffusion Monte Carlo method, employing the Tang-Toennies-Yiu (TTY) He-He potential. The clusters 3He4HeM (
) and 3He24HeM (L = 0, S = 0) are stable for M > 1, while to bind two 3He in a triplet state the minimum number of 4He is four. Considering clusters with three 3He, 3He34He4 is the smallest stable system in the L = 1 state, while 3He34He8 is the smallest stable system in the L = 0 state. 相似文献
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K.P. Lohs 《Nuclear Physics A》1978,312(3):297-310
Scattering lengths of pionic 3He and 4He and the charge exchange contribution to the 1s width of pionic 3He are calculated within the fixed scatterer approximation of the multiple scattering formalism. Particular attention is focussed on the nuclear physics part and on πN p-wave contributions. For the first time triple scattering and double-spin-flip contributions have been included. We find significant deviations from previous estimates and calculations. Good agreement is achieved with the experimental π?3He scattering length, whereas in the case of 4He a repulsive dispersion contribution is clearly needed. We propose to use the measured 1s level shift of pionic 3He as a constraint to deduce a precise value of the isoscalar πN scattering length. Furthermore, we find that multiple scattering reduces the impulse approximation value for Γ1s(π?3He → π0 3H) by more thsn 20 %. This result casts some doubt on impulse approximation calculations of radiative pion capture as well. 相似文献
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Yu. Aksyutina H.T. Johansson T. Aumann K. Boretzky M.J.G. Borge A. Chatillon L.V. Chulkov D. Cortina-Gil U. Datta Pramanik H. Emling C. Forssén H.O.U. Fynbo H. Geissel G. Ickert B. Jonson R. Kulessa C. Langer M. Lantz T. LeBleis A.O. Lindahl K. Mahata M. Meister G. Münzenberg T. Nilsson G. Nyman R. Palit S. Paschalis W. Prokopowicz R. Reifarth A. Richter K. Riisager G. Schrieder H. Simon K. Sümmerer O. Tengblad H. Weick M.V. Zhukov 《Physics letters. [Part B]》2009
The unbound nucleus 7He, produced in neutron-knockout reactions with a 240 MeV/u 8He beam in a liquid-hydrogen target, has been studied in an experiment at the ALADIN-LAND setup at GSI. From an R-matrix analysis the resonance parameters for 7He as well as the spectroscopic factor for the 6He(0+) + n configuration in its ground-state have been obtained. The spectroscopic factor is 0.61 confirming that 7He is not a pure single-particle state. An analysis of 5He data from neutron-knockout reactions of 6He in a carbon target reveals the presence of an s -wave component at low energies in the α+n relative energy spectrum. 相似文献
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M. Schneider R. Bacher P. Blüm D. Gotta K. Heitlinger W. Kunold D. Rohmann J. Egger L. M. Simons K. Elsener 《Zeitschrift für Physik A Hadrons and Nuclei》1991,338(2):217-222
Antiprotonic X-rays from the helium isotopes have been observed at pressures of 36, 72, 375 and 600 mbar. The antiproton beam from LEAR with momenta of 309 and 202 MeV/c has been stopped at these pressures using the cyclotron trap. The X-rays were detected with Si (Li) and intrinsic Ge semiconductor detectors. Absolute X-ray yields were determined and the strong-interaction 2p shifts and the 2p and 3d broadenings measured to be 2p=(–17±4) eV, 2p=(25±9) eV and 3d=(2.14 ±0.18) meV for ¯p3He and 2p=(-18±2) eV, 2p =(45±5) eV and 3d=(2.36±0.10) meV for ¯p4He.The efforts of the LEAR staff and the help of P. Gauss from the CERN Cryogenic Group as well as the technical assistance of M. Dröge and M. Stoll are gratefully acknowledged. This work is part of the Ph.D. of one of us (M.S.), University of Karlsruhe (1987), KfK report no. 4222. 相似文献
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从密度泛函理论为基础的第一性原理出发,运用全势能线性缀加平面波(FLAPW)方法,对氚衰变后氦在合金中的占位以及LaNiHe晶体结构进行了理论计算,并系统给出了氦在间隙间的迁移曲线.结果表明,氦原子在十二面体(1 b)格位最稳定,并且氦从6m格位向1 b格位迁移不存在势垒,而从2d格位向1 b格位迁移则需越过1.55 eV高的势垒.另外,氦从12n格位穿过12o格位最后到达6m格位也无明显势垒存在,并且处于4h格位之间的氦原子可以自由迁移,而相应12n格位之间的直接迁移则需跨越13.6 eV高的势垒.最后还计算给出了氚衰变后合金的态密度、电子密度以及势能分布图,并与相应的LaNi5H结构作了详细比较. 相似文献
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We have compared the surface properties of crystals respectively grown from normal 4He containing 130 ppb of 3He and from ultrapure 4He (0.4 ppb). Below 0.4 K, 3He impurities are found to decrease both the surface tension and the step energy. Our results are consistent with the existence of two-dimensional bound states for 3He atoms at the solid-liquid interface. Quantitative agreement with the data is found with a binding energy s ≈ 4.3 K and a 3He density saturating around 0.4 monolayer. The presence of steps is found to increase the binding energy by about 10 mK. 相似文献
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M. Aliotta F. Raiola G. Gyürky A. Formicola R. Bonetti C. Broggini L. Campajola P. Corvisiero H. Costantini A. D'Onofrio Z. Fülp G. Gervino L. Gialanella A. Guglielmetti C. Gustavino G. Imbriani M. Junker P. G. Moroni A. Ordine P. Prati V. Roca D. Rogalla C. Rolfs M. Romano F. Schümann E. Somorjai O. Straniero F. Strieder F. Terrasi H. P. Trautvetter S. Zavatarelli 《Nuclear Physics A》2001,690(4):1570-800
The cross section of the reactions 3He(d, p)4He and d(3He, p)4He has been measured at the center-of-mass energies E=5 to 60 keV and 10 to 40 keV, respectively. The experiments were performed to determine the magnitude of the electron screening effect leading to the respective electron-screening potential energy Ue=219±7 and 109±9 eV, which are both significantly higher than the respective values from atomic physics models, Ue=120 and 65 eV. 相似文献