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1.
We point out that although the neutrino mass is finite,the left-handed neutrino density still dominates over the righthanded one in the universe unless there exists one or more elementary fernions (quark or lepton) whose mass is larger than 106 GeV. or MWR/MWL≤102. (MWLand MWR are the left and right handed intermediate boson respectively.If there exists neutrino the mass of which is about 34 ev. as indicated in some experiments, then one can conclude that the total neutrino mass of the universe s,bvld contribute abput 99%. to the whole masses and lead to the closeness of the universe.This conclusion can be brought to the agreement of all observation datd which have been-obtained so far. A mass limit of all species of neutrinos obtained by reexamining all data is ≤ 200 eV.  相似文献   

2.
W. Gabsdil 《Nuclear Physics A》1968,120(3):555-560
The decay of the isomers in 101Tc, 103Ru, 158Tb and 208Bi produced by 28 MeV bremsstrahlung has been re-investigated with a Ge(Li) counter. The previously deduced decay schemes of 158Tb and 208Bi have been confirmed. The previously reported isomer in 159Gd has not been found by irradiation of a 160Gd sample. It is argued that this isomer is identical with the 158Tb isomer.  相似文献   

3.
We discuss in this paper a stellar model of degenerate massive neutrinos with a core made of heavy matter. Dimension of the core is much smaller than the scale of neutrino star. The Oppenheimer-Volkoff equation is solved for such a system. Our calculation shows that under certain conditions, this neutrino halo will resemble a pure neutrino star. We have further obtained insides the neutrino star (or halo) the rdtation curve and the gravitational red shifts. It is interesting to note that the relative rotation velocity v(r)EV(r)/V(R) (R is the radius of the neutrino star) depends only on the relative coordinate ξ=r/R in the nonrelativistic cases. Therefore, all nonrelativistically degenerate neutrino systems will have a universa1 relative rotation curve(v versus ξ). Within the accuracy of numeri calcalculation, we have also obtained a useful relation connecting the maximum velocity Vm and the corresponding coordinate Rm as VmRm2=0.231. By comparing this relation with the observed rotation data at large distances for some galaxies, we have obtained an upper bound for neutrino mass of about 6-9eV.  相似文献   

4.
We continually use the phenomenological of the galaxy with two constituents (v+B) as in a previous paper [1] and uniformly handle S galaxy, E galaxy, etc. through the normalization method. At the same time, we extend this model from degenerate condition to isoentropic condition and from low temperature to high temperature. Thus, on a much more perfect foundation it is indirectly verified that the massive neutrino can account for the missing mass hidden in different celestial scales between galaxy and galactic cluster, but it can not rule out the possibiilty that there are some new massive fermions which are lighter than neutrino. Besides, in this paper we handle 21 samples of Sc galaxy yet, and obtain the average upper limit (15 eV.) of mv. Because the spherically symmetric model is insufficient for calculation of mv, we will progres sively research the non-spherically symmetric model, in another paper.  相似文献   

5.
We present a simple and crude model of galaxies consisting of baryons and neutrinos with spherical symmetry. The baryon matter is rotatinq. in the central region of the galaxy as a nucleus. If the rotational curve of the heavy matter is known from the observational data, then the gravitational potential, and therefore the density distribution in this region, can also be obtained. This enables us to estimate the mass and the radius of the neutrino halo. Furthermore, the condition on the interface of the nucleus-halo will set an upper bound on neutrino mass. If the corresponding parameters duoted in Ref.[10] are adopted, then a value of ≤20eV. for the neutrino mass is obtained. By choosing mv=15eV and a parameter in the rotational curve n=4, one can deduce that neutrino halo radius is about four times the heavy matter radius, and the total mass of neutrinos is about 14 times that of baryons. It seems, that these results are not in contradiction with the observations on the missing mass of the galaxies[6].  相似文献   

6.
本文讨论了μ中微子的静质量在各种过程中的效应,特别分析了两个此效应表现得明显的过程,μ介子与电子的湮没和π辐射衰变。指出给μ中微子以一个不太小的静质量,例如5me能和目前已有的一切实验不矛盾,并指出进一步确定μ中微子的质量的可能的实验。  相似文献   

7.
By using a highly accurate variational wave function with 50 parameters for hydrogen molecule[4] and the wave function of HeH+ used by Wolniewicz with 64 parameters[5], the behavior of the β-spectrum of H-T→ HeH+-+νe is discussed. The spectral shape thus obtained deviates remarkably from the β-spectrum of an atomic triton, and hence is different from the for mula used by Lyubimov et al. in determining the neutrino mass. This means that the "atomic approximation" is invalid in describing the molecular β-spectrum of valine, and the conclusion about the value of neutrino mass based upon the analysis of β -spectrum of valine also cannot be regarded as a reliable one. Therefore, in order to obtain ari accurate value of neutrino mass from the β-spectral shape, it is important to investigate the structure of the radioactive source, from which the corection has arisen.  相似文献   

8.
Spin-echo NMR measurements on 155Gd, 159Tb and 175Lu have been done for the cubic Laves phase compounds Gd1−xLuxFe2 and Tb1−xLuxFex. The observed hyperfine fields of Gd and Lu in those compounds increase with increasing Lu concentration. The concentration dependence of the Lu hyperfine field is qualitatively discussed.  相似文献   

9.
何景棠 《物理学进展》2001,21(2):216-224
本介绍中微子质量测量的历史和现状。介绍太阳中微子丢失实验的结果和大气μ中微子丢失实验结果。这些结果表明存在中微子振荡,即中微子具有质量。它是超出标准模型的信号。本还介绍了21世纪初研究中微子振荡的若干重要实验,例如长基线中微子振荡实验以及建造μ子 贮存环来产生高能电子中微子束进行中微子振荡的实验以及测量中微子振荡时的CP破坏的设想。  相似文献   

10.
戴长江  盛祥东  何会林 《物理》2000,29(11):679-682
综述了中微子静止质量mυe的测量方法与结果,侧重介绍了超新星SN87A中微子测量的结果,即得到具有能量为8MeV和36MeV的中微子飞行时间差,对于Kamiokande,IMB,Bakson分别为1.9s,6s和9s,由此给出电子中微子静止质量上限为14eV「95%置信水平(C.L.)」,并且描述了计划建造的新型太阳中微子能谱仪,该谱仪在观测太阳中微子能谱的同时,将兼测超新星中微子,提供了在mυe〈1eV范围内测量中微子静止质量的可能性。  相似文献   

11.
The excited states of the deformed odd-proton nucleus 161Ho have been studied in the reactions 159Tb(, 2n), 161Dy(d, 2n) and 161Dy(p, n). Gamma-ray spectra in single and coincidence modes as well as angular distributions and excitation functions of the transitions were measured. The proposed level scheme of 161Ho contains besides of the ground state band [523] the bands +[404], +[411], +[411] and [541] (band heads at 252.7, 298.7, 211.2 and 423.9 keV, respectively). An attempt was made to estimate the influence of Coriolis coupling between the bands + [411] and + [411], which are very close in energy. The + [404] band was found to de-excite by very fast E1 transitions to the ground state band [523]. Nilsson retardation factors of about 0.03 for these transitions were deduced using the E2/E1 branching ratios. An investigation has also been made of the independent feeding of the levels from high-lying states.  相似文献   

12.
本文认为M .Goldhaber对中微子螺旋性测量结果不能证实二分量中微子是否正确 ,也即中微子的静止质量并非为零 ,分析了其产生的原因  相似文献   

13.
In superstring E6 models right-handed leptonic currents can arise from the mixing between the ordinary leptons and tha exotic leptons. Contributions to the neutrino magnetic moment due to this new interaction are examined. Although the result appears to be directly proportional to the heavy exotic charged lepton mass, it is shown, however, that the mixing is proportional to the ratio of the neutrino mass and the exotic lepton mass. The combination of these two factors yields a result which is of the order of that given by the SU(2)LxU(1)Y model.  相似文献   

14.
There is some experimental evidence for a 17 keV component of the electron neutrino, in the form of the recent observations of kinks in the beta-decay spectra of tritium, 14C, 35S and 63Ni. In this paper I show that most particle-physics models consistent with the 17 keV neutrino require a baryogenesis scale below 106 GeV. Furthermore, models with a 17 keV neutrino typically contain new sources of CP violation, and the cosmological baryon asymmetry could be generated by anomalous electroweak interactions during a first-order weak phase transition.  相似文献   

15.
The crystalline Stark splitting of the electronic ground state and various properties of Tb3+ in tetragonal sites in Tb: SrF2 have been determined with the crystal field parameters of Antipin et al. Two singlets are found to lie lowest, the separation between them being 0.363 cm−1. The χ has a Curie type variation in the range 4–1.0 K below which saturation effects set in. χ has a maximum at 110 K and becomes nearly temperature independent at around 4 K. The magnetic moment turns out to be 9.58 at 300 K which is very close to the free ion value 9.72. There is only a small variation of the magnetic moment with temperature. Two anomalies are found to occur in the Schottky heat capacity curve, one at 100 K, and the other at 0.22 K. The magnetic hyperfine field at the nucleus of Tb3+ is obtained as 3.456 MG, neglecting the core polarization. The temperature averaged electric quadrupole splitting of the nuclear ground state of 159Tb has been calculated at different temperatures and is found to rise smoothly with the decrease of temperature to attain saturation at 10 K. The behavior of the hyperfine heat capacity CN has been studied theoretically in the range 4.2–0.01 K. A Schottky anomaly appears at 0.1 K. The computations have been carried out in the intermediate coupling approximation.  相似文献   

16.
杜九林 《物理》1998,27(10):609-612
非标准电弱模型似乎可以说明长达二十几年的太阳中微子问题,3类不同味的中微子可以彼此振荡地转变.但这个模型要求中微子必须具有质量,从而将带来粒子物理学沉重而激动人心的变革.新的实验正在探索发现中微子振荡的证据  相似文献   

17.
A method of using the Bardeen-Cooper-Schrieffer (BCS) nuclear wave function to treat the two-nucleon mechanism for neutiinoless double beta decay process 0+ → 0+ is proposed.The neutrinoless decay mode and the neutrinoless decay accompanied by a Majoron emission mode of 82Se are studikd. Our cdculated results show that to reproduce the experimental value of γ(ov) > 1.8 × 1022 yr for neutrinoless double beta decai of 82Se the Majorana neutrino mass mv < 6.2 eV and the mixing parameter of right-handed current η < 7.0 × 10-6 In the emission with a Majoron mode the effective Majoron coupling to neutrino is deduced from the experimental value of γ(ov,H) > 4.4 × 1020 yr for 82Se with the result H0> < 6.2 × 10-4.  相似文献   

18.
本文测定了α-溴代丙烯酰胺与丙氨酸反应产物的1H,13C-NMR谱,采用NMR的各种技术对其谱线进行归属,鉴定出该产物的化学结构,是氮丙啶化合物的一对等量的非对映异构体的混合物,并讨论了1H,13C-NMR谱与立体化学的关联。本文测定的氮丙啶化合物的非对映异构体的13CNMR谱未见报道。  相似文献   

19.
本文对同心环几何条件,用Lobatto求积公式近似求解了中子慢化积分方程,得到了比较精确的超热能谱,并由此算出了共振积分。用逐步递推方法计算慢化源,用予制的Pij表内插求首次碰撞几率,大量节省了机器时间。同时,本文用多能级公式计算235U、239Pu核的共振截面,从而使共振峰间的重叠和干涉也得到了考虑。用文献提供的模型做了校核计算,取得比较满意的结果。  相似文献   

20.
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