共查询到20条相似文献,搜索用时 46 毫秒
1.
The electron capture decays of133Ba (10.4 y) and139Ce (140 d) were investigated with high resolution Ge(Li) detectors. By x-ray — γ-ray coincidences values of the quantityP k ω k ? k for various transitions in the decay of133Ba and139Ce are obtained. The factor ω k ? k was measured independently by means ofK-conversion electron-K x-ray coincidences and was then used to determineP k , theK-capture probability. The independent measurement of the product ω k ? k , together with recent accurate values of ω k , provides a new method for the accurate calibration of semiconductor x-ray detectors. In the decay of139Ce, a value ofP k =0.78±0.03 is found (where the error represents twice the standard deviation) from whichQ ec =326 ?30 +70 keV to the139La ground-state is found by use of theory. In133Ba decay, values are found ofP k 1=0.72±0.04 for theEC transition to the 437 keV level in133Cs,P k 2=0.80±0.07 to the 384 keV level, and from an independent measurement, the ratioP k 1/P k 2=0.87±0.07. From these results the ground-state value ofQ ec =522 ?10 +20 keV is derived from theory for133Ba decay. The gamma spectrum of133Ba also was remeasured. From the present gamma intensities and previous conversion electron intensities, new values forK-shell conversion coefficients are obtained. Previously reported γ-rays at 35 and 391 keV are not confirmed. 相似文献
2.
G. N. P. Oliveira A. M. L. Lopes T. M. Mendon?a J. P. Araújo J. Agostinho Moreira A. Almeida V. S. Amaral J. G. Correia 《Hyperfine Interactions》2010,197(1-3):123-128
This work presents an electric field gradient and magnetic hyperfine field study, in the AgCrO2 multiferroic with triangular spin lattice. The temperature dependence of the electric field gradient (efg) and magnetic hyperfine field (mhf) at Cr site was studied at isolde via perturbed angular correlation measurements with the 111In probe, at room temperature and below the Néel temperature (T?≤?21 K) down to 12 K. The results show the presence of two distinct local environments. One axial symmetric efg with a very low mhf, and a non axially symmetric efg with a much higher one. The temperature dependences of mhf magnitude and of the angle between the mhf and the principle component of the efg are investigated. 相似文献
3.
The electron capture decay energy of183Re has been determined from the fraction ofK-capture in the transition to the 453.08 keV level in183W by delayed coincidences. From this value the total decay energy from183Re→183W is obtained to beQ=555 ?7 +9 keV according to the theory ofBrysk andRose with corrections ofBahcall. The resulting logft values and consequences for the decay scheme are discussed. 相似文献
4.
Klaus -Dieter Usadel 《Zeitschrift für Physik A Hadrons and Nuclei》1968,215(1):77-90
Thin superconducting films in a surface parallel magnetic field are considered, assuming that the order parameter is constant in space. Without any further restrictions on the film thickness,a, an equation for the critical field is derived. In the clean limit, this equation is valid only in the vicinity of Tc, but in the dirty limit it is valid for all temperatures. Our results, for specular reflection, are identical with those obtained byThompson andBaratoff. But for not too thin films we find essential differences between the results for specular and for diffus reflection. For very thin films (a?v/2πT c), considered in detail byde Gennes andTinkham and byShapoval, our results are in agreement with those obtained byShapoval. In the opposit limit (a?v/2π T c), the most essential corrections to the Ginzburg-Landau result obtained byLüders are rederived. 相似文献
5.
Investigations of the rotational band based on the 3+ 3 two quasiparticle state in172Yb have shown that some of its properties can be well described by the collective model of Bohr and Mottelson. As a result of these investigations we have derived the ratio (g k – g R )/Q o =? (0.0136 ± 0.0007). The magneticg-factor of the band head has also been determined by an integral angular correlation measurement perturbed by an external magnetic field. As a result we foundg=0.201 ± 0.030. Using this value and our result of (g k – g R )/Q o we have calculated theg R -factor of the two quasiparticle state asg R =0.283 ± 0.018 which is out of the errors smaller than theg R -factor of the ground state rotational band. An analysis of our angular correlation experiments gave for the mixing parameter δ of theK-forbidden 1094 keV intraband transition: δ=? (3.63 ?0.06 +0.14 ) in agreement with the results of other authors. 相似文献
6.
The hfs in the 72 P 3/2-state of133Cs has been investigated by optical double resonance in a strong magnetic field. From the positions of the magnetic dipole transitions Δm j =± 1, Δm i =0 the magnetic hfs coupling con slanta (72 P 3/2)=16.591(25) MHz and theg j -factorg j (72 P 3/2)=1.33410(15) could be derived. Contrarily to recent measurements,g j agrees well with the value calculated from the Lande formula. 相似文献
7.
J. Sólyom 《Zeitschrift für Physik A Hadrons and Nuclei》1970,238(3):195-207
The effect ofs-d exchange interaction on the relaxation rate of host nuclear spins has been investigated in dilute magnetic alloys. The leading logarithmic corrections to the Korringa relaxation rate have been calculated together with some lower order logarithmic terms to avoid a divergence at the Kondo temperature (T k ). The obtained formulae are valid at and aboveT k and in weak or strong magnetic fields (ω i ?T or ω i ?T, respectively, where ω i is the Larmor frequency of the impurity spin). In second order of the perturbation theory our result reproduces that obtained by Giovannini and Heeger apart from a numerical factor of the order of unity and from some contribution of order (J/? f )2. 相似文献
8.
F. Bonetto J. L. Lebowitz J. Lukkarinen S. Olla 《Journal of statistical physics》2009,134(5-6):1097-1119
We investigate a class of anharmonic crystals in d dimensions, d≥1, coupled to both external and internal heat baths of the Ornstein-Uhlenbeck type. The external heat baths, applied at the boundaries in the 1-direction, are at specified, unequal, temperatures T l and T r . The temperatures of the internal baths are determined in a self-consistent way by the requirement that there be no net energy exchange with the system in the non-equilibrium stationary state (NESS). We prove the existence of such a stationary self-consistent profile of temperatures for a finite system and show that it minimizes the entropy production to leading order in (T l ?T r ). In the NESS the heat conductivity κ is defined as the heat flux per unit area divided by the length of the system and (T l ?T r ). In the limit when the temperatures of the external reservoirs go to the same temperature T, κ(T) is given by the Green-Kubo formula, evaluated in an equilibrium system coupled to reservoirs all having the temperature T. This κ(T) remains bounded as the size of the system goes to infinity. We also show that the corresponding infinite system Green-Kubo formula yields a finite result. Stronger results are obtained under the assumption that the self-consistent profile remains bounded. 相似文献
9.
FangXia An XianZhong Zheng YanZhi Meng Yang Chen ZhangZheng Wen GuoLiang Lü 《中国科学:物理学 力学 天文学(英文版)》2013,56(11):2226-2235
A study of [S iii]λλ9096, 9532 emitters at z = 1.34 and 1.23 is presented using our deep narrow-band H 2 S 1 (centered at 2.13 μm) imaging survey of the Extended Chandra Deep Field South (ECDFS). We combine our data with multi-wavelength data of ECDFS to build up spectral energy distributions (SEDs) from the U to the K s-band for emitter candidates selected with strong excess in H 2 S 1 ? K s and derive photometric redshifts, line luminosities, stellar masses and extinction. A sample of 14 [S iii] emitters are identified with H 2 S 1 < 22.8 and K s < 24.8 (AB) over 381 arcmin2 area, having [S iii] line luminosity L [SIII] =~ 1041.5–42.6 erg s?1. None of the [S iii] emitters is found to have X-ray counterpart in the deepest Chandra 4Ms observation, suggesting that they are unlikely powered by AGNs. The HST/ACS F606W and HST/WFC3 F160W images show their rest-frame UV and optical morphologies. About half of the [S iii] emitters are mergers and at least one third are disk-type galaxies. Nearly all [S iii] emitters exhibit a prominent Balmer break in their SEDs, indicating the presence of a significant post-starburst component. Taken together, our results imply that both shock heating in post-starburst and photoionization caused by young massive stars are likely to excite strong [S iii] emission lines. We conclude that the [S iii] emitters in our sample are dominated by star-forming galaxies (SFGs) with stellar mass 8.7 < log(M/M ⊙) < 9.9. 相似文献
10.
M. Bogdanović M. Mladjenovi'c R. Stepić 《Zeitschrift für Physik A Hadrons and Nuclei》1968,216(3):267-273
Internal conversionK/L 3 ratio forE2 transitions was measured for nuclei with mass numbers from 152–198, and the energy interval of 80–500keV. The results of all the 11 transitions measured are in good agreement with theoretical values ofSliv andBand, Pauli, Bhalla andHager andSeltzer.152Eu,160Tb,166Ho,182Ta,186Re,188Re, Radioactivity192Ir,198Au/all (n, γ)/measuredc c ratios. 相似文献
11.
Using a Cf252-fission source and two semiconductor detectors in 180°-position the specific energy loss of heavy ions in A1-, Ag-, and Au-foils was measured. The agreement with the results ofMoak andBrown, and ofKahn andForgue is better than 15%. The energy loss predicted byLindhard is 10–25% lower than the measured values. A better agreement — especially for absorbers with low atomic numberZ — is achieved by a semiempirical formula proposed byMünzel. 相似文献
12.
The surface tension of highly purified, liquid alkali metals and its temperature dependence have been measured under ultra-high-vacuum conditions. The results obtained for sodium agree with those ofAddison andTaylor as well as with theoretical values given byStratton andZadumkin, whereas the results on K, Rb and Cs are different from all values obtained hitherto by others. The temperature dependence of surface tension of all alkalis follows theoretical predictions. There is no observable influence of Ar and O2 on the surface tension up to 10?3 Torr. 相似文献
13.
H. Haken 《Zeitschrift für Physik A Hadrons and Nuclei》1969,219(5):411-433
We start from a density matrix equation in its most general form. It comprises the action of external fields on the system, internal interactions, as well as the action of dissipative mechanisms (heat-baths or reservoirs), which may be Markoffian or non-Markoffian. We then define a distribution function of a type introduced previously byHaken, Risken, Weidlich for atoms. This distribution function,f, which is now formulated quite generally with aid of projection operators,P ik , establishes a connection between theP ik 's and classical variablesv ik . By means off it is possible to exactly calculate all quantum mechanical expectation values by purec-number procedures. If the basic density matrix equation is Markoffian, it is even possible to calculate all time-ordered multitime averages byc-number procedures usingf, as had been demonstrated byHaken, Risken andWeidlich. In the present paper we derive in an explicit way an exactc-number partial differential equation forf. It contains derivatives of arbitrarily high order. In important classes of problems, it can be reduced to an ordinary FokkerPlanck equation, however. Our new equation has many applications, e.g. in the quantum theory of lasers, nonlinear quantum optics, spinresonance, and spin-wave-theory, as will be demonstrated in forthcoming papers. We wish to thank Prof. W.Weidlich and Dipl. Phys. H.Vollmer for several valuable discussions. In addition, H.Vollmer has kindly checked our calculations. 相似文献
14.
J. Repp C. B?hm J. R. Crespo López-Urrutia A. D?rr S. Eliseev S. George M. Goncharov Y. N. Novikov C. Roux S. Sturm S. Ulmer K. Blaum 《Applied physics. B, Lasers and optics》2012,107(4):983-996
The novel five-Penning-trap mass spectrometer Pentatrap is developed at the Max-Planck-Institut für Kernphysik (MPIK), Heidelberg. Ions of interest are long-lived highly charged nuclides up to bare uranium. Pentatrap aims for an accuracy of a few parts in 1012 for mass ratios of mass doublets. A physics program for Pentatrap includes Q-value measurements of β-transitions relevant for neutrino physics, stringent tests of quantum electrodynamics in the regime of extreme electric fields, and a test of special relativity. Main features of Pentatrap are an access to a source of highly charged ions, a multi-trap configuration, simultaneous measurements of frequencies, a continuous precise monitoring of magnetic field fluctuations, a fast exchange between different ions, and a highly sensitive cryogenic non-destructive detection system. This article gives a motivation for the new mass spectrometer Pentatrap, presents its experimental setup, and describes the present status. 相似文献
15.
Vibrational spectra of α-naphthol,β-naphthol andβ-naphthol-OD have been recorded in the solid and solution phases. A number of bands, common to all the three compounds, have been correlated with earlier naphthalene assignments and an attempt has been made to identify certain frequencies with vibrational modes that are centred in the substituentsOH andOD. TheC s symmetry is assumed for each molecule. 相似文献
16.
17.
Leif Lönnblad 《Zeitschrift fur Physik C Particles and Fields》1993,58(3):471-478
A new jet clustering algorithm-Arclus-is presented. The main difference between this and conventional algorithms is that while the latter in each step join two clusters into one,Arclus joins three clusters into two. The performance ofArclus in terms of the size of hadronization corrections is studied for some jet-reconstruction tasks ine + e ? andep collisions, and is found to be as good as or, for some tasks inep collisions, better than conventional clustering algorithms. 相似文献
18.
TheK conversion coefficient α k of the 74.38 keVM3 isomeric transition in191Os was measured with a curved crystal spectrometer of DuMond type. The experimental result α k =106±11 is in agreement with theoretical calculations taking the dynamic correction coefficient λ=9.4±0.5 into account. 相似文献
19.
The Bethe-Salpeter (bs) dynamics of harmonic confinement developed byanm and collaborators over the last three years and already applied with considerable experimental success to various hadron spectra and coupling structures has been significantly improved through (i) a more exact treatment of a certain momentum-dependent operator \(\hat Q_q \) appearing in thebs equation, using the techniques of SO (2, 1) Lie algebra, and (ii) a sharpened definition of theqcd Coulomb term, so as to yield unambiguous values for different flavour sectors. The resulting mass spectra of light \((q\bar q)\) meson towers and semi-heavy \((Q\bar q)\) quarkonia which are most sensitive to the improved treatment of \(\hat Q_q \) , reveal excellent agreement with experiment, one in which only slight changes in the reduced spring constant \((\tilde \omega )\) and quark masses (m q ) over the earlier parametrizations are involved. These changes are however found to have a negligible effect on the (already good) numerical values of the other predictions (electroweak and pionic couplings) depending on the \(q\bar q\) andqqq wave functions. A critical assessment of the strong and weak points of this method is madevis-a-vis other related approaches. 相似文献
20.
N. D. Christensen P. de Aquino N. Deutschmann C. Duhr B. Fuks C. Garcia-Cely O. Mattelaer K. Mawatari B. Oexl Y. Takaesu 《The European Physical Journal C - Particles and Fields》2013,73(10):1-23
Support for interactions of spin- $\frac{3}{2}$ particles is implemented in the FeynRules and ALOHA packages and tested with the MadGraph 5 and CalcHEP event generators in the context of three phenomenological applications. In the first, we implement a spin- $\frac{3}{2}$ Majorana gravitino field, as in local supersymmetric models, and study gravitino and gluino pair-production. In the second, a spin- $\frac{3}{2}$ Dirac top-quark excitation, inspired from compositeness models, is implemented. We then investigate both top-quark excitation and top-quark pair-production. In the third, a general effective operator for a spin- $\frac{3}{2}$ Dirac quark excitation is implemented, followed by a calculation of the angular distribution of the s-channel production mechanism. 相似文献