首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
Using gaseous sources of Tc2O7 containing the radioactive isotopes94Tc,95Tc and96Tc, levels at 871.0keV (94Mo), 765.8, 820.6, 947.8, 1074.0keV (95Mo) and 778.3keV (96Mo) have been excited. From the effective cross sections for nuclear resonance scattering and from the lifetimes of the 947.8, 1074.0 and 778.3keV levels known from Coulomb excitation experiments the profiles of theγ-lines have been determined. A broadening of theγ-lines due to Coulomb explosion of the molecules has been observed. Making use of the line profiles, lifetimes ofΤ=(6.4±1.0) ps andΤ=(0.90 ± 0.20) ps have been determined for the 765.8 and 820.6keV levels, respectively. The angular distribution of the resonantly scattered radiation yields an amplitude ratioδ for the mixed M1 E2 765.8keV transition ofδ=0.14 ?0.009 +0.08 . TheB(E2) from a Coulomb excitation experiment and the lifetimeΤ from the present experiment yield ¦δ¦=0.07±0.01 for the 820.6keV transition.  相似文献   

2.
The parity-violating mixing of the 17/2? and 17/2+ levels in93Tc nuclei, polarized by the tilted multifoil interaction, was measured by the observation of the forwardbackwardγ-ray asymmetry. The asymmetry was determined to beA γ=1.18(48)×10?3. The nuclear polarization was determined in a measurement of the quadrupole interaction in a92Mo isomer and the parity violation matrix element 〈H PV〉 is found to be ¦〈H PV〉¦ =0.8(4) meV.  相似文献   

3.
The resonance fluorescence of the transitions 3d 2 D 5/2,3/2 3p 2 P 3/2,1/2 in the Al I-spectrum was observed as a function of a magnetic field. Adding an electric field parallel to the magnetic field the shifts of level crossing signals caused by the Stark effect of the electric field were used to separate overlapping signals of the 3d 2 D 5/2- and 3d 2 D 3/2-states. The following values of the Stark parametersβ of both states and the hyperfine structure constantsA andB of the 3d 2 D 3/2-states were deduced: 3d 2 D 3/2∶ ¦A¦=99(1) Me/sec · gJ/0,8,B/A=?0,22(12), ¦β¦=0.45 (8) Mc/sec/(kV/cm)2 · gJ,/0.8, A/β< 0 3d2D5/2∶ ¦β¦=0.16 (4) Mc/sec/(kV/cm)2 · gJ/1.2, A/β>0. Some qualitative aspects of interconfiguration mixing in the 3d2D-states are discussed.  相似文献   

4.
This report describes the detection and dosimetry of gamma ray emitted from Thallium-201 (201Tl) and Technetium-99m (99mTc) based on chemiluminescence technique. H2O2 produced by two gamma emitter radioisotopes of 201Tl and 99mTc were quantitatively measured by chemiluminescence method. Upon producing H2O2 in a luminol alkaline solution, in the presence of diperiodatocuprate, as catalyst a chemical reaction was accrued and consequently the emitted light was measured. The determined H2O2 concentration was correlated with the gamma ray detection and dosimetry. The sensitivity of chemiluminescence technique for 201Tl and 99mTc dosimetry was determined to be 0.20 and 0.08 MBq/l (Mega Becquerel per liter) respectively (R.S.D. = %5, N = 3). The plotted calibration curves showed detection limits of 3.24 and 1.76 MBq/l for 201Tl and 99mTc, respectively.  相似文献   

5.
The angular correlation of the99Tc 739-181 keV gamma-gamma cascade has been measured in a liquid molybdenium source. The result was:A 2=0.0930 ± 0.0028,A 4=?0.0095 ± 0.0042. The spin of the 921 keV level was determined to 3/2+. The mixing ratio of the 739 keV gamma-transition was measured to δ (E2/M1)=5.9 ?0.3 +0.4 .  相似文献   

6.
Using time-differential perturbed-angular-correlation technique, hyperfine fields at 99Tc (←99Mo) in the Mo layers in polyimide/Fe (10 nm)/[Mo (t Mo)/Fe (2.0 nm)]120, where t Mo is in the range between 0.4 and 1.5 nm, were measured at room temperature. The values of the magnetic hyperfine field at the Mo/Fe interface were extracted. Its dependence on the Mo layer thickness suggests that the oscillatory interlayer exchange coupling is due to conduction electron spin polarization in the Mo layer, which in turn is produced via an RKKY-type mechanism.  相似文献   

7.
This paper studies the boundedness of solutionsf of the initial-value problem for the space-homogeneous Boltzmann equation for inverse kth power forces, whenk>5, and under angular cutoff. The main result is that if the initial value isf 0 ? 0 with (1 + ¦υ¦20 εL 1 and (1 + ¦υ¦)s f 0ε L for somes > 2, then (1 + ¦υ¦s'f tεL fort>0 and essυ,t sup(1 + ¦υ¦)s'f(υ, t,) < ∞ for anys′ ? s whens ? 5, and anys′ ? s ifs > 5.  相似文献   

8.
The static electric quadrupole interaction of181Ta and178Hf in polycrystalline barium and lead titanate at the site of titanium has been measured using time differential PAC and the Mössbauer effect. The electric field gradients (EFG) at room temperature at the181Ta nucleus are ¦V zz¦=(3.6±0.2)·1017V/cm2 in BaTiO3 and ¦V zz¦=(14.6±0.6)·1017 V/cm2 in PbTiO3. The temperature dependence of the quadrupole interaction has been studied giving the following EFG values: ¦V zz¦=(2.4±0.2)·1017 V/cm2 in the monoclinic and ¦V zz¦=(1.1±0.3)·1017 V/cm2 in the rhomboedral phase of BaTiO3, and ¦V zz¦=(15.7±0.6)·1017 V/cm2 for181Ta/PbTiO 3 at 77 °K. The EFG of178Hf in PbTiO3 has been derived from a Mössbauer effect experiment to beV zz=+(10.7±0.5)·1017 V/cm2. The results are compared with EFG's calculated in a point charge model and with experimental EFG's measured at44Sc and57Fe in the same titanates by other authors. Contributions of covalent bonds to the effective EFG's in perovskit crystals are discussed.  相似文献   

9.
The generator with gel matrix is considered a perspective type for obtaining 99mTc. The elution yield of a generator and the course of the elution profile AVn = f(Vn) are affected by the properties and conditions of preparation of zirconium molybdate (generator matrix). Furthermore, it is influended by neutron flux density as well as irradiation time and temperature of cooling water during the irradiation. Zirconium molybdate, Mo: Zr = 1.72, in the form of a monodispersion (mean particle size x = 0.175 mm), was irradiated under the neutron flux density ?n = (0.7 … 2.2) × 1013 cm?2 s?1. The elution profile and the elution yield of 99mTc were examined in dependence on the temperature of drying the Zr–Mo matrix (40–100 °C). The kinetics of the passage of 99mTc into the solution, in dependence on the temperature of drying the hydrogel, was investigated. Some predetermined substitutional functions were tested and the mechanism of the 99mTc passage into solution was explained.  相似文献   

10.
The level scheme of99Tc was studied byγ-ray spectroscopy with the96Zr(6Li, 3n γ)99Tc reaction. New levels were established and spins and parities assigned.99Tc is compared with93, 95, 97Tc, with the neighbouring even-even Mo-isotopes and with the results of an IBFM calculation.  相似文献   

11.
For the investigation of vibrational states in odd A nuclei we have studied the level structure of239U by the238U (n thermal,γ) reaction. Various complementary measurement techniques as curved-crystal-, anti-Compton-,γ-γ coincidence- and conversion electron spectroscopy have been applied. The resulting data have been used to establish the deexcitation scheme of239U up to ~1.3 MeV and to make spin assignments. Most of the levels are interpreted in terms of the Nilsson model. The data also indicate the presence of the Nilsson states ¦501?¦ and ¦750¦. Three members of theΒ-vibrational band built on the ¦631?¦ state and one member of theΒ-vibration built on the ¦622↑¦ ground state have been identified through transitions with strongE0 admixtures. The octupole vibrational state built on the ¦631?¦ band is proposed at 815 keV.  相似文献   

12.
Decay scheme, half life andQ EC value of88Tc were deduced from aβ-decay study. The neutron deficient nucleus88Tc was produced by the58Ni(32S,pn)88Tc reaction using beam energies of 100, 101 and 105 MeV. The ground- and isomeric states of88Tc were found to decay to88Mo with similar half lives of 5.8±0.2 and 6.4±0.8 sec. The most probable spins and parities of these states are 3+ and 6+, respectively, though the order in energy could not be determined. TheQ EC value was deduced to be 8.6±1.3 MeV.  相似文献   

13.
The energy levels of 98Tc were studied with the 99Tc(p, d)98Tc reaction at a bombarding energy of 22.9 MeV and 15 keV resolution (FWHM). The Q-value for this reaction was found to be ?6.755 ± 0.009 MeV and the 98Tc mass excess was calculated to be ?86.421 ± 0.011 MeV. This reaction provided the excitation energies for 49 neutron hole states below 1.5 MeV excitation. Comparison of experimental angular distributions with DWBA calculations permitted assignment of lf-values and the extraction of spectroscopic factors for 44 of these levels. Extensive configuration mixing is observed except in the low-lying multiplet. Effective proton-particle, neutron-hole interaction matrix elements were obtained from the low-lying positive-parity multiplet of 98Tc.  相似文献   

14.
Several protecting procedures were applied to ensure good operating performances of the universal 99mTc generators based on fission produced 99Mo. These procedures include the modifications of the adsorbent. Instead of 1 g of pure Al2O3 the adsorption of 99Mo is carried out on the multicomponent adsorbent containing the mixture of either Al2O3 + SiO2 or Al2O3 · Cu2+ + SiO2. The protection by drying should ensure that the columns contain minimum of moisture during the growth period of 99mTc. It was found experimentally that the best results are obtained when the ratio of alumina in the mixture was 15 ± 5 (wt.%) and content of copper 365 μg Cu2+/column. The comparison of efficiency and applicability of the used protecting procedures is also given.  相似文献   

15.
The 98Mo(3He, d)99Tc and 99Tc(d, d') reactions have been used to study the levels of of 99Tc. Spin-parity assignments are made for nearly all states below 1.5 MeV excitation. Strong j-dependence is noted for l = 1 transitions in the proton stripping reaction, making possible several new spin assignments. The inelastic scattering data on 99Tc are compared to similar data on 98Mo, and are found to be in agreement with a coupling scheme based on a shell model with good seniority.  相似文献   

16.
The quadrupole interaction of nuclear spin polarized8Li (I=2) and9Li (I=3/2) in LiNbO3 has been studied at room temperature. The polarization was achieved by optical pumping of a fast atomic beam with circularly polarized laser light. The atoms were implanted into a hexagonal LiNbO3 single crystal and the quadrupole splitting ofβ-NMR spectra was measured. A ratio of ¦Q(9Li)/Q(8Li)¦=0.88(4) for the nuclear quadrupole moments was deduced, yielding a new value of ¦Q(9Li)¦=25.3 (9) mb for the quadrupole moment of9Li.  相似文献   

17.
The resonance fluorescence of the transition 5d 2 D 5/2?5p 2 P 3/2 (λ=3256Å) in the In I-spectrum was observed as a function of an external magnetic field. From the level crossing signals the following values of the hyperfine constantsA andB of the 5d 2 D 5/2-state were deduced: ¦A¦=148(8) Mc/sec·g J/1.2 and ¦B/A¦≦0.3. The widths of the signals yielded the mean lifetimet=7.1 (6)·10?9 sec · 1.2/g J . From the shifts of the signals caused by a constant electric field parallel to the magnetic field the value of the Stark parameter ¦β¦=0.19(4) Mc/sec/(kV/cm)2 ·g J /1.2 and the sign of the ratioA/β<0 were determined. Calculations with Coulomb wave functions show that the Stark shifts of the electric field are mainly due to admixtures of the 6p 2 P 3/2-state.  相似文献   

18.
Using the level crossing technique the ratios and absolute values of the hyperfine structure (hfs) constants of the levelsz 4F9/2 andz 4F7/2 of the configuration 3d 74s4p of Co I were measured:z 4 F 9/2: ¦A¦=(811±12)MHz; ¦B¦=(48±93) MHz;B/A=?0.06±0.11 A>0; B<0z 4 F 7/2: ¦A¦ = (659 ±11)MHz; ¦B¦=(33±84)MHz;B/A=?0.05±0.13 A>0; B<0. In addition the hfs constants of three other excited levels of Co I could be determined by optical methods:z 4 F 9/2:A=525±26 MHz;B=200 MHzy 4 F 9/2:A=300±30 MHz;B=?500 MHzy 4 G 11/2:A=315±20 MHz;B=400 MHz. The experimental results are compared with known experimental and also with theoretical values which where calculated using the parametric potential method.  相似文献   

19.
Positive and negative parity bands have been followed up to 10+ (possibly 12+) and 11? in224Ra and are compared to the corresponding bands in the isotone226Th. If a constant value of the intrinsic quadrupole moment is assumed for allE2 transitions in224Ra theE1/E2 branching ratios are consistent with an intrinsic dipole moment of ¦Q1¦=0.032(3)e·fm. This small value, as compared to ¦Q1¦=0.30(2)e·fm for226Th, can be explained by an almost complete cancellation of large positive liquid-drop and negative shell-model contributions.  相似文献   

20.
We calculate distributions for τ+τ?γ production at LEP 1 taking into account a potentially existing anomalous magnetic moment a τ of the τ lepton. The existing upper limits for ¦a τ¦ are known from the dependence of the decay Z 0 → τ+τ?γ on a τ 2 and are of the order of (1–5)%. We show that such limits are also sensitive to linear terms in a τ, which are of equal importance at ¦a τ¦ ~ (1–2)% and dominate below this value. Contributions from an electric dipole moment dτ do not interfere with the electromagnetic vertex or with the anomalous magnetic moment. Appropriate formulae are derived.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号