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1.
TheΒ- andγ-radiations of98Zr and98m, g Nb have been investigated employing scintillation and semiconductor spectrometers and coincidence techniques. Sources of98Nb were produced by the98Mo(n, p)98Nb reaction, sources of98Zr by fission of235U with thermal neutrons applying chemical separations. For98Zr, a half-life of 30.7±0.4 sec and aQ β-value of 2.3±0.2 MeV were obtained, for the98Nb isomers, half-lives of 2.86±0.06 sec and 51.3±0.4 min, andQ β-values of 4.8±0.2 MeV and 4.5±0.2 MeV, respectively. Noγ-rays were observed in the decay of98Zr. The decay of 2.9 sec98Nb was found to involve 11γ-ray transitions. In the decay of 51 min98Nb, 54γ-transitions were detected. Spin and parity of 1+ and 4? were deduced for the isomeric states of98Nb.  相似文献   

2.
Theβ ? — andγ-activities of 18.4 min104Tc have been studied with singles and coincidence measurements. Sources were prepared by chemical separation of technetium from the fission products of thermal-neutron-induced fission of235U. A revised level scheme of104Ru up to an excitation energy of 4.26 MeV is proposed. Fromβ-γ coincidence measurements, aQ β-value of 5.62±0.07 MeV has been obtained.  相似文献   

3.
The decay of125m Xe produced by the reaction122Te(α, n)125m Xe using a target enriched in122Te (95.4%) and the decay of127m Xe produced by the reaction127J(d, 2n)127m Xe have been investigated: 125m Xe decays with a half-life ofT 1/2=(56±3) sec by ayy- cascade withE γ1=(140.4 ±0.5) keV andE γ2=(110.5 ±0.5) keV. The experimental conversion coefficients yield multipolarities ofE3 for the 140.4 keV isomeric transition and predominantlyM1 for the 110.5 keV-transition. 127m Xe decays with a half-life ofT 1/2=(71±2) sec. The decay also proceeds by aγγ-cascade with an isomeric E3 transition ofE γ1=(172.5±0.3) keV and a predominantlyM1 transition ofE γ2=(124.6±0.3) keV. In the decay of127g Xe an additional branching of the electron capture to a level at (618.1±0.3) keV was observed. The relative probability forK-captureP K618/PK375=0.40 ±0.07 yields a total transition energyQ EC=(664 ±4)keV. A spin of 1/2+ was assigned to the ground state.  相似文献   

4.
Theβ-decays of99Y and99Zr have been investigated with the two recoil fission product separators JOSEF and LOHENGRIN. Half-lives of 1.51±0.08s and 2.1±0.1s respectively, have been determined. Aβ-decaying isomeric state has been observed in99Y. The level schemes of 40 99 Zr59 and 41 99 Nb58 have been established fromγ-ray spectroscopy. Absoluteγ-intensities have been obtained by means of two independent techniques. Halflives of 293±10 ns for the 251.9 keV state and 10.2±1.5 ns for the 614.0 or 667.2 keV level in99Zr have been measured through delayedβ,γ- andγ,γ-coincidence experiments. Values for the spins and parities of the low lying levels in99Zr are proposed in accordance with the systematics of lighter odd Zr isotopes. Spins and partities are assigned to some levels in99Nb fromγ,γ-angular correlation measurements. In this nucleus there is evidence for three-particle configurations of some excited states, where the odd proton is coupled to two neutrons which are in different orbits.  相似文献   

5.
A delayed fission activity with a half-life of (55±7) s and a production cross section of (5±1)nb has been observed in the irradiation of237Np with 104 MeVα particles. It is tentatively assigned to the electron capture decay of232Am followed by fission of232Pu With a probability of (1.3 ?0.8 +4 )· 10?2 A barrier height of (5.3±0.4) MeV is extracted for232Pu exceeding theoretical barrier heights by about 2MeV. Systematic deviations between experimental and theoretical barrier heights previously observed in particular for U and Th isotopes are now also established for neutron deficient Pu isotopes indicating severe defects in the procedure of calculating static fission barriers.  相似文献   

6.
After bombardments of enriched152Sm with 14-MeV neutrons, three isomers of125Pm reaction, have been observed with half-lives of 4.2±0.2 min, 7.5±0.2 min and 15.0±1.0 min. Sources of pure 4.2-min152Pm were obtained by separating the promethium from its parent 11-min152Nd produced by thermal-neutron induced fission of235U. The beta and gamma radiations of the 4.2-min152Pm have been investigated using semiconductor and scintillation spectrometers. Most of theγ-ray transitions could be placed in a level scheme for 152Sm. Especially interesting is a level at 1083 keV for which the assignmentI π=0+ is proposed. In a 4πβγ experiment, the ground state feeding of152Sm in theβ ?-decay of the 4.2-min152Pm has been measured to be 61% of allβ-ray transitions. AQ β-value of 3.4±0.2 MeV has been obtained.  相似文献   

7.
TheK-fluorescence yieldΩ K of Titanium has been measured using the coincidence method and investigating the electron capture decay of48V. The detectors used have been a Si(Li)- and a Ge(Li)-detector for the X- andγ-rays. The experimental results areP K Ω K =0.2005 ±0.0030 andΩ K (Ti)=0.224±0.003 usingP K =0.896. For the branching ratios of the decay of48V we obtainedEC (3.239) 7.9±0.6%EC (3.224) 2.9±0.4%EC (2.295) 35.6±2.0% Β+ (2.295) 52±1.0% all others 1.6%. Additionally someγ-ray-energies of the decay of48V and the half-life,T 1 2=(16.23 ±0.03)d, have been measured.  相似文献   

8.
Study of theβ-decay of98Y and of the level scheme of98Zr was undertaken by the use of the two recoil fission product separators JOSEF and LOHENGRIN. Twoβ-decay modes have been detected for98Y, the half-lives of which are 0.65±0.05 s and 2.0±0.2 s. The spins and parities of the two states which undergoβ-decay are proposed to be 1+ and 4?, respectively, with the configurations (π1g 9/2)(ν1g 7/2) and (π2p 1/2 (ν1g 7/2). The measuredQ β -value is 7300±400 keV for the 0.65 s decay. The level scheme of98Zr was deduced fromγ,γ-coincidence data. Absoluteγ-intensities were obtained from two independent measurements. The half-life of the first excited state of98Zr at 853.0 keV with spin and parity 0+ was determined through delayedγ, e?-measurements to be 63 ±7ns. No indication of the coexistence of two different nuclear shapes of98Zr was found.  相似文献   

9.
Short lived Ru isotopes produced in thermal fission of235U have been chemically separated from the other fission products. Successiveγ-ray spectra were taken by means of Ge(Li) detectors. The observedγ-lines have been assigned to the various Ru isotopes (A=107 to 110) or to their daughter elements on the basis of their half-lives, intensity ratios and known level properties. Partial decay schemes are discussed and relative fission yields are given.111Ru has been identified (T 12: 1.5±0.3 s).  相似文献   

10.
Decay of90m,g Rb     
The decay of mass separated90Rb has been studied usingβ,γ and conversion electron spectrometers in single and coincidence modes. The half-lives of the ground state and the isomeric level have been confirmed to be 162± 3 and 258±4 s, respectively. Theγ-rays from the decays of ground state and metastable state have been identified by measuring the decay of individual photopeaks using Ge(Li) detectors. The multipolarity of the 106.6 keV isomeric transition has been determined to beM3. Separate decay schemes of the ground and metastable states are presented. The levels of90Sr are discussed in terms of the available experimental and theoretical information. Radioactivity.90m,gRb [from238U(p, f)]; measuredT 1/2,E γ,I γ,γ—γ coin,I ce,cc,E β deduced logft,90Sr levels, mass separated90Rb.  相似文献   

11.
The branching ratios of theγ rays of the second and fourth excited states of208Tl have been investigated by coincidence measurements between the α rays of212Bi and subsequent 40keVγ ray. The detectors employed were a silicon surface barrier counter for α particles, and a 1.5 in ×2 mm NaJ (Tl) crystal forγ rays. It has been found that (75.6±3.7)% of all transitions of the 328 keV state and (94±7)% of all transitions of the (492 keV+473 keV) states populate the first excited state of208Tl. The 40 keV state is excited to (3.4±0.3)% by transitions of higher excited states relative to the direct excitation by α particles. The number of α particles with energyE α = 6.047 MeV and the number of subsequent 40keVγ rays resulted in a conversion coefficient α(40keV)=22.55± 0.46. Similarly coincidence measurements between Tl-x rays and α particles have been used to determine theK- conversion coefficients αK(328 keV)=0.31±0.03 and αK(492 keV+ 473keV)=0.100±0.015. The experimental results are in good agreement with the theoretical values ofSliv.  相似文献   

12.
The level scheme of102Rh has been investigated by the102Ru(p, nγ) reaction in the proton energy range 3.1 MeV≦E p≦6 MeV. Excitation functions,γ-γ coincidences and pulsed beam measurements have been performed and a level scheme including 33 excited states up toE x≈650 keV has been constructed. Theγ-branchings of several levels have also been measured. The lifetimes of 5 excited states have been determined with the centroid-shift method:τ m(105.2 keV)=(1.3±0.3) ns,τ m(123.7 keV)=(0.6±0.3) ns,τ m(178.6 keV)=(1.5±0.3) ns,τ m(208.7 keV)=(0.5±0.3) ns,τ m(359.6 keV)=(0.8±0.4) ns. Upper limits have been placed for the lifetimes of 20 other levels.  相似文献   

13.
The decay of115m In has been investigated using accurate counting methods. The emission rate of conversion electrons plusβ ?-particles was determined with a 4π proportional flow counter. The total andK-shell internal conversion coefficients of the 336 keVγ-ray in115In were measured by the electron X-ray coincidence method using combinations of a Si surface barrier with a NaI(Tl) detector and of a magneticβ-spectrometer with a high energy resolution Si(Li) detector, respectively. The conversion ratioR=K/(L+M+...) was deduced from electron spectra recorded with the magneticβ-spectrometer. The 336 keVγ-ray emission rate of all used sources was determined with a calibrated NaI(Tl)γ-ray spectrometer. A Ge(Li) detector has been used to determine the relative intensity of the 497 keVγ-ray in115Sn. As results have been deduced the 336 keVγ-ray emission per decay (N γ1/N 0=(45.9 ± 0.1)%), the total internal conversion coefficient (α=1.073 ± 0.014), theK-shell internal conversion coefficient (α K=0.843±0.012), the conversion ratioR=3.63±0.07, theβ ?-transition per decay going to the ground state (N β1/N 0=(5.0 ± 0.7)%) and to the first excited level in115Sn115Sn(N β2/N 0=(0.047 ± 0.002)%), and the 497 keVγ-ray emission (N γ2/N γ1=(0.103 ± 0.004)%). From the obtained internal conversion data it follows that the 336 keVγ-ray transition is ofM4 character with anE5 admixture of less than (3.5±1.5)%. The half-life of the isomeric state115 mIn has been determined with four different methods. The result isT 1/2=(4.486±0.004) h.  相似文献   

14.
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   

15.
Theβ-decay of100Y has been investigated at the gas filled recoil separator JOSEF by means ofγ-ray and conversion electron spectroscopy. Twoβ-decay modes, of half lives 0.94±0.03 s and 0.55±0.15 s, have been observed. Using Xγ-, Xce-, γγ- andγce-coincidences the level scheme of100Zr has been constructed. An excited 0 2 + state at 331.3 keV has been discovered in this nucleus. Theβ-decay from the 0.55 s decay mode in100Y shows a strong preference for the ground state compared to the 0 2 + state in100Zr. The structure of100Zr and the nature of the 0 2 + level is discussed in the light of the present results.  相似文献   

16.
The internal conversion process of theM1+E 2 mixed 279 keVγ-ray transition in the decay of203Hg has been reinvestigated. The emission rate of theK-shell internal conversion electrons was determined with an electron X-ray coincidence measurement using a magneticΒ-spectrometer and a Si(Li) detector of high energy resolution. Conversion electron ratios were obtained from electron spectra recorded as a function of momentum. The disintegration rate has been taken from measurements with a calibrated NaI(Tl)γ-ray spectrometer. Following results have been deduced: α=0.2279±0.0024, α K =0.1653±0.0017, α L =0.0475±0.0013,K/(L+M+?)=2.64±0.03,K/L=3.48±0.12,L/(M+N+ ?)=3.14±0.12. On the basis of the experimental results on theK-shell internal conversion coefficient,α k , and the conversion ratioK/(L+M+?) the penetration effect on the internal conversion of theM1 part and the mixing ratio,δ 2, of the 279 keVγ-ray transition in203Tl have been studied. Calculations were made using Hager and Seltzer's formalism and their theoretical internal conversion coefficients. The results are consistent with a mixing ratio ofδ 2=1.32±0.11 and a penetration parameter ofλ=6.8 ±0.8.  相似文献   

17.
The spectrum ofK X-rays andγ-rays following the decay of170Tm has been reinvestigated using a high resolution Si(Li) detector. The intensities of theEC-branches from the ground state of170Tm to the ground state as well as to the first excited level in170Er have been measured. The total intensity of theEC-decay is (0.25 ± 0.05)% of all170Tm disintegrations with (0.18 ± 0.05)% leading to the ground state and (0.07±0.02)% leading to the first excited level of170Er. The energy of the de-excitingγ-ray has been determined to (78.7±0.5) keV. Its intensity is (0.28 ± 0.06)% of that of the 84.3 keVγ-ray in170Yb.  相似文献   

18.
Using the method ofγ-detection, the NMR in the metastable 40 keV-state of103Rh in Fe (thin foils with diffused103Pd activity) was measured in external fields of 0.5 to 14 kG. We find a zero-field resonance frequency ofv 0=(550.3±0.5) MHz and a slope ofdv/dH= ?(0.933 ±0.017) MHz/kG, yielding g=1.22 ± 0.02. The resulting value for the hyperfine field, Hhf=(590±10) kG, is inconsistent with that of an NMR measurement in the ground state of103Rh. Possible reasons for this discrepancy are discussed.  相似文献   

19.
TheK conversion coefficient of the 67.075 keV-transition of174m Lu has been measured to beα K=11.01 ±0.44. The half-life of174m Lu and relativeγ-intensities were also determined.  相似文献   

20.
The productP K ω K of theK-capture probability and theK-fluorescence yieldω K was measured in the EC decay of 17.7 y145Pm and 60.14d125I by means ofK x-ray-γ-ray coincidences with semiconductor detectors. Accepting a best value ofω K =0.920 forZ=60 from the literature, values ofP K =0.606±0.025 and 0.554±0.025 for decay of145Pm to the 67.2 and 72.4 keV levels in145Nd, respectively, were determined, from which the application of EC theory givesQ EC=153±4 keV to the ground state. TheP K ω K ratio to the 67.2 and 72.4 keV levels also was determined independently to be 1.11±0.01, which serves as a good check on theγ-ray-gatedP K values. Theγ-ray energies were determined more accurately to be 72.4±0.1 and 67.2±0.1 keV, together with a ratio of their relative intensities,I 72.4/I 67.2=3.35±0.09. In the decay of125I, a value ofP K ω K =0.699±0.030 was measured, and by using an independent determination ofQ EC=178±2 keV to the ground-state from the literature, a value ofP K=0.801 is calculated from allowed EC theory, from whichω K =0.873±0.017 atZ=52 is obtained. This value is in good agreement with theoretical values and with a value of 0.875±0.028 predicted by the best fit curve of Bambyneket al.  相似文献   

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