Decay Modes Of Levels Research Articles

Nuclear Data Sheets for A = 79

Nuclear spectroscopic information for known nuclides of mass number 79 (Ni,Cu,Zn,Ga,Ge,As,Se,Br,Kr,Rb, Sr,Y,Zr) has been evaluated and presented together with adopted energies, Jπ, and decay modes of levels in these nuclei. No data are yet available for excited states in 79Ni, 79Cu and 79Zr. The half–life of 79Se, a nuclide of importance in reactor–irradiated fuel composition has been measured by several independent groups and reported in a number of publications after 1995, and seems to be converging to a narrow margin of experimental values. These measurements were likely prompted by a recommendation made in the 1993 update of A = 79 nuclides (1993Si28), that since a 1949PaZZ report, there had been no measurement until 1993, and that based on simulation studies by 1993HeZW, the value listed in 1949PaZZ, and cited in all data tables and charts for 44 years, was quite likely in error, being too low by a factor of 10. According to conclusions in recent papers such as 2014Do20, there is still room for improvement in the measurement of this half–life, and further experiments are expected. This evaluation supersedes earlier Nuclear Data Sheets for A = 79 (2002Si13,1993Si28, 1982Si21,1975Ur03).

Nuclear Data Sheets for A = 190

Nuclear spectroscopic information for known nuclides of mass number 190 (W,Re,Os,Ir,Pt,Au,Hg,Tl,Pb,Bi,Po) has been evaluated and presented together with adopted energies, Jπ, and decay modes of levels in these nuclei. This evaluation supersedes earlier (1990Si09,1982Le22,1973Sc42) Nuclear Data Sheets for A=190.

Nuclear Data Sheets for A = 79

Nuclear spectroscopic information for known nuclides of mass number 79 (Cu,Zn,Ga,Ge,As,Se,Br,Kr,Rb,Sr, Y,Zr) has been evaluated and presented together with adopted energies, Jp, and decay modes of levels in these nuclei. No data are yet available for excited states in 79 Cu, 79 Zn and 79 Zr. In the previous A=79 NDS (1993Si28) it was pointed out in the abstract section that 79 Se radioactivity was of importance in reactor--irradiated fuel composition and that its half--life was not well established. It was reported in only one secondary reference (1949PaZZ), the results of which were later questioned by 1993HeZW in a private communication to the evaluator. Perhaps, motivated by the comment made in 1993Si28, several measurements (mainly from one research group) have since been reported, some using AMS (accelerator mass spectrometry) technique. From the most recent study of 2001Ji04, the half--life of 79 Se isotope now seems as better established, although, results available from different publications are not in good agreement. In the opinion of the evaluator, further confirmatory measurements are still desirable. This evaluation supersedes earlier Nuclear Data Sheets for A=79 (1993Si28, 1982Si21,1975Ur03).

Nuclear Data Sheets for A = 188

Nuclear spectroscopic information for known nuclides of mass number 188 (Hf,Ta,W,Re,Os,Ir,Pt,Au,Hg,Tl, Pb,Bi,Po) has been evaluated and presented together with adopted energies, J# , and decay modes of levels in these nuclei. No data are yet available for excited states in 188 Hf, 188 Ta, 188 Bi, and 188 Po. This evaluation supersedes earlier Nuclear Data Sheets for A=188: 1990Si04, 1981Si14, 1973Sc41.

Nuclear Data Sheets for A = 86

Nuclear spectroscopic information for known nuclides of mass number 86 (Ga, Ge, As, Se, Br, Kr, Rb, Sr, Y, Zr, Nb, Mo, Tc) has been evaluated and presented together with adopted energies, Jπ, and decay modes of levels in these nuclei. No data are yet available for excited states in 86Ga, 86Ge and 86As. This evaluation supersedes earlier Nuclear Data Sheets for A=86 (1997Ki04, 1988Mu14, 1978Te01, 1971Au13).

Nuclear Data Sheets for A=164

Nuclear spectroscopic information for known nuclides of mass number 164 (Gd,Tb,Dy,Ho,Er,Tm,Yb,Lu,Hf, Ta,W,Re,Os,Ir) has been evaluated and presented together with adopted energies, Jπ, and decay modes of levels in these nuclei. No data are yet available for excited states in 164Gd, 164Tb, 164Re, and 164Ir. This evaluation supersedes earlier (1992Sh07,1986Sh03,1974Bu30) Nuclear Data Sheets for A=164.

Nuclear Data Sheets for A = 130

Abstract: Nuclear spectroscopic information for known nuclides of mass number 130 (Ag,Cd,In,Sn,Sb,Te,I,Xe,Cs,Ba, La,Ce,Pr,Nd,Pm,Sm) has been evaluated and presented together with adopted energies, Jp, and decay modes of levels in these nuclei. No data are yet available for excited states in 130Ag and 130Pm. This evaluation supersedes earlier (1989Se13,1974Hi08) Nuclear Data Sheets for A=130. In the opinion of the evaluator the decay schemes of 130In, 130Sn, 130Sb and 130Pr nuclides are not well established. The identification of 130Ag isotope is only tentative. The ground state and possible low-lying isomer of 130Pr are still not established in energy and Jp assignment. Search (by 1983La27) for proton decay from 130Eu decay proved negative, thus 130Eu isotope remains unidentified.

Nuclear Data Sheets for A = 163

Nuclear spectroscopic information for known nuclides of mass number 163 (Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Os) has been evaluated and presented together with adopted energies, J??, and decay modes of levels in these nuclei. No data are yet available for excited states inn 163Gd, 163Ta, 163W and 163Os. This evaluation represents a revision of earlier Nuclear Data Sheets for A = 163 (1989Bu02, 1980Da03, 1972Bu43).

Lifetimes, spins and decay modes of levels below 5.3 MeV in33S

The reaction 30Si( alpha , n)33S was used to populate levels in 33S at alpha particle energies between 7.00 and 10.00 MeV. Gamma rays in 33S were observed in a Ge(Li)-NaI(Tl) escape-suppressed and pair-escape spectrometer. The Doppler shift attenuation method was used to measure the mean lifetimes of 20 levels and to set limits on the lifetimes of 3 levels in 33S. The analysis of angular distributions of gamma rays together with the measured lifetimes and branching ratios gave gamma ray multipole mixing ratios and spin and parity assignments of 7/2+, (5/2, 9/2)+, (3/2+, 5/2) and (7/2, 11/2)- for the levels at 2971, 4050, 4145 and 4868 keV respectively.

Transition rates in 89Zr

The lifetimes of a number of levels in 89Zr have been measured with the Doppler-shift attenuation method using the 89Y(p, nγ) 89Zr reaction and observing the γ-rays in a Ge(Li) detector. The results are: τ(1628) = 370 ± 50fs, τ(1743) = 710 ± 180 fs, τ(1835) = 460 ± 190 fs, τ(2100) = 180 ± 60 fs, τ(2298) = 105 ± 30 fs, τ(2388) = 180 ± 60 fs and τ(2572) = 130 ± 30 fs. Level decay modes are also reported. The level at 2.13 MeV was found to be a doublet and a new level was found at 2568 keV.

Further experimental evidence for collective effects in 40Ca

Measurements of lifetimes, spins and decay modes of levels in 40Ca excited by inelastic proton scattering have been made. The lifetimes were measured using the Doppler shift attenuation technique in a proton-gamma ray coincidence arrangement. The “level” at 6.03 MeV was found to be a doublet, with energies 6.026 MeV and 6.030 MeV. Proton-gamma ray angular correlation measurements, in conjunction with the lifetime results, showed the spins to be 2 − and (3 +, 2 −) respectively. Similar measurements on the levels at 6.51 MeV and 6.54 MeV showed them both to be 4 +. The results of the lifetime measurements are as follows, 5.61 MeV (4 −), 950 −190 +280 fsec: 5.63 MeV (2 +), 76±21 fsec: 5.90 MeV(1 −), 60±20 fsec: 6.026 MeV (2 −), 260±30 fsec: 6.030 MeV (3 +, 2 −), 560±190 fsec: 6.51 MeV(4 +), 160±60 fsec: 6.54 MeV(4 +), 190±60 fsec: 6.58 MeV (3 −), 250±70 fsec. Mixing ratios are also reported: in particular the E2/M1 mixing ratio for the transition between the 2 + states at 5.25 MeV and 3.90 MeV was found to be −13 −6 +3. Levels are identified with the rotational states predicted by Gerace and Green, and the measured E2 matrix elements, some of which are strongly enhanced, are found to be consistent with the model.

Some branching ratios in 26Mg

The decay modes of levels at 3.943, 4.350 and 4.830 MeV in 26Mg are established and those of levels at 1.805 and 2.941 MeV are confirmed using the 25Mg(d, pγ) 26Mg reaction. The protons were detected at 0° and the gamma rays observed in coincidence with selected proton groups. Relative l = 0 spectroscopic factors are also extracted and compared with existing measurements. Gamma rays from the 23Na(α, p) 26Mg reaction were also observed using Ge(Li) detectors enabling the branching ratios of levels at 3.584, 4.319, 4.331 and 4.896 MeV to be estimated.