Energy levels of A = 21−44 nuclei (V)

Electric monopole transitions between 0+ states for nuclei throughout the periodic table

The experimental techniques of measuring the mean lifetimes tau of excited nuclear states is reviewed. Emphasis is put on direct measurements of tau in the region 10-18-10-6 s, especially on techniques involving the observation of Doppler energy shifts of gamma -rays. Indirect methods of obtaining tau by measuring the widths or partial widths are discussed. Comparisons are made of the applicability, accuracy and reliability of the different experimental techniques.

https://iopscience.iop.org/article/10.1088/0034-4885/42/1/001/pdf

The measurement of the lifetimes of excited nuclear states

Nuclear Data Sheets for A = 44

Nuclear Data Sheets for A=40☆

MEASUREMENT OF THE MEAN LIFE OF THE 4.49-MeV (5$sup -$) STATE OF $sup 40$Ca. EFFECTS OF DEFORMED COMPONENTS ON THE LIFETIMES OF THE ODD-PARITY STATES.

The lifetime of the 3.74 MeV (3−) state of 40Ca

The mean lifetime and $g$ factor of the 2.95-MeV ${6}^{+}$ state of $^{54}\mathrm{Fe}$ were measured to be $\ensuremath{\tau}=1.76\ifmmode\pm\else\textpm\fi{}0.03$ nsec and $|g|=1.37\ifmmode\pm\else\textpm\fi{}0.03$, respectively. These results are in agreement with the shell-model assignment ${({{f}_{\frac{7}{2}}}^{\ensuremath{-}2})}_{\ensuremath{\pi}}$ plus a small amount of configuration mixing which accounts for the quenching of the magnetic moment from the Schmidt limit and the enhanced $E2$ rate $B(E2;{6}^{+}\ensuremath{\rightarrow}{4}^{+})=3.2$ Weisskopf units.

MEAN LIFETIME AND MAGNETIC MOMENT OF THE 2.95-MeV (6$sup +$) STATE OF $sup 54$Fe.

The $E0$ pair decay branching ratio ($\frac{{\ensuremath{\Gamma}}_{\ensuremath{\pi}}}{\ensuremath{\Gamma}}$) for the 5.21-MeV ${0}^{+}$ fifth excited state of $^{40}\mathrm{Ca}$ was measured. The state was excited by inelastic proton scattering. The ${e}^{\ensuremath{-}}\ensuremath{-}{e}^{+}$ pairs were detected in two $\ensuremath{\Delta}E\ensuremath{-}E$ scintillation telescopes in coincidence with backscattered protons. A branching ratio limit of 1.4\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}3}$ was determined which corresponds to a monopole strength $\ensuremath{\rho}l0.06$. This result is consistent with theoretical descriptions which contain multiparticle excitations and core deformations. In addition, the branching ratio $R(\frac{({2}_{2}^{+}\ensuremath{\rightarrow}{0}_{2}^{+})}{({2}_{2}^{+}\ensuremath{\rightarrow}{0}_{1}^{+})})=(2.1\ifmmode\pm\else\textpm\fi{}0.1)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}2}$ for the decay of 5.25-MeV ${2}^{+}$ state was measured and corresponds to a $B(E2)=(3.5\ifmmode\pm\else\textpm\fi{}0.6) {e}^{2}$${\mathrm{fm}}^{4}$.NUCLEAR REACTIONS $^{40}\mathrm{Ca}(p, {p}^{\ensuremath{'}})$, $E=7\ensuremath{-}10$ MeV; $^{40}\mathrm{Ca}$, measured $E0$ branching ratios. Deduced $E0$ matrix elements. Natural targets.

Electric monopole transitions in Ca 40

The $g$ factor of the 4.49-MeV (${5}^{\ensuremath{-}}$) state of $^{40}\mathrm{Ca}$ has been measured in a time integral, external magnetic field, perturbed angular correlation experiment. A value of $g=0.54\ifmmode\pm\else\textpm\fi{}0.10$ was obtained. The angular rotation of the ${p}^{\ensuremath{'}}\ensuremath{-}\ensuremath{\gamma}$ correlation for the 4.49-MeV (${5}^{\ensuremath{-}}$) state was also measured for calcium nuclei implanted into a polarized iron foil. This measurement yields an average hyperfine magnetic field on calcium in iron which differs by a factor of 2 from the hyperfine field result obtained for $^{42}\mathrm{Ca}$ (3.19-MeV, ${6}^{+}$ state) implanted in iron. The discrepancy in observed fields indicates a multiplicity of lattice sites for this system. The theoretical estimate of the ${5}^{\ensuremath{-}}$ state $g$ factor is in agreement with the experimental value.NUCLEAR MOMENTS $^{40}\mathrm{Ca}(p,{p}^{\ensuremath{'}}\ensuremath{\gamma})$; measured $\ensuremath{\mu}$ (${5}^{\ensuremath{-}}$, 4.49-MeV level) and ${H}_{\mathrm{hyp}}$ at Ca(Fe).

J. W. Tape

Papers

MEASUREMENT OF THE MEAN LIFE OF THE 4.49-MeV (5$sup -$) STATE OF $sup 40$Ca. EFFECTS OF DEFORMED COMPONENTS ON THE LIFETIMES OF THE ODD-PARITY STATES.

The lifetime of the 3.74 MeV (3−) state of 40Ca

MEAN LIFETIME AND MAGNETIC MOMENT OF THE 2.95-MeV (6$sup +$) STATE OF $sup 54$Fe.

Electric monopole transitions in Ca 40

Measurement of the magnetic moment of the 4.49-MeV (5 - ) state of 40 Ca