Reaction Q-value Research Articles

Low spin, negative parity states in the N = 103 isotones of 171Er, 173Yb and 175Hf identified by thermal neutron capture reactions

Energies and intensities of the γ-rays following thermal neutron capture in enriched samples of 170Er, 172Yb and 174Hf have been measured using internal reactor targets and a three-crystal Ge(Li) pair and anti-Compton spectrometer. The reaction Q-values, excitation energies and intensity values have been deduced. Decay schemes of 171Er, 173Yb and 175Hf are presented together with the spins and Nilsson assignments of the low-lying rotational bands populated from the capture states.

A Nuclear Structure Study of 23Ne and 21Ne by Means of Thermal Neutron Capture in Natural Neon

The energies and intensities of thermal-neutron capture γ-rays from natural neon have been measured with a Ge(Li) detector in pair and anti-coincidence spectrometer arrangements. Internal target of neon gas has been used. The reaction Q-value and excitation energies have been determined. Cross sections for thermal neutron capture in 20Ne and 22Ne have been deduced. The level schemes of 21Ne and 23Ne are discussed on the basis of the Nilsson model. Calculations with and without inclusion of Coriolis interaction have been made for 23Ne. These are compared with corresponding calculations on 25Al and 23Na.

Gamma decay of 39K levels measured with the 38Ar(p, γ) 39 reaction

The 38Ar(p,γ) 39K reaction has been studied in the E p = 1.25–2.35 MeV range. The strengths of 41 resonances have been determined relative to the strength of a 36Ar(p,γ) 37K. resonance. The branching ratios often resonances and often bound states have been measured with a 50 cm 3 Ge(Li) detector; the reaction Q-value is Q = 6380.6 ± 1.2 keV. A spin J = 3 2 has been assigned to the 3.02, 4.08 and 7.74 MeV levels on the basis of angular distribution measurements. Doppler shift attenuation measurements have been performed on γ-rays deexciting the 2.52, 3.02 and 4.08 MeV levels. The 7.74 MeV state is interpreted as the analogue of the first excited state (E x = 1.2 MeV, J π = 3− 2 ) in 39Ar. The experimental properties of 39K levels are compared with recent shell-model calculations. The analogue to anti-analogue Ml strength is compared with the strengths of other similar transitions and with theoretical calculations.

A Study of the Reaction 73Ge(n, γ)74Ge

The energies and intensities of thermal-neutron capture gamma rays from 74Ge have been measured with a Ge(Li) detector. An internal target of enriched 73Ge has been used. The reaction Q-value and excitation energies have been determined. The decay scheme of 74Ge is discussed in view of the vibrational model.

Thermal neutron capture gamma rays from the 26Mg(n, γ) 27Mg reaction

Thermal-neutron capture γ-rays from 26Mg have been measured with a Ge(Li) detector in pair and anticoincidence spectrometer arrangements. An internal target of enriched 26Mg has been used. The reaction Q-value has been determined. Energies and intensities of the γ-rays are reported and a decay scheme is presented. Absolute thermal-neutron capture cross sections for 24Mg(n, γ) 25Mg and 25Mg(n,γ) 26Mg have been determined from neutron capture in natural magnesium.

Energy levels of some Zn, Ga, As, Se and Br isotopes from (p, n) reactions

The energy level schemes of 65Zn, 67Ga, 70Ga, 74As, 76As, 75Se, 78Br, 80Br and 82Br were determined by (p, n) compound reactions using time-of-flight techniques. The deduced level schemes contain many more levels than known from the literature and will be complete except for states with high spin values, which are only weakly populated by compound nucleus reactions. The comparison with the results of γ-investigations showed that some γ-transitions in 67Ga and 70Ga are assigned erroneously. The reaction Q-values are in agreement with published values.

Thermal Neutron Capture in Natural Argon

The energies and intensities of gamma rays from thermal neutron capture in natural argon have been determined by means of a Ge(Li) pair spectrometer and anti-Compton spectrometer. An internal reactor target has been used. The reaction Q-value, excitation energies and decay schemes of 37Ar and 41Ar have been deduced.

Energy levels of 91Nb, 93Mo, 95Tc and 97Tc via (p, n) reactions and the reaction Q-values

The (p, n) reactions on isotopically enriched targets of 91Zr, 95Mo and 97Mo and monoisotopic 93Nb were investigated for a bombarding energy range 4 to 5.4 MeV. The neutron groups populating the low-lying excited states of 91Nb, 93Mo, 95Tc and 97Tc were studied by the use of a time-of-flight system. The reaction Q-values for 91Zr, 95Mo and 97Mo target nuclei were determined to be −2.045 ± 0.006, −2.490 ± 0.006 and −1.128 ± 0.008 MeV, respectively. Many low-lying states were populated by these reactions and their excitation energies determined with a high precision.

Energy levels of 26Mg studied with the (n, γ) reaction

The energies and intensities of thermal-neutron capture γ-rays from 26Mg have been measured with a Ge(Li) detector in pair and anticoincidence spectrometer arrangements An internal target of enriched 25Mg has been used The reaction Q-value and excitation energies have been determined The decay scheme of 26Mg is discussed on the basis of branchings found in this investigation

Investigation of the 42Ca(n, γ) 43Ca reaction

Gamma rays from thermal-neutron capture in enriched 42Ca were investigated with Ge(Li) detectors. Gamma-gamma coincidence measurements were performed with a Ge(Li)NaI detector combination. A decay scheme of 43Ca has been constructed containing 42 of the 47 observed γ-lines. The excitation energies of 16 levels of 43Ca were determined with uncertainties of 0.2 to 1.1 keV. The 42Ca(n,γ) reaction Q-value is Q = 7932.7±0.5 keV. From the γ-decay, J π = 3 2 − can be assigned to the l n(d, p) = 1 level at E x = 2046 keV. A strong correlation between the (n, γ) and (d, p) strengths was found.

Thermal-neutron capture gamma rays from the 27Al(n, γ) 28Al reaction

The energies and intensities of thermal-neutron capture gamma rays from 28Al have been measured by means of a Ge(Li) pair spectrometer and anti-Compton spectrometer. An internal reactor target was used. The reaction Q-value, excitation energies and a decay scheme of 28Al have been deduced.

A study of the excited states of 31P with the 30Si(p, γ) 31P reaction

The γ-ray spectra of 46 resonances in the 30Si(p, γ) 31P reaction were measured with a 20 cm 3 Ge(Li) detector. Branching ratios of resonances and bound states were determined. Radioactive sources were used for accurate determination of the energies of the bound states and of the reaction Q-value. The latter, Q 0 = 7 297.4±1.2 keV, is 10.2±4.0 keV higher than the value from the 1964 mass table. Lifetimes of 13 bound states were obtained from γ-ray Doppler shift measurements. The latter measurements prove that there are two levels at about E x = 5.0 MeV, with excitation energies differing less than 1 keV.They also yield even parity for the E x = 4.78 MeV level.

High energy gamma ray energy measurements

An easy method to measure gamma ray energies to about 0.003 MeV is suggested which utilizes the reaction Q-value, and demands consistency between the sum of the cascade gamma ray energies between two levels and the energy of the direct transition. This procedure is applied to the 0.9363-MeV resonance in the 27Al(p, γ) 28Si reaction.

The reaction 26Mg(p, γ) 27Al : (I). Excitation energies and branching of 27Al levels

The gamma-ray spectra of thirty 26Mg(p, γ) 27Al resonances in the range E p = 0.3−2.8 MeV, were measured with a 20 cm 3 Ge(Li) detector. Internal calibration based only on the reaction Q-value and the 511 keV annihilation line, leads to level energies with a precision ranging from a few tenths of a keV for the lower levels to 2 or 3 keV for the higher levels. Branching ratios are reported for the thirty resonance levels and most of the known bound states. A remarkable grouping of resonances which strongly decay to highly excited ( E x6–7 MeV bound states suggests some form of intermediate structure even at the widely spaced low-energy resonances; it can be described only partly in terms of isobaric analogue states.

Energy levels in the stable isotopes of titanium

The excitation energies of a number of nuclear levels in the stable Ti-isotopes have been determined from inelastic proton and deuteron scattering and from (d, p) reactions. New levels were found in Ti 47, Ti 49 and Ti 50. The (d, p) reaction Q-values and the nuclear level schemes derived from the measurements are compared to older data and are discussed briefly in terms of the quasi-particle model.

Deuteron Stripping and Heavy-Particle-Stripping Reactions

The formulation of the preceding paper is applied to the analysis of experimental differential cross sections of (d, n) reactions; especially, their dependences on the incident energies of deuteron are compared with the results of previous workers', in which the ratio (). 1/~) between the matrix element of the stripping and that of the heavy-particle-stripping reactions has been taken to .be an adjustable parameter. B11(d, n)Cl2, BeD(d, n)BlO, and Cl2(d, n)NlB reactions are treated in detail. Quantitative discussions are also added concerning the dependence of the cross sections on the reaction Q-value, on the binding energy of the emitted nucleon in target nucleus, and on the orbital angular momentum of· th~ captured deuteron. It is pointed out that the energy-dependences of (A1/A2) obtained phenomenologically by previous workers are rather unreasonable : The experimental differential cross sections and, especially, their energy-dependences can hardly be well explained by merely the stripping and the heavy-particle-stripping mechanisms, provided the cutoff Born approximation be adopted in the calculation of the cross sections. It is emphasized that the calculations by means of the ''distorted wave method will be highly required.