Zr Reaction Research Articles

Measurement and analysis of the 4.71 MeV d[formula omitted] analogue resonance in the 90Zr(p, po)90Zr reaction

The analogue of the ground state of 91Zr has been studied via the 90Zr(p, po)90Zr reaction. Excitation functions were measured for elastically scattered protons at laboratory angles of 115°, 125°, 135°, and 160° with respect to the beam direction for incident proton energies between 4.61 and 4.83 MeV. It is shown that the compound elastic contribution to the cross section is significant, and must be evaluated in order to determine the resonance parameters. The proton width (Γp = 4 keV) for this state implies a neutron spectroscopic factor in agreement with analysis of the 90Zr(d, p)91Zr measurements.

The (p, t) reaction on the even zirconium isotopes

The 90,92,94,96Zr(p,t) reactions have been studied with 38 MeV protons. An examination of the L = 0 transitions shows evidence for excitation of a pair-vibrational like state in the 92Zr(p,t) 90Zr reaction. This type of state does not appear to be excited in the 94Zr(p,t) and 96Zr(p,t) reactions. The low-lying L = 0 transitions seem to be well accounted for in terms of a simple shell model picture.

Inelastic proton scattering from 91Zr at 18.7 MeV

The level structure of 91Zr has been investigated by inelastic proton scattering at 18.7 MeV. Angular distributions were obtained for the excitation of 19 levels in 91Zr. The results for the low-lying states, seen strongly in the 90Zr(d, p) reaction, were compared to distorted wave calculations using shell model form factors for the excitation of the odd neutron beyond the closed shell of 50. The resulting depth of the interaction potential indicated a relatively strong core excitation admixture for these states. Calculations using more complicated wave functions gave better results especially if core polarization effects were included. At higher excitation energies the six states resulting from the coupling of the d 5 2 neutron to the 3 − excited state of 90Zr were observed. The cross sections were consistent with the predictions of the weak coupling model.

Levels of 88Zr Excited with the Reaction 90Zr(p, t)88Zr

Levels of ⁸⁸Zr Excited with the Reaction ⁹⁰Zr(<i>p</i>, <i>t</i>)⁸⁸Zr

Analogues of Excited States in 91Zr

The level structure in 91Zr has been investigated by Cohen and Chubinsky (1963) with the 90Zr (d, p)91Zr reaction. They noted some 14 levels up to an excitation energy of 3�9 MeV. All these states were found to have positive parity and their structure is fairly well understood in terms of coupling a single-particle neutron to the ground state and the first two excited states of 90Zr (Ramavataram 1964). A study of the isobaric analogues of the 9lZr states with the 90Zr(p, pO)90Zr reaction was carried out by Moore (1964).

Energy levels of excited in the decay of the isomeric pair and

The γ-ray spectra accompanying the decay of 96gTc (4.3 d) and 96mTc (52 m), produced in the reactions 96Mo (p, n) 96Tc and 97Mo (p, 2n) 96Tc, have been studied with lithium-drifted Ge detectors.Gamma rays (relative intensities are in parentheses) of 314.2 ± 0.2 (2.4), 316.3 ± 0.2 (1.5), 434.8 ± 0.4 (0.8), 460.2 ± 0.4 (0.48), 568.9 ± 0.4 (.95), 778.2 ± 0.2 (100), 812.5 ± 0.2 (83), 849.8 ± 0.2 (98), 1091.3 ± 0.4(0.9), 1126.8 ± 0.3 (15.3), 1200.0 ± 0.4 (0.41), and 1497.7 ± 0.5 keV (0.081), plus several other very weak lines, have been observed in the decay of 96Tc (4.3 d). Several transitions never previously reported were found in the decay of 96mTc (52 m). All but four of these transitions could fit already known excited levels in 96Mo at 778.2, 1497.9, 1628.0, 1869.6, and 1978.3 keV, whereas the placing of the remaining 616.1-, 966.6-, 1096.6-, and 1816.2-keV gamma rays required the existence of a new level in 96Mo at 2594.5 keV.In view of the results obtained from the study of the decay of the 96Tc isomeric pair, it was considered very desirable to reinvestigate the decay of 96Nb to levels in 96Mo. The 96Nb source was produced in the reaction 96Zr (p, n) 96Nb. Ge(Li) detectors were again employed and gamma–gamma directional correlation measurements were performed with two NaI(Tl) crystals, a fast coincidence circuit, and a multiparameter analyzer to record the data.The experimental directional correlation coefficients of the 1200.1–778.2, 1200.1–460.1, 778.2–460.1, 1091.4–778.2, 1091.4–568.7, and 778.2–568.7 keV cascades are[Formula: see text]respectively.These values seem to be compatible with spin assignments of 4+, 3+, and 5+ for the 1869.6-, 1978.3-, and 2438.4-keV levels in 96Mo respectively.

Level structure of 89Zr via the reaction 90Zr(p, d) 89Zr

Levels in 89Zr up to about 13 MeV have been excited via the reaction 90Zr(p,d) 89Zr. The over-all level structure obtained is qualititively consistent with the concept that most of the levels are due to 9 2 , 2 p 1 2 , 2 p 3 2 , 1 f 5 2 , and possibly 1 7 2 neutron hole states fragmented by isospin splitting and core-polarization effects.

The 90Zr and 92Mo(α, α′) reactions at 31 MeV

The 90Zr and 92Mo(α, α′) reactions have been studied at 31 MeV with 80 keV resolution and with an extremely small slit scattering tail associated with the elastic peak. Spin and parity assignments have been made on the basis of the shapes of the differential cross sections by systematics and by comparison with distorted-wave Born approximation calculations. These assignments have been made to an excitation energy of approximately 6 MeV in each nucleus. Three 2 + states were found in each nuclide. Five 4 + states were found in 90Zr and three in 92Mo. Four 3 − states were located in 90Zr and six in 92Mo. The cross sections of the higher 3 − states relative to the lowest 3 − states is 30% in 90Zr and 57% in 92Mo. The fractionation of the octupole strength found here is similar to that found previously in the 1 f 7 4 shell. The relative strengths of the lowest 3 − state in 90Zr and 92Mo are approximately equal. This differs from the situation in the Ca isotopes in which the octupole strength drops rapidly as A increases. The fractionation of the octupole strength is in qualitative agreement with theoretical estimates.

Isomer Ratios for 87m/87Y Formed by 90Zr (d,α n) Reaction

Isomer Ratios for ^87m/87Y Formed by ⁹⁰Zr (d,α n) Reaction

Elastic scattering of protons at the threshold for the quasi-elastic (p, n) process

The excitation functions for elastic scattering of protons from 48Ca and 91Zr have been measured at several observation angles for proton energies in the vicinity of the threshold for the quasi-elastic (p, n) scattering process. For 91Zr, the excitation function for the quasi-elastic (p, n) reaction has been measured by observing the decay protons from the analogue state. A theoretical investigation of the threshold effects in the framework of the coupled-channel Lane model is carried out, and the calculated cross sections are compared to the measured ones. The present results suggest that the expected energy dependence of the proton wave function due to the isovector coupling in the nucleon channel does not explain the threshold anomalies observed previously in the 90Zr(d, p) reaction.

Fractionization of the octupole strength in 90Zr

The 90Zr ( α, α′) reaction has been studied at 31 MeV with 80 keV resolution. Three octupole states have been found between 5 and 6 MeV with a total strength of 31% of the lowest 3 − state. This extends the study of the fractionization of the octupole state previously found in the f 7 2 shell.

Angular distributions of the 90Zr(d, p) reaction and the coupling of analogous (d, p) and (d, n) channels

The excitation functions and spectroscopic factors of several final levels in the reaction 90Zr(d, p) show an anomaly at the threshold energy for the (d, n) reaction to the 91Zr ground state analog 91Nb. This indicates a more complicated coupling of the (d, n) and (d, p) analog channels than described by the two channel approach.

Multiple excitation and the shell model description of the 90Zr (p, p′) reaction

It is shown that multiple excitation effects are small for the inelastic scattering of 10 to 20 MeV protons from 90Zr when a microscopic description of the reaction with shell model wavefunctions is used.

Yttrium-96 and strontium-93: New nuclear data

Targets of 96Zr have been irradiated with 14·5 MeV neutrons and the decay of the resultant β-particle and γ-ray activity has been found to have two components with half-lives of 2·3 and 8·3 min. Only the shorter lived component was present in yttrium fractions chemically separated from the targets. This activity has been assigned to the previously unreported isotope 96Y produced by the reaction 96Zr ( n,p) 96Y. The longer-lived component was due to the ( n,a) product 93Sr whose half-life has been reported previously. Other details are as follows: 96 Y:T 1 2 2·3 ± 0·1 min ; Eβ max 3·5 MeV; Eγ 0–2·5 MeV, resolved peaks at 0·7 and 1·0 MeV. 93 Sr: T 1 2 8·3 ± 0·5 min ; Eβ max 2·0 MeV; Eγ 0–2 MeV, resolved peaks at 0·6 and 2·0 MeV. The short-lived 96Y was chemically separated from other activation products using an automatically controlled centrifuge. As the apparatus has some novel features and may be employed for other rapid chemical separations, it is described in detail.